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Sample records for por resina epoxi

  1. Dermatosis profesional por resina epoxi: Presentación de un caso clínico Professional dermatosis for epoxy resin: A clinical case report

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    S Gaviola

    2008-06-01

    Full Text Available Mostramos un caso de dermatosis profesional originado por plásticos (resinas epoxi y la importancia de la detección precoz. Las resinas epoxi son de gran utilización en todo tipo de industrias (artes graficas, construcción, electrónica, componentes de prótesis traumatológicas, prótesis odontológicas, etc. y sus componentes pueden ser causa de dermatitis de contacto irritativa y por sensibilización.We describe a case of professional dermatosis caused by exposition to plastic products (epoxy resin and importance of early detection. The epoxy resins are widely used in all types of industries (graphics arts, construction, electronics, traumathological and odontological prothesis, etc. and their components may be the cause of contact dermatitis and sensitivity. Risk factors at work with epoxy resins are present during the production base resins, hardening agents, plasticizers and dilutants increase the risk of exposition at work. This requires preventive measures and early diagnosis.

  2. Sensibilización a bisfenol A y bisfenol F en trabajadores expuestos a resinas epoxi

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    L. Jiménez Bajo

    2008-06-01

    Full Text Available Las aplicaciones de las diferentes resinas epoxi basadas en bisfenol A y F son extensas. Las resinas epoxi basadas en bisfenol F son más nuevas y resistentes que las de bisfenol A, y ambas son causa conocida de dermatitis de contacto alérgica. Se estudian 39 casos de sensibilización a resinas epoxi en los últimos 5 años. Los resultados obtenidos son: prevalencia de sensibilización a resinas epoxi entre los pacientes estudiados del 2%, 27 varones y 8 mujeres, con una edad media de 42.77, un período de medio sensibilización de 23,8 meses. La sensibilización a bisfenol F desde que se incluye para las pruebas del parche en la batería de resinas epoxi es del 100% para los casos sensibilizados a la resina. La localización mayoritaria se dio en las manos, con una relevancia actual del 84%. Se recomendó un cambio de puesto en el trabajo al 46% de estos pacientes. El aumento de la sensibilización encontrada a bisfenol F puede explicarse por una sensibilización concomitante con bisfenol A, una declaración incorrecta de la composición de la resina o una reactividad cruzada de ambos.The applications of epoxy resins based on bisphenol A and F are extensive. Epoxy resins based on bisphenol F are new and more resistant than epoxy resins based on bisphenol A. Both of them cause allergic contact dermatitis. In the last 5 years, we have studied 39 cases of sensitization to epoxy resin. The results of our study were these: the global prevalence of epoxy resin sensitization was 2%, 27 men and 8 women. The mean age was 42.77 years and the sensitization period was 23.8 months. The most frequent localization of the lesions were hands (84% of the patients. Since bisphenol F was included in epoxy resin battery for patch testing, a 100% of positives responses in patients sensitized to epoxy resin have been found. Sensitization to epoxy resins was a cause of change in workplace in 46% of cases in our series. There has been an increase in sensitization of

  3. Chemical and microbiological evaluation of the internal surfaces of aluminum tubes both unlined and lined with epoxi resin by means of the stereoscope and scanning electron microscope Avaliação química e microbiológica da superfície interna dos tubos de alumínio não revestido e revestido com resina epóxi por meio de microscópio estereoscópio e eletrônico de varredura

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    Elisabeth Loshchagin Pizzolitto

    2001-12-01

    Full Text Available The internal surfaces of aluminum tubes, both unlined and lined with epoxy resin, which are used for packaged medicines such as creams, ointments, gels, etc., were evaluated chemically, and microbiologically with regard to microorganism adherence. Proof of porosity of the unlined aluminum surface and lined with epoxy resin, and the resistance to removal of the resin were observed using a scanning electron microscope and a stereoscope, with a digitalized image system. To evaluate the microorganisms adherence to the aluminum surface, unlined and lined with epoxy resin, sterilized disks (10mm in diameter were immersed in Mueller Hinton Broth and placed in tubes of polypropylene with screw caps. The liquid culture medium was then inoculated with suspensions (10(9CFU/ml of the following microorganisms: Streptococcus agalactiae, Staphylococcus aureus, Acinetobacter lwoffii and Candida albicans and incubated at 37°C under constant agitation (100rpm for 12 days. The culture broth was changed every 3 days, after which the disks were removed, and observed under the scanning electron microscope. Microscopic observations revealed adherence of the microorganisms and biofilm on the aluminum surfaces both unlined and lined with epoxy resin.A superfície interna das bisnagas fabricadas com alumínio não revestido e revestido com resina epóxi, utilizadas para acondicionar cremes, pomadas, géis, etc., foram avaliadas quimicamente e por métodos microbiológicos correlacionados com a aderência de microrganismos. A prova da porosidade e da resistência à remoção da resina foi observada por meio do microscópio eletrônico de varredura (Topcon FM300 e estereoscópio Leica (MZ12 acoplado a Sistema de Digitalização de Imagens. Para avaliar a ação dos microrganismos foram utilizados corpos-de-prova esterilizados (discos de 10mm de diâmetro, imersos em caldo Mueller Hinton (Difco e colocados em tubos de polipropileno com tampa de rosca (Corning. Foram

  4. Los morteros epoxi en la construcción

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    Fernández Cánovas, Manuel

    1968-02-01

    Full Text Available Epoxi resins are being increasingly applied in construction in recent years. This is due to their excellent properties and an improving technology, which enables these resins to be applied to more delicate and difficult uses. This article describes the work done by the author as part of an extensive program of experimental work at the Instituto Eduardo Torroja laboratory. This program of work refers particularly to mortars with a low content of epoxi resins. By this is meant a mixture of none fine aggregate with the least quantity of resin necessary to obtain a suitable bond. The investigation involved a study of the proportioning of sand and resin, the relation between proportioning, the age and the mechanical strength and also the physical properties of the resulting mortars.Desde hace unos años las resinas epoxi están encontrando una mayor aplicación en el campo de la construcción. Esto es debido a sus excelentes propiedades y a una tecnología cada vez más perfeccionada, las cuales permiten realizar, con éxito, muchas de sus aplicaciones a problemas cada día más difíciles y delicados. El autor da cuenta, en este artículo, de los trabajos que ha realizado sobre morteros epoxi como parte de un amplio plan de ensayos experimentales que el Instituto Eduardo Torroja lleva a cabo en sus laboratorios. Este estudio se refiere a los morteros epoxídicos pobres, entendiéndose por tales, la mezcla de árido exento de finos con la mínima cantidad de resina precisa para su confección. En el mismo se estudian las influencias de: la granulometría de la arena en la cantidad de resina a emplear; de la dosificación y de la edad en la resistencia mecánica, así como de las propiedades físicas de los morteros así formados.

  5. Evaluación de la adherencia de uniones adhesivas metálicas con adhesivos epoxídicos modificados Evaluation of the adherence of bonded metallic joints with modified epoxy adhesives

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    Filiberto González Garcia

    2008-03-01

    Full Text Available En este trabajo fueron evaluadas las propiedades adhesivas de la resina epoxídica del tipo éter diglicidílico del bisfenol A. La resina fue modificada con dos modificadores poliméricos, uno de ellos un copolímero derivado del butadieno, y el otro un copolímero acrílico con el propósito de aumentar la tenacidad de la resina. Tres aminas alifáticas primarias fueron utilizadas como agentes de curado, trietilentetramina, N-(2-aminoetilpiperazina e isoforondiamina. Las propiedades adhesivas fueron investigadas usando la resina pura, así como la resina modificada. Las propiedades adhesivas de la resina modificada y pura fueron estudiadas usando como adherente una aleación de acero (ASTM A36. La adherencia fue evaluada por ensayos de adhesión usando tres geometrías de uniones adhesivas de acero-acero. El comportamiento reológico de los adhesivos fue investigado en condiciones isotérmicas. Los parámetros reológicos relacionados con la reacción de polimerización tales como velocidad de reacción, tiempo de manipulación, y tiempo de gelación de los adhesivos puros fueron relacionados con la estructura química del agente de curado. El tiempo de separación de fases, y de gelación de los adhesivos modificados fue relacionado con la morfología generada, y con la velocidad de la reacción, respectivamente. La morfología fue caracterizada por microscopia electrónica de barrido. La adherencia de las uniones adhesivas sometidas a las diferentes solicitaciones mecánicas fue relacionada a la morfología generada por la fase dispersa de cada modificador, y con las estructuras de redes de los adhesivos.In this work the adhesive properties of epoxy resins based on diglycidyl ether of bisphenol A have been evaluated. The epoxy resin was modified with butadiene and acrylic copolymers to obtain toughened adhesives. The aliphatic primary amines triethylenetetramine, N-(2-aminoethylpiperazine and isophorone diamine were investigated as curing

  6. Tratamiento de protección para tuberías de hormigón pretensado a base de resinas sintéticas (epoxi y poliuretano

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    Soria Santamaría, Francisco

    1977-12-01

    Full Text Available Amongst the different systems of protection used against the corrosion phenomenon under stress, we find those which physically try to prevent the corrosive agent from reaching the prestressed steel. Such is the case of water-proofing by means of synthetic resin-base membranes. The article describes the different tests to which this type of membrane should be submitted, with regard to the type of concrete used. It is also necessary to take into consideration the peculiarities of each job. The object of the tests made was to show the ideal characteristics of epoxy and polyurethane synthetic resins, especially formulated for specific functions. Three kinds of solutions are established with the use of these resins in those cases of protection against «aggressive» liquids, coming from water pipe exteriors, subjected to high pressures, where prestressed concrete piping has been used to solve this problem. Details are given on a specific job carried out in which one of the mentioned solutions was used.Entre los distintos sistemas de protección contra el fenómeno de corrosión bajo tensión, se encuentran aquellos que tratan de impedir físicamente que el agente corrosivo llegue al acero pretensado. Este es el caso de las impermeabilizaciones mediante membranas a base de resinas sintéticas. En el artículo se describen distintos ensayos a que deben someterse este tipo de membranas en lo que respecta al hormigón soporte. Es preciso, además, adaptarse a las particularidades propias del tipo de obra a que van destinadas. El objetivo de los ensayos ha sido el mostrar la idoneidad de resinas sintéticas de epoxi y de poliuretano, específicamente formuladas para unas funciones concretas. Se establecen tres tipos de soluciones mediante el empleo de las citadas resinas, en el caso de protección, respecto a líquidos «agresivos» provenientes del exterior en conducciones de agua, sometidas a altas presiones, en tuberías de hormig

  7. ESTUDO DA RETENÇÃO ENTRE RESINA ACRÍLICA PARA BASE DE DENTADURA E DENTES DE RESINA ACRÍLICA

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    FAJARDO Renato Salviato

    1997-01-01

    Full Text Available Foi avaliada a resistência de união entre dentes e base de dentadura, ambos de resina acrílica. Os dentes foram incluídos em blocos cilíndricos de resina e, posteriormente, torneados, para se obterem cilindros de 5mm de diâmetro. Sobre a extremidade do dente, era adaptado um padrão de cera de mesmo diâmetro, que, após inclusão na mufla, era substituído por resina acrílica termicamente ativada pelo método de processamento convencional de base de dentadura. Como variáveis, usaram-se duas marcas de dentes, duas fases de inclusão (plástica e borrachóide e aplicação ou não de detergente e monômero sobre os dentes. Os corpos-de-prova, antes dos ensaios de ruptura por tração, foram armazenados em água destilada, a 37ºC, por 2 semanas. Os resultados mostraram que: marca de dente e fase de condensação não influíram nos resultados; somente o uso de detergente ou de monômero aumenta a retentividade e o seu uso conjunto apresenta efeito acumulativo.

  8. Análise por imagem digital dos níveis de cinza de fibras de reforço associadas a uma resina composta = Digital image analysis of the gray levels of reinforcement fibers associated with composite resin

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    Mussatto, Cristiane Maria Boniatti

    2005-01-01

    Full Text Available Mensurar a densidade óptica das fibras de reforço Connect, Ribbond e Interlig incluídas em resina composta Filtek Z250, no sistema DenOptix. Materiais e método: Foram confeccionados 10 blocos de resina composta associadas a cada tipo de fibra e dois blocos de resina Z250 pura (controle não-reforçado, totalizando 32 corpos-de-prova. Foram obtidas 3 radiografias digitais de cada corpo-de-prova, sobre uma placa óptica do sistema DenOptix, para cada posição: (A face lateral da fibra exposta aos raios -X; (B face tramada da fibra exposta aos raios-X. Em cada uma foram realizadas 3 leituras ópticas dos níveis de cinza em cada corpo-de-prova, em pontos aleatórios, sendo obtida uma média. Os valores médios dos níveis de cinza foram analisados pelo teste t de Student, ANOVA e teste de Tukey, ao nível de significância de 1%. Resultados e conclusões: Com relação à associação da resina + fibra na posição (A, observou-se a maior média de níveis de cinza para a resina pura, seguido por resina + Connect, resina + Interlig (que não diferiram entre si, e resina + Ribbond. Com relação à associação da resina + fibra na posição (B, observou-se que a resina pura apresentou maior média, seguida por resina + Connect, resina + Interlig e resina + Ribbond, sendo que as duas últimas não foram diferentes entre si. Os resultados sugerem que os níveis de cinza variaram em função do tipo de fibra de reforço e da posição na radiografia

  9. Comportamiento dieléctrico de compuestos epoxi/aluminio/BaTiO3

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    Castro, M. S.

    2009-06-01

    Full Text Available In order to improve the dielectric behaviour of epoxi/BaTiO3, in this work the influence of micrometric aluminum metal flakes (Al, on the dielectric properties of epoxy / BaTiO3 composites was studied. Epoxy resin, Al and BaTiO3 were mixed using an ultrasonic mixer and composites were deposited onto glass substrates by dipping technique. Obtained materials presented good dielectric properties at room temperature, and relaxation process appeared due to the resin behaviour. Obtained results were compared with those reported in literature for similar systems.Con el objetivo de mejorar el comportamiento dieléctrico de los compuestos epoxi/BaTiO3, en este trabajo se estudió la influencia de partículas metálicas de aluminio (Al, con forma de escamas y tamaño micrométrico, sobre las propiedades dieléctricas de sistemas epoxi / BaTiO3. El material compuesto fue obtenido por la técnica de inmersión o “dipping”. La mezcla de los componentes fue llevado a cabo en mezclador ultrasónica y la deposición se realizó sobre sustratos de vidrio. Los materiales obtenidos presentaron buenas propiedades dieléctricas a temperatura ambiente, sin alcanzar el límite de percolación, y los fenómenos de relajación fueron generados por los dominios de la resina. Los valores obtenidos fueron comparados con los reportados en la bibliografía para sistemas similares.

  10. Resinas quelantes amidoxímicas Amidoxime chelating resins

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    Fernanda M. B. Coutinho

    1999-12-01

    Full Text Available Resinas quelantes com grupos amidoxima foram sintetizadas por copolimerização em suspensão de acrilonitrila (AN e divinilbenzeno (DVB e subsequente modificação química dos grupos ciano por reação com hidroxilamina. Na copolimerização, a proporção de divinilbenzeno e o grau de diluição foram variados. Gelatina e carbonato de cálcio foram usados como estabilizadores de suspensão e sulfato de sódio foi adicionado para reduzir a solubilidade da acrilonitrila em água, por meio do efeito salting out. Os copolímeros de AN/DVB e as resinas amidoxímicas obtidos foram caracterizados por meio de densidade aparente, área específica, volume de poros e teor de nitrogênio. As resinas amidoxímicas foram também avaliadas em relação a capacidade de complexação de íons cobre.Chelating resins with amidoxime groups were synthesized by suspension copolymerization of acrylonitrile (AN and divinylbenzene (DVB and subsequent chemical modification of cyano groups by reaction with hydroxylamine. In the copolymerization, the proportion of divinylbenzene and the dilution degree were varied. Gelatin and calcium carbonate were used as suspension stabilizers and sodium sulphate was added in order to reduce acrylonitrile solubility in water, by salting out effect. The AN/DVB copolymers and amidoxime resins obtained were characterized by apparent density, surface area, pore volume and by the content of nitrogen. The amidoxime resins were also evaluated in relation to the complexation capacity of copper ion.

  11. Resistência à microtração entre uma cerâmica hidrotérmica, silanizada ou não, aderida à uma resina composta por um cimento resinoso

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    Lopes, Angela; Leite, Fabiola; Valandro, Luis Felipe; Siqueira, Luciana; Pimenta, Luiz André; Neisser, Maximiliano Piero

    2010-01-01

    Esse trabalho teve como objetivo avaliar a resistência adesiva entre uma cerâmica hidrotérmica (Symbio ceram, Degussa), silanizada ou não e aderida à uma resina composta (Filtec Z100- 3M ESPE) por um cimento resinoso (Panavia F, Kuraray). Foram confeccionados 2 blocos, divididos em 2 grupos assim constituídos: Grupo I-tratamento de superfície da cerâmica com ácido fluorídrico a 10% e união a um substrato (resina compost...

  12. Propriedades mecânicas de materiais compósitos à base de cimento Portland e resina epoxi Mechanical properties of composite materials based on portland cement and epoxy resin

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    T. H. Panzera

    2010-03-01

    Full Text Available O estudo de materiais de alto desempenho e multifuncionais, como os compósitos poliméricos cimentícios, tem sido o foco de inúmeras pesquisas na indústria da construção civil. Este trabalho investiga o efeito da combinação de uma fase polimérica termorrígida, uma resina epóxi, com cimento Portland branco estrutural, seguido da avaliação da resistência à compressão e módulo de elasticidade. Este compósito, quando comparado individualmente com as suas matérias-prima originais, promove um aumento da resistência mecânica à compressão, redução da massa específica e, também uma mudança significativa do comportamento mecânico. As mudanças nas propriedades mecânicas estão associadas à hidratação da fase cimentícia na presença da resina, fato comprovado através da análise espectroscópica na região do infravermelho.The study of multi-functional materials of high performance, as the polymeric-cementitious composites, has been the focus of several researches in the industry of the civil engineering. This work investigates the effect of the combination of a thermorigid epoxy phase and the white Portland cement, followed by the evaluation of its compressive strength and modulus of elasticity. This composite, when the phases are individually compared, provides an increase of the compressive strength, a reduction of the density, and a significant change of the mechanical behaviour. The changes in mechanical behaviour are associated with the hydration of cement in the presence of resin, which was evident after infrared spectroscopy analysis.

  13. Retention of oral microorganisms on conventional and resin-modified glass-ionomer cements Retenção de microrganismos bucais em cimentos de ionômero de vidro convencionais e modificados por resina

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    Denise PEDRINI

    2001-09-01

    Full Text Available Secondary caries are a worldwide public and socioeconomic problem. The placement of restorations can lead to the development of environmental conditions favorable to microbial colonization, especially on the tooth/restoration interface, which is a predisposing factor for secondary caries. The aim of this study was to evaluate microbial retention on conventional (Chelon-Fil and Vidrion R and resin-modified (Vitremer and Fuji II LC glass-ionomer cements, in situ, using a hybrid composite resin (Z100 as a control. Twelve volunteers wore Hawley appliances with specimens made of all tested filling materials for 7 days. The specimens were then removed from the appliances and transferred to tubes containing 2.0 ml of Ringer-PRAS. Microorganisms from the samples were inoculated onto blood agar and Mitis Salivarius Bacitracin agar and incubated under anaerobiosis (90% N2, 10% CO2, at 37°C, for 10 and 2 days, respectively. The resin-modified glass-ionomer cements and the composite resin retained the same levels of microorganisms on their surfaces. The resin-modified glass-ionomers retained less mutans streptococci than the composite resin and conventional glass-ionomer cements. The conventional glass-ionomer cements retained less mutans streptococci than the composite resin, but that difference was not statistically significant.A cárie secundária representa problema de saúde pública e socioeconômico no mundo. A restauração de dentes acometidos por cárie pode criar condições favoráveis à proliferação microbiana na superfície do material restaurador ou na interface dente/restauração, criando ambiente propício para o estabelecimento de cárie secundária. O objetivo deste estudo foi avaliar a capacidade de retenção de placa bacteriana em cimentos de ionômero de vidro convencionais (Chelon-Fil e Vidrion R e modificados por resina (Vitremer e Fuji II LC e de resina composta híbrida (Z100, utilizada como controle. Nos testes de reten

  14. Emprego de resina epóxi em vigas danificadas de madeira de Pinus elliottii

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    Marília da Siva Bertolini

    Full Text Available A utilização da madeira em estruturas está vinculada a condições que permitam sua utilização por muitos anos sem a perda de suas propriedades de resistência e de rigidez. Entretanto, por se tratar de material natural, as estruturas em madeira projetadas podem estar sujeitas ao ataque de agentes biológicos, ação de intempéries, entre outros fatores, requerendo soluções na forma de reparo ou reforço. O presente trabalho objetivou investigar a influência do uso de resina epóxi como agente reparador em vigas danificadas de madeira de Pinus elliottii no cálculo do produto de rigidez à flexão. Para tanto, foi realizado um planejamento experimental completo, tendo a posição dos defeitos provocados (central ou laterais, o uso ou não da resina nos defeitos, e a posição desses defeitos (superior - compressão ou Inferior - tração como fatores. Os resultados da análise estatística revelaram que o uso da resina epóxi nas regiões danificadas das vigas apresentaram valores do produto de rigidez na flexão significativamente superiores quando comparados com as vigas da condição com defeito e sem a resina epóxi. Mesmo sendo significativo o uso da resina nas regiões danificadas, o produto de rigidez à flexão das vigas reparadas foi inferior ao produto de rigidez à flexão das vigas sem defeito (referência, evidenciando a necessidade de outros estudos com outras resinas e outros materiais visando à recuperação total da rigidez da peça de madeira danificada.

  15. Fechamento de Diastema com resina composta

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    Vanessa Schwarz

    2015-02-01

    Full Text Available A presença de diastemas na região de incisivos centrais e laterais superiores é considerado um fator antiestético altamente prejudicial do ponto de vista social. Os diastemas podem ser decorrentes da presença de inserção baixa do freio labial, presença de mesiodens, fatores genéticos ou mesmo estar ligado a doenças periodontais associadas ao tabagismo ou não. Contudo, podem comprometer a estética do sorriso substancialmente em função de sua extensão. Este trabalho descreve, através de um relato de caso clínico, a técnica de fechamento de diastema entre incisivos centrais e laterais superiores por meio de resinas compostas, realizado na faculdade de Odontologia da Faculdade Meridional (IMED. Concluiu-se que o uso de sistemas adesivos e resinas compostas, através de mínimas intervenções, podem proporcionar um melhor contorno aos dentes, resultando em um sorriso com aspecto mais estético e agradável.

  16. Effect of repeated microwave disinfection on surface roughness and baseplate adaptation of denture resins polymerized by different techniques = Efeito da desinfecção repetida por microondas sobre rugosidade superficial e adaptação de bases de resinas polimerizadas por diferentes técnicas

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    Campos, Maria Agnese Pinto de

    2009-01-01

    Full Text Available Objetivo: Avaliar o efeito cumulativo de dois protocolos de desinfecção por energia de micro-ondas (Protocolo 1: 690 W/6 min; Protocolo 2: 345 W/6 min na rugosidade superficial (Ra e adaptação de bases de dentadura de duas resinas polimerizadas por micro-ondas (Onda Cryl ou banho de água quente (QC-20. Metodologia: Para Ra, espécimes retangulares foram fabricados e divididos de acordo com o tratamento de desinfecção (n=8/grupo: 1 Controle (sem desinfecção, 2 Protocolo 1, e 3 Protocolo 2. Para medir Ra usou-se um rugosímetro no baseline (T0 e após 2 procedimentos de desinfecção (T1, T2 com intervalo de 7 dias de imersão em água destilada. Para avaliar a estabilidade dimensional, bases maxilares foram divididas nos 3 grupos (n=6 e a adaptação foi medida por pesagem de uma película de silicone que reproduzia o espaço entre a base de resina e um modelo-mestre metálico. Resultados: Para Ra, houve interação significativa entre tipo de resina e técnica de polimerização, tratamento de desinfecção, e número de procedimentos desinfecção (P<0,001. Os grupos Protocolo 2 e controle apresentaram aumento semelhante de Ra ao longo do tempo, mas os grupos Protocolo 1 tiveram uma redução significativa de Ra em T2. A adaptação da base foi afetada por uma interação significante entre tratamento de desinfecção e número de procedimentos de desinfecção (P<0,001; o Protocolo 1 apresentou a maior média em T2. Conclusão: Onda Cryl teve maiores alterações de Ra e adaptação que QC-20. O Protocolo 1 promoveu dano geral para ambos os tipos de resina após dois procedimentos de desinfecção

  17. Morteros y hormigones de resinas

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    Rodríguez, G.

    1973-07-01

    Full Text Available In this article, the growing use is explained of resins and plastics (PVC and others in building, replacing the standard binder which is cement, or filling passages of pieces of set and hard concrete, to improve 3 to 5 fold their compressive and tensile strengths. Likewise, some rules are given on dryness of the aggregates to be used, speed in form removal, greater adherence, easier to handle, price problems, not very fire-proof, etc. Use in facing frontages, industrial flooring, treating cracks and fissures by injecting resins, joints, etc.Se explica en este artículo la creciente utilización de las resinas y materiales plásticos (cloruro de polivinilo y otros en la construcción, sustituyendo al aglomerante normal que es el cemento, o rellenando canalículos de piezas de hormigón fraguado y endurecido, para mejorar su resistencia a la compresión y a la tracción unas 3 a 5 veces. Igualmente se dan algunas normas sobre sequedad de los áridos a emplear, rapidez de desencofrado, mayor adherencia, mejor manejabilidad, inconvenientes de precio, poca resistencia al fuego, etc. utilización en revestimientos de fachadas, solados industriales, tratamiento de grietas y fisuras: por inyección de resinas, juntas, etc.

  18. Influência do tempo de fotopolimerização de diferentes resinas compostas na sorpção de água = Influence of polymerization time of different composites on water sorption

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    Guimarães, Fabrício Barbosa Rocha

    2008-01-01

    Full Text Available Objetivo: Verificar a influência do tempo de polimerização de resinas compostas na absorção de água por diferentes resinas compostas. Metodologia: As resinas multiuso Z250®, compactável P60® e de micropartículas A110® foram utilizadas para a confecção de corpos-de-prova (n=5 por grupo de acordo com o tempo de fotopolimerização (o indicado pelo fabricante, a metade e o dobro do tempo preconizado. A quantidade de água absorvida pelos espécimes foi medida pela variação da massa dos mesmos, que foram pesados imediatamente após sua confecção, a cada 24h por 10 dias, e após 15 e 30 dias. Os dados foram analisados por ANOVA e teste de Tukey. Resultados: A absorção de água das resinas compostas foi diferente quando o tempo de polimerização foi alterado. A resina de micropartículas teve o melhor comportamento perante a mudança no tempo de fotopolimerização, enquanto que a resina de multiuso foi a que mais absorveu água quando o tempo foi alterado para menos (P<0,05. Conclusão: O tempo de polimerização sugerido pelo fabricante deve ser respeitado para assegurar a manutenção das propriedades desses materiais, independentemente do tipo de resina utilizado

  19. Moisture Absorption of Epoxy Matrix Composites Immersed in Liquids and in Humid Air.

    Science.gov (United States)

    1979-10-01

    Eq. 4). -34- TEMPERATURE, T (K) 165 40 350 300 Neat ResinA / Fit to Data 0\\ 0 o Composite Calculated 0- Data Delasi and Whiteside (1977) 168 AS/3501...moisture ab - sorption characteristics of T300/1034, AS/3501-5 and T300/5208 graphite-epoxy composites. 1) Material immersed in liquid at temperatures 300 to

  20. Avaliação do monômero residual de resinas acrílicas utilizadas para prótese ocular, polimerizadas convencionalmente e por energia de microondas = Evaluation of residual monomer between conventional and microwave heat-cured acrylic resins used for ocular prostheses

    Directory of Open Access Journals (Sweden)

    Moroni, Pedro Alexandre

    2005-01-01

    Full Text Available Este trabalho objetivou comparar a quantidade de monômero residual das resinas acrílicas utilizadas para confecção de prótese ocular, termopolimerizável incolor (grupo controle e Onda-Cryll incolor após a polimerização convencional (MC e com energia de microondas (MW respectivamente. Para o experimento foram confeccionados três corpos-de-prova para cada tipo de resina e período de investigação, num total de 30 corpos-de-prova, os quais foram submetidos a ensaios titulométricos nos períodos de 5, 30 60, 120 e 1. 440 minutos (24 horas após a demuflagem. A resina acrílica termopolimerizável incolor apresentou índice inferiores de concentração de monômero residual em relação à resina acrílica Onda-Cryll incolor. A resina acrílica polimerizada por microondas apresentou baixos indíces de concentração de monômero residual, porém um pouco superiores (até 120 minutos em relação à resina termopolimerizável incolor. Ambos os materiais apresentaram valores numéricos estatisticamente semelhantes de concentração de monômero residual no período de 1440 minutos (24horas. Uma técnica de confecção de prótese ocular através de forno de microondas é exeqüível, pois os acrílicos apresentam concentrações normais de monômero residual após 120 minutos da sua polimerização, em relação ao grupo controle

  1. O Uso de Resina de Poliéster em Trabalho de Campo para Recobrir Espécimes Fragmentados

    Directory of Open Access Journals (Sweden)

    Helder de Paula

    2005-01-01

    Full Text Available Freqüentemente, fósseis de vertebrados são encontrados como partes de esqueletos erodidos superficialmente. Em vários casos, os ossos estão demasiadamente danificados para suportar os estresses decorrentes das etapas de coleta e transporte. Não é incomum o fato de fósseis nesta situação serem deixados no campo ou mesmo serem perdidos devido a sua fragilidade. Aqui, descrevemos um simples procedimento que pode ser utilizado no campo para recobrir fósseis danificados. Aplicamos este procedimento com grande sucesso no fêmur de um dinossauro saurópoda coletado no sítio Confusão (município de Tesouro, uma localidade recentemente descoberta no estado do Mato Grosso. O material é preservado numa matriz conglometrática correlacionável com o Grupo Bauru. O fêmur (MN 6813-V possui aproximadamente 110 cm de largura e tinha a metade distal parcialmente exposta devido as periódicas enchentes do rio Confusão. Ele possui uma Saliên cia lateral bem desenvolvida a qual é considerada como uma característica titanossauriforme. A porção distal, incluindo a articulação, estava preservada principalmente como uma impressão na rocha, juntamente com alguns fragmentos da parte mais cortical do osso. Esta porção do fêmur estava demasiadamente friável para ser coletada como uma peça única. Após uma limpeza geral da superficie, recobrimos as porções mais frágeis da parte distal do fêmur (incluindo as impressões com diversas camadas finas de resina de poliéster que foram gentilmente aplicadas com um pincel. Usamos 0,75% de metil etil cetona (MEK como catalisador para a resina de poliéster e esperamos até que cada camada de resina secasse lentamente. Na seqüência, uma camada mais espessa de resina com gaze foi utilizada para fazer esta região mais resistente e forte o bastante para se manter por si só. As demais partes do processo de coleta seguiram os procedimentos tradicionais incluindo o uso de uma jaqueta de gesso. Entre os

  2. Interesantes aplicaciones de las resinas sintéticas en obras de ingeniería civil

    Directory of Open Access Journals (Sweden)

    Vié, G.

    1970-12-01

    Full Text Available The author describes the growing importance of epoxy resins in construction, especially in public works. A brief account is given of the physical and chemical properties, such as almost total resistance to chemical action; high anticorrosive strength; better mechanical strength than concrete; insensibility to icing-deicing cycles and thermal changes; high bond with most materials; no changes due to ageing; great resistance to wearing and abrasive actions; good aspect; high electrical resistance; and others. The article also describes some of its most common uses, including fillings, injections, fixings, industrial floorings, tunnel facing, and waterproofing of cracks. Examples of some recent uses in France are also cited.El autor describe la importancia creciente que han adquirido las resinas epoxi en la construcción y, particularmente, en las obras públicas. Hace una exposición sucinta de sus propiedades físicas y químicas más destacadas: resistencia química prácticamente total, poder anticorrosivo elevado, mejores características mecánicas que el hormigón, insensibilidad a los ciclos hielo-deshielo y a las variaciones térmicas, poder adhesivo notable para todos los materiales, ninguna modificación por envejecimiento, gran resistencia al desgaste y a la abrasión, efecto decorativo, y gran resistividad eléctrica; así como de las utilizaciones más usuales: recrecidos, inyecciones, empotramientos, suelos industriales, revestimientos en túneles, impermeabilización de fisuras, etc. Se añaden algunos ejemplos recientes de su empleo en Francia.

  3. Análise da Fragilidade do Core - Quando reconstruído com diferentes resinas e pinos pré-fabricados não metálicos

    OpenAIRE

    Ávilal, Gisseli Bertozzi; Dias, Sérgio Cândido; Ribeiro, José Carlos Rabelo; Gomes, Priscila Nogueira; Moysés, Marcos Ribeiro

    2016-01-01

    Para realização deste estudo vinte condutos artificiais foram construídos em blocos formados por esmalte e dentina, a partir de dentes bovinos. Dez pinos de fibra de vidro e dez de fibra de carbono foram cimentados nos condutos com cimento resinoso C&B. Empregou-se matriz de policarbonato para confecção do core em resina composta, perfazendo quatro grupos: Grupo (1) pino de fibra de vidro e core com resina composta Charisma; Grupo (2) pino de fibra de carbono e core com resina composta Charis...

  4. ORGANIC/INORGANIC HYBRID EPOXY NANOCOMPOSITES BASED ON OCTA(AMINOPHENYL)SILSESQUIOXANE

    Institute of Scientific and Technical Information of China (English)

    Hai-bo Fan; Rong-jie Yang; Xiang-mei Li

    2013-01-01

    Octa(aminophenyl)silsesquioxane (OAPS) was used as the curing agent of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin.A study on comparison of DGEBA/OAPS with DGEBA/4,4'-diaminodiphenyl sulfone (DDS) epoxy resins was achieved.Differential scanning calorimetry was used to investigate the curing reaction and its kinetics,and the glass transition of DGEBA/OAPS.Thermogravimetric analysis was used to investigate thermal decomposition of the two kinds of epoxy resins.The reactions between amino groups and epoxy groups were investigated using Fourier transform infrared spectroscopy.Scanning electron microscopy was used to observe morphology of the two epoxy resins.The results indicated that OAPS had very good compatibility with DGEBA in molecular level,and could form a transparent DGEBA/OAPS resin.The curing reaction of the DGEBA/OAPS prepolymer could occur under low temperatures compared with DGEBA/DDS.The DGEBA/OAPS resin didn't exhibit glass transition,but the DGEBA/DDS did,which meant that the large cage structure of OAPS limited the motion of chains between the cross-linking points.Measurements of the contact angle indicated that the DGEBA/OAPS showed larger angles with water than the DGEBA/DDS resin.Thermogravimetric analysis indicated that the incorporation of OAPS into epoxy system resulted in low mass loss rate and high char yield,but its initial decomposition temperature seemed to be lowered.

  5. Avaliação das características da resina epóxi com diferentes aditivos desaerantes

    Directory of Open Access Journals (Sweden)

    Alexsandro Oliveira

    2015-04-01

    Full Text Available Este trabalho tem por objetivo a busca por técnicas alternativas para diminuir a incidência de vazios em resinas poliméricas e, por consequência, em materiais compósitos. Foram produzidas formulações diferentes utilizando resina epóxi à base de éter diglicidílico do Bisfenol A, endurecedor de poliamina alifática com e sem a adição de diferentes aditivos desaerantes a base de éteres e ésteres modificados. As formulações produzidas foram submetidas a condições extremas de agitação e processamento, sendo posteriormente avaliadas quanto a incidência de bolhas e vazios, densidade, propriedades mecânicas, morfológicas e térmicas. Os resultados foram bastante positivos quanto à diminuição da quantidade e do tamanho de poros pela utilização de técnicas de desgaseificação a vácuo e pelo uso de aditivos desaerantes.

  6. Caracterização de um pré-impregnado aeronáutico por FT-IR e análise térmica Characterization of pre-impregnated of epoxy resin/carbon fiber

    Directory of Open Access Journals (Sweden)

    Vanesa C. G. M. Ferrari

    2012-01-01

    Full Text Available Este trabalho consiste na caracterização de um pré-impregnado ("prepreg" de resina epoxídica/fibra de carbono, usando-se espectroscopia no infravermelho com transformada de Fourier (FT-IR, análise termogravimétrica (TG, calorimetria exploratória diferencial (DSC e análise térmica dinâmico-mecânica (DMTA. A análise por FT-IR foi realizada nos modos de transmissão (pastilha de KBr, pirólise em bico de Bunsen e controlada e detecção fotoacústica (PAS. Os espectros de FT-IR de transmissão revelaram a presença de resina epoxídica, grupos ciano, amínicos e bisfenol A, que possibilitaram identificar o provável agente de cura:a cianoguanidina (ou dicianodiamida do sistema epoxídico. Os espectros de FT-IR/PAS permitiram acompanhar as alterações espectrométricas causadas pela cura. A análise térmica auxiliou na observação e compreensão dos eventos durante o processo de cura, etapas de gelificação e vitrificação, e da influência destas nas temperaturas de transição vítrea (Tg do material curado e na escolha do intervalo de temperatura de cura, que é um dos parâmetros mais importantes do processo produtivo.This work explores the characterization of pre-impregnated ("prepreg" materials made with an epoxy resin/carbon fiber, using FT-IR spectroscopy, thermogravimetry (TG, differential scanning calorimetry (DSC and dynamic mechanical thermal analysis (DMTA. FT-IR spectroscopy was used in the transmission mode (KBr pellets, pyrolysis without control and controlled pyrolysis and photoacoustic detection (FT-IR/PAS. The transmission FT-IR spectra revealed the presence of epoxy resin, cyano groups, amine and bisphenol A, which allowed us to identify the probable agent of cure: cyanoguanidine (or DCD. With FT-IR/PAS it was possible to monitor spectrometric changes caused by curing. The thermal analysis assisted in observing and understanding events during the curing process, including the gelation and vitrification steps. It

  7. Effectiveness of composite resin polymerization using light-emitting diodes (LEDs or halogen-based light-curing units Efetividade de polimerização de uma resina composta fotopolimerizada por diodos emissores de luz (LEDs ou luz halógena

    Directory of Open Access Journals (Sweden)

    Bianca Micali

    2004-09-01

    acrílicas e fotopolimerizada por 40 segundos por um aparelho fotopolimerizador de diodos emissores de luz (Ultraled/Dabi Atlante ou de luz halógena (Degulux/Degussa Hüls. Imediatamente depois, os corpos-de-prova foram imersos em 1 ml de solução de azul de metileno a 2% e mantidos em estufa a 37°C ± 2°C. Após 24 horas, foram lavados com água corrente destilada por 1 minuto e armazenados em estufa a 37°C ± 2°C em umidade relativa por 24 horas. As resinas compostas foram removidas das matrizes, individualmente trituradas e imersas em 1 ml de álcool absoluto por 24 horas. As soluções foram filtradas e centrifugadas por 3 minutos a 4.000 rpm, e o sobrenadante foi utilizado para determinar a absorbância em um espectrofotômetro a 590 nm. O teste t foi aplicado para verificar as diferenças entre os grupos. Não houve diferenças estatísticas entre os grupos fotopolimerizados por diodos emissores de luz ou luz halógena (p > 0,05. O aparelho fotopolimerizador de diodos emissores de luz apresentou a mesma efetividade em polimerizar uma resina composta micro-híbrida quanto o de luz halógena.

  8. FUNCIONALIZACIÓN DE UNA RESINA DE INTERCAMBIO IONICO PARA LA PRECONCENTRACION DE Hg(II

    Directory of Open Access Journals (Sweden)

    Cecilia De Asmundis

    2011-01-01

    Full Text Available Se estudiaron las condiciones óptimas para funcionalizar una resina aniónica (Dowex 1X8 con un reactivo (difenilcarbazida específicamente adecuado para la determinación de Hg(II en soluciones acuosas. Se llevo a cabo el ajuste de las condiciones para la determinac ión del complejo Hg-DFC, las que permiten lograr un método eficaz, rápido y de bajo costo para detectar concentraciones de Hg en matrices complejas, mediante la realización de espectrofotometría de absorción UV-Vis en fase sólida. La resina puede ser utilizada para pre- concentrar Hg(II durante el pretratamiento para el análisis con métodos instrumentales específicos (absorción/emisión atómica. La intensidad del color desarrollado por la resina funcionalizada se encuentra estrechamente ligada con las concentraciones de Hg(II presentes en las muestras, lo que conduce a que el método pueda realizarse aún si no se tiene el equipamiento necesario, aplicando técnicas semi-cuantitativas como, colorimetria visual (naked eye.

  9. Comportamiento mecánico de mezclas de resina furanopoxídica con polisulfuros para su uso como adhesivos de alta resistencia. Acción de las cargas estáticas. // Mechanical behaviour of epoxi-modified furan polymer blends with polysulfyde for use as high st

    Directory of Open Access Journals (Sweden)

    D. Díaz Batista

    1999-01-01

    Full Text Available La modificación de polímeros furánicos con otros de diferentes propiedades ha sido una vía para lograr el mejoramiento deestos impartiéndoles propiedades específicas. La incorporación de polisulfuros como tiokol caucho a la resina furfural-acetonamodificada con grupos epoxídicos es estudiada en base a ensayos estáticos observándose un incremento discreto sobre laadhesividad de las mezclas y un aumento notable en el módulo elástico. Se estudió el comportamiento de estos adhesivos sobreun grupo de substratos de uso estructural.Palabras claves: resinas, pol isul furos, adhesivos de al ta resi st encia.__________________________________________________________________________AbstractModification of furan polymers with other ones having different behaviour has been an alternative to improve them developingspecific properties. Blends of polysulfide in the rubbery form with epoxi-modified furan resin are studied based on static tests.It has been observed a small increase in adhesive strength and a higher elastic modulus. Four substrates commonly used instructural parts were evaluated.Key words: Resin, polysul fyde, high strength adhesive.

  10. Avaliação in vitro da atividade antibacteriana de um cimento odontológico à base de óleo-resina de Copaifera multijuga Hayne

    Directory of Open Access Journals (Sweden)

    Kátia Regina Felizardo Vasconcelos

    Full Text Available Um dos materiais utilizados para a adequação do meio bucal no serviço público é o cimento produzido a partir de óxido de zinco e eugenol. Entretanto, o eugenol é uma substância citotóxica que pode desencadear alguns efeitos adversos. Por essa razão, procura-se substituir o eugenol por uma substância que apresente baixa toxicidade, mantendo ou mesmo melhorando as propriedades do cimento. O óleo-resina de copaíba é um produto natural, utilizado pelas populações amazônicas e reconhecido por suas propriedades medicinais. Baseando-se nas propriedades desse óleo-resina, na ação antimicrobiana comprovada do hidróxido de cálcio e na ação anti-séptica do óxido de zinco, propôs-se formular um cimento odontológico obtido da associação do ZnO, Ca(OH2 e óleo-resina de Copaifera multijuga Hayne e avaliar sua atividade antibacteriana através do teste de diluição em meio líquido frente às cepas padrão de Streptococcus mutans (ATCC 25175 e S. sanguinis (ATCC 15300. Nesse ensaio, utilizaram-se os seguintes grupos experimentais: o cimento contendo ZnO, Ca(OH2 e óleo-resina de copaíba (G1 e cada um dos constituintes isoladamente, ZnO (G2, Ca(OH2 (G3 e óleo-resina de copaíba (G4. Todos os grupos analisados demonstraram atividade antibacteriana, o G4 apresentou os melhores resultados e o G1 mostrou-se um cimento promissor a ser utilizado em odontologia.

  11. Fingerprint analysis of Resina Draconis by ultra-performance liquid chromatography

    OpenAIRE

    Xue, Yudi; Zhu, Lin; Yi, Tao

    2017-01-01

    Background Resina Draconis, a bright red resin derived from Dracaena cochinchinensis, is a traditional medicine used in China. To improve its quality control approach, an ultra-performance liquid chromatography (UPLC) fingerprint method was developed for rapidly evaluating the quality of Resina Draconis. Methods The precision, repeatability and stability of the proposed UPLC method were validated in the study. Twelve batches of Resina Draconis samples from various sources were analyzed by the...

  12. Hyperbranched polyester: single route synthesis, characterization and evaluation as impact modifier of an epoxy resin; Poliester hiperramificado: sintese por uma rota simples, caracterizacao e avaliacao como modificador de impacto de uma resina epoxi

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, B.H.S.; Sousa, A.R., E-mail: rangel@deii.cefetmg.br [Centro Federal de Educacao Tecnologica de Minas Gerais (DEMAT/CEFET-MG), Belo Horizonte (Brazil). Departamento de Engenharia de Materiais; Alves, A.P.P.; Silva, G.G. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Quimica. Lab. de Materiais Polimericos Multicomponentes

    2015-07-01

    Two hyperbranched polyesters were obtained using glycerol and adipic acid as monomers, they were characterized through nuclear magnetic resonance ({sup 13}C NMR) to branching degree determination, size exclusion chromatography to molar mass obtention and thermogravimetric analysis (TGA) to evaluate the thermal stability. The polyesters synthesized were added to epoxy resin, at 10% by weight, to evaluate the implication on mechanical properties, impact and stress strain, and thermal (glassy transition temperature - Tg). We observed that rising the synthesis time from 6 to 15,5 hours the degree of branching, molar mass and thermal stability of the polyester increased. The addition of hyperbranched polyesters did not change the mechanical properties of epoxy resin significantly, but the Tg was reduced. (author)

  13. Evaluación del efecto citotóxico de una resina dental a base de siloranos sobre fibroblastos L929

    Directory of Open Access Journals (Sweden)

    Milena Guerrero F

    2016-04-01

    Full Text Available Introducción: Las resinas dentales basadas en siloranos, son el resultado de la unión química de siloxanos y oxiranos. Dentro del proceso de evolución de las resinas, se han modificado sus formulaciones para optimizar sus propiedades físicas, mecánicas y estéticas. Sin embargo, aún presentan problemas como la contracción de polimerización, problemas alérgicos y toxicológicos. Objetivo: Determinar el potencial efecto citotóxico de las resinas a base de siloranos sobre la viabilidad celular en un cultivo de fibroblastos de la línea L929. Metodología: Se estudió la exposición de fibroblastos de ratón L929 a resinas dentales a base de siloranos Filtek p90 y metacrilatos Filtek p60 en tres tiempos de fotocurado durante 6 días. Se evaluó el efecto sobre la viabilidad celular mediante pruebas de exclusión vital, micrografías electrónicas y composición elemental de superficie (Mg, Na, K y Ca por ESEM/EDAX. Resultados: La resina Filtek p90 mostró un mayor efecto citotóxico a tiempos de fotocurado prolongados (20 segundos o más respecto a la resina Filtek p60. El efecto resultó más marcado para 20 segundos de fotocurado, ya que las concentraciones de Ca y K en la superficie celular fueron las más afectadas. Conclusiones: La resina dental Filtek p90 ejerce un efecto citotóxico relativamente bajo sobre las células de fibroblastos L929 (p <0.01. Su uso en la práctica odontológica se puede considerar bioseguro, pero un tiempo de fotocurado prolongado con la resina dental a base de siloranos puede afectar significativamente la viabilidad de los tejidos dentales

  14. Avaliação da toxicidade aguda e potencial neurotóxico do óleo-resina de copaíba (Copaifera reticulata Ducke, Fabaceae

    Directory of Open Access Journals (Sweden)

    Camile Giaretta Sachetti

    Full Text Available O óleo-resina de copaíba obtido do gênero Copaifera L., Fabaceae, é largamente utilizado na medicina popular como antiinflamatório, antimicrobiano e antitumoral. Porém, informações sobre seu potencial tóxico são escassos na literatura. O objetivo deste estudo foi estabelecer a toxicidade oral aguda e os possíveis efeitos neurotóxicos relacionados à ingestão do óleo-resina de Copaifera reticulata Ducke, Fabaceae, em ratas Wistar. O estudo foi conduzido com quinze ratas nulíparas distribuídas nos grupos de doses 300 e 2000 mg/kg pc de óleo-resina administrado por gavagem. Os resultados obtidos mostraram que nestas doses não houve sinais clínicos de toxicidade ou neurotoxicidade, alteração no consumo de ração ou alteração no peso corpóreo. A dose letal aguda foi estimada como maior que 2000 mg/kg pc e classificada como categoria 5, segundo o Guia OECD 423. Estes resultados indicam que existe uma relativa margem de segurança para o uso do óleo-resina de copaíba como agente terapêutico, embora estudos toxicológicos adicionais sejam ainda necessários, principalmente com a administração repetida de baixas doses.

  15. ANÁLISE AO MICROSCÓPIO ELETRÔNICO DE VARREDURA DAS PROJEÇÕES DE RESINA ("TAGS" EM DENTES RESTAURADOS APÓS INTERVENÇÃO ENDODÔNTICA

    Directory of Open Access Journals (Sweden)

    SHIMABUKO Danilo Minor

    1998-01-01

    Full Text Available Avaliou-se in vitro, em 25 caninos humanos restaurados em nível coronário com resina composta fotopolimerizável após sofrerem intervenção endodôntica, a formação de projeções de resina ("tags" quanto a sua uniformidade e quantidade, variando-se o modo de aplicação, e a influência do ataque ácido e do uso de adesivos dentinários nas superfícies restauradas. Através da avaliação qualitativa por 3 observadores de fotomicrografias obtidas ao microscópio eletrônico de varredura, observou-se que houve formação de "tags" com melhor uniformidade no grupo em que se aplicou a resina fluida com bolinhas de algodão e imediata colocação da resina composta, sendo os dois materiais polimerizados conjuntamente, e com maior quantidade no grupo em que a resina fluida foi homogeneizada com jateamento de ar. A ausência de ataque ácido ou a não aplicação do sistema de adesão à dentina podem prejudicar a formação dos "tags" de resina.

  16. Estudo da reação entre polietileno glicol e resina epoxídica na presença de N,N-dimetilbenzilamina Study of the reaction between polyethylene glycol and epoxy resins Using N,N-dimethylbenzylamine as catalyst

    Directory of Open Access Journals (Sweden)

    Mario Zacharuk

    2011-01-01

    Full Text Available Neste trabalho foi estudada a reação entre polietileno glicol (PEG e uma resina epoxídica à base de diglicidil éter de bisfenol A (DGEBA, na presença de N,N-dimetilbenzilamina (DMBA, sendo os produtos desta reação avaliados por espectroscopia no infravermelho (FTIR, espectroscopia de ressonância magnética nuclear de próton (RMN-1H e medidas de viscosidade cone-prato. Amostras curadas com um endurecedor à base de poliamina foram também submetidas a ensaios de tração e calorimetria exploratória diferencial (DSC. Os resultados das análises de viscosidade, FTIR e RMN (1H confirmaram a ocorrência da reação entre grupos epóxi do DGEBA e grupos hidroxila do PEG na presença de DMBA, a 100 ºC. As análises de DSC e os ensaios de tração dos sistemas curados mostram que a reação de DGEBA com PEG gera um material com temperatura de transição vítrea (Tg significativamente menor, em conjunto com o aumento da deformação na ruptura e decréscimo do modulo de elasticidade, quando comparados ao sistema epoxídico de referência (DGEBA.In this work the reaction of polyethylene glycol (PEG and epoxy resin (BADGE in the presence of N,N-dimethylbenzylamine (DMBA was studied. The reaction products were evaluated by infrared spectroscopy (FTIR, nuclear magnetic resonance spectroscopy (NMR and viscosity measurements. Samples cured with a polyamine-based hardener were also submitted to tensile tests and differential scanning calorimetry (DSC. The results of the viscosity analyses, FTIR and RMN (¹H confirmed the reaction between DGEBA epoxy groups and PEG hydroxyl groups in the presence of DMBA, at 100 ºC. DSC analyses and tensile tests of cured systems showed that the reaction of DGEBA with PEG leads to a reduction of Tg, generating a more flexible material.

  17. Efecto del oxígeno y la glucosa en la metanogénesis y mineralización de resinas poliméricas

    Directory of Open Access Journals (Sweden)

    Ulises Durán Hinojosa

    2010-01-01

    Full Text Available En el presente trabajo se evaluó el efecto de la concentración de oxígeno disuelto (OD y la presencia de la glucosa en la metanogénesis y mineralización de los compuestos de resinas poliméricas, mediante cultivos en lote. El inóculo utilizado para los cultivos fueron lodos procedentes de un reactor de lecho de lodos con flujo ascendente UASB (por sus siglas en inglés, alimentado con glucosa y aguas residuales de resinas poliméricas, y 1,0 mg L-1 d-1 de oxígeno disuelto en estado estacionario. Todas las pruebas fueron realizadas con 1500 mg L-1 de demanda química de oxígeno, a 30±2° C, con 23,8 g L-1 de sólidos suspendidos volátiles como inóculo y una relación demanda química de oxígeno / sólidos suspendidos volátiles de 1. El efecto de diferentes concentraciones de oxígeno disuelto mostró que, para la glucosa, con bajas concentraciones (0,6 y 1,0 mg L-1 la eficiencia de remoción de la demanda química de oxígeno y la actividad metanogénicas permanecieron constantes, pero la eficiencia de remoción de la demanda química de oxígeno para los compuestos de resinas poliméricas aumentó 58,1±1% y el rendimiento de metano disminuyó, debido a que una mayor fracción del carbono alimentado fue mineralizada a dióxido de carbono, posiblemente por una ruta aerobia. Los resultados con diferentes proporciones de glucosa / compuestos de resinas poliméricas (CRP en presencia de 0,6 mg L-1 de oxígeno disuelto mostraron que la presencia de glucosa no mejoró la eliminación de los compuestos de resinas poliméricas. Sin embargo, la actividad metanogénica disminuyó en un 75% cuando solamente se usó a los compuestos de resinas poliméricas como sustrato, al compararla con la actividad metanogénica con glucosa como única fuente de carbono, sugiriendo que la glucosa no favorece la eliminación de los compuestos de resinas poliméricas, pero proporciona una mejor tolerancia al oxígeno. Se concluye que la presencia de bajas

  18. Clinical effect of Resina Draconis capsules on primary dysmenorrhoea

    African Journals Online (AJOL)

    Clinical effect of Resina Draconis capsules on primary dysmenorrhoea. Li Sun, Jia Wang. Abstract. Purpose: To examine the effectiveness of Resina Draconis capsules in the treatment of primary dysmenorrhoea. Methods: In total, 324 patients with primary dysmenorrhoea were randomly allocated to three groups based on ...

  19. Tableros de partículas de bambú (Bambusa vulgaris Schrad y resina poliuretana a base de aceite de rícino (Ricinus communis L.

    Directory of Open Access Journals (Sweden)

    Flávio Januário José

    Full Text Available Esta investigación tiene como objetivo la elaboración y la evaluación de tableros de partículas homogéneas aglomeradas, utilizándose dos materiales alternativos en la búsqueda de la sustentabilidad del proceso productivo. Fueron utilizadas partículas de Bambusa vulgaris Schrad por la rapidez del ciclo de producción de esta especie de bambú. Como pegante fue utilizada la resina poliuretana a base de aceite de ricino (Ricinus communis L., por su origen parcialmente renovable, y por ser considerada no tóxica. Para la caracterización del material, fueron fabricadas, en escala de laboratorio, tableros de partículas de bambú con dimensiones inferiores al 2.4 mm, combinadas con 5%, 10% y 15% de resina en relación a la masa de partículas de bambú. Probetas fueron evaluadas de acuerdo con las especificaciones de la norma NBR 14810 - Tableros de madera aglomerada. Antes de los ensayos de compresión las probetas fueron evaluadas por medio del ensayo no destructivo por ultra-sonido. Los resultados obtenidos indicaron que los tableros con el contenido de 10% de resina no fue estadísticamente diferente al contenido de 15%, siendo ambos superiores al contenido de 5%. La mayoría de las propiedades de los tableros fueron inferiores a aquellas de los tableros comerciales. No fue posible correlacionar la velocidad del pulso de ultra-sonido con la resistencia a la compresión longitudinal.

  20. Cierre de diastema con resinas compuestas híbridas

    Directory of Open Access Journals (Sweden)

    Alain Manuel Chaple Gil

    Full Text Available El tratamiento para el cierre de diastemas fundamentalmente está enfocado a otorgar estética y salud periodontal. Los diastemas pueden ser resueltos con prótesis y ortodoncia, sin embargo, estas opciones generalmente requieren de preparaciones del tejido sano, incluyen procedimientos de laboratorio y aumentan el tiempo clínico. La utilización de resinas compuestas constituye una opción estética y funcional para estos casos en los que se requiere de mínima intervención sobre el tejido sano o de ninguna. El propósito de esta presentación es describir un caso de cierre de diastema central anterosuperior utilizando resinas compuestas híbridas. Una paciente femenina de 21 años de edad acude a consulta para tratarse un diastema central superior. Se le propuso realizarle un cierre con resina compuesta híbrida. Se aplicó consentimiento informado y se obtuvo aprobación. Se realizó resolución del diastema con técnica incremental con resina híbrida hasta lograr el punto de contacto cuidando la salud periodontal. Se planificó el tratamiento, se pulieron las superficies a incrementar, se aplicaron sistemas adhesivos y se aplicaron capas de resina hasta lograr el resultado deseado. Mejoró la estética y se logró la total satisfacción de la paciente. En este caso, los pasos de la técnica de restauración directa con incremento d4e resina compuesta híbrida fueron seguidos adecuadamente. Se logró el cierre del diastema y el restablecimiento del punto de contacto sin forzar la papila interdental.

  1. Mechanical properties of unidirectional laminates with carbon fiber and epoxy resin DA4518U USG0540; Propiedades mecanicas de los laminados unidireccionales de fibra de carbono con resina epoxica DA4518U Y USG0540

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Melo, Monica I.; Rubio Gonzalez, Carlos; Del Llano Vizcaya, Luis [CIDESI. Centro de Ingenieria y Desarrollo Industrial Queretaro, Queretaro (Mexico)]. E-mail: monica.sanchez.melo@gmail.com; crubio@cidesi.mx; lvizcaya@cidesi.mx

    2010-11-15

    In this paper, a study of the mechanical properties of composite materials with carbon fiber and epoxy resin DA4518U USG0540 is described, due to no such properties have been published to date, this study is performed. This work is developed at the Center for Engineering and Industrial Development (CIDESI). As a part of this research, the elastic modulus, Poisson's ratio and shear modulus are obtained both analytical and experimentally. Tests are performed to high cycle fatigue in both materials, and then these specimens are examined by ultrasound with the immersion technique in order to detect variations in material delamination, changes in obtain the attenuation and wave propagation. Finally, the tensional test to the specimen fatigue is repeated for changes in their mechanical properties. Also, a comparison is made between the results to determine which of those materials is more reliable for future applications in the aerospace industry. [Spanish] En este articulo se describe el estudio de las propiedades mecanicas de los materiales compuestos de fibra de carbono con resina epoxica DA4518U y USG0540, dicho estudio se lleva a cabo debido a que, a la fecha, no se han publicado tales propiedades, este trabajo se desarrollo en el Centro de Ingenieria y desarrollo Industrial (CIDESI). Como parte de esta investigacion, se obtienen analitica y experimentalmente el modulo de elasticidad, modulo de Poisson y modulo de corte. Tambien se realizan pruebas de fatiga a altos ciclos en ambos materiales, posteriormente estos especimenes se examinan por ultrasonido con la tecnica de inmersion para detectar variaciones en el material como delaminaciones, cambios de atenuacion y en la velocidad de propagacion de onda. Por ultimo se repite la prueba de tension a la probeta fatiga para conocer los cambios en sus propiedades mecanicas. Asi mismo se hace una comparacion entre los resultados obtenidos, para determinar cual material es mas confiable para futuras aplicaciones en la

  2. [Furfural degradation by filamentous fungus Amorphotheca resinae ZN1].

    Science.gov (United States)

    Wang, Xiaofeng; Zhang, Jian; Xin, Xiujuan; Bao, Jie

    2012-09-01

    Some degradation products from lignocellulose pretreatment strongly inhibit the activities of cellulolytic enzymes and ethanol fermentation strains, thus the efficient removal of the inhibitor substances ("detoxification") is the inevitable step for the biotransformation processes. In this study, the biological detoxification of furfural by a newly isolated fungus, Amorphotheca resinae ZN1, was studied and the metabolic pathways of furfural degradation was analyzed. The metabolic pathway of furfural degradation in A. resinae ZN1 was described as follows: first, furfural was quickly converted into the low toxic furfuryl alcohol; then the furfuryl alcohol was gradually converted into furfural again but under the low concentration under aerobic condition, which was not lethal to the growth of the fungi; furfural continued to be oxidized to furoic acid by A. resinae ZN1. It is likely that furoic acid was further degraded in the TCA cycle to complete the biological degradation of furfural. The present study provided the important experimental basis for speeding up the biodetoxification of furfural by A. resinae ZN1 and the rate-limiting step in the lignocellulose biotransformation to ethanol.

  3. Resinas acetálicas: diversas aplicaciones en odontoestomatología

    OpenAIRE

    Puigpelat Martí, Ana M.; Casanellas Bassols, Josep M. (Josep Maria)

    1994-01-01

    La resina acetálica o Polioxime­tileno (POM) es un nuevo material estético de reciente aplicación en el campo de la Odontoestomatolo­gía. En este artículo presentamos al­gunas de las aplicaciones donde la estética desempeña una función importante. Una de las aplicaciones de las re­sinas acetálicas es el campo de la Prótesis Parcial Removible, cuan­do queremos sustituir los retene­dores vestibulares convencionales (metálicos) por retenedores más es­téticos. Otra posible aplicación puede ser la...

  4. Resistência à compressão entre uma resina composta direta e dois cerômeros = Resistence of compression between a direct composite resin and two “cerômeros”

    Directory of Open Access Journals (Sweden)

    Gouvêa, Cresus Vinícius Depes de

    2007-01-01

    Full Text Available Esse estudo avaliou a resistência à fratura de duas resinas laboratoriais que se encontram no mercado, a Artglass® e a Targis® e como grupo comparador, a resina composta direta TPH®. Foram utilizados cinco corpos de prova de cada resina a ser testada. Com o auxílio de matrizes em aço inoxidável com forma de um cone segmentado, com medidas internas de 8,0 mm de diâmetro na base, 9,0 mm na porção superior e 4,0 mm de altura, foram confeccionados os corpos de prova. As amostras foram mantidas em água destilada por 72 horas e submetidas a uma carga axial por ação de uma ponta de extremidade arredondada de 2 mm diâmetro, adaptada a uma máquina de teste universal EMIC 500. A velocidade foi de 0,5 mm/min, com uma célula de capacidade de carga de 200 kgf. A carga e o ponto de fratura foram registrados na máquina. As médias foram calculadas em kgf, sendo o Artglass® apresentando A = 223,46; Targis® T = 204,13; TPH® Tp = 98,26. Os dados foram submetidos à análise estatística. Observou-se que a resina TPH obteve significativamente menor resistência à compressão enquanto Targis e Artiglass não apresentaram diferença estaticamente significativamente entre si; o conteúdo de carga inorgânica influencia positivamente na resistência à compressão

  5. Estudo de resistência à tração de três sistemas adesivos associados a resina composta em superfícies dentinárias

    Directory of Open Access Journals (Sweden)

    MATOS Adriana Bona

    2001-01-01

    Full Text Available Este trabalho teve como objetivo comparar a resistência à tração de três sistemas adesivos associados a resina composta aderidos à superfície dentinária. Quarenta e cinco superfícies de dentina foram obtidas a partir de molares humanos extraídos, sobre elas foi preparado "smear layer" e foram divididas em 3 grupos: G1 adesivo autocondicionante + resina micro-híbrida; G2 adesivo de componente único + ácido e resina micro-híbrida e G3 adesivo convencional (ácido + "primer" + bond + resina micro-híbrida, aplicados de acordo com as instruções dos fabricantes. Os corpos-de-prova foram preparados para teste de tração, imersos em água destilada por 24 horas a 37ºC. Findo este tempo, o teste de tração foi realizado em máquina de ensaio Inströn com velocidade constante de 0,5 mm/min. Os resultados foram expressos em MPa e submetidos a análise de variância (p < 0,05. Os autores concluíram que: o tipo de sistema adesivo influenciou na resistência à tração das resinas compostas testadas; o sistema adesivo de componente único apresentou os melhores resultados de resistência adesiva.

  6. Avaliação da temperatura de transição vítrea de compósitos poliméricos reparados de uso aeronáutico Evaluation of glass transition temperature of the repaired polymeric composites of aeronautical use

    Directory of Open Access Journals (Sweden)

    Jane M. F. de Paiva

    2006-03-01

    Full Text Available Este trabalho mostra a avaliação da temperatura de transição vítrea (Tg, por DMTA, de três famílias de compósitos poliméricos reparados, tendo como laminados base tecidos de fibras de carbono/resina epóxi modificada com elastômero (F584, vidro/resina epóxi (F161 e aramida/resina epóxi (F161. Os compósitos foram laminados manualmente por processo convencional e curados em autoclave de indústria aeronáutica. Posteriormente, danos foram simulados sendo, em seguida, reparados adotando-se a técnica de sobreposição de camadas de pré-impregnados de resina epóxi (F155, com adição de filme adesivo de epóxi (FM 73. As curvas DMTA mostram os efeitos da combinação de diferentes sistemas de resinas na Tg e, conseqüentemente, na temperatura de serviço do componente reparado. O material de reparo utilizado, baseado em pré-impregnados com resina epóxi F155 e filme adesivo de epóxi, provocou a redução da Tg dos compósitos reparados. Para os laminados base com tecido de fibras de carbono e vidro foram verificadas reduções de aproximadamente 30 °C na Tg. Este efeito foi mais pronunciado (redução de aproximadamente 40 °C quando o laminado reparado de aramida foi submetido a condicionamento higrotérmico a temperatura e umidade elevadas. Esta redução na Tg dos laminados reparados é atribuída à migração do adesivo para o pré-impregnado de resina epóxi F155 utilizado no reparo, durante o processo de cura, e à plasticização do sistema polimérico pela água, durante o condicionamento higrotérmico. A redução da Tg leva a uma conseqüente redução da temperatura de serviço do compósito polimérico reparado.This work shows the evaluation of the glass transition temperature (Tg by DMTA of three different families of repaired polymeric composites, manufactured with carbon fiber fabric/epoxy F584, glass fabric/epoxy F161 and aramide fabric/epoxy F161, respectively. The composites were laminated by conventional hand

  7. Analysis of biodegradation performance of furfural and 5-hydroxymethylfurfural by Amorphotheca resinae ZN1

    Science.gov (United States)

    2014-01-01

    Background Furfural and 5-hydroxymethylfurfural (HMF) are the degradation products of lignocellulose during pretreatment operations and significantly inhibit the consequent enzymatic hydrolysis and fermentation processes. The biodetoxification fungus Amorphotheca resinae ZN1 had demonstrated its excellent capacity on degrading lignocellulose derived inhibitors and helped the fermentation processes to achieve high yield of ethanol and biochemicals. Analysis of the biological degradation performance of furfural and HMF by A. resinae ZN1 will provide essential information for their fast and complete removal from the pretreated lignocellulose materials and facilitate the consequent ethanol fermentation. Results The degradation performance of furfural and HMF by A. resinae ZN1 was investigated by capturing intermediate metabolic products at various culture conditions. A. resinae ZN1 converts furfural/HMF into furfuryl/HMF alcohols and furoic/HMF acids simultaneously at aerobic condition, and only the corresponding furfuryl/HMF alcohols are obtained at anaerobic condition. The existence of glucose accelerates the degradation rate of furfural and HMF by A. resinae ZN1 and the cell mass growth rate aerobically. Remarkably, glucose is not consumed before furfural or HMF is degraded to a low threshold concentration. The finding suggests that furfural or HMF has a substrate priority of utilization by A. resinae ZN1 than glucose. This property may help the detoxification of furfural and HMF to be operated without consuming glucose. Conclusions The biological degradation performance of furfural and HMF by A. resinae ZN1 was investigated experimentally. Oxygen supply is important on the complete biodegradation of furfural and HMF by A. resinae ZN1. Furfural or HMF has the priority of substrate utilization than glucose by A. resinae ZN1. This study provided important information for detoxification enhancement and strain modification. PMID:24708699

  8. Modificação de fibra de carbono com PBLH e sua utilização em compósitos com resina epoxídica Hydroxyl-terminated polybutadiene-grafted carbon fiber in epoxy resin-based composites

    Directory of Open Access Journals (Sweden)

    Fábio L. Barcia

    1999-06-01

    Full Text Available Fibras de carbono contendo 1,4 e 2,1mmol/g de grupos carboxila e hidroxila fenólica, respectivamente, foram modificadas através de reação com TDI, resultando em fibras contendo 3,1 mmol/g de grupos isocianato. A introdução de grupos isocianato na superfície da fibra tornou possível a sua modificação com polibutadieno líquido hidroxilado. Fibras de carbono modificadas e não modificadas foram empregadas na preparação de compósitos com resina epoxídica, sendo observado um aumento considerável de resistência ao impacto em compósitos constituídos de fibras de carbono enxertadas com PBLH, devido, provavelmente, à natureza elastomérica da interface e à melhor adesão interfacial.Carbon fibers containing 1,4 e 2,1 mmol/g of carboxyl and phenolic hydroxyl groups, respectively, were modified through the reaction with TDI. The presence of isocyanate groups at the fiber surface made possible the fiber modification with hydroxyl terminated polybutadiene (HTPB. These modified and unmodified carbon fibers were employed in the preparation of epoxy resin-based composites. A substantial improvement in the impact properties was observed in the composites with HTPB-grafted carbon fibers when compared to unmodified carbon fibers. These results may be attributed to a higher interfacial adhesion promoted by reactions between the functional groups present at the modified carbon fiber surface and the epoxy matrix.

  9. Aging of Organic Matrices, Epoxy Resins; Causas de envejecimiento de matrices organicas. Resinas epoxidicas

    Energy Technology Data Exchange (ETDEWEB)

    Pazos, M.; Prendes, P.; Varela, M.; Paz, S. [Departamento de I mas D de Gairesa, La Coruna (Spain)

    1997-09-01

    Epoxy resins are very important polymers widely used in advance materials. Approximately 200.000 Tns/year are used in different fields such as coating, floor and paving, adhesives, composites, etc. Due to the importance of these polymers, aging studies are necessary. In this work most important aging-factors are described. We have observed that the water plays a very important role in the degradation-process. (Author)

  10. Evaluación de resinas de intercambio iónico para el control del hierro en soluciones de electro-obtención de cobre

    Directory of Open Access Journals (Sweden)

    Parada, F.

    2010-08-01

    Full Text Available Two commercial resins were evaluated for the extraction of iron from a copper electrowinning solution. Both resins efficiently extract iron. TheMonophosphonic resin has a greater charge capacity than the Diphonix resin and the Diphonix resin shows faster kinetics. Experimental results of the interrupted test and tests with different particle size of resins have demonstrated that extraction kinetics is controlled by diffusion into the particle in both resins. A good agreement with Fick’s model for diffusion inside the particles confirms the proposed mechanism. Finally, temperature favors the process kinetics and its effect on the diffusion coefficient follows Arrhenius law, obtaining a value of 4,89 kcal/mol for theMonophosphonic resin and 4,94 kcal/mol for the Dphonix resin. The aforementioned values are close to typical values for the proposed diffusional control which are 6 to 10 kcal/mol.

    Se evaluaron dos resinas comerciales para la extracción del hierro desde una solución de electro-obtención de cobre. Ambas resinas extraen en forma eficiente el hierro, pero se diferencian en que la resina Monophosphonic tiene una mayor capacidad de carga que la resina Diphonix, mientras que la Diphonix muestra una cinética más rápida. Los resultados de la prueba interrumpida y de las pruebas para determinar el efecto del tamaño de partícula permiten concluir que el control más probable para la cinética de extracción es por la difusión en la partícula en ambas resinas. Un buen ajuste al modelo de Fick para difusión en la partícula confirman el tipo de control propuesto. Finalmente, la temperatura favorece la cinética del proceso de extracción y su efecto en el coeficiente de difusión sigue la ley de Arrhenius obteniendo un valor para la energía de activación de 4,89 kcal/mol para la resina Monophosphonic y 4,94 kcal/mol para la resina Diphonix. Estos valores están cercanos al valor típico para el control propuesto que es de 6 a

  11. Polymerization shrinkage evaluation of three packable composite resins using a gas pycnometer Avaliação da contração de polimerização de três resinas compactáveis, medida por picnômetro a gás

    Directory of Open Access Journals (Sweden)

    Ricardo Amore

    2003-09-01

    Full Text Available Modern restorative dentistry has been playing an outstanding role lately since composite resins, allied to adhesive systems, have been widely applied on anterior and posterior teeth restorations. The evolution of composite resins has mostly been verified due to the improvement of their aesthetic behavior and the increase in their compressive and abrasive strengths. In spite of these developments, the polymerization shrinkage inherent to the material has been a major deficiency that, so far, has been impossible to avoid. Using a gas pycnometry, this research investigated the polymerization shrinkage of three packable composite resins: Filtek P60 (3M, Prodigy Condensable (Kerr, and SureFil (Dentsply/Caulk, varying the distance from the light source to the surface of the resins (2 mm or 10 mm. The pycnometer Accupyc 1330 (Micromeritics, USA precisely records helium displacement, allowing fast and reliable measurements of the volume of composite resin immediately before and after polymerization, without interference of temperature or humidity. Results were not found to be statistically different for the three tested resins, either for 2 mm or 10 mm-distance from the light source to the composite surface.A Odontologia Restauradora moderna tem se destacado nos últimos anos e as resinas compostas, aliadas aos sistemas adesivos, têm sido muito empregadas para restaurações de dentes anteriores e posteriores. A evolução das resinas compostas tem sido constatada na melhoria do seu comportamento estético e no aumento da sua resistência à compressão e à abrasão. Apesar dos avanços mencionados, a contração de polimerização, inerente a esse material, continua sendo uma grande deficiência e, por enquanto, impossível de ser evitada. Nesta pesquisa a contração de polimerização de três resinas compostas compactáveis, Filtek P60 (3M, Prodigy Condensável (Kerr e SureFil (Dentsply/Caulk, variando-se a distância entre a fonte de luz e a

  12. Bond strength of hard chairside reline resins to a rapid polymerizing denture base resin before and after thermal cycling Resistência de união de resinas rígidas para reembasamento imediato a resina para base de prótese de rápida polimerização antes e após termociclagem

    Directory of Open Access Journals (Sweden)

    Karin Hermana Neppelenbroek

    2006-12-01

    analisados por análise de variância (ANOVA e teste de Newman-Keuls (alfa=0,05. RESULTADOS: A resina QC-20 demonstrou a menor resistência de união entre os materiais reembasadores (p<0,05 e apresentou falhas predominantemente coesivas. De modo geral, os valores de resistência de união das resinas rígidas para reembasamento imediato foram similares (10,09±1,40 a 15,17±1,73 MPa e a maioria de falhas foram do tipo adesiva/coesiva (mista. Entretanto, a resina Ufi Gel Hard unida à resina QC-20 polimerizada pelo ciclo A e não termociclada apresentou a maior resistência de união (p<0,001. Quando as resinas Tokuso Rebase Fast e Duraliner II foram unidas à resina QC-20 polimerizada pelo ciclo A, a resistência de união aumentou (p=0,043 após a termociclagem. CONCLUSÕES: QC-20 apresentou os menores valores de resistência de união em todos os grupos. Em geral, os valores de resistência de união das resinas reembasadoras rígidas foram comparáveis e não foram influenciados pelo ciclo de polimerização da resina QC-20 e pela termociclagem.

  13. Comparação dos valores de desgaste abrasivo e de microdureza de 13 resinas compostas usadas em odontologia através do método do disco retificado

    OpenAIRE

    Bianchi,Eduardo C.; Aguiar,Paulo R. de; Alves,Manoel C. S.; Freitas,César A. de; Rodrigues,Ana R.; Carvalho Jr.,Oscar B. de

    2007-01-01

    Atualmente tem-se buscado simplificar a tarefa de caracterização da vida útil de restaurações dentárias realizadas por resinas compostas através de métodos laboratoriais, que são mais rápidos e não sofrem influência de variáveis pessoais inerentes às análises clínicas. Com este propósito, este trabalho apresenta uma nova metodologia de ensaio laboratorial para a avaliação do desgaste abrasivo de resinas compostas através do método do disco retificado. Realizaram-se ensaios de resistência ao d...

  14. Estudio de minerales cubanos para la preparación de resinas compuestas

    Directory of Open Access Journals (Sweden)

    Rubén Álvarez-Brito

    2004-03-01

    Full Text Available Las resinas compuestas o composites se ubican entre los materiales restauradores que se emplean en la reparación de tejido dental dañado. Las cargas inorgánicas que se le incorporan a las resinas compuestas le confieren mejores propiedades físico-mecánicas. Se prepararon resinas compuestas autocuradas a base de Bis-GMA y dimetacrilato de tetraetilenglicol (TEEDGMA, utilizando como carga inorgánica minerales de cuarzo procedente de Santa Lucía y de El Cacahual, caolín de la Isla de la Juventud y sheridanita de Holguín. Los rellenos fueron tratados previamente con metacriloxipropiltrietoxisilano y aminopropiltrietoxisilano como agentes de acoplamiento. Se les determinó la distribución de tamaños de partículas antes y después del tratamiento, y se observó en todos los casos un aumento del tamaño de partícula luego del tratamiento. Además, se determinó el grado de blancura, correspondiendo el mayor valor al cuarzo de El Cacahual. Se realizaron análisis químicos para determinar cuantitativamente los óxidos de silicio, hierro, magnesio, calcio, aluminio y titanio, además plomo y cadmio. Las resinas preparadas con los rellenos fueron evaluadas mediante el ensayo de resistencia a la compresión y comparación de la coloración con resinas comerciales, y se encontró que las preparadas con cuarzo presentan mayor resistencia mecánica y mejor coloración.

  15. Influence of a cobalt-chromium metal framework on surface roughness and Knoop hardness of visible light-polymerized acrylic resins Influência de estrutura metálica de cobalto-cromo na rugosidade e dureza Knoop superficiais de resinas acrílicas polimerizadas por luz visível

    Directory of Open Access Journals (Sweden)

    Joane Augusto de Souza Júnior

    2006-06-01

    Full Text Available Although visible light-polymerized acrylic resins have been used in removable partial dentures, it is not clear whether the presence of a metal framework could interfere with their polymerization, by possibly reflecting the light and affecting important properties, such as roughness and hardness, which would consequently increase biofilm accumulation. The aim of this study was to compare the roughness and Knoop hardness of a visible light-polymerized acrylic resin and to compare these values to those of water-bath- and microwave-polymerized resins, in the presence of a metal framework. Thirty-six specimens measuring 30.0 x 4.0 ± 0.5 mm of a microwave- (Onda Cryl, a visible light- (Triad and a water-bath-polymerized (Clássico (control acrylic resins containing a cobalt-chromium metal bar were prepared. After processing, specimens were ground with 360 to 1000-grit abrasive papers in a polishing machine, followed by polishing with cloths and 1-µm diamond particle suspension. Roughness was evaluated using a profilometer (Surfcorder SE 1700 and Knoop hardness (Kg/mm² was assayed using a microhardness tester (Shimadzu HMV 2000 at distances of 50, 100, 200, 400 and 800 µm from the metal bar. Roughness and Knoop hardness means were submitted to two-way ANOVA and compared by Tukey and Kruskal Wallis tests at a 5% significance level Statistically significant differences were found (p0.05. Within the limitations of this in vitro study, it was concluded that the presence of metal did not influence roughness and hardness values of any of the tested acrylic resins.Resinas acrílicas polimerizadas por luz visível têm sido indicadas para a confecção de próteses parciais removíveis. Entretanto, não há estudos determinando se a presença de estrutura metálica interfere ou não na polimerização, considerando que essa estrutura pode refletir a luz e afetar propriedades como rugosidade e dureza e, consequentemente, facilitar o acúmulo de biofilme

  16. Intensidade de fluorescência em resina composta: influência do polimento superficial e dos meios de armazenagem

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    Ângela Dalla Nora

    Full Text Available INTRODUÇÃO: A resina composta é um material versátil em Odontologia Estética, principalmente por suas propriedades ópticas, dentre as quais a fluorescência. Poucos são os estudos que avaliaram esta propriedade e a comparação dos resultados encontrados torna-se difícil em função da inexistência de padronização nas metodologias na confecção e na armazenagem dos corpos de prova. OBJETIVO: Verificar a influência do polimento superficial e do meio de armazenagem, em estudos in vitro, em que se avalia a propriedade óptica de fluorescência em resinas compostas. MATERIAL E MÉTODO: Foram preparados 70 corpos de prova circulares (10 mm × 2 mm com resina composta microhíbrida (Opallis,- A2E - FGM. Os meios de armazenagem foram: água deionizada, água da torneira e saliva artificial. Os protocolos de polimento superficial, realizados em politriz após a obtenção dos corpos de prova, utilizaram lixas de granulações 600, 1200 e 2500. Os valores de intensidade de fluorescência foram avaliados através do espectrofotômetro Cary Eclipse, após 1, 7 e 21 dias. RESULTADO: Não houve diferença estatisticamente significativa na Intensidade de Fluorescência entre os grupos submetidos aos diferentes protocolos de polimento. Quanto aos meios de armazenagem, a partir do sétimo dia, a variação de fluorescência foi significativamente maior em água da torneira e deionizada, quando comparada à variação observada em saliva artificial, resultado que se manteve após 21 dias. CONCLUSÃO: O protocolo de polimento superficial não promoveu alterações significativas na fluorescência da resina composta avaliada. Quanto ao meio de armazenagem, a intensidade de fluorescência foi menos afetada quando em saliva artificial.

  17. Factores determinantes que ejercen influencia sobre el redimiento clínico de restauraciones con resina

    OpenAIRE

    Lahoud Salem, Víctor

    2014-01-01

    Las resinas compuestas pertenecen a los materiales más modernos empleados en la odontología contemporánea. Representan un mejoramiento significativo sobre los primeros restauradores de tipo polímero que consistieron de resinas metacrílicos sin relleno, de calidad inferior, y han tenido muchas deficiencias y limitaciones, los resultados obtenidos con las resinas compuestas de la última generación han dado satisfacción tanto al paciente como al odontólogo debido a que ofrecen una estética supe...

  18. Infiltração marginal em restaurações de resina composta com diferentes materiais adesivos intermediários = Marginal leakage in resin composite restorations lined with different adhesive materials

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    Moraes, Rafael Stanziona de

    2007-01-01

    Full Text Available Este estudo avaliou a capacidade de selamento de restaurações de resina composta com diferentes materiais adesivos intermediários. Cavidades Classe V padronizadas, com margens em esmalte e dentina/cemento, foram confeccionadas em incisivos bovinos. A resina de alto escoamento Fill Magic (Vigodent e o cimento ionomérico Vitremer (3M ESPE foram empregados como intermediários de restaurações com os compósitos Charisma e Solitaire (Heraeus Kulzer, formando 6 grupos (n = 14: [C1] – compósito microhíbrido Charisma; [C2] – Fill Magic + Charisma; [C3] – Vitremer + Charisma; [S1] – compósito condensável Solitaire; [S2] – Fill magic + Solitaire; [S3] – Vitremer + Solitaire. Após acabamento e polimento, as amostras foram armazenadas em solução fisiológica a 37ºC, por 30 dias, e então imersas em solução de fucsina básica a 0,5% por 24h. Os dentes foram longitudinalmente seccionados e a penetração do corante avaliada sob magnificância (40×, por dois examinadores, com escores padronizados. Os dados foram submetidos ao teste estatístico não-paramétrico de Kruskal-Wallis. Nas margens em esmalte, diferenças significativas foram verificadas apenas para a associação de intermediários à resina Solitaire, com os grupos S2 (p < 0,05 e S3 (p < 0,001 apresentando escores de infiltração significativamente maiores em relação aos demais. As margens em dentina/cemento apresentaram maior penetração em relação às margens em esmalte (p < 0,001. Apenas a associação do Vitremer às duas resinas melhorou o selamento deste substrato, com os grupos C3 (p < 0,001 e S3 (p < 0,05 apresentando os menores escores de infiltração

  19. Utilização de resinas de troca-iônica em efluentes de galvanoplastia.

    OpenAIRE

    Josiane Costa Riani

    2008-01-01

    A crescente industrialização acompanhada do uso de metais pesados nos processos industriais nas últimas décadas resultou num aumento da contaminação do meio ambiente, principalmente em ambientes aquáticos. Assim, sendo a água um recurso natural de suma importância para a vida, métodos de tratamento de efluentes tornam-se indispensáveis para empresas geradoras de efluentes. O objetivo desse trabalho é a utilização de um sistema de troca iônica constituído por micro-colunas de resinas catiônica...

  20. Análise de custo de materiais utilizados em restaurações dentárias em resina composta

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    Eduardo Hebling

    Full Text Available INTRODUÇÃO: As resinas compostas são materiais usualmente utilizados em restaurações dentárias diretas de dentes posteriores. O custo dos materiais faz parte do cálculo do valor dos honorários odontológicos. OBJETIVO: O objetivo deste trabalho foi determinar e analisar o valor total do custo dos materiais utilizados para a confecção de restaurações dentárias diretas de dentes posteriores em resina composta. MATERIAL E MÉTODO: O cálculo dos custos foi baseado no método de sistema de custeio variável. A lista dos materiais foi obtida por meio de consulta a uma banca de juízes e baseada nos padrões de excelência comprovados na literatura para atendimento em equipe. Os valores dos materiais foram obtidos de uma média dos valores consultados no mercado fornecedor. As repetições foram obtidas de preparos cavitários Classes I e II em dentes pré-molares e molares artificiais pré-fabricados. Os materiais foram quantificados para cada tipo de preparo. As resinas compostas utilizadas foram pesadas em balança de precisão após a sua inserção em cada tipo de preparo. Os dados foram avaliados por estatística descritiva e pelos testes de Mann-Whitney e Kruskal-Wallis. RESULTADO: O custo encontrado para restauração de Classe I foi de R$17,56 e, para a de Classe II, de R$17,73. Não houve diferença estatística no custo entre os tipos de preparo e de dentes, sendo a média total de R$17,65. CONCLUSÃO: Os valores encontrados podem ser utilizados no cálculo do valor final do procedimento restaurador, auxiliando na gestão de serviços odontológicos públicos ou privados.

  1. Resistência à tração entre amálgama e resina composta em diferentes condições de oxidação - estudo in vitro

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    YOUSSEF Michel Nicolau

    1999-01-01

    Full Text Available Este trabalho estuda in vitro a resistência à tração de corpos-de-prova de amálgama-resina composta unidos pelo adesivo dental Scotchbond Multi-Uso Plus. Os corpos-de-prova foram divididos em três grupos de dez, sendo que cada corpo era o resultado da união de dois discos, um de amálgama e outro de resina composta. Esses discos foram obtidos dentro de cilindros de baquelite e sofreram acabamento superficial com lixa de grana 600. Pretendeu-se simular a técnica do amalcomp e verificar a resistência à tração entre o amálgama e a resina composta em diferentes condições de oxidação do amálgama. Dos resultados obtidos e mediante análise de variância e teste de Tukey a 5%, pôde-se concluir que: o Grupo 3, que ficou na saliva artificial por trinta dias e portanto sofreu maior oxidação, apresenta resistência à tração superior e estatisticamente significante em relação aos grupos 1 e 2; o Grupo 2, que ficou na saliva por sete dias e sofreu menor oxidação, não apresenta resistência à tração estatisticamente superior ao Grupo 1 de amálgama recém-condensado.

  2. Comportamiento del los aplacados de piedra reforzados

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    Vera Soriano, Roberto

    2003-04-01

    Full Text Available The improvement of the mechanical performance Bateig Novelda stone coatings anchored in back-ventilated facades has been studied after being reinforced with glass fiber frames adhered with epoxy resin.Esta trabajo presenta el resultado de la investigación llevada a cabo por un grupo del Departamento de Construcciones Arquitectónicas de la Escuela de Arquitectura de Alicante en colaboración con la industria de la piedra aplicada a la construcción. El trabajo muestra el comportamiento mecánico de las placas de piedra Bateig de Novelda, empleadas en fachadas ventiladas, reforzadas con fibra de vidrio adherida con resina epoxi.

  3. Regeneración de una resina de cambio iónico para su uso en la disminución de la dureza del agua. Simulación animada del proceso.

    OpenAIRE

    Milla González, Miguel

    2015-01-01

    Mediante una sencilla animación se muestra la sustitución de los iones metálicos (calcio) por protones en la regeneración con HCl de una resina catiónica para su uso posterior en el ablandamiento de una muestra de agua.

  4. Avaliação de monômero residual em resinas acrílicas de uso ortodôntico e protético: análise por espectroscopia Evaluation of residual monomer in autopolymerizing acrylic resins: spectroscopy analysis

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    Roberto Rocha Filho

    2007-04-01

    Full Text Available OBJETIVO: duas marcas comerciais de resinas acrílicas ativadas quimicamente (RAAQ, uma de uso ortodôntico (Orto Cril® e outra de uso protético (Jet®, polimerizadas em presença e ausência de pressão, foram analisadas em relação ao conteúdo de monômero (MMA residual liberado em solução, em diferentes intervalos de tempo (0,083; 0,25; 1; 1,25; 2,17; 5; 9; 14 e 21 dias. METODOLOGIA: a espectroscopia de absorção no ultravioleta foi utilizada na análise de soluções aquosas de MMA, com concentrações conhecidas, visando a determinação de uma curva de calibração. Soluções aquosas contendo corpos-de-prova, confeccionados com as citadas RAAQ, foram também submetidas à análise por espectroscopia de absorção no ultravioleta. RESULTADOS E CONCLUSÕES: os resultados foram comparados aos dados da curva de calibração, visando estabelecer a concentração de MMA residual das amostras. Eles permitiram concluir que o nível de MMA residual liberado em solução foi mais elevado durante as primeiras 24 horas, havendo uma tendência à estabilização a partir desse período e que a resina acrílica de uso ortodôntico apresentou níveis mais elevados de MMA em solução do que a de uso protético, em ambas as condições de polimerização empregadas, com presença e ausência de pressão. Além disso, a presença de pressão, durante a polimerização das duas resinas, elevou a concentração de MMA em solução, não havendo, entretanto, efeito da interação entre as marcas das resinas e a presença e ausência de pressão na concentração de MMA em solução, medida ao longo do tempo. Porém, todas as três variáveis (tempo, resina e pressão foram significantes.AIM: Two comercial brands of auto polymerizing acrylic resins (one for orthodontics use, Orto Cril®, and the other for prosthetics use, Jet® were analyzed concerning the amount of methyl methacrilate (MMA monomer dissolved in solution, processed under and not under

  5. RECICLAGEM DE PLACAS DE CIRCUITO IMPRESSO DE COMPUTADORES SUCATADOS PARA A RECUPERAÇÃO DE ESTANHO POR ELETROELUIÇÃO DE RESINAS POLIMÉRICAS DE TROCA IÔNICA

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    Afonso Henriques Martins

    2014-08-01

    Full Text Available Este trabalho apresenta os resultados experimentais para a recuperação de estanho presente em soluções aquosas a parir da reciclagem de computadores sucatados, através da técnica de eletroeluição de resina polimérica catiônica Amberlite IR-120®(Merck, USA. A resina foi carregada pela passagem de 200ml de solução aquosa 0,2g/l de Sn em 2,18N H2SO4 (concentração do licor de lixiviação de placas de circuito impresso-PCI de microcomputadores sucatados através do leito de 10g de resina. A realização dos experimentos foi baseada em um planejamento estatístico pelo método fatorial completo replicado de três variáveis a dois níveis. A otimização foi feita pelo método do passo ascendente. As condições consideradas ótimas visando a eletrorrecuperação de estanho foram 150A/m2 de densidade de corrente catódica, tempo de eletroeluição de 45 minutos e intensidade de agitação moderada do eletrólito (100rpm.

  6. Avaliação em curto e médio prazo da sorção e da solubilidade de resinas compostas à base de metacrilato e de silorano em saliva artificial

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    Isabel Cristina Celerino de Moraes Porto

    Full Text Available INTRODUÇÃO: A absorção/adsorção de moléculas de água por monômeros hidrofílicos dentro de materiais resinosos expostos à umidade da boca pode resultar em degradação. OBJETIVO: Este estudo avaliou sorção e solubilidade de resinas compostas à base de metacrilato e silorano em contato com saliva artificial, nos períodos de um dia (curto prazo, e 30 e 90 dias (médio prazo. MATERIAL E MÉTODO: Sessenta corpos de prova foram confeccionados com as resinas Filtek® Z250 e Filtek® P90 Silorano (3M/ESPE, e depois imersos em saliva artificial a 37 ± 1 ºC durante um, 30 e 90 dias. Os dados foram analisados usando-se ANOVA um fator/dois fatores seguido dos testes Tukey ou Tamhane (α = 0,05. RESULTADO: As médias de sorção das duas resinas aumentaram com o tempo (p = 0,001. A sorção de Z250 (1 e 90 d foi significativamente maior do que de P90 (p = 0,008, com valores semelhantes após 30 dias. A solubilidade das resinas também aumentou com o tempo, com diferença significativa entre todos os períodos (p = 0,001, exceto para a resina P90 (entre 1 e 30 d. Não houve diferença estatística significante entre os grupos Z250 (1 d e P90 (1 dia, Z250 (1 d e P90 (30 d, e Z250 (30 d e P90 (90 d. Para os demais pares, comprovaram-se diferenças significativas (p < 0,001. CONCLUSÃO: As propriedades de sorção e solubilidade das resinas compostas testadas foram influenciadas pelo tempo de exposição à saliva artificial. O silorano teve desempenho ora melhor ora semelhante à resina de metacrilato.

  7. Estudo do comportamento fotofísico de prepregs de fibra de vidro e resina fenólica.

    OpenAIRE

    Rogério da Silva Rosa

    2007-01-01

    O objetivo desse trabalho é a aplicação da Espectroscopia de Luminescência em modo estacionário para o estudo do processo de cura de pré-impregnados (prepregs) de fibra de vidro e resina fenólica, tratadas termicamente em três diferentes temperaturas 90, 120 e 150 C. O processo de cura dos prepregs também foi monitorado por Espectroscopia de absorção na região do Infravermelho com transformada de Fourier (FT-IR). Os espectros de luminescência dos prepregs mostram mudanças significativas atrib...

  8. Influência de três modos de fotopolimerização sobre a microdureza de três resinas compostas

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    Andréa Cristina Schneider

    2016-01-01

    Full Text Available Resumo A adequada fotopolimerização das resinas compostas é fundamental para obtenção de uma boa dureza capaz de resistir aos esforços mastigatórios. Assim, o objetivo deste estudo foi avaliar a influência das técnicas de fotopolimerização - Convencional (CONV, Soft-start (SS e Pulso atrasado (PA na microdureza Knoop de três resinas compostas. Para a confecção dos corpos-de-prova foram utilizadas as resinas compostas Filtek Z350 (3M ESPE, Empress Direct (IvoclarVivadent e P90 (3M ESPE. Foram obtidos nove grupos experimentais em função da técnica de polimerização e resina composta. Vinte e quatro horas após a fotopolimerização foi realizado o teste de microdureza Knoop nas superfícies de base e topo de cada corpo-de-prova. Assim, os valores obtidos foram submetidos ao teste de Kruskall Wallis, seguido do teste de Dunn, p < 0,05. A eficácia da polimerização na superfície de topo das resinas compostas testadas não foi afetada pelos diferentes modos de polimerização. A resina composta Empress Direct apresentou os mais baixos valores de dureza para todos os modos de polimerização quando comparada às demais resinas compostas avaliadas.

  9. Resistência à flexão de resinas de metacrilato de metila e bisacrilato de metila submetidas à termociclagem

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    Ataís Bacchi

    Full Text Available OBJETIVO: Verificar a resistência à flexão de quatro resinas utilizadas para a confecção de restaurações temporárias submetidas à termociclagem. MÉTODO: Foram utilizadas as resinas da marcas Luxatemp e Structur 2, à base de bisacrilato de metila, e as resinas das marcas Duralay e Alike, à base de metacrilato de metila. Vinte espécimes de cada material foram confeccionados e divididos em dois grupos, para serem submetidos às seguintes condições: (I - 24 horas de armazenagem em saliva artificial, e (II - 24 horas de armazenagem em saliva artificial seguida de termociclagem (2000 ciclos, 5 °C-55°C. Cada amostra foi levada ao teste de resistência à flexão em uma Máquina de Ensaios Universal (EMIC DL 10000 e os dados obtidos foram analisados pelo teste ANOVA (dois fatores e, em seguida, pelo teste Tukey (p < 0,05. RESULTADO: As resinas de bisacrilato apresentaram resultados superiores de resistência à flexão após ambos os tempos de armazenagem, não diferindo estatisticamente entre si após 24 horas (p = 0,3594. A resina Luxatemp apresentou os maiores valores de resistência à flexão após a termociclagem, sendo estatisticamente superior às demais. A termociclagem alterou as propriedades mecânicas de todas as resinas, diminuindo a sua resistência à flexão (p = 0,001. CONCLUSÃO: As resinas de bisacrilato apresentam maior resistência à flexão do que as resinas de metacrilato para os fatores estudados. Todos os materiais utilizados neste estudo tiveram sua resistência reduzida pela ciclagem térmica.

  10. Implante de um floculado de resina de mamona em alvéolo dental de rato

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    CALIXTO Romeu Felipe Elias

    2001-01-01

    Full Text Available Os objetivos do presente trabalho foram: 1 testar a biocompatibilidade de uma resina natural, derivada do óleo de mamona, implantada na cavidade de extração dental de ratos, e 2 estudar a possível interferência do material na cronologia do reparo alveolar. O material (AUG-EX, Poliquil Araraquara Polímeros Químicos Ltda., Araraquara - SP foi implantado no alvéolo imediatamente após a extração do incisivo superior direito e os ratos foram sacrificados de 1 a 6 semanas após a extração ou extração + implante. As hemimaxilas foram descalcificadas e processadas para inclusão em parafina e obtenção de cortes semi-seriados, corados com hematoxilina-eosina. Os flocos da resina, de forma irregular e tamanho variável, localizaram-se entre os terços alveolares médio e cervical, inicialmente circundados por tecido de granulação e a seguir por quantidade progressivamente maior de tecido ósseo, no geral com a presença de um tecido conjuntivo interposto, mas em algumas áreas estabelecendo aparente osseointegração direta. Não houve persistência da reação inflamatória, mas observou-se pequena quantidade de células gigantes aderidas à superfície do material, em todos os períodos. A análise histométrica (contagem diferencial de pontos do terço apical mostrou um atraso de 13% a 20% no reparo alveolar dos ratos implantados, com menor neoformação óssea associada a maiores volumes percentuais de tecido conjuntivo e de remanescentes do coágulo sangüíneo.

  11. Complejación de la resina de intercambio de iones: enmascaramiento del sabor amargo de cefuroxime acetil Ion-exchange resin complexation: Masking the bitter taste of cefuroxime axetil

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    Inderbir Singh

    2011-06-01

    Full Text Available OBJECTIVE: the purpose of this research was to formulate taste masked complexes of cefuroxime axetil and to evaluate them for taste, drug loading and characterized by FTIR, XRD. Tablets were formulated of selected batches and evaluated for drug release and physical parameters. METHODS: complexation technique is used to prepare complexes of drug where ion exchange resins such as Indion® 214, Indion® 234 and Indion® 414 were used with a drug-resin ratio of 1:0.5, 1:1, 1:2. The drug resinates were characterized by Infrared Spectroscopy, DSC and X-Ray Diffraction pattern and evaluated for drug loading and taste. Direct compression method was used to formulate tablets. In vitro dissolution was carried out using USP II apparatus. RESULT: potential taste masking increased with increasing concentration of resin. Indion® 214 resin showed better taste masking effect as compared to Indion® 234 and Indion® 414. Percent of drug loading was maximum at drug : resin ratio of 1:1, after that it decreased. Prolonged (upto 5 h and slow drug release was observed with resin 214 at higher concentration. CONCLUSIONS: out of three resins chosen, Indion® 214 at higher concentration exhibit excellent taste masking as well as sustained drug release action.OBJETIVO: el objetivo de esta investigación fue formular los complejos con sabor amargo de cefuroxime acetil y evaluarlos por sabor, carga medicamentosa y caracterización por FTIR, XRD. Las tabletas fueron formuladas a partir de lotes seleccionados y evaluados en busca de la liberación medicamentosa y parámetros físicos. MÉTODOS: la técnica de complejación se utilizó para preparar complejos farmacológicos donde las resinas de intercambio iónico como Indion® 214, Indion® 234 y el Indion® 414 se emplearon a una proporción resina-medicamento de 1:0.5, 1:1, 1:2. Los resinados medicamentosos fueron caracterizados mediante espectroscopia infrarroja, DSC y el patrón de difracción-rayos-X, y evaluados

  12. Effect of the surface treatment of plain carbon fiber posts on the retention of the composite core: an in vitro evaluation Efeito do tratamento superficial de pinos de fibra de carbono lisos na retenção da resina de preenchimento: uma avaliação in vitro

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    Adriana Ferreira QUINTAS

    2001-03-01

    Full Text Available This study aims to evaluate the role of surface treatments performed on plain carbon fiber posts, in relation to serrated carbon fiber posts, in the retention of the composite core. Fifty carbon fiber posts received surface treatments in order to verify their influence on the retention of the core material. An acrylic resin mold was developed in order to precisely fit the post, leaving a machined space to accommodate a self-curing composite resin. After the surface treatment, a primer was applied on the coronal portion of all posts, which were then dried. They were fitted to the mold and received a 3 mm composite core. All specimens were thermocycled and then stored in distilled water for a week. Tension test was performed at a speed of 0.5 mm/min until there was lack of adhesion or fracture of the core. The conclusions were: a the values of retention related to aluminum oxide spray (group A, depth cutter diamond burs (group C and posts with machined coronal portion (group D were comparable to those of serrated posts (group E, although no statistically significant difference between these groups was found; b the mean values of core retention in group B (medium grit diamond burs were statistically lower than those of other groups.Foi avaliado o possível efeito de tratamentos superficiais em pinos de fibra de carbono lisos, quando comparados aos pinos serrilhados, na retenção à resina composta empregada na confecção de núcleos de preenchimento. Foram utilizados cinqüenta pinos de fibra de carbono, divididos em cinco grupos: os quatro primeiros grupos eram constituídos por pinos do tipo liso, cujas superfícies foram tratadas, e o último grupo por dez pinos do tipo serrilhado. Foram desenvolvidas matrizes de resina acrílica com um leito ajustado para conter o pino, com um alargamento na porção coronária para posterior preenchimento com resina composta. Após o tratamento superficial, todos os pinos receberam camadas de "primer", foram

  13. Influência da contaminação pela manipulação durante o procedimento restaurador sobre as propriedades mecânicas de duas resinas compostas fotopolimerizáveis

    OpenAIRE

    Heck, Mary A. Pereira

    2006-01-01

    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em Odontologia Avaliou-se, in vitro, o efeito da contaminação pela manipulação digital sobre a microdureza e resistência flexural das resinas Tetric Ceram e Filtek Z250, e identificou-se os agentes contaminantes por meio da microanálise por energia dispersiva. Os resultados mostraram que a manipulação com luva contaminada e luva contaminada limpa com álcool diminuiu a microdure...

  14. Evaluación de la dispersión de pigmento en resinas acrílicas para la fabricación de dientes artificiales

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    Germán Ricaurte Avella

    2010-01-01

    Full Text Available En la primera etapa de fabricación de dientes artificiales los pigmentos se dispersan en seco en un polvo de resina acrílica conformado por finas partículas esféricas. Esta dispersión tiene características especiales diferentes a la dispersión de pigmentos en resinas líquidas usual en el campo de las pinturas y recubrimientos o en la fabricación de plásticos. No hay muchos reportes sobre los métodos de análisis y control de este tipo de procesos. En este trabajo se pretende evaluar el método de poder colorante, usual en la industria de recubrimientos, contrastando sus resultados con el porcentaje de área de pigmento adherida a las esferas de resina aplicando técnicas de procesamiento digital de imágenes (PDI a micrografías SEM. Se proponen y discuten, además, otros tres métodos alternativos basados en análisis de curvas de reflectancia, que permiten una evaluación rápida del proceso de dispersión, e incluso determinar el valor de la energía de la banda prohibida del pigmento. El método de poder colorante resulta ser el más sensible a las diferencias de dispersión. Finalmente, se aplican los cuatro métodos a una comparación entre tres procesos de molienda con diferentes energías y se discuten los resultados y las limitaciones de cada uno.

  15. Comportamento de cura de adesivo epoxídico contendo grupo mercaptana avaliado por espectroscopia no infravermelho (MIR/NIR e calorimetria exploratória diferencial (DSC Cure behavior of epoxy adhesive containig mercaptan group evaluated by infrared spectroscopy (MIR/NIR and differential scanning calorimetry (DSC

    Directory of Open Access Journals (Sweden)

    Hilzette P. C. Andrade

    2008-01-01

    Full Text Available No presente trabalho, a flexibilidade de um adesivo epoxídico contendo diglicidiléter de bisfenol A (DGEBA e dietilenotriamina (DETA como agente de cura foi modificada pela adição de um segundo componente contendo grupos mercaptana (CAPCURE. A adição de amianto ao adesivo contendo CAPCURE também foi avaliada. As reações entre os grupos epoxídicos e os grupos amina, assim como entre os grupos epoxídicos e os grupos mercaptana, foram estudadas nas regiões espectrais do infravermelho médio (MIR e próximo (NIR. Observou-se que o amianto não interfere nas reações de cura e que a espectroscopia FT-NIR evidencia melhor as alterações espectrométricas ocorridas durante as reações em relação à análise FT-MIR. O tempo das reações de cura foi monitorado por calorimetria exploratória diferencial (DSC, observando-se que a introdução do CAPCURE acelerou a cura da resina. A energia de ativação (Ea das reações de cura foi obtida pelos métodos de Barrett e Borchardt-Daniels. Os adesivos contendo CAPCURE mostraram Ea em torno de 30 kJ.mol-1, enquanto o adesivo DGEBA/DETA apresentou Ea de 46 kJ.mol-1, ambas calculadas pelo método de Barrett.In the present work, the flexibility of an epoxy adhesive containing diglycidylether of bisphenol-A (DGEBA and diethylenetriamine (DETA as curing agent was changed by the addition of a second component containing mercaptan groups (CAPCURE. The addition of asbestos as a filler in the adhesive containing CAPCURE was also evaluated. Epoxy-amine and epoxy-mercaptan reactions were studied in NIR and MIR spectral regions. The filler addition did not cause influence on the cure reactions and spectrometric changes of cure reactions could be better observed by FT-NIR than FT-MIR analysis. The cure reaction time was monitored by DSC experiments and it was observed that the introduction of CAPCURE accelerated the cure reaction. The activation energies (Ea of curing reactions were obtained using Barrett

  16. Avaliação in vitro da microinfiltração em cavidades classe II de molares decíduos, restaurados com resina composta auto e fotopolimerizável

    OpenAIRE

    CAVALCANTI Alessandro Leite; CHELOTTI Adolpho

    1999-01-01

    Estudou-se a microinfiltração marginal presente na interface da parede gengival de cavidades classe II em molares decíduos, restaurados com resina composta (auto e fotopolimerizável), através da penetração de uma solução corante. Os preparos cavitários apresentavam a parede gengival em esmalte e foram restaurados segundo 4 diferentes técnicas: 1) resina composta fotopolimerizável; 2) resina composta autopolimerizável; 3) resina composta auto e fotopolimerizável; e 4) ionômero de vidro/resina ...

  17. Utilização de ligninas em resinas fenólicas: 1. Preparação de novolacas a partir de lignossulfonatos Use of lignins in phenolic resins: 1. Preparation of novolacs from lignosulfonates 49

    Directory of Open Access Journals (Sweden)

    Fernando dos Santos

    1999-01-01

    Full Text Available Este trabalho descreve uma utilização mais nobre para a lignina obtida de processos industriais de polpação. Foram preparadas resinas fenólicas tipo novolaca, utilizando-se lignossulfonato de amônio e lignossulfonato de sódio (com diferentes teores de açúcares residuais como correagentes, em substituição parcial ao fenol. As resinas foram preparadas mantendo-se o processo utilizado industrialmente. As resinas foram caracterizadas por análises químicas, quanto à distribuição de massa molar e análises térmicas. As resinas preparadas com lignossulfonatos apresentaram maior reatividade com hexametilenotetramina (agente de reticulação. Isto é uma vantagem, pois pode-se ter ciclos de moldagem de peças mais curtos, o que economicamente é favorável.This work describes the production of high value products using lignins obtained from industrial pulping processes. Novolac phenolic resins were prepared employing ammonium lignosulfonates and sodium lignosulfonates (with different residual sugar contents in a partial replacement of phenol. The resins were prepared using the same conditions employed in the industrial phenolic resins production. The lignin based resins were characterized by chemical analysis, molecular weight distribution and thermal analysis. The resins prepared using lignosulfonates showed higher reactivity with hexamethylenetetramine (crosslink agent. This behavior lead to another economic advantage as consequence of the reduction in the expended time for molding cycles.

  18. Relações entre fósforo extraído por resina e respostas da cultura do alho vernalizado à adubação fosfatada em cinco solos com e sem adubação orgânica

    Directory of Open Access Journals (Sweden)

    L. T. Büll

    1998-09-01

    Full Text Available Estudaram-se respostas à adubação fosfatada pelo alho vernalizado cv. Roxo Pérola de Caçador em cinco solos com diferentes classes texturais, com e sem adubação orgânica, visando contribuir para o estabelecimento de curva de calibração para fósforo extraído por resina de troca iônica. Foram instalados dois experimentos entre maio e outubro de 1995 e 1996, em vasos (16 L, em casa de vegetação telada do Departamento de Ciência do Solo da Faculdade de Ciências Agronômicas/UNESP, município de Botucatu (SP. Cada experimento constituiu um fatorial com cinco solos e seis doses de fósforo (original, 50, 100, 200, 400 e 800 mg dm-3 de P. A adubação orgânica foi aplicada apenas no primeiro ano, na dosagem de 40 t ha-1 de esterco bovino decomposto. Verificou-se que a aplicação de matéria orgânica dificultou a discriminação dos níveis de fósforo extraído pela resina entre os tratamentos com menores doses de adubação fosfatada. A elevação nos níveis de fósforo aumentou a concentração de clorofila e de N, P, K e Mn e reduziu a concentração de Mg nas folhas; não foram observados efeitos antagônicos do P sobre a absorção de Zn. O nível crítico de fósforo extraído pela resina para os solos utilizados situou-se em torno de 50 mg dm-3 de P, enquanto a concentração foliar crítica de fósforo nas plantas de alho foi de 2,5 g kg-1 de P. A adubação orgânica, na dosagem recomendada para o estado de São Paulo, pode substituir a adubação fosfatada na cultura do alho vernalizado.

  19. Comparação da influência entre tempos de polimerização em resinas compostas polimerizadas com LED e Luz Incandescente Comparison of the influence of curing times applied to composite resins cured with LED and Incandescent Light

    Directory of Open Access Journals (Sweden)

    Michele P. M. Ulhoa

    2007-09-01

    Full Text Available O propósito deste trabalho é fazer uma comparação entre resinas poliméricas dentárias, polimerizadas por aparelhos baseados em lâmpada halógena e diodo emissor de Luz (LED, utilizando-se o método do disco retificado aperfeiçoado para odontologia e os respectivos valores de microdureza. Foram realizados testes em amostras de resinas compostas de 5 diferentes marcas, polimerizadas a tempos de 10, 20 e 40 s, pelos dois aparelhos. A análise estatística dos valores de microdureza e agressividade permitiu concluir que estatisticamente não há correlação entre essas propriedades. Na análise de microdureza, a heterogeneidade característica do material implicou em resultados com valores de desvio padrão relativamente altos, de forma que não foi encontrada diferença estatística entre as amostras avaliadas. Na análise estatística dos ensaios baseados no método do disco retificado, a resina que apresentou maior desgaste nos ensaios, foi a Tetric Ceram, polimerizada pelo aparelho de LED por 10 s, cujo valor médio de agressividade obtido foi 0,170 mm³/N.m. A resina que sofreu menor desgaste foi a Charisma, polimerizada por Lâmpada Incandescente, por um tempo de 20 s, cuja média dos valores de agressividade foi 0,057 mm³/N.m.The purpose of this work was to compare polymeric dental resins cured with halogen lamp and with light emission diode (LED devices, using the grinding disk method customized for dentistry and the corresponding microhardness values. Tests were carried out on resin samples of five brands, which were cured for 10, 20 and 40 s with the two devices. The analysis of microhardness and aggressiveness has allowed us to conclude that there is no correlation between these properties. In Microhardness tests, the material heterogeneity has produced relative high standard deviation values and has not shown statistical differences between the analyzed samples. In the statistical analysis for the results with the grinding disk

  20. The anticancer effects of Resina Draconis extract on cholangiocarcinoma.

    Science.gov (United States)

    Wen, Feng; Zhao, Xiangxuan; Zhao, Yun; Lu, Zaiming; Guo, Qiyong

    2016-11-01

    Cholangiocarcinoma (CCA) is a relatively rare, heterogeneous malignant tumor with poor clinical outcomes. Because of high insensitivity to chemotherapy and radiotherapy, there are no effective treatment options. Efforts to identify and develop new agents for prevention and treatment of this deadly disease are urgent. Here, we assessed the apoptotic cytotoxicity of Resina Draconis extract (RDE) using in vitro and in vivo assays and identified the mechanisms underlying antitumor effects of RDE. RDE was obtained via vacuum distillation of Resina Draconis with 75 % ethanol. The ethanol extract could inhibit CCA cell proliferation and trigger apoptotic cell death in both QBC939 and HCCC9810 cell lines in a time- and concentration-dependent manner. RDE treatment resulted in intracellular caspase-8 and poly (ADP-ribose) polymerase protease activation. RDE significantly downregulated antiapoptotic protein survivin expression and upregulated proapoptotic protein Bak expression. RDE also inhibited CCA tumor growth in vivo. We observed that human CCA tissues had much higher survivin expression than did paired adjacent normal tissue. Taken together, the current data suggested that RDE has anticancer effects on CCA, and that RDE could function as a novel anticancer agent to benefit patients with CCA.

  1. OPACIDAD Y TRANSLUCIDEZ DE DIFERENTES RESINAS COMPUESTAS DE ACUERDO A SU TAMAÑO DE PARTÍCULA Y SU APLICACIÓN CLÍNICA

    Directory of Open Access Journals (Sweden)

    Manuel Roberto Sarmiento Limas

    2012-01-01

    Full Text Available Propósito: El objetivo de este estudio fue determinar el grado de opacidad o translucidez de acuerdo a su tamaño de partícula que nos ofrecen las resinas compuestas para seleccionar cual es la ideal de acuerdo al grado de dificultad estética. Materiales Y Metodos: Se realizaron muestras de resina circunferenciales, distribuidos así: Filtek Z350 XT®, Premisa Direct®, Exthet-X HD®, Tetric N Ceram®, Helio Molar®, Vit-l-escense, Amleogen Plus®, Miris 2 ® y Brilliant NG ®. Y se realizaron lecturas de reflectancia y transmitancia a través del Espectrofotometro Cary 5000.  Resultados: Las muestras estudiadas presentan un comportamiento similar tanto en reflectancia como en transmitancia, encontrando dos extremos opuestos, uno hacia opacidad (dentinas y otro hacia translucidez (esmaltes, pero con un gran número de muestras con valores intermedios, y comportamiento similar que no permite clasificarlas como dentinas o esmaltes a pesar de la clasificación dada por cada marca. Amleogen Plus®, Vit - L- Escence® Y Esthet X HD®  son las marcas que presentan mayor diferencia en el comportamiento de sus esmaltes en comparación con sus dentinas, contrario a lo observado con Helio Molar®, Brilliant NG® y Tetric N Ceram®. En cuanto al tamaño de partícula no se encuentran diferencias significativas en su comportamiento. Finalmente, los datos obtenidos demuestran que existen dentinas con comportamiento de esmaltes y esmaltes con comportamientos de dentinas. Conclusiones: Existe diferencia significativa entre las masas de resina compuesta de dentina y esmalte, valoradas en relación a las variables de opacidad y translucidez a través reflectancia y transmitancia, entre las diferentes marcas y dentro de cada una de ellas.

  2. TRATAMENTO DA CASCA DE QUEIJO CANASTRA COM RESINA E SEUS EFEITOS DURANTE A MATURAÇÃO E NA QUALIDADE COMO FORMA DE MELHORAR O ASPECTO E AGREGAR VALOR AO PRODUTO

    Directory of Open Access Journals (Sweden)

    Paulo Henrique Costa Paiva

    2012-08-01

    aspecto global, cor, textura, consistência e sabor. Quanto às características microbiológicas dos queijos com e sem aplicação de resina na casca, após 15 dias de maturação, a diferença das contagens microbiológicas entre as quatro estações do ano não chegou a um ciclo logarítmico, exceto para mesófilos aeróbios e Staphylococcus aureus. Os coeficientes de variação referentes aos parâmetros microbiológicos dos queijos maturados por 15 dias, em relação às quatro estações do ano, apresentaram-se relativamente baixos, exceto para contagens de Staphylococcus aureus em queijos com e sem aplicação de resina na casca, e para contagem de coliformes totais em queijos sem aplicação de resina na casca. Após 15 dias de maturação, observou-se ausência de Listeria sp. e Salmonella sp. nos queijos com e sem aplicação de resina na casca, nas quatro estações do ano. Nos queijos com aplicação de resina na casca houve menor crescimento de mofos durante a maturação (45 dias em relação àqueles sem aplicação de resina, reduzindo-se as perdas com raspagens ("toalete" dos queijos durante esse período.

  3. PROPRIEDADES FÍSICAS E MECÂNICAS DE PAINÉIS MDF DE DIFERENTES MASSAS ESPECÍFICAS E TEORES DE RESINA

    Directory of Open Access Journals (Sweden)

    Jackson Roberto Eleotério

    2000-08-01

    Full Text Available Painéis MDF foram preparados, em escala laboratorial, com base em fibras de Pinus spp. com diferentes teores de resina (6, 8, 10, 12 e 14% e massas específicas (600 a 800 kg/m3 com o objetivo de avaliar suas propriedades físicas e mecânicas. Os efeitos da massa específica e do teor de resina, bem como sua interação foram avaliados tendo como base as propriedades físicas e mecânicas dos painéis MDF. As propriedades mecânicas avaliadas foram módulo de elasticidade e de ruptura e adesão interna, enquanto as propriedades físicas foram absorção de água e inchamento em espessura. Todas as variáveis se relacionaram significativamente com os fatores massa específica e teor de resina e a interação foi significativa a 1% apenas no inchamento em espessura. Foram propostos modelos para avaliar as propriedades físicas e mecânicas em razão da massa específica e do teor de resina.

  4. Análise de peças anatômicas preservadas com resina de poliester para estudo em anatomia humana

    Directory of Open Access Journals (Sweden)

    Ítalo Martins de Oliveira

    Full Text Available OBJETIVO: avaliar o uso da resina de poliéster na preservação de peças anatômicas para estudo da anatomia humana. MÉTODOS: foram utilizadas 150 peças anatômicas, sendo as mesmas não fixadas (frescas, fixadas em formol a 10% e moldes vasculares de órgãos injetados com acetato de vinil e a resina de poliéster. A solução utilizada foi composta de resina de poliéster com seu diluente monômero de estireno e catalisador (peroxol. Foram obtidos, após a inclusão nesta solução, modelos em resina transparente, que permitiam a plena observação das estruturas e conservação da peça utilizada. RESULTADOS: na avaliação das peças, foi observado grau de extrema transparência, promovendo uma completa visualização das estruturas com a perfeita preservação da anatomia. A duração média para a completa finalização da inclusão foi 48 horas. Apenas 14 peças (9,3% foram inutilizadas durante o preparo. CONCLUSÃO: a resina de poliéster pode ser utilizada para a preservação de peças anatômicas para o ensino da anatomia humana, de maneira prática, estética e duradoura.

  5. Effect of post-polymerization heat treatments on the cytotoxicity of two denture base acrylic resins Efeito de tratamentos térmicos após a polimerização sobre a citotoxicidade de duas resinas acrílicas para base de próteses

    Directory of Open Access Journals (Sweden)

    Janaina Habib Jorge

    2006-06-01

    biocompatibilidade e das propriedades físicas. Para assegurar a utilização desses materiais, testes preliminares de citotoxicidade in vitro têm sido desenvolvidos para avaliação da biocompatibilidade. Um dos ensaios biológicos sugeridos para a análise da citotoxicidade é o teste de incorporação de ³H-timidina, o qual mede o número de células por meio da síntese de DNA. OBJETIVO: O objetivo do presente estudo foi avaliar, por meio do teste de incorporação de ³H-timidina, a citotoxicidade de duas resinas acrílicas para base de próteses submetidas aos tratamentos em microondas e em banho de água após a polimerização. MATERIAL E MÉTODO: Nove corpos-de-prova em forma de discos (10 x 1 mm foram confeccionados com as resinas acrílicas Lucitone 550 e QC 20 de acordo com as instruções dos fabricantes, e foram armazenados em água destilada a 37ºC por 48 h. Os corpos-de-prova foram divididos em três grupos: 1 tratamento em forno de microondas por 3 min a 500 W; 2 tratamento em banho de água a 55ºC por 60 min; e 3 sem tratamento térmico. Extratos foram preparados pela colocação de 3 discos em tubos de ensaio estéreis com 9 mL de meio de cultura Eagle e incubação a 37ºC por 24 h. O efeito citotóxico dos extratos foi avaliado utilizando o teste de incorporação de ³H-timidina. RESULTADOS: Os resultados indicaram que os componentes liberados pelas resinas foram citotóxicos para as células L929 exceto para as amostras tratadas em banho de água (p<0.05. Em comparação com o grupo sem tratamento, o banho de água diminuiu a citotoxicidade das resinas acrílicas. CONCLUSÃO: O tratamento em microondas não influenciou a citotoxicidade das resinas acrílicas para bases de próteses.

  6. Comparación biomecánica entre los sistemas convencionales y uni-lock en osteosíntesis del ángulo mandibular: Estudio fotoelástico Biomechanical comparison of the conventional and uni-lock systems for mandibular osteosynthesis: A photoelastic study

    Directory of Open Access Journals (Sweden)

    José Luis Cebrián-Carretero

    2012-03-01

    Full Text Available Introducción: Las implicaciones biomecánicas de la interacción de las placas y tornillos de titanio con la mandíbula fracturada no son del todo conocidas. Los modelos matemáticos desarrollados hasta hoy en día muestran ciertas limitaciones, y los estudios experimentales han fracasado en reproducir las fuerzas musculares y la distribución de las tensiones internas en la interfaz entre mandíbula e implante. Material y métodos: En el presente estudio, empleamos un simulador estático del sistema músculo-esquelético masticatorio para demostrar en réplicas mandibulares de resina epoxi, por medio de la fotoelasticidad tridimensional, la distribución de tensiones que se produce en fracturas del cuerpo mandibular tras la aplicación de diferentes métodos de osteosíntesis. Resultados: Los resultados muestran que el simulador y la fotoelasticidad 3D son útiles para estudiar las interacciones entre el hueso y el material de osteosíntesis. Los sistemas «lock» o bloqueados reflejaron la distribución de tensiones más favorable en la mandíbula de resina epoxi fracturada. Conclusiones: La fotoelasticidad tridimensional en modelos de resina epoxi es un método útil para evaluar la distribución de tensiones en una estructura para estudios biomecánicos. En lo que se refiere a la osteosíntesis mandibular, las placas tipo «lock» mostraron ser las menos agresivas para el hueso.Introduction: The biomechanical effects of the interaction between titanium plates and screws and the fractured mandible are not well known. The mathematical models that have been developed to date show limitations and the experimental studies fail in reproducing muscle forces and internal stress distributions in the bone-implant interface with the mandibular structure. Material and methods: In the present study we use a static simulator of the masticatory system to show, in epoxy resin mandibular models, by means of 3D (three-dimensional photoelasticity, the stress

  7. Microdureza de caries incipientes artificiales infiltradas con resinas de baja viscosidad antes y después del termociclado

    OpenAIRE

    X. Zamorano Pino; V. Valenzuela Aránguiz; C. Vial Prado; M. Vidal Tardón

    2015-01-01

    Introducción: En Odontología Mínimamente Invasiva, el procedimiento denominado Infiltración de caries, pretende detener la progresión de las caries incipientes mediante el sellado de las microporosidades del esmalte afectado. Este tratamiento se realiza con la aplicación de resinas de baja viscosidad. El objetivo de este trabajo fue evaluar la microdureza superficial de caries incipientes artificiales infiltradas con resinas de baja viscosidad antes y después del proceso de termociclado. Meto...

  8. Exposure to creosote bush phenolic resin causes avoidance in the leaf-cutting ant Acromyrmex lobicornis (Formicidae: Attini La exposición a la resina fenólica de jarilla causa deterrencia en la hormiga cortadora de hojas Acromyrmex lobicornis (Formicidae: Attini

    Directory of Open Access Journals (Sweden)

    ANA I MEDINA

    2012-06-01

    Full Text Available We focused our study on the effects of Larrea cuneifolia phenolic resin on leaf-cutting ants from two populations (Sierra de las Quijadas National Park and San Roque of Acromyrmex lobicornis in San Luis, Argentina. We conducted two bioassays of food choice (field and laboratory to compare the effects of phenolic resin on ant workers from these two populations. Results of the field experiment indicated that there were no differences in preference for either leaves treated with resin or untreated leaves among colonies from both localities. However, results of the laboratory experiments with individual ants indicated a significant effect of population and treatment on the time spent in different treatments. While leaf-cutting individual workers from Quijadas preferred the phenolic resin, workers from San Roque avoided it. These results evidence that ants respond according to time of exposure to chemicals from plants (presence or absence and that the effects of resin among a population can be observed and measured on individual ant workers, even in the absence of fungus garden influences in the nest.Este estudio se ha centrado en los efectos que produce la resina fenólica de Larrea cuneifolia sobre dos poblaciones distintas (Parque Nacional de Sierra de las Quijadas y la localidad de San Roque de Acromyrmex lobicornis en San Luis, Argentina. Se disenaron dos tipos de bioensayos (a campo y en laboratorio para comparar los efectos de la resina fenólica sobre las hormigas obreras de estas dos poblaciones. Los resultados de los experimentos de elección de la oferta alimentaria en el campo, indicaron que no hubo ninguna diferencia de preferencia entre las colonias, ni por las hojas tratadas con resina ni por las hojas sin tratar para ambas localidades. Sin embargo, los resultados de los experimentos de laboratorio con las hormigas obreras individualmente indicaron efectos significativos entre las poblaciones y entre los tratamientos. Mientras que las

  9. Knoop hardness of enamel and shear bond strength of brackets bonded with composite resin with and without fluoride Dureza Knoop do esmalte e resistência ao cisalhamento de braquetes colados com resina composta com e sem flúor

    Directory of Open Access Journals (Sweden)

    Silvia Amélia Scudeler Vedovello

    2012-08-01

    foram divididos em dois grupos: resina com flúor (Ortho Lite Cure, Ortho Source® e resina sem flúor (Orthobond, Morelli®. Após a colagem, os corpos de prova foram submetidos ao ciclo de desmineralização e remineralização durante 14 dias, e submetidos ao ensaio de resistência ao cisalhamento em máquina universal de ensaios EMIC, com velocidade de 0,5mm/min. RESULTADOS: o ensaio de resistência de união mostrou que não houve diferença significativa entre os grupos. Após o processo de desmineralização e remineralização, os corpos de prova colados com a resina composta com flúor apresentaram maior dureza, comparados aos colados com resina sem flúor. Para ambos os grupos houve predominância de falhas na interface resina/braquete. CONCLUSÃO: os corpos de prova colados com a resina composta com flúor apresentaram maior microdureza após os processos de desmineralização e remineralização, comparados aos colados com resina composta sem flúor, porém sem diferença para a resistência de união ao cisalhamento.

  10. Avaliação in vitro da microinfiltração em cavidades classe II de molares decíduos, restaurados com resina composta auto e fotopolimerizável

    Directory of Open Access Journals (Sweden)

    CAVALCANTI Alessandro Leite

    1999-01-01

    Full Text Available Estudou-se a microinfiltração marginal presente na interface da parede gengival de cavidades classe II em molares decíduos, restaurados com resina composta (auto e fotopolimerizável, através da penetração de uma solução corante. Os preparos cavitários apresentavam a parede gengival em esmalte e foram restaurados segundo 4 diferentes técnicas: 1 resina composta fotopolimerizável; 2 resina composta autopolimerizável; 3 resina composta auto e fotopolimerizável; e 4 ionômero de vidro/resina composta. Após a análise estatística dos resultados, concluiu-se que todos os grupos apresentaram microinfiltração em graus variados; todavia, os grupos 2, 3 e 4 apresentaram os menores graus de infiltração.

  11. Epoxy cracking in the epoxy-impregnated superconducting winding: nonuniform dissipation of stress energy in a wire-epoxy matrix model

    International Nuclear Information System (INIS)

    Tsukamoto, O.; Iwasa, Y.

    1985-01-01

    The authors present the epoxy-crack-induced temperature data of copper wires imbedded in wire-epoxy resin composite model at 4.2 K. The experimental results show that the epoxy-crackinduced temperature rise is higher in the copper wires than in the epoxy matrix, indicating that in stress-induced wire-epoxy failure, stress energy stored in the wire-epoxy matrix is preferrentially dissipated in the wire. A plausible mechanism of the nonuniform dissipation is presented

  12. Oxidación catalítica de a-pineno con metiltrioxorenio inmovilizado en resinas

    Directory of Open Access Journals (Sweden)

    Lina María González R.

    2004-01-01

    Full Text Available Se investigó la inmovilización del catalizador homogéneo metiltrioxorenio (MTO, CH3ReO3, en resinas basadas en vinilpiridina sintetizadas por diferentes procedimientos. Los catalizadores se caracterizaron por espectroscopia IR y UV-Vis y la composición elemental de nitrógeno y renio se determinó por ICP-MS. Los análisis FTIR indicaron la presencia de grupos ReO3 y ReO en los catalizadores heterogeneizados; en los análisis UV-Vis se observaron nuevas bandas después de tratar los soportes con MTO. La eficiencia de incorporación de renio fue mayor en PVP comercial y en el copolímero preparado en suspensión. Además, la oxidación del soporte disminuyó la incorporación del MTO. Los catalizadores se evaluaron en la oxidación de α-pineno con peróxido de hidrógeno. Los catalizadores soportados en PVP presentaron baja conversión del α-pineno (7%, pero la selectividad al epóxido de α-pineno fue alta (92%. Además, la más alta conversión del α-pineno (50% se obtuvo con el MTO en los soportes copolimerizados y oxidados; con MeCN/DCM como solvente se obtuvieron principalmente aldehído canfolénico y sobrerol, productos de rearreglo del epóxido. En general, la eficiencia del oxidante fue baja y ésta se favoreció en terbutanol y acetato de etilo como solventes

  13. Influencia de la remoción químico-mecánica del "smearlayer" y la presencia de un adhesivo dentinario en la microfiltración de restauraciones de resina compuesta

    OpenAIRE

    Macorra García, José Carlos de la; Gómez Martínez, Ana; Gutiérrez Argumosa, B.

    1989-01-01

    Se presenta un estudio comparativo "in vitro" de la microfiltración en restauraciones de resina compuesta cuyos márgenes cavosuperficiales están situados por completo en cemento. Se compara la capacidad de sellado de un adhesivo dentinario (ScotchBond I) utilizado según la técnica habitual, sin acondicionar la dentina y empleando el sistema Caridex como acondicionador dentinario. Este último sistema no mejoró los resultados de microfiltración en las condiciones del estudio.// We present an...

  14. Study of a hybrid solar-electric oven to the curing composite materials used in aeronautics; Estudio de un horno hibrido solar-electrico para el curado de materiales compuestos utilizados en aeronautica

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Roman, M. A.; Pineda Pinon, J.; Sanchez Sanchez, A. [CICATA - Unidad Queretaro, Santiago de Queretaro, Queretaro (Mexico)]. E-mail: mhernandezr0900@ipn.mx

    2010-11-15

    The study covers the curing of advanced composites in a hybrid solar electric oven. The furnace uses electricity from the grid power and solar energy provided by the heliostat concentrator system. The materials used in the experiments will be composite materials such as prepreg. The prepreg are fiberglass and carbon fiber. The resin used in the pre-impregnate will be epoxy resin. The work temperatures inside the furnace will be maximum 300 degrees Celsius. The obtained results will be useful to characterize the use of the solar energy and the characterize of the curing chamber. [Spanish] Se presenta el alcance para el estudio, el cual abarca el curado de materiales compuestos avanzados dentro de un horno hibrido solar electrico. El horno utilizara energia electrica suministrada por la red y energia solar suministrada por el sistema heliostato concentrador. Los materiales utilizados en los experimentos seran materiales compuestos tipo prepreg. Los prepreg seran de fibra de vidrio y de fibra de carbono. La resina utilizada en el preimpregando sera resina epoxica. Las temperaturas de trabajo dentro del horno seran como maximo de 300 grados centigrados. Los resultados obtenidos serviran para caracterizar el uso y aprovechamiento de la energia solar y la caracterizacion de la camara de curado.

  15. Los cambios de temperatura en los revestimientos epoxi II

    Directory of Open Access Journals (Sweden)

    Fernández Cánovas, M.

    1970-04-01

    Full Text Available This article is the second part of a previous paper published by the author in no. 189 of this magazine. It describes the tests carried out to check the theoretical results published in the earlier article. The tests have consisted in submitting concrete slabs covered with a layer of epoxi mortar to certain thermal conditions, to check the behaviour of the covering in the face of thermal changes. In all the tests, described in detail in the article, the epoxi layer has behaved extremely well, and no bonding failure has been observed, nor failures in the concrete base or in the epoxi layer.Este artículo es la segunda parte de un trabajo publicado por el autor en el número 189 de esta revista, y en él se realiza una descripción de los ensayos prácticos llevados a cabo para complementar el estudio teórico publicado en aquella primera parte. Los ensayos han consistido en someter a placas de hormigón revestidas de una Kipa de mor tero epoxi a determinadas condiciones térmicas, con el fin de poder comprobar el comportamiento del revestimiento frente a los cambios de temperatura. En todos los ensayos realizados y que, con detalle, están descritos en este artículo, el comportamiento de los revestimientos de mortero epoxi ha sido excelente, no habiéndose notado ningún fallo de adherencia, ni roturas en la base de hormigón, ni en la capa de mortero epoxi.

  16. Infiltración de resina como tratamiento mínimamente invasivo de lesiones de caries dental incipiente

    Directory of Open Access Journals (Sweden)

    Alain Manuel Chaple Gil

    Full Text Available La mínima intervención en cariología ha sido definida como la filosofía de cuidados estomatológicos que se encarga del tratamiento de la primera aparición, la detección temprana y el tratamiento de la caries dental. Una de las técnicas para el tratamiento temprano y detención de lesiones incipientes es la infiltración de resina. El objetivo es mostrar la utilidad de las resinas fluidas para la infiltración de un primer y segundo molar inferior permanentes con una lesión incipiente de caries dental. Se trata de un paciente masculino de 17 años de edad sin antecedentes patológicos, que acude a consulta estomatológica. En hemiarcada inferior izquierda se observaron manchas en forma de punto de color marrón oscuro cerca de la fosita central y en la estría vestibular del 36 y 37 respectivamente, que no presentaban más de 1 mm de profundidad. Se diagnosticaron lesiones de caries dental incipiente y se decidió realizar una infiltración con resina compuesta de baja viscosidad o fluida en consulta única. El uso de resinas compuestas fluidas es beneficioso en la infiltración de lesiones cariosas incipientes de esmalte, pues evita su propagación y sella las brechas de esmalte afectado. Es una técnica de mínima intervención en cariología, que propicia una solución inmediata para estos procesos y mayor sencillez para la solución de la enfermedad caries dental al equilibrar las expectativas estéticas y de mantenimiento de las estructuras dentarias sanas.

  17. Avaliação das propriedades elétricas de barras estatóricas fabricadas com resina do tipo éter diglicidílico do bisfenol F (DGEBF contendo nanopartículas de silica

    Directory of Open Access Journals (Sweden)

    Rafael Novaes da Conceição

    Full Text Available Resumo O presente trabalho visa apresentar resultados da aplicação de uma resina epóxi bisfenólica (DGEBF à base de nanopartículas de sílica (RN e comparar suas propriedades com a resina convencional de referência epóxi bisfenólica (DGEBA (RE, atualmente utilizada. Neste sentido fabricaram-se protótipos de barras estatórica, destinadas a hidrogeradores, através do sistema VPI (Vácuo-Pressão-Impregnação e avaliaram-se as propriedades elétricas pelas técnicas de fator de dissipação e envelhecimento acelerado. Dentre os resultados para as resinas observou-se que: (i o fator de dissipação e de envelhecimento são praticamente os mesmos para ambas as resinas; (ii o valor de tip-up resultaram em 0,014% para RE e 0,020% para a resina RN e (iii a estimativa do tempo de vida útil esta em cerca de 40 anos, o que é aplicável para a maioria das aplicações industriais. Neste sentido sugere-se que a resina RN pode ser uma alternativa a resina RE, com um desempenho elétrico equivalente.

  18. Preparation and characterization of polyhedral oligomer silsesquioxane nanocomposites incorporated in epoxy resin; Elaboracao e caracterizacao de nanocompositos de oligomero poliedrico de silsesquioxano incorporados na resina epoxidica

    Energy Technology Data Exchange (ETDEWEB)

    Longhi, Marielen; Zini, Lucas Pandolphi; Birriel, Eliena Jonko; Kunst, Sandra Raquel; Zattera, Ademir Jose, E-mail: marielen_longhi@hotmail.com [Universidade de Caxias do Sul (LPOL/UCS), RS (Brazil). Laboratorio de Polimeros; Pistor, Vinicius [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

    2015-07-01

    The incorporation of nanofiller in thermosetting like epoxy resin as has been studied in order to modify its properties. In this research, nanocomposites were obtained by incorporating 5% by weight of three polyhedral oligomeric silsesquioxane (POSS) with different number of functionalization: Glicidilisobutil-POSS, Triglicidilisobutil- POSS and Glicicil POSS in an epoxy matrix by sonification process. The nanocomposites were characterized by analysis of X-ray diffraction (DRX), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The DRX analysis showed the characteristic peak of POSS and TEM images showed that there is a difference in the dispersion of nanocages for the difference in the number of epoxy groups on the POSS. The incorporation of Glicidilisobutil-POSS showed a significant increase in the glass transition temperature (Tg) value, and also that the most effective from the viewpoint of the dispersion, on the other hand, the Glycidyl-POSS had a greater influence on the thermal stability demonstrating that the dispersion medium is an important characteristic to define the most desirable properties. (author)

  19. Synthesis and characterization of cement slurries additives with epoxy resins - kinetics, thermodynamic and calorimetric analysis; Sintese e caracterizacao de pastas de cimento aditivadas com resinas epoxi - analises cineticas, termodinamicas e calorimetricas

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, A.M.G.; Andrade Junior, M.A.S.; Cestari, A.R.; Vieira, E.F.S., E-mail: macleybiane@gmail.co [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil)

    2010-07-01

    Cement has been used in the world, presenting a wide versatility. However, due to its chemical nature, it is subject to several types of chemical damages, especially for agents of acidic nature. With the purpose of increase its life-time, new cement slurries have been modified with the addition of specific additives. The objective of this work is to modify cement slurries with epoxy resins, which promote higher resistance of those materials in relation to acid attacks. Three cement slurries were synthesized with epoxy resins and a standard slurries, which was composed by cement and water. After 30 days of hydration, the samples were characterized by XDR, FTIR and thermal analysis (TG and DSC). The hydration processes of the cement slurries were studied by heat-conduction microcalorimetry. A kinetic study of HCl interaction with the new slurries were performed by the batch methodology at 25, 35, 45 e 55 deg C. It was verified that the addition of the polymers delayed the processes of hydration of the slurries, decreasing the flow of heat released as a function of the amount of added resin and, increased the resistance of those slurries to the acid attack. (author)

  20. Preparación y valoración de resinas compuestas para uso dental basadas en nuevas matrices orgánicas

    OpenAIRE

    Cuevas Suárez, Carlos Enrique

    2013-01-01

    Las resinas compuestas son materiales que se utilizan en una gran variedad de aplicaciones en odontología. Éstos materiales comprenden una combinación de varios monómeros bimetacrílicos, materiales de relleno y un sistema fotoiniciador. Desde su aparición, los materiales de éste tipo han mejorado significativamente sus propiedades físicas, mecánicas y de biocompatibilidad. A pesar de esto avances, hoy en día las resinas compuestas tienen limitaciones en su aplicación clínica; problemas como l...

  1. Estabilidade dimensional de uma resina acrílica para coroas provisórias em função de diferentes técnicas de processamento ao longo do tempo

    Directory of Open Access Journals (Sweden)

    David Alejandro García-López

    Full Text Available INTRODUÇÃO: A estabilidade dimensional das resinas acrílicas influencia na adaptação das coroas provisórias e, consequentemente, no resultado do tratamento reabilitador. OBJETIVO: Avaliar a estabilidade dimensional, ao longo do tempo, de uma resina acrílica processada de diferentes maneiras. MATERIAL E MÉTODO: Cinco técnicas de polimerização da resina acrílica foram testadas: I - polimerização térmica utilizando líquido de polimerização rápida em mufla; II - autopolimerização sob pressão; III - autopolimerização utilizando pincel; IV - autopolimerização após mistura (pó + líquido em pote Dappen e inserção em matriz de aço na fase arenosa; V - autopolimerização após mistura em pote Dappen com inserção na matriz metálica na fase plástica. Foram confeccionados dez corpos de prova para cada tipo de processamento. Avaliou-se a estabilidade dimensional por meio de matriz de aço inox confeccionada segundo a especificação nº19 da ADA. Os corpos de prova foram armazenados em água destilada a 37ºC e examinados nos períodos de 1 hora, 1, 7, 15, 10, 90 e 180 dias após a polimerização, com o auxílio de um microscópio óptico com aumento de 20×. Os resultados foram submetidos à análise de dupla variância (Teste de Tukey para Tempo e Técnica de processamento em nível de 5% de significância. RESULTADO: Todos os grupos experimentais apresentaram alterações dimensionais entre o sétimo e o 15º dia; após esse período de tempo, houve alterações dimensionais estatisticamente significantes, para as diferentes técnicas estudadas. CONCLUSÃO: A estabilidade dimensional da resina acrílica não sofreu influência das diferentes técnicas de processamento avaliadas; entretanto, foi influenciada pelo tempo de armazenamento.

  2. Preparación y caracterización de filmes epoxi basados en aceite de linaza para aplicación

    OpenAIRE

    Gómez Carrera, Marta

    2015-01-01

    En este proyecto se preparan diferentes composiciones de filmes epoxi basados en aceite de linaza químicamente epoxidado (Epoxidized Linseed Oil-ELO) y su posterior curado con dos tipos de endurecedores, una poliaminoamida comercial y una poli(etilenimina) con dos pesos moleculares distintos. El objetivo final es la preparación de una pintura epoxi menos tóxica para el ser humano, sustituyendo parcialmente la molécula de diglicidil éter de bisfenol A (DGEBA), de las formulaciones epoxi, por m...

  3. Tenacidade à fratura translaminar dinâmica de laminados compósitos de fibras de carbono e resina epóxi de grau aeronáutico Translaminar dynamic fracture toughness of aeronautic grade composite laminates made with carbon fiber-epoxy resin

    Directory of Open Access Journals (Sweden)

    José R. Tarpani

    2010-01-01

    Full Text Available A tenacidade à fratura translaminar dinâmica de quatro laminados compósitos de fibras de carbono e resina epóxi foi determinada nas velocidades de impacto de 2,25 e 5,52 m/s, sob as temperaturas de -70, +25 e +100 °C. Concluiu-se que a tenacidade à iniciação da fratura dos laminados confeccionados com fibras na forma de fita unidirecional é, em qualquer condição de ensaio, muito superior à dos laminados manufaturados com fibras dispostas na forma de tecido bi-direcional. Quanto à tenacidade à propagação de danos, constatou-se que o laminado fita processado a 180 °C é o mais indicado para operar sob impacto em temperaturas intermediárias, enquanto que o manufaturado a 120 °C é a melhor opção para trabalhar sob ambos os extremos do intervalo de temperatura avaliado.The translaminar dynamic fracture toughness of four carbon fiber - epoxy resin composite laminates was compared at the impact velocities of 2.25 and 5.52 m/s, under the temperatures of -70, +25 and +100 °C. It has been concluded that the initiation fracture toughness of unidirectional tape laminates is quite higher than bidirectional woven fabric composites, despite the testing conditions. In regard to the damage propagation toughness, it has been shown that the tape laminate processed at 180 °C is the best option at intermediate temperatures, whereas the tape composite manufactured at 120 °C is the most suitable to operate under impact at both the extremes of the temperature range evaluated.

  4. Avaliação da interação entre resina composta e diferentes adesivos dentinários Evaluation of the interaction between composite resin and different dentin adhesives

    Directory of Open Access Journals (Sweden)

    Luciana Lourenço RIBEIRO

    1999-01-01

    Full Text Available O objetivo deste estudo foi avaliar a resistência à tração de quatro diferentes sistemas adesivos. Scotchbond Multi Purpose Plus, 3M (Grupo 1, Prime & Bond 2.0, Dentsply (Grupo 2 ProBOND, Dentsply (Grupo 3, PAAMA 2, (Grupo 4 foram usados com a resina composta Glacier (SDI. Um grupo sem a utilização de qualquer sistema adesivo serviu como controle (Grupo 5. Cinqüenta espécimes foram divididos em cinco grupos com dez espécimes cada. Uma matriz de aço inoxidável com 6,0 mm de diâmetro e 1,0 mm de profundidade foi usada para se obterem dois discos de resina composta. A resina composta foi inserida em uma metade da matriz em pequenas porções e fotopolimerizada por 40 segundos. Os adesivos foram então aplicados na superfície dos discos de resina, seguindo a instrução dos fabricantes. A segunda parte da matriz foi colocada em posição e preenchida com a resina composta. Após uma hora, a matriz foi adaptada em um dispositivo especial na máquina de ensaios Kratos para determinar a resistência de união, a uma velocidade de 0,05 mm/min. Os resultados, expressos em kgf, foram: Grupo 1 (3,99 ± 1,47, Grupo 2 (4,24 ± 2,00, Grupo 3 (3,84 ± 0,88, Grupo 4 (4,33 ± 1,23 e Grupo 5 (4,21 ± 1,38. Os resultados foram analisados pelo teste estatístico ANOVA a um critério. Não houve diferença estatisticamente significante (p The purpose of this study was to evaluate the tensile bond strength of four different adhesive systems. Scotchbond Multi-Purpose Plus, 3M (Group 1, Prime & Bond 2.0, Dentsply (Group 2, ProBOND, Dentsply (Group 3, PAAMA 2, SDI (Group 4 were used with GLACIER (SDI composite resin. One group without any adhesive was used as control (Group 5. Fifty specimens were divided into 5 groups of 10 each. A stainless steel split matrix with 6.00 mm diameter and 1.00 mm depth was used to obtain two discs of composite resin. The composite resin was applied into one half of the matrix in small portions and light cured for 40 seconds

  5. Atenuação da intensidade de luz e profundidade de polimerização de resinas compostas

    OpenAIRE

    Werlang, Jean Felipe Garlet; Dalfovo, Ricardo João; Neiva, Ivana Froede; Obici, Andresa Carla

    2016-01-01

    Objetivo: Avaliar a atenuação da luz através de diferentes espessuras de resina composta e a profundidade de polimerização. Materiais e Métodos: Foram utilizadas as resinas Opallis e Llis de esmalte (E) e de dentina (D), na cor A3. Para atenuação da luz foram empregadas matrizes metálicas (6,0mm de diâmetro e espessuras de 0,5, 1,0, 1,5 e 2,0mm), as quais foram posicionadas na janela de leitura do radiômetro e a intensidade de luz medida antes e após a interposição do material. A profundidade...

  6. Chemical tools: epoxic resins; Herramientas quimicas: resinas epoxidicas

    Energy Technology Data Exchange (ETDEWEB)

    Paz, S.; Pazos, M.; Prendes, P.

    1998-10-01

    Epoxy resins are very useful products for different applications in different fields. Due to the fact that they are a highly versatile products they can be considered as chemical tools. However the epoxy resins must be correctly formulated in order to obtain the final properties. In this article an easy and reliable method to optimise the energy formulation is presented. (Author)

  7. Comparação dos valores de desgaste abrasivo e de microdureza de 13 resinas compostas usadas em odontologia através do método do disco retificado Comparing abrasive wear and microhardness of 13 dental composite resins

    Directory of Open Access Journals (Sweden)

    Eduardo C. Bianchi

    2007-06-01

    Full Text Available Atualmente tem-se buscado simplificar a tarefa de caracterização da vida útil de restaurações dentárias realizadas por resinas compostas através de métodos laboratoriais, que são mais rápidos e não sofrem influência de variáveis pessoais inerentes às análises clínicas. Com este propósito, este trabalho apresenta uma nova metodologia de ensaio laboratorial para a avaliação do desgaste abrasivo de resinas compostas através do método do disco retificado. Realizaram-se ensaios de resistência ao desgaste abrasivo com 13 resinas compostas odontológicas e buscou-se analisar o comportamento da resistência ao desgaste abrasivo em relação à microdureza dessas resinas. Com a análise dos resultados concluiu-se que o método de discos retificados é eficiente para a obtenção da resistência ao desgaste abrasivo. Notou-se também ser extremamente pequeno o nível de correlação entre microdureza e desgaste abrasivo o que indica que cada resina composta tem características próprias e que o desgaste é dependente também de outros fatores.It is now commonplace to search for methods to assess the useful lifetime of dental restorations made of resins, which are quicker and less subjective than clinical analyses. With this purpose, this work presents a new methodology based on the grinding disk for evaluating the abrasive wear of composed resins. Resistance tests to the abrasive wear were made with 13 composed resins used as dental material, and a comparison was done with the hardness of those resins. From the data analysis, we concluded that the method of rectified disks is efficient for obtaining the resistance to the abrasive wear. Furthermore, the correlation between hardness and abrasive wear was very small, which indicates that each composed resin has its own characteristics and that the wear also depends on other factors.

  8. Evaluation of the surface hardness of composite resins before and after polishing at different times Avaliação da dureza superficial de resinas compostas antes e após o polimento em diferentes tempos

    Directory of Open Access Journals (Sweden)

    Michelle Alexandra Chinelatti

    2006-06-01

    Full Text Available PURPOSE: The aim of this study was to evaluate the surface hardness of six composite resins: Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables, Silux Plus (microfilled and Z100 (minifilled before and after polishing at different times. MATERIALS AND METHODS: For this purpose, 240 specimens (5mm diameter, 1.4mm high were prepared. Vickers hardness was determined before and after polishing at different times: immediately, 24h, 7 and 21 days after preparation of the samples. Statistical analysis was performed by ANOVA and Tukey test. RESULTS: There was no difference in the hardness of flowable resins, which had lower hardness than the minifilled resin. The minifilled resin showed the highest surface hardness as compared to the other materials (pPROPOSIÇÃO: O objetivo deste estudo foi avaliar a dureza superficial de seis resinas compostas - Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables, Silux Plus (micropartículas e Z100 (híbrida - antes e após o polimento realizado em diferentes tempos. MATERIAL E MÉTODO: Foram confeccionados 240 corpos-de-prova circulares (5mm de diâmetro e 1,4mm de altura. A dureza Vickers foi obtida antes e após o polimento realizado em diferentes tempos: imediatamente, 24 horas, 7 dias e 21 dias após a confecção do corpo-de-prova. Os dados foram analisados estatisticamente por meio da ANOVA e do Teste de Tukey. RESULTADOS: Não houve diferença entre as resinas compostas flowable, as quais apresentaram os menores valores de dureza. A resina composta híbrida demonstrou os melhores resultados. Todos os materiais exibiram aumento de dureza após a realização do polimento, que foi mais evidente após 7 dias. CONCLUSÃO: Pôde-se concluir que, independente do tipo de resina composta, a dureza superficial foi consideravelmente maior quando o polimento foi realizado 1 semana após a confecção dos corpos-de-prova.

  9. Estudio de la fractura de materiales compuestos por una matriz de plástico

    OpenAIRE

    Maspoch, M. Ll. (Maria Lluïsa)

    1992-01-01

    Se estudia el comportamiento a fractura de materiales, compuestos por una matriz de plástico en la que se ha dispersado una segunda fase en forma de partículas elastoméricas. Como matriz se han utilizado dos materiales diferentes: una resina de poliéster insaturada y poliestireno. Se estudia la morfología de los materiales compuestos preparados, se determinan los parámetros de fractura y otras propiedades mecánicas, se realiza el estudio fractográfico y finalmente se analizan los resultados e...

  10. Uso da cromatografia de exclusão por tamanho na caracterização de substâncias húmicas de Latossolo Vermelho-Escuro sob efeito da calagem

    Directory of Open Access Journals (Sweden)

    C. A. Silva

    2000-09-01

    Full Text Available Este estudo avaliou o peso molecular estimado (PM e as proporções de frações ácidos húmicos (FAH e frações ácidos fúlvicos (FAF presentes em substâncias húmicas (SH, extraídas com NaOH 0,1 M e resina trocadora de íons, originárias de Latossolo Vermelho-Escuro sob floresta e cultivado com laranja, em áreas com e sem calagem, por meio da cromatografia de exclusão por tamanho de alta eficiência (CETAE. Na calibração do PM com o tempo de retenção de diferentes compostos na coluna cromatográfica, utilizaram-se moléculas de sulfonato de poliestireno de sódio (SPS e acetona. A análise das substâncias húmicas revelou que as FAFs e FAHs dos materiais de solo apresentaram tempo de eluição e, portanto, pesos moleculares muito similares àqueles determinados para os ácidos padrões. Os cromatogramas obtidos mostraram que o uso e o manejo do solo não introduziram mudanças no PM e na relação FAF:FAH das substâncias húmicas. Por outro lado, o método de extração influenciou, de forma marcante, as proporções de FAH e FAF, com mais FAH nos materiais extraídos com a resina trocadora de íons e maiores proporções de FAF nas substâncias húmicas extraídas com NaOH. As proporções de FAF e FAH obtidas por meio do método proposto pela SISH estiveram muito próximas àquelas determinadas com a CETAE, no material húmico extraído com a resina Chelex, demonstrando o potencial desta técnica na determinação do PM e das proporções de FAH e FAF em substâncias húmicas originárias de solos.

  11. Efecto de surfactantes polimerizables en la distribución de tamaño de partícula, pH, viscosidad, contenidos de sólidos y de monómero residual de una resina estireno-butilacrilato Effect of polymerizable surfactants on particle size distribution, pH, viscosity, contents of solids and residual monomer of a styrene-butylacrylate resin

    Directory of Open Access Journals (Sweden)

    Luis A. Rios

    2013-01-01

    Full Text Available Se presentan los resultados de la polimerización en emulsión de una resina acrílica estirenada usando surfactantes polimerizables, los cuales presentan ventajas técnicas como baja formación de espuma, alta resistencia de la película al contacto con agua y buena estabilidad en la polimerización. Se evaluó el efecto de estos surfactantes polimerizables en la distribución de tamaños de partícula de la resina; además se determinaron propiedades finales de la resina tales como porcentaje de sólidos, porcentaje de monómero libre, viscosidad y pH. Estos resultados se compararon con los obtenidos usando surfactantes convencionales no polimerizables del tipo alquil fenol etoxilado y alquilarilpoliglicol éter sulfato de sodio. Los resultados indican que que se pueden remplazar totalmente los surfactantes convencionales no polimerizables por los surfactantes poliméricos evaluados sin afectar significativamente las propiedades de la resina, mientras que la sustitución parcial de los surfactantes no polimerizables por los polimerizables induce, en algunos casos, a la formación de partículas con mayor tamaño a las presentes en la muestra estándar.Results on the emulsion polymerization of a styrenated acrylic resin using polymerizable surfactants are presented. These surfactants exhibit low foaming, high film strength upon contact with water and good stability in the polymerization. A comparison was made with results for conventional non-polymerizable alkyl aryl polyglycol ether sulphate, sodium salt and nonylphenolethoxylate surfactants. The effect of these polymerizable surfactants on the particle size distribution of the resin was evaluated; in addition to determining the final properties of the resin such as solids content, free monomer content, viscosity and pH. It is feasible to totally replace non-polymerizable surfactants by the polymerizable surfactants evaluated without affecting significantly the properties of the resin, while

  12. RESINAS COMPOSTAS EM DENTES POSTERIORES: UMA REVISÃO SISTEMÁTICA

    OpenAIRE

    Lima, Cláudia Fonseca de Albuquerque; de Souza, Fábio Barbosa; da Silva, Claudio Heliomar Vicente

    2016-01-01

    As resinas compostas vêm sendo largamente utilizadas em dentes posteriores. Objetivou-se realizar uma revisão sistemática acerca das publicações de avaliações clínicas do emprego deste material em restaurações que envolvessem a superfície oclusal e/ou proximal de pré-molares e molares de forma a avaliar os critérios empregados para execução das mesmas. As publicações foram selecionadas aleatoriamente a partir de uma pesquisa bibliográfica a partir dos pré-requisitos: publicação em revista ind...

  13. Rugosidade e microscopia de força atômica de resinas compostas submetidas a diferentes métodos de polimento

    Directory of Open Access Journals (Sweden)

    Larissa Márcia Martins Alves

    2013-01-01

    Full Text Available Este trabalho avaliou a rugosidade e a topografia de superfície de resinas compostas submetidas a diferentes métodos de polimento. Foram utilizadas 5 resinas (Filtek Z350, Master Fill, Vênus, Charisma e Durafill VS e confeccionou-se 90 corpos de prova distribuídos em 6 grupos (n:15: SP: sem polimento; TB: ponta de borracha abrasiva; DL: disco de lixa em três granulações; FP: disco de feltro com pasta diamantada; ECS: escova de carbeto de silício; PS: ponta de silicone abrasiva. Após os polimentos, foram realizadas as análises da rugosidade com auxílio de um rugosímetro e da topografia de superfície com a microscopia de força atômica. Os valores foram tabulados e analisados estatisticamente pelos testes de Kruskal-Wallis, DUNN e ANOVA (α = 0,05. As médias variaram entre 0,01 µm (Filtek Z 350 - TB e 0,27 µm (Charisma - ECS. Concluiu-se que para todas as resinas testadas o melhor método de polimento foi o feltro com pasta diamantada (FP.

  14. EFECTO DE LOS OBSTÁCULOS TIPO POLIMERO RESINA EN RENDIMIENTO DE REDES TCP/IP/IEEE 802.11g MODO AD-HOC

    OpenAIRE

    Márquez Barriobero, David

    2011-01-01

    La investigación tiene como objetivo primordial el desarrollo de un modelo matemático para evaluar el efecto de los obstáculos de tipo polímero resina en el rendimiento de redes TCP/IP/IEEE 802.11g modo ad-hoc; esto con el propósito de establecer la relación existente entre el diámetro de los obstáculos de tipo polímero resina y el rendimiento de una red inalámbrica en modo ad-hoc, al transmitir datos vía protocolo FTP. El tipo de investigación es explicativa con un diseño experimental. Los t...

  15. Dureza knoop de resinas compostas em função do número relativo de radicais livres Relative number of free radicals and knoop hardness of composites

    Directory of Open Access Journals (Sweden)

    Marco Aurélio de MENEZES

    1998-07-01

    Full Text Available A pesquisa teve a finalidade de determinar o número relativo de radicais livres e a dureza Knoop de três resinas compostas (Z100, Silux Plus e Heliomolar RO. Para o ensaio dos radicais livres, as irradiações foram: 110, 180, 300, 580 mW/cm2, pelos tempos de 10, 20, 30, 40, 50, 60, 80 e 90 segundos. As durezas foram determinadas com as cores claras com irradiação de 110 e 300 mW/cm2, por 20, 40, 60 e 80 segundos, nas faces da frente e do fundo, nas idades de 5 minutos, 1 hora, 1 dia, 1 semana e 1 mês. As conclusões foram: a resina Z100 apresentou cerca de 3 vezes mais radicais livres do que as outras; o número relativo de radicais livres aumenta com a intensidade e tempo de exposição; maior intensidade de luz aumentou a dureza; maior tempo de exposição aumentou as durezas das resinas Silux Plus e Heliomolar, mas não da Z100; a dureza aumentou com a idade até 1 mês; o lado da irradiação apresentou maior dureza do que o do fundo; a resina Z100 foi bem mais dura e sofreu menos a influência da irradiação.The present study had the purpose of determining the relative number of free radicals of three composites with clear and dark colors. Intensities of irradiation were: 110, 180, 300, and 580 mW/cm2, for 10, 20, 30, 40, 50, 60, 80 and 90 seconds. Hardness was determined for the clear colors of the composites, using 110 and 300 mW/cm2 irradiation intensities, for 20, 40, 60, and 80 seconds, on front and deep surfaces, at the ages of 5 minutes, 1 hour, 1 day, 1 week, and 1 month. The conclusions were that: depending on the resin, clear colors present more free radicals; the number of free radicals increases with higher intensity and longer irradiation time; composite Z100 is much richer in free radicals than Silux Plus and Heliomolar RO; higher intensity of irradiation leads to increasing hardness; longer irradiation time increases hardness of Silux Plus and Heliomolar RO, but not that of Z100; hardness increases with age; in depth

  16. Synthesis of polyoxometalate-loaded epoxy composites

    Science.gov (United States)

    Anderson, Benjamin J

    2014-10-07

    The synthesis of a polyoxometalate-loaded epoxy uses a one-step cure by applying an external stimulus to release the acid from the polyoxometalate and thereby catalyze the cure reaction of the epoxy resin. Such polyoxometalate-loaded epoxy composites afford the cured epoxy unique properties imparted by the intrinsic properties of the polyoxometalate. For example, polyoxometalate-loaded epoxy composites can be used as corrosion resistant epoxy coatings, for encapsulation of electronics with improved dielectric properties, and for structural applications with improved mechanical properties.

  17. Avaliação clínica de uma resina composta modificada por poliácido, utilizada como selante oclusal, quando aplicada por dentista, THD e graduando Clinical evaluation of a polyacid-modified resin composite, used as an occlusal sealant, when applied by dentist, dental hygienist and undergraduate

    Directory of Open Access Journals (Sweden)

    Roberta Tarkany BASTING

    1999-04-01

    Full Text Available O presente trabalho tem por finalidade comparar as diferenças de retenção de uma resina composta modificada por poliácido (Variglass V.L.C., utilizada como selante oclusal, quando aplicada por dentista, THD e graduando em Odontologia. Foram seladas as superfícies oclusais de 370 primeiros molares permanentes superiores de crianças entre 6 e 8 anos de idade provenientes de escolas públicas do município de Piracicaba. As avaliações clínicas foram realizadas após seis e oito meses da aplicação do selante. Aos seis meses, verificou-se que 78,42% dos selantes clinicamente aceitáveis permaneceram retidos sobre a superfície oclusal. O índice de perdas totais corresponderam a 10,20% do total de selantes aplicados. O melhor índice de retenção total foi obtido quando aplicado por graduando. Aos 12 meses, houve um aumento do número de selantes perdidos (43,79% e conseqüente decréscimo do número de selantes totalmente retidos (18,96%, não havendo diferenças significativas de retenção do selante quando aplicado por dentista, THD e graduando. Nos casos de perdas totais do selante, não se constatou presença de lesão cariosa.The aim of this work is to evaluate the differences of clinical retention of a polyacid-modified resin composite (Variglass V.L.C., used as an occlusal sealant, when applied by dentist, dental hygienist and undergraduate in Dentistry. The occlusal surfaces of 370 superior first molars of children ageing from 6 to 8 years from public schools in Piracicaba, were sealed. The presented data are related to the final evaluation after 6 and 12 months. It was observed that after 6 months, 78.42% of the sealants clinically acceptable, remained on the occlusal surfaces and that the completely lost sealants reached 10.20%. The best results of the sealants retention were obtained when the sealants were applied by an undergraduate. After 12 months, there was an increase of completely lost sealants (43.79% and a decrease of

  18. Evaluación del grado de sellado marginal y resistencia adhesiva de restauraciones de resina compuesta con adhesivo convencional en dentición primaria y definitiva

    OpenAIRE

    Monsalves Bravo, Silvia Isabel; Terrazas Soto, Pedro; Toro Urbina, Georgina; Bader Mattar, Marcelo

    2014-01-01

    El presente estudio evaluó el grado de sellado marginal y resistencia adhesiva de restauraciones de resinas compuestas confeccionadas con un sistema adhesivo de grabado y lavado en dentición primaria y definitiva. Para realizar ambos test se utilizaron 20 piezas primarias y 20 piezas definitivas. En resistencia al cizallamiento, los dientes fueron seccionados longitudinalmente y se les adhirió un cilindro de resina compuesta, utilizando la técnica adhesiva de grabado y lavado para ambas denti...

  19. Avaliação in vitro da efetividade de polimerização da resina acrílica dental ativada através de energia de microondas, quando em contato com metal Use of microwave energy for processing acrylic resin near metal

    Directory of Open Access Journals (Sweden)

    Katia Olmedo BRAUN

    1998-04-01

    Full Text Available Com o objetivo de verificar a efetividade da energia de microondas na polimerização da resina acrílica próxima ao metal, foram confeccionados 36 corpos-de-prova cilíndricos com 30,0 mm de diâmetro x 4,0 mm de espessura, contendo no seu interior uma sela metálica com 28,0 mm x 8,0 mm x 0,5 mm, divididos aleatoriamente em 3 grupos e submetidos aos seguintes processamentos: G1 resina Clássico polimerizada em ciclo curto; G2 resina Acron-MC polimerizada em forno de microondas por 3 minutos a 500 W; G3 resina Clássico polimerizada em forno de microondas por 3 minutos a 500 W. Após a polimerização, cada amostra foi dividida em duas partes aproximadamente iguais, sendo que uma das partes foi utilizada para a avaliação de monômero residual, enquanto a outra foi submetida aos testes de dureza e porosidade. A dosagem de monômero liberada na água durante doze dias consecutivos foi avaliada através da espectrofotometria. A dureza Knoop foi verificada nas distâncias de 50, 100, 200, 400 e 800 mm da sela metálica, e a porosidade interna e externa foi avaliada a olho nu e com auxílio de microscópio com aumento de 100 X. Diante dos resultados obtidos, concluiu-se que a energia de microondas pode ser utilizada para a polimerização da resina acrílica contendo sela metálica no seu interior e que as resinas acrílicas convencionais, quando polimerizadas através da energia de microondas, apresentaram maior quantidade de poros.The conventional method to process acrylic resin is a time consuming step to construct removable prosthodontics. Microwave energy could provide a solution, but there are still questions regarding this process taking place in the presence of metal. The aim of this study was, therefore, to compare residual monomer, microhardness and porosity of two acrylic resins cured by different methods in the presence of a metal framework. The conditions evaluated were: Group 1 - Acrylic resin Clássico, short cycle heatcured for 3

  20. Method for immobilizing invertase by adsorption on Dowex® anionic exchange resin Método para a imobilização da invertase por adsorção em resinas trocadoras de ânions (DOWEX

    Directory of Open Access Journals (Sweden)

    Ester Junko Tomotani

    2006-06-01

    Full Text Available This communication describes a method for adsorbing the invertase (EC.3.2.1.26 on DOWEX® anion exchange resin. Among the types of DOWEX® resins studied (1x8:50-400; 1x4:50-400 and 1x2:100-400, 1X4-200 was the most suitable, because it adsorbed the invertase molecules completely and the complex 1X4-200/invertase retained 100% of the catalytic activity. Moreover, no leakage of enzyme from the support was noted at the end of the sucrose hydrolysis.O presente trabalho descreve um método de adsorção da invertase (EC. 3.2.1.26 na resina de troca aniônica do tipo Dowex®. Entre os tipos de resinas Dowex® estudados (1x8:50-400; 1x4:50-400 e 1x2:100-400, 1x4-200 foi a mais apropriada devido à completa adsorção das moléculas de invertase e a sua retenção de atividade catalítica de 100% do complexo 1x4-200/invertase. Salienta-se ainda a ausência do desprendimento da enzima do suporte após o término da hidrólise da sacarose.

  1. Epoxy-based carbon nanotubes reinforced composites

    CSIR Research Space (South Africa)

    Kesavan Pillai, Sreejarani

    2011-04-01

    Full Text Available of the three major epoxy resin producers worldwide [May, 1987]. Epoxy resin is most commonly used as a matrix for advanced composites due to their superior thermal, mechanical and electrical properties; dimensional stability and chemical resistance. Epoxy... and modifiers to create products with an almost unlimited range and variety of performance properties [The epoxy book, 2000]. Epoxy resins are widely used as high-grade synthetic resins, for example, in the electronics, aeronautics and astronautic industries...

  2. Interaction of water with epoxy.

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Dana Auburn

    2009-07-01

    The chemistries of reactants, plasticizers, solvents and additives in an epoxy paint are discussed. Polyamide additives may play an important role in the absorption of molecular iodine by epoxy paints. It is recommended that the unsaturation of the polyamide additive in the epoxy cure be determined. Experimental studies of water absorption by epoxy resins are discussed. These studies show that absorption can disrupt hydrogen bonds among segments of the polymers and cause swelling of the polymer. The water absorption increases the diffusion coefficient of water within the polymer. Permanent damage to the polymer can result if water causes hydrolysis of ether linkages. Water desorption studies are recommended to ascertain how water absorption affects epoxy paint.

  3. Preparação de fibras de polipropileno modificadas com grupos mercaptan e sua utilização em compósitos com resina epoxídica

    Directory of Open Access Journals (Sweden)

    Dutra Rita C. L.

    1999-01-01

    Full Text Available Fibras de polipropileno modificadas com grupos mercaptan foram desenvolvidas através de processo de extrusão/fiação de misturas contendo PP e EVA modificado com grupos mercaptan (EVASH. A superfície destas fibras foi analisada por espectroscopia foto-eletrônica de raios-X (XPS, espectroscopia no infravermelho com transformada de Fourier, utilizando-se a técnica de refletância difusa (DRIFTS, tensão superficial e microscopia eletrônica de varredura. A partir destas técnicas, chegou-se à conclusão que o componente polar (EVASH se situa próximo à superfície da fibra. A utilização destas fibras em compósitos com resina epoxídica resultou em aumento considerável da resistência ao impacto e da temperatura de transição vítrea do material, indicando boa adesão interfacial matriz-fibra. Estas interações foram comprovadas por análise dinâmico-mecânicas.

  4. Contact allergy to epoxy resin

    DEFF Research Database (Denmark)

    Bangsgaard, Nannie; Thyssen, Jacob Pontoppidan; Menné, Torkil

    2012-01-01

    Background. Epoxy resin monomers are strong skin sensitizers that are widely used in industrial sectors. In Denmark, the law stipulates that workers must undergo a course on safe handling of epoxy resins prior to occupational exposure, but the effectiveness of this initiative is largely unknown...... in an educational programme. Conclusion. The 1% prevalence of epoxy resin contact allergy is equivalent to reports from other countries. The high occurrence of epoxy resin exposure at work, and the limited use of protective measures, indicate that reinforcement of the law is required....

  5. Erosão em compósitos à base de fibras de vidro/kevlar e resina epóxi de uso aeronáutico Erosion on composite materials based on glass and kevlar fibers/epoxy resin used in the aeronautical industry

    Directory of Open Access Journals (Sweden)

    Rogério A. Silva

    2003-01-01

    Full Text Available Este trabalho tem como objetivo principal o estudo e a análise da eficiência de dois diferentes tipos de recobrimentos usados na proteção contra o processo de desgaste por erosão em substratos fabricados em materiais compósitos poliméricos de uso aeronáutico, dando ênfase às peças fabricadas em fibras de vidro / kevlar impregnadas com resina epóxi. Revestimentos protetores baseados em um determinado tipo de tinta de poliuretano e um filme incolor de poliuretano foram utilizados para a avaliação da resistência à erosão, quando submetidos ao jateamento com microesferas de vidro. Para a realização dos ensaios de erosão foi projetado e construído um dispositivo específico para esse fim. Nos ensaios alguns fatores foram considerados, tais como: a natureza física das partículas abrasivas de microesferas de vidro, a distância, a velocidade e o ângulo de ataque das partículas durante o processo de jateamento. Os corpos-de-prova foram analisados quanto à sua variação de massa. Foram, também, utilizadas técnicas metalográficas na preparação de corpos-de-prova que foram analisados por microscopias óptica e eletrônica de varredura, assistida pela técnica de EDS, caracterizando o processo de erosão. Os resultados mostraram que os corpos-de-prova de compósitos poliméricos revestidos somente com a tinta de poliuretano apresentaram baixa resistência no ensaio de erosão. Entretanto, esta tinta quando protegida pelo filme incolor de poliuretano teve sua resistência à erosão aumentada na ordem de 5 vezes, aumentando, conseqüentemente, a vida útil do componente aeronáutico em sua aplicação final. Devido à facilidade de aplicação do filme de poliuretano no componente a ser protegido, os resultados deste estudo já estão sendo utilizados pelos fabricantes de aeronaves e operadores.The main goal of the present work is to evaluate the efficiency of two different coatings used as protection against the erosion wear

  6. Observación del sistema poroso de rocas carbonatadas al microscopio electrónico de barrido

    Directory of Open Access Journals (Sweden)

    Alonso, F.

    1988-08-01

    Full Text Available The pore system of three carbonate rocks is studied through observation of resin and latex casts, under scanning electron microscope. The selected rocks -Hontoria and Seville limestones, and Boñar dolomite- have been broadly employed in the construction of outstanding monuments of the Spanish Historical Heritage. The degree of impregnation achieved by the epoxy resins, according to different procedures, is also checked by means of mercury injection porosimetry techniques. The observation of the pore casts displays, generally, the complexity of the pore systems of these rocks.Se estudia en este trabajo el sistema poroso de tres rocas carbonatadas, a partir de observaciones de moldes de resina y réplicas de látex al microscopio electrónico de barrido. Las rocas seleccionadas -calizas de Hontoria y Sevilla, y dolomía de Boñar- han sido ampliamente utilizadas en la construcción de importantes monumentos del Patrimonio Histórico Español. Se ha comprobado, asimismo, el grado de impregnación alcanzado por las resinas epoxídicas en diferentes procedimientos, a partir de técnicas de porosimetria de inyección de mercurio. Los resultados obtenidos ponen de manifiesto, en general, la complejidad de la estructura porosa de dichas rocas.

  7. Biodetoxification of toxins generated from lignocellulose pretreatment using a newly isolated fungus, Amorphotheca resinae ZN1, and the consequent ethanol fermentation

    Directory of Open Access Journals (Sweden)

    Wang Wei

    2010-11-01

    Full Text Available Abstract Background Degradation of the toxic compounds generated in the harsh pretreatment of lignocellulose is an inevitable step in reducing the toxin level for conducting practical enzymatic hydrolysis and ethanol fermentation processes. Various detoxification methods have been tried and many negative outcomes were found using these methods, such as the massive freshwater usage and wastewater generation, loss of the fine lignocellulose particles and fermentative sugars and incomplete removal of inhibitors. An alternate method, biodetoxification, which degrades the toxins as part of their normal metabolism, was considered a promising option for the removal of toxins without causing the above problems. Results A kerosene fungus strain, Amorphotheca resinae ZN1, was isolated from the microbial community growing on the pretreated corn stover material. The degradation of the toxins as well as the lignocelluloses-derived sugars was characterized in different ways, and the results show that A. resinae ZN1 utilized each of these toxins and sugars as the sole carbon sources efficiently and grew quickly on the toxins. It was found that the solid-state culture of A. resinae ZN1 on various pretreated lignocellulose feedstocks such as corn stover, wheat straw, rice straw, cotton stalk and rape straw degraded all kinds of toxins quickly and efficiently. The consequent simultaneous saccharification and ethanol fermentation was performed at the 30% (wt/wt solid loading of the detoxified lignocellulosic feedstocks without a sterilization step, and the ethanol titer in the fermentation broth reached above 40 g/L using food crop residues as feedstocks. Conclusions The advantages of the present biodetoxification by A. resinae ZN1 over the known detoxification methods include zero energy input, zero wastewater generation, complete toxin degradation, processing on solid pretreated material, no need for sterilization and a wide lignocellulose feedstock spectrum

  8. OPACIDAD Y TRANSLUCIDEZ DE DIFERENTES RESINAS COMPUESTAS DE ACUERDO A SU TAMAÑO DE PARTÍCULA Y SU APLICACIÓN CLÍNICA

    Directory of Open Access Journals (Sweden)

    Manuel Roberto Sarmiento Limas

    2011-12-01

    Full Text Available Normal 0 21 false false false ES-CO X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} Propósito: El objetivo de este estudio fue determinar el grado de opacidad o translucidez de acuerdo a su tamaño de partícula que nos ofrecen las resinas compuestas para seleccionar cual es la ideal de acuerdo al grado de dificultad estética. Materiales Y Metodos: Se realizaron muestras de resina circunferenciales, distribuidos así: Filtek Z350 XT®, Premisa Direct®, Exthet-X HD®, Tetric N Ceram®, Helio Molar®, Vit-l-escense, Amleogen Plus®, Miris 2 ® y Brilliant NG ®. Y se realizaron lecturas de reflectancia y transmitancia a través del Espectrofotometro Cary 5000.  Resultados: Las muestras estudiadas presentan un comportamiento similar tanto en reflectancia como en transmitancia, encontrando dos extremos opuestos, uno hacia opacidad (dentinas y otro hacia translucidez (esmaltes, pero con un gran número de muestras con valores intermedios, y comportamiento similar que no permite clasificarlas como dentinas o esmaltes a pesar de la clasificación dada por cada marca. Amleogen Plus®, Vit - L- Escence® Y Esthet X HD®  son las marcas que presentan mayor diferencia en el comportamiento de sus esmaltes en comparación con sus dentinas, contrario a lo observado con Helio Molar®, Brilliant NG® y Tetric N Ceram®. En cuanto al tamaño de partícula no se encuentran diferencias significativas en su

  9. Wettability of nano-epoxies to UHMWPE fibers.

    Science.gov (United States)

    Neema, S; Salehi-Khojin, A; Zhamu, A; Zhong, W H; Jana, S; Gan, Y X

    2006-07-01

    Ultra high molecular weight polyethylene (UHMWPE) fibers have a unique combination of outstanding mechanical, physical, and chemical properties. However, as reinforcements for manufacturing high performance composite materials, UHMWPE fibers have poor wettability with most polymers. As a result, the interfacial bonding strength between the fibers and polymer matrices is very low. Recently, developing so-called nano-matrices containing reactive graphitic nanofibers (r-GNFs) has been proposed to promote the wetting of such matrices to certain types of fiber reinforcements. In this work, the wettability of UHMWPE fibers with different epoxy matrices including a nano-epoxy, and a pure epoxy was investigated. Systematic experimental work was conducted to determine the viscosity of the epoxies, the contact angle between the epoxies and the fibers. Also obtained are the surface energy of the fibers and the epoxies. The experimental results show that the wettability of the UHMWPE fibers with the nano-epoxy is much better than that of the UHMWPE fibers with the pure epoxy.

  10. Epoxy-based carbon nanotubes reinforced composites

    CSIR Research Space (South Africa)

    Kesavan Pillai, Sreejarani

    2011-04-01

    Full Text Available of the three major epoxy resin producers worldwide [May, 1987]. Epoxy resin is most commonly used as a matrix for advanced composites due to their superior thermal, mechanical and electrical properties; dimensional stability and chemical resistance. Epoxy... are electrical insulators, and the widespread use of the epoxy resins for many high-performance applications is constrained because of their inherent brittleness, delamination and fracture toughness limitations. There were quite a few approaches to enhance...

  11. SUSTENTAÇÃO DE ESMALTE COM IONÔMEROS DE VIDRO E RESINA COMPOSTA: EFEITO NA RESISTÊNCIA À FRATURA DAS CÚSPIDES DE DENTES RESTAURADOS SUPPORTING ENAMEL WITH GLASS IONOMER CEMENT AND COMPOSITE RESIN: EFFECT ON FRACTURE RESISTANCE OF CUSPS OF RESTORED TEETH

    Directory of Open Access Journals (Sweden)

    Angelo Stefano SECCO

    1997-10-01

    Full Text Available Este estudo determinou a resistência e o tipo de fratura do esmalte suportado pelos materiais restauradores ionômeros de vidro convencional e modificado por resina e resina composta, bem como a influência dessa técnica restauradora na resistência das cúspides dos dentes. A remoção da estrutura dental para o preparo de cavidades tipo classe II e a presença de esmalte socavado diminuiram significativamente a resistência das cúspides dos dentes em relação ao dente hígido (p This study determined the resistance to fracture and its pattern for enamel supported with conventional and modified glass ionomer cements, and composite resin restorative materials, as well as the influence of these restorative techniques on cuspal strength of teeth. Removal of dental structure by class II cavity preparations and unsupported enamel had decreased significantly the cuspal strength in relation to healthy teeth (p < 0.01. Restorative materials used to support enamel reduced the fracture rate of restored cusps, but did not increase the fracture resistance values statistically. All tested groups presented alterations in the fracture pattern

  12. Thermally activated, single component epoxy systems

    KAUST Repository

    Unruh, David A.; Pastine, Stefan J.; Moreton, Jessica C.; Frechet, Jean

    2011-01-01

    A single component epoxy system in which the resin and hardener components found in many two-component epoxies are combined onto the same molecule is described. The single molecule precursor to the epoxy resin contains both multiple epoxide moieties and a diamine held latent by thermally degradable carbamate linkages. These bis-carbamate "single molecule epoxies" have an essentially infinite shelf life and access a significant range in curing temperatures related to the structure of the carbamate linkages used. © 2011 American Chemical Society.

  13. Thermally activated, single component epoxy systems

    KAUST Repository

    Unruh, David A.

    2011-08-23

    A single component epoxy system in which the resin and hardener components found in many two-component epoxies are combined onto the same molecule is described. The single molecule precursor to the epoxy resin contains both multiple epoxide moieties and a diamine held latent by thermally degradable carbamate linkages. These bis-carbamate "single molecule epoxies" have an essentially infinite shelf life and access a significant range in curing temperatures related to the structure of the carbamate linkages used. © 2011 American Chemical Society.

  14. Dentine bond strength of a composite resin polymerized with conventional light and argon laser Resistência de união à dentina de resina composta polimerizada com luz halógena e laser de argônio

    Directory of Open Access Journals (Sweden)

    Patricia Ramos Lloret

    2004-09-01

    Full Text Available The use of argon laser (488 nm has been suggested as a new alternative for polymerizing adhesive materials. This study aimed to evaluate the tensile bond strength of a microfilled composite (A110, 3M inserted by incremental technique (3 increments of 1 mm and by single increment (3 mm polymerized by argon laser for 10, 20 and 30 seconds and halogen light for 40 seconds. Eighty (8 groups of 10 teeth freshly extracted bovine teeth were stored in a freezer in distilled water for one week. The crowns were cross-sectioned from the roots. Pulpectomy was performed and the pulp chambers were sealed with wax. The buccal surfaces of the teeth were ground with wet sandpaper (grains: 120, 400, and 600 to expose the surface dentin, and the teeth were then included in acrylic resin. A metal device was used to fix each sample and a black propylene matrix25 (3 mm high with an internal millimetric delimitation was used to insert the material according to the groups studied. The polymerization intervals were of 10, 20 and 30 seconds for the laser polymerization and 40 seconds for the conventional polymerization. Tensile tests were performed by a Universal Testing Machine 4442 (Instron at a speed of 0.5 mm/min and 500 N load. According to the methodology used, the incremental technique increased bond strength values. There was no difference between the studied polymerization techniques when resin was filled in 3 increments.O uso do laser de argônio (488 nm tem sido sugerido como uma nova alternativa para polimerização de materiais adesivos. Este estudo tem o objetivo de avaliar a resistência adesiva de uma resina composta microparticulada (A110, 3M inserida pela técnica incremental (3 incrementos de 1 mm e de incremento único (3 mm polimerizada com laser de argônio por 10, 20 e 30 segundos e com luz halógena por 40 segundos. Oitenta (8 grupos com 10 dentes dentes bovinos recém-extraídos foram armazenados em geladeira, em água destilada, por uma semana

  15. Characterization of Epoxy Functionalized Graphite Nanoparticles and the Physical Properties of Epoxy Matrix Nanocomposites

    Science.gov (United States)

    Miller, Sandi G.; Bauer, Jonathan L.; Maryanski, Michael J.; Heimann, Paula J.; Barlow, Jeremy P.; Gosau, Jan-Michael; Allred, Ronald E.

    2010-01-01

    This work presents a novel approach to the functionalization of graphite nanoparticles. The technique provides a mechanism for covalent bonding between the filler and matrix, with minimal disruption to the sp2 hybridization of the pristine graphene sheet. Functionalization proceeded by covalently bonding an epoxy monomer to the surface of expanded graphite, via a coupling agent, such that the epoxy concentration was measured as approximately 4 wt.%. The impact of dispersing this material into an epoxy resin was evaluated with respect to the mechanical properties and electrical conductivity of the graphite-epoxy nanocomposite. At a loading as low as 0.5 wt.%, the electrical conductivity was increased by five orders of magnitude relative to the base resin. The material yield strength was increased by 30% and Young s modulus by 50%. These results were realized without compromise to the resin toughness.

  16. Surface treated fly ash filled modified epoxy composites

    Directory of Open Access Journals (Sweden)

    Uma Dharmalingam

    2015-01-01

    Full Text Available Abstract Fly ash, an inorganic alumino silicate has been used as filler in epoxy matrix, but it reduces the mechanical properties due to its poor dispersion and interfacial bonding with the epoxy matrix. To improve its interfacial bonding with epoxy matrix, surface treatment of fly ash was done using surfactant sodium lauryl sulfate and silane coupling agent glycidoxy propyl trimethoxy silane. An attempt is also made to reduce the particle size of fly ash using high pressure pulverizer. To improve fly ash dispersion in epoxy matrix, the epoxy was modified by mixing with amine containing liquid silicone rubber (ACS. The effect of surface treated fly ash with varying filler loadings from 10 to 40% weight on the mechanical, morphological and thermal properties of modified epoxy composites was investigated. The surface treated fly ash was characterized by particle size analyzer and FTIR spectra. Morphological studies of surface treated fly ash filled modified epoxy composites indicate good dispersion of fillers in the modified epoxy matrix and improves its mechanical properties. Impact strength of the surface treated fly ash filled modified epoxy composites show more improvement than unmodified composites.

  17. Uso de incrustaciones de resina compuesta tipo onlay en molares estructuralmente comprometidos Use of onlay-type composite resin inlays in structurally involved molars

    Directory of Open Access Journals (Sweden)

    Alberto Carlos Cruz González

    2012-03-01

    Full Text Available Las incrustaciones en resina compuesta son una alternativa de bajo costo ante los métodos de obturación directos, frente a las dificultades de la adaptación marginal y la ubicación de contactos proximales, porque permiten otorgar una mejor anatomía dental a la restauración y superar el fenómeno de contracción al polimerizar grandes capas de material por fuera de la cavidad dental. El objetivo del presente artículo fue exponer el uso de la resina compuesta bajo técnica indirecta como una alternativa de fácil manipulación y resultados clínicos considerables ante la afectación estructural de molares. Se presentaron dos casos clínicos de incrustaciones con resina compuesta de tipo inlay onlay en dos molares permanentes afectados estructuralmente, uno de ellos fue tratado endodónticamente. Para la obtención de un troquel de trabajo sobre el que se confecciona la incrustación bajo técnica incremental se obtienen modelos al impresionar con alginato la arcada de los dientes seleccionados, se realiza vaciado en silicona liviana del diente preparado y el resto en yeso piedra tipo III. El proceso de cementación en la cavidad bucal se lleva a cabo con cemento resinoso de doble curado. Las incrustaciones fueron sometidas a un control a los seis meses para evaluar los signos de filtración o desadaptación marginal mediante el secado con aire de la jeringa triple, explorador y radiografías periapicales, que mostraron ausencia de desadaptación o pigmentación marginal. Se concluyó que ante la afectación estructural de molares, las incrustaciones con resina compuesta bajo técnica indirecta fueron de fácil manipulación y se obtuvieron satisfactorios resultados clínicos.The composite resin inlays are a low cost alternative which seeks improvements to the direct filling methods meet the challenges of the marginal adaptation, location of proximal contacts, allows us to improve the restoration dental anatomy and overcome the phenomenon of

  18. Viscoelastic characterization of carbon fiber-epoxy composites by creep and creep rupture tests; Caracterizacao viscoelastica por meio de ensaios de fluencia e ruptura por fluencia de compositos polimericos de matriz de matriz de resina epoxidica e fibra de carbono

    Energy Technology Data Exchange (ETDEWEB)

    Farina, Luis Claudio

    2009-07-01

    One of the main requirements for the use of fiber-reinforced polymer matrix composites in structural applications is the evaluation of their behavior during service life. The warranties of the integrity of these structural components demand a study of the time dependent behavior of these materials due to viscoelastic response of the polymeric matrix and of the countless possibilities of design configurations. In the present study, creep and creep rupture test in stress were performed in specimens of unidirectional carbon fiber-reinforced epoxy composites with fibers orientations of 60 degree and 90 degree, at temperatures of 25 and 70 degree C. The aim is the viscoelastic characterization of the material through the creep curves to some levels of constant tension during periods of 1000 h, the attainment of the creep rupture envelope by the creep rupture curves and the determination of the transition of the linear for non-linear behavior through isochronous curves. In addition, comparisons of creep compliance curves with a viscoelastic behavior prediction model based on Schapery equation were also performed. For the test, a modification was verified in the behavior of the material, regarding the resistance, stiffness and deformation, demonstrating that these properties were affected for the time and tension level, especially in work temperature above the ambient. The prediction model was capable to represent the creep behavior, however the determination of the equations terms should be considered, besides the variation of these with the applied tension and the elapsed time of test. (author)

  19. Effect of the hardener to epoxy monomer ratio on the water absorption behavior of the DGEBA/TETA epoxy system

    Directory of Open Access Journals (Sweden)

    Ayrton Alef Castanheira Pereira

    2016-02-01

    Full Text Available Abstract The water absorption behavior of the DGEBA/TETA epoxy system was evaluated as a function of the epoxy monomer to amine hardener ratio. Weight gain versus immersion time curves were obtained and the experimental points were fitted using Fickian and Non-Fickian diffusion models. The results obtained showed that for all epoxy monomer to hardener ratios analyzed water diffusion followed non-Fickian behavior. It was possible to correlate the water absorption behavior to the macromolecular structure developed when the epoxy/ hardener ratio was varied. All epoxy/hardener ratios present a two-phase macromolecular structure, composed of regions with high crosslink density and regions with lower crosslinking. Epoxy rich systems have a more open macromolecular structure with a lower fraction of the dense phase than the amine rich systems, which present a more compact two-phase structure.

  20. Síntesis intermatricial y comparación de nanopartículas metálicas de Pd y Co soportadas en resinas catiónicas y aniónicas

    OpenAIRE

    Bastos Arrieta, Julio; Universitat Autònoma de Barcelona. Departament de Química

    2010-01-01

    Esta memoria de investigación es producto del trabajo experimental que se realizó con resinas de intercambio iónico para la síntesis intermatricial de nanopartículas metálicas de Co y Pd. Los estudios que se realizaron correspondieron a la iniciación en esta modalidad de síntesis de nanopartículas. En ellos se contemplaron las propiedades intrínsecas de la resina como: la capacidad de intercambio iónico, y funcionalidad química, tanto antes como después de la síntesis. Uno de los objetivos...

  1. The application of epoxy resin coating in grounding grid

    Science.gov (United States)

    Hu, Q.; Chen, Z. R.; Xi, L. J.; Wang, X. Y.; Wang, H. F.

    2018-01-01

    Epoxy resin anticorrosion coating is widely used in grounding grid corrosion protection because of its wide range of materials, good antiseptic effect and convenient processing. Based on the latest research progress, four kinds of epoxy anticorrosive coatings are introduced, which are structural modified epoxy coating, inorganic modified epoxy coating, organic modified epoxy coating and polyaniline / epoxy resin composite coating. In this paper, the current research progress of epoxy base coating is analyzed, and prospected the possible development direction of the anti-corrosion coating in the grounding grid, which provides a reference for coating corrosion prevention of grounding materials.

  2. Contact allergy to epoxy (meth)acrylates.

    Science.gov (United States)

    Aalto-Korte, Kristiina; Jungewelter, Soile; Henriks-Eckerman, Maj-Len; Kuuliala, Outi; Jolanki, Riitta

    2009-07-01

    Contact allergy to epoxy (meth)acrylates, 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (bis-GMA), 2,2-bis[4-(2-hydroxy-3-acryloxypropoxy)phenyl]-propane (bis-GA), 2,2-bis[4-(methacryl-oxyethoxy)phenyl] propane (bis-EMA), 2,2-bis[4-(methacryloxy)phenyl]-propane (bis-MA), and glycidyl methacrylate (GMA) is often manifested together with contact allergy to diglycidyl ether of bisphenol A (DGEBA) epoxy resin. To analyse patterns of concomitant allergic reactions to the five epoxy (meth)acrylates in relation to exposure. We reviewed the 1994-2008 patch test files at the Finnish Institute of Occupational Health (FIOH) for reactions to the five epoxy (meth)acrylates, and examined the patients' medical records for exposure. Twenty-four patients had an allergic reaction to at least one of the studied epoxy (meth)acrylates, but specific exposure was found only in five patients: two bis-GMA allergies from dental products, two bis-GA allergies from UV-curable printing inks, and one bis-GA allergy from an anaerobic glue. Only 25% of the patients were negative to DGEBA epoxy resin. The great majority of allergic patch test reactions to bis-GMA, bis-GA, GMA and bis-EMA were not associated with specific exposure, and cross-allergy to DGEBA epoxy resin remained a probable explanation. However, independent reactions to bis-GA indicated specific exposure. Anaerobic sealants may induce sensitization not only to aliphatic (meth)acrylates but also to aromatic bis-GA.

  3. Parâmetros de modelagem por injeção de termoplásticos em moldes fabricados por estereolitografia com resina SOMOS 7110

    OpenAIRE

    Busato, Fábio André

    2004-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Mecânica Este trabalho consistiu em avaliar comparativamente os principais parâmetros envolvidos no processo de moldagem por injeção, utilizando os termoplásticos PP, ABS e PA 6,6, em insertos fabricados pelo processo convencional em aço ABNT 1045 e pelo processo de ferramental rápido por estereolitografia. As cavidades selecionadas tiveram todas a mesma forma geomét...

  4. Biochemical analysis of the Hormoconis resinae fungal mycelium in the corrosion of aeronautical aluminium alloys

    Directory of Open Access Journals (Sweden)

    Araya, R.

    2007-06-01

    Full Text Available Biochemical analyses of the Hormoconis resinae fungal mycelium would explain behaviour differences of corrosive and non-corrosive strains on Al and its aeronautical alloys. In previous works its aggressiveness had been studied through SEM-EDX surface analysis, electrochemical techniques and immersion testing. In this paper separation of the proteins of the mycelium produced by a non-corrosive strain and its culture along three generations was performed. Cultures were prepared in batch in the presence and absence of pure Al and AA 2024, AA 7005 and AA 7075 alloys. The mycelia grown throughout the three generations increasingly
    recovered usual characteristics at the third replication, included their corrosiveness on Al and its alloys previously shown by all our strains. Amongst the bio-molecule fractions isolated and analysed during this preliminary study only the proteins revealed changes with the generation grown. When this fungal strain was cultured in the presence of alloy metal sheets electrophoresis of the protean fraction was correlative with the distinct mycelia behaviour observed, including corrosiveness on Al and its alloys.

    Las diferencias entre el comportamiento corrosivo y no corrosivo de una cepa del hongo Hormoconis resinae sobre aluminio y sus aleaciones aeronáuticas se explicarían a través de análisis bioquímicos del micelio. En trabajos previos, el comportamiento corrosivo se estudió mediante análisis de superficie SEM-EDX, técnicas electroquímicas y ensayos de inmersión. En este trabajo, se llevó a cabo la separación de proteínas del micelio producido por una cepa que perdió su corrosividad y su cultivo a través de tres generaciones. Cultivos en batch, en presencia y ausencia de aluminio y sus aleaciones AA 2024, AA 7005 y AA 7075, a través de tres generaciones del micelio crecido, fueron recuperando sus características, incluida su habitual corrosividad, en la tercera replicaci

  5. Caracterización cualitativa de poliaminas libres en endurecedores de resinas epoxídicas del tipo etilenaminas por espectroscopia de resonancia magnética nuclear Qualitative characterization of free polyamines in ethyleneamines epoxide hardeners by nuclear magnetic resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    Filiberto González Garcia

    2008-03-01

    Full Text Available La caracterización cualitativa de dos agentes de curado comerciales de resinas epoxídicas del tipo etilenaminas comercializados por la ACROS (U.S.A. fue realizada usando la espectroscopia de resonancia magnética nuclear de carbono-13. Los productos comerciales corresponden a la trietilentetramina (TETA y a la tetraetilenpentamina (TEPA. El producto TETA presentó cuatro compuestos diferentes. El compuesto mayoritario correspondió a la trietilentetramina en una concentración de 60% molar que corresponde a una etilenamina de estructura linear. Los otros tres compuestos, uno de ellos mostró estructura ramificada, y los otros dos compuestos presentaron estructuras cíclicas del tipo piperazina. El producto TEPA mostró cinco compuestos con estructuras semejantes a las encontradas en el producto TETA. El compuesto mayoritario correspondió a la tetraetilenpentamina en una concentración aproximada de 55% molar. Los resultados encontrados en este trabajo están de acuerdo con la composición cualitativa de los productos semejantes comercializados por la Compañía Química Dow, productos DEH 24 y DEH 26, respectivamente.The qualitative characterization of two commercial ethyneamines epoxide hardeners marketed by ACROS (U.S.A. was carried out by using carbon-13 nuclear magnetic resonance spectroscopy. The products were triethylenetetramine (TETA and tetraethylenepentamine (TEPA. TETA had four components, the most importante one being triethylenetetramine, an ethyleneamine of lineal structure, in a concentration of 60 mol%. Another component had ramified structure, while the other two exhibited recurrent structures of the piperazina type. TEPA had five components with similar structures. The major component was tetraethylenepentamine in an approximate concentration of 55 mol%. These results agree with the composition of similar products marketed by Dow Chemical Company, namely DEH 24 and DEH 26, respectively.

  6. Design of carbon nanofiber embedded conducting epoxy resin

    International Nuclear Information System (INIS)

    Gantayat, Subhra; Sarkar, Niladri; Rout, Dibyaranjan; Swain, Sarat K.

    2017-01-01

    Acid treated carbon nanofiber (t-CNF) reinforced epoxy nanocomposites were fabricated by hand lay-up method with various wt % of t-CNF loadings. Pristine or unmodified carbon nano fibers (u-CNFs) were made compatible with epoxy matrix by means of mixed acid treatment. Fabricated nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) study, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Mechanical and thermal properties of the nanocomposites were measured as a function of t-CNF content. Effect of acid treated CNFs on to the mechanical properties of epoxy nanocomposites was justified by comparing the mechanical properties of epoxy/t-CNF and epoxy/u-CNF nanocomposites with same loading level. The electrical conductivity was achieved by epoxy resin with a threshold at 1 wt % of t-CNF. Substantial improvement in thermal, mechanical and electrical properties of the synthesized epoxy/t-CNF nanocomposites may be suitable for fabricating electronic devices. - Highlights: • Epoxy/t-CNF nanocomposites are characterized by XRD, FTIR, SEM, AFM and TEM. • Electrical conductivity was achieved by epoxy with a threshold at 1 wt% of t-CNF. • Tensile strength is enhanced by 40% due to dispersion of t-CNF. • Synthesized nanocomposites are suitable for fabricating electronic devises.

  7. Design of carbon nanofiber embedded conducting epoxy resin

    Energy Technology Data Exchange (ETDEWEB)

    Gantayat, Subhra [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India); School of Applied Sciences, KIIT University, Bhubaneswar 751024, Odisha (India); Sarkar, Niladri [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India); Rout, Dibyaranjan [School of Applied Sciences, KIIT University, Bhubaneswar 751024, Odisha (India); Swain, Sarat K., E-mail: swainsk2@yahoo.co.in [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India)

    2017-01-15

    Acid treated carbon nanofiber (t-CNF) reinforced epoxy nanocomposites were fabricated by hand lay-up method with various wt % of t-CNF loadings. Pristine or unmodified carbon nano fibers (u-CNFs) were made compatible with epoxy matrix by means of mixed acid treatment. Fabricated nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) study, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Mechanical and thermal properties of the nanocomposites were measured as a function of t-CNF content. Effect of acid treated CNFs on to the mechanical properties of epoxy nanocomposites was justified by comparing the mechanical properties of epoxy/t-CNF and epoxy/u-CNF nanocomposites with same loading level. The electrical conductivity was achieved by epoxy resin with a threshold at 1 wt % of t-CNF. Substantial improvement in thermal, mechanical and electrical properties of the synthesized epoxy/t-CNF nanocomposites may be suitable for fabricating electronic devices. - Highlights: • Epoxy/t-CNF nanocomposites are characterized by XRD, FTIR, SEM, AFM and TEM. • Electrical conductivity was achieved by epoxy with a threshold at 1 wt% of t-CNF. • Tensile strength is enhanced by 40% due to dispersion of t-CNF. • Synthesized nanocomposites are suitable for fabricating electronic devises.

  8. Efeito do ascorbato de sódio na adesividade da resina composta em dentes clareados = Effect of sodium ascorbate on composite resin bond strength to bleached teeth

    Directory of Open Access Journals (Sweden)

    Xavier, Ana Claudia Carvalho

    2014-01-01

    Full Text Available Objetivo: Avaliar o efeito do ascorbato de sódio na adesão de resina composta em dentes submetidos a tratamento clareador. Métodos: Foram utilizados 40 pré-molares humanos, divididos em 4 grupos: C – (controle dentes não clareados; S – dentes clareados com peróxido de hidrogênio 35% e armazenados por 48 horas em saliva artificial; AS – dentes clareados com peróxido de hidrogênio 35% e irrigados com solução de ascorbato de sódio 10% por 10 minutos; AG – dentes submetidos a tratamento clareador com peróxido de hidrogênio 35% e imersos em gel de ascorbato de sódio 10% por 3 horas. Após a restauração, as amostras foram seccionadas e submetidas ao teste de microtração em máquina de ensaios universais (Emic sob velocidade de 1 mm/min. Os dados foram avaliados e submetidos aos testes estatísticos ANOVA e Tukey, com nível de significância 5%. Resultados: O grupo C apresentou o maior valor de adesividade, diferindo estatisticamente dos grupos S e AG. Conclusão: A manutenção dos dentes clareados em saliva por 48 horas não é suficiente para a recuperação da resistência adesiva. No entanto, a utilização da solução de ascorbato de sódio 10% por 10 minutos pode promover uma resistência adesiva adequada, permitindo a imediata restauração dos dentes

  9. Thermo-curable epoxy systems for nanoimprint lithography

    International Nuclear Information System (INIS)

    Wu, Chun-Chang; Hsu, Steve Lien-Chung

    2010-01-01

    In this work, we have used solvent-free thermo-curable epoxy systems for low-pressure and moderate-temperature nanoimprint lithography (NIL). The curing kinetic parameters and conversion of diglycidyl ether of bisphenol A (DGEBA) resin with different ambient-cure 930 and 954 hardeners were studied by the isothermal DSC technique. They are useful for the study of epoxy resins in the imprinting application. The DGEBA/930 and DGEBA/954 epoxy resists can be imprinted to obtain high-density nano- and micro-scale patterns on a flexible indium tin oxide/poly(ethylene terephthalate) (ITO/PET) substrate. The DGEBA/930 epoxy resin is not only suitable for resist material, but also for plastic mold material. Highly dense nanometer patterns can be successfully imprinted using a UV-curable resist from the DGEBA/930 epoxy mold. Using the replicated DGEBA/930 epoxy mold instead of the expensive master can prevent brittle failure of the silicon molds in the NIL

  10. Fatigue life extension of epoxy materials using ultrafast epoxy-SbF5 healing system introduced by manual infiltration

    Directory of Open Access Journals (Sweden)

    X. J. Ye

    2015-03-01

    Full Text Available The present paper is devoted to the verification of the capability of epoxy-SbF5 system as a healing chemistry for rapidly retarding and/or arresting fatigue cracks in epoxy materials at room temperature. Owing to the very fast curing speed of epoxy catalyzed by SbF5, epoxy monomer and the hardener (ethanol solution of SbF5–ethanol complex are successively infiltrated into the fracture plane under cyclic loading during the tension-tension fatigue test. As a result, the mechanisms including hydrodynamic pressure crack tip shielding, polymeric wedge and adhesive bonding of the healing agent are revealed. It is found that the healing agent forms solidified wedge at the crack tip within 20 s after start of polymerization of the epoxy monomer, so that the highest healing effect is offered at the moment. The epoxy-SbF5 system proves to be effective in rapidly obstructing fatigue crack propagation (despite that its cured version has lower fracture toughness than the matrix, and satisfies the requirement of constructing fast self-healing polymeric materials.

  11. Design and Analysis of Drive Shaft using Kevlar/Epoxy and Glass/Epoxy as a Composite Material

    Science.gov (United States)

    Karthikeyan, P.; Gobinath, R.; Kumar, L. Ajith; Jenish, D. Xavier

    2017-05-01

    In automobile industry drive shaft is one of the most important components to transmit power form the engine to rear wheel through the differential gear. Generally steel drive shaft is used in automobile industry, nowadays they are more interested to replace steel drive shaft with that of composite drive shaft. The overall objective of this paper is to analyze the composite drive shaft using to find out the best replacement for conventional steel drive shaft. The uses of advanced composite materials such as Kevlar, Graphite, Carbon and Glass with proper resins ware resulted in remarkable achievements in automobile industry because of its greater specific strength and specific modulus, improved fatigue and corrosion resistances and reduction in energy requirements due to reduction in weight as compared to steel shaft. This paper is to presents, the modeling and analysis of drive shaft using Kevlar/Epoxy and Glass/Epoxy as a composite material and to find best replacement for conventional steel drive shafts with an Kevlar/epoxy or Glass/Epoxy resin composite drive shaft. Modeling is done using CATIA software and Analysis is carried out by using ANSYS 10.0 software for easy understanding. The composite drive shaft reduces the weight by 81.67 % for Kevlar/Epoxy and 72.66% for Glass/Epoxy when compared with conventional steel drive shaft.

  12. Comparison of structural health assessment capabilities in epoxy – carbon black and epoxy – carbon nanotube nanocomposites

    Directory of Open Access Journals (Sweden)

    F. Inam

    2014-01-01

    Full Text Available A novel method for comparing structural health of different types of brittle epoxy nanocomposites filled with carbon nanostructured fillers is presented. Epoxy – 0.2 vol% carbon black (CB and epoxy – 0.2 vol% carbon nanotube (CNT nanocomposite bars were prepared by calendering and thermal curing. Nanocomposite bars were subjected to Vickers diamond indentation to produce sub-surface damage. Electrical conductivities were analysed by 4-point method to estimate the structural damage caused by indentation. For comprehensive comparison, fracture toughness and percolation threshold were analysed as well. Because of the systematically induced indentation damage, a sharp decrease of 89% was observed in the electrical conductivity of epoxy – CNT nanocomposite as compared to 25% in the electrical conductivity of epoxy – CB nanocomposite. CNTs impart superior damage sensing capability in brittle nanocomposite structures, in comparison to CB, due to their high aspect ratio (fibrous nature and high electrical conductivity.

  13. Fracture behavior of α-zirconium phosphate-based epoxy nanocomposites

    International Nuclear Information System (INIS)

    Sue, H.-J.; Gam, K.T.; Bestaoui, N.; Clearfield, A.; Miyamoto, M.; Miyatake, N.

    2004-01-01

    The fracture behaviors of α-zirconium phosphate (α-ZrP) based epoxy nanocomposites, with and without core-shell rubber (CSR) toughening, were investigated. The state of exfoliation and dispersion of α-ZrP nanofiller in epoxy were characterized using X-ray scattering and various microscopy tools. The level of enhancement in storage moduli of epoxy nanocomposite against neat epoxy is found to depend on the state of exfoliation of α-ZrP as well as the damping characteristics of the epoxy matrix. The fracture process in epoxy nanocomposite is dominated by preferred crack propagation along the weak intercalated α-ZrP interfaces, and the presence of α-ZrP does not alter the fracture toughness of the epoxy matrix. However, the toughening using CSR can significantly improve the fracture toughness of the nanocomposite. The fracture mechanisms responsible for such a toughening effect in CSR-toughened epoxy nanocomposite are rubber particle cavitation, followed by shear banding of epoxy matrix. The ductility and toughenability of epoxy do not appear to be affected by the incorporation of α-ZrP. Approaches for producing toughened high performance polymer nanocomposites are discussed

  14. Obtención de nano-estructuras bi-dimensionales de SnO2 utilizando el método pechini: estudio de la conformación de la resina

    Directory of Open Access Journals (Sweden)

    Rodriguez Paez, J. E.

    2008-10-01

    Full Text Available Pechini method has been widely used in the synthesis of oxides, but the physicochemical process that happens during this one have not been discussed in detail, for example the resin conformation that is obtained in one of the stages of the process. Knowing the resin evolution and since the most important parameter of this one are modified, it could determinate the most appropriate conditions to conform thin films though the Pechini method. In this work the resin evolution of the tin system considering parameters like pH, viscosity, time and temperature of heating were studied. Infrared spectroscopy (FTIR and viscosity measures in differents steps of the process were used. The IR spectroscopy results shows that as it advances the aging time of the resin, to a temperature between 80 and 100ºC and a pH of 6,5, Sn-O bonds are strengthen. Films were conformed with the resin obtained during the pechini process, it being defined a value of 110cP as the most appropriate to favor the homogeneity and adherence of this ones. The grain size film was of ∼110nm what indicates that the realized process allows to obtain bidimensional nano-structures.A pesar que el método de precursor polimérico, Pechini es ampliamente utilizado en la síntesis de óxidos, los procesos fisicoquímicos que ocurren durante el mismo no se han discutido en detalle; tal es el caso de la conformación de la resina que se obtiene en una de las etapas del proceso. Conociendo la evolución de esta resina, y como se modifican los parámetros más importantes de la misma, se podrían determinar las condiciones más adecuadas para conformar películas delgadas a través de este método. En este trabajo se estudio la evolución de la resina del sistema de estaño considerando parámetros como pH, viscosidad, tiempo y temperatura de calentamiento de la misma. Para este estudio se utilizó espectroscopía infrarroja (FTIR y medidas de viscosidad de la resina en diferentes instantes del

  15. Environmental Degradation and Durability of Epoxy-Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Raman P. Singh

    2010-01-01

    Full Text Available This experimental investigation reports on the durability of epoxy-clay nanocomposites upon exposure to multiple environments. Nanocomposites are fabricated by mixing the clay particles using various combinations of mechanical mixing, high-shear dispersion, and ultrasonication. Clay morphology is characterized using X-ray diffraction and transmission electron microscopy. Specimens of both neat epoxy and the epoxy-clay nanocomposite are subjected to two environmental conditions: combined UV radiation and condensation on 3-hour repeat cycle and constant temperature-humidity, for a total exposure duration of 4770 hours. The presence of nanoscale clay inhibits moisture uptake, as demonstrated by exposure to constant temperature-humidity. Nonetheless, both materials lose mass under exposure to combined UV radiation and condensation due to the erosion of epoxy by a synergistic process. Surprisingly, the epoxy-clay specimens exhibit greater mass loss, as compared to neat epoxy. Mechanical testing shows that either environment does not significant affect the flexure modulus of either material. On the other hand, both materials undergo degradation in flexural strength when exposed to either environment. However, the epoxy-clay nanocomposite retains 37% more flexure strength than the neat epoxy after 4072 hours of exposure.

  16. Environmental Degradation and Durability of Epoxy-Clay Nanocomposites

    International Nuclear Information System (INIS)

    Singh, R.P.; Zunjarrao, S.C.; Pandey, G.; Khait, M.; Korach, C.S.

    2010-01-01

    This experimental investigation reports on the durability of epoxy-clay nanocomposites upon exposure to multiple environments. Nanocomposites are fabricated by mixing the clay particles using various combinations of mechanical mixing, high-shear dispersion, and ultrasonication. Clay morphology is characterized using X-ray diffraction and transmission electron microscopy. Specimens of both neat epoxy and the epoxy-clay nanocomposite are subjected to two environmental conditions: combined UV radiation and condensation on 3-hour repeat cycle and constant temperature-humidity, for a total exposure duration of 4770 hours. The presence of nanoscale clay inhibits moisture uptake, as demonstrated by exposure to constant temperature-humidity. Nonetheless, both materials lose mass under exposure to combined UV radiation and condensation due to the erosion of epoxy by a synergistic process. Surprisingly, the epoxy-clay specimens exhibit greater mass loss, as compared to neat epoxy. Mechanical testing shows that either environment does not significant affect the flexure modulus of either material. On the other hand, both materials undergo degradation in flexural strength when exposed to either environment. However, the epoxy-clay nanocomposite retains 37% more flexure strength than the neat epoxy after 4072 hours of exposure.

  17. Occupational exposure to epoxy resins

    NARCIS (Netherlands)

    Terwoert, J.; Kersting, K.

    2014-01-01

    Products based on epoxy resins as a binder have become popular in various settings, among which the construction industry and in windmill blade production, as a result of their excellent technical properties. However, due to the same properties epoxy products are a notorious cause of allergic skin

  18. Comparison of structural health assessment capabilities in epoxy – carbon black and epoxy – carbon nanotube nanocomposites

    OpenAIRE

    F. Inam; B. R. Bhat; N. Luhyna; T. Vo

    2014-01-01

    A novel method for comparing structural health of different types of brittle epoxy nanocomposites filled with carbon nanostructured fillers is presented. Epoxy – 0.2 vol% carbon black (CB) and epoxy – 0.2 vol% carbon nanotube (CNT) nanocomposite bars were prepared by calendering and thermal curing. Nanocomposite bars were subjected to Vickers diamond indentation to produce sub-surface damage. Electrical conductivities were analysed by 4-point method to estimate the structural damage caused by...

  19. Biobased Epoxy Nanocomposites Derived from Lignin-Based Monomers.

    Science.gov (United States)

    Zhao, Shou; Abu-Omar, Mahdi M

    2015-07-13

    Biobased epoxy nanocomposites were synthesized based on 2-methoxy-4-propylphenol (dihydroeugenol, DHE), a molecule that has been obtained from the lignin component of biomass. To increase the content of hydroxyl groups, DHE was o-demethylated using aqueous HBr to yield propylcatechol (DHEO), which was subsequently glycidylated to epoxy monomer. Optimal conditions in terms of yield and epoxy equivalent weight were found to be 60 °C with equal NaOH/phenolic hydroxyl molar ratio. The structural evolution from DHE to cured epoxy was followed by (1)H NMR and Fourier transform infrared spectroscopy. The nano-montmorillonite modified DHEO epoxy exhibited improved storage modulus and thermal stability as determined from dynamic mechanical analysis and thermogravimetric analysis. This study widens the synthesis routes of biobased epoxy thermosets from lignin-based molecules.

  20. Atomistic modeling of thermomechanical properties of SWNT/Epoxy nanocomposites

    Science.gov (United States)

    Fasanella, Nicholas; Sundararaghavan, Veera

    2015-09-01

    Molecular dynamics simulations are performed to compute thermomechanical properties of cured epoxy resins reinforced with pristine and covalently functionalized carbon nanotubes. A DGEBA-DDS epoxy network was built using the ‘dendrimer’ growth approach where 75% of available epoxy sites were cross-linked. The epoxy model is verified through comparisons to experiments, and simulations are performed on nanotube reinforced cross-linked epoxy matrix using the CVFF force field in LAMMPS. Full stiffness matrices and linear coefficient of thermal expansion vectors are obtained for the nanocomposite. Large increases in stiffness and large decreases in thermal expansion were seen along the direction of the nanotube for both nanocomposite systems when compared to neat epoxy. The direction transverse to nanotube saw a 40% increase in stiffness due to covalent functionalization over neat epoxy at 1 K whereas the pristine nanotube system only saw a 7% increase due to van der Waals effects. The functionalized SWNT/epoxy nanocomposite showed an additional 42% decrease in thermal expansion along the nanotube direction when compared to the pristine SWNT/epoxy nanocomposite. The stiffness matrices are rotated over every possible orientation to simulate the effects of an isotropic system of randomly oriented nanotubes in the epoxy. The randomly oriented covalently functionalized SWNT/Epoxy nanocomposites showed substantial improvements over the plain epoxy in terms of higher stiffness (200% increase) and lower thermal expansion (32% reduction). Through MD simulations, we develop means to build simulation cells, perform annealing to reach correct densities, compute thermomechanical properties and compare with experiments.

  1. Atomistic modeling of thermomechanical properties of SWNT/Epoxy nanocomposites

    International Nuclear Information System (INIS)

    Fasanella, Nicholas; Sundararaghavan, Veera

    2015-01-01

    Molecular dynamics simulations are performed to compute thermomechanical properties of cured epoxy resins reinforced with pristine and covalently functionalized carbon nanotubes. A DGEBA-DDS epoxy network was built using the ‘dendrimer’ growth approach where 75% of available epoxy sites were cross-linked. The epoxy model is verified through comparisons to experiments, and simulations are performed on nanotube reinforced cross-linked epoxy matrix using the CVFF force field in LAMMPS. Full stiffness matrices and linear coefficient of thermal expansion vectors are obtained for the nanocomposite. Large increases in stiffness and large decreases in thermal expansion were seen along the direction of the nanotube for both nanocomposite systems when compared to neat epoxy. The direction transverse to nanotube saw a 40% increase in stiffness due to covalent functionalization over neat epoxy at 1 K whereas the pristine nanotube system only saw a 7% increase due to van der Waals effects. The functionalized SWNT/epoxy nanocomposite showed an additional 42% decrease in thermal expansion along the nanotube direction when compared to the pristine SWNT/epoxy nanocomposite. The stiffness matrices are rotated over every possible orientation to simulate the effects of an isotropic system of randomly oriented nanotubes in the epoxy. The randomly oriented covalently functionalized SWNT/Epoxy nanocomposites showed substantial improvements over the plain epoxy in terms of higher stiffness (200% increase) and lower thermal expansion (32% reduction). Through MD simulations, we develop means to build simulation cells, perform annealing to reach correct densities, compute thermomechanical properties and compare with experiments. (paper)

  2. Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

    Science.gov (United States)

    Patel, Binay S.

    Epoxies are widely used as underfill resins throughout the microelectronics industry to mechanically couple and protect various components of flip-chip assemblies. Generally rigid materials largely surround underfill resins. Improving the mechanical and thermal properties of epoxy resins to better match those of their rigid counterparts can help extend the service lifetime of flip-chip assemblies. Recently, researchers have demonstrated that silica nanoparticles are effective toughening agents for lightly-crosslinked epoxies. Improvements in the fracture toughness of silica-filled epoxy nanocomposites have primarily been attributed to two toughening mechanisms: particle debonding with subsequent void growth and matrix shear banding. Various attempts have been made to model the contribution of these toughening mechanisms to the overall fracture energy observed in silica-filled epoxy nanocomposites. However, disparities still exist between experimental and modeled fracture energy results. In this dissertation, the thermal, rheological and mechanical behavior of eight different types of silica-filled epoxy nanocomposites was investigated. Each nanocomposite consisted of up to 10 vol% of silica nanoparticles with particle sizes ranging from 20 nm to 200 nm, with a variety of surface treatments and particle structures. Fractographical analysis was conducted with new experimental approaches in order to accurately identify morphological evidence for each proposed toughening mechanism. Overall, three major insights into the fracture behavior of real world silica-filled epoxy nanocomposites were established. First, microcracking was observed as an essential toughening mechanism in silica-filled epoxy nanocomposites. Microcracking was observed on the surface and subsurface of fractured samples in each type of silica-filled epoxy nanocomposite. The additional toughening contribution of microcracking to overall fracture energy yielded excellent agreement between experimental

  3. Mechanical properties of graphene oxide (GO/epoxy composites

    Directory of Open Access Journals (Sweden)

    Shivan Ismael Abdullah

    2015-08-01

    Full Text Available In this study, the effects of graphene oxide (GO on composites based on epoxy resin were analyzed. Different contents of GO (1.5–6 vol.% were added to epoxy resin. The GO/epoxy composite was prepared using the casting method and was prepared under room temperature. Mechanical tests’ results such as tensile test, impact test and hardness test show enhancements of the mechanical properties of the GO/epoxy composite. The experimental results clearly show an improvement in the Young’s modulus, tensile strength and hardness. The impact strength was seen to decrease, pointing to brittleness increase of the GO/epoxy composite. A microstructure analysis using Scanning Electron Microscopy (SEM and X-ray diffraction (XRD analysis was also performed, which showed how GO impeded the propagation of cracks in the composite. From the SEM images we observed the interface between the GO and the epoxy composite. As can be seen from this research, the GO/epoxy composites can be used for a large number of applications. The results of this research are a strong evidence for GO/epoxy composites being a potential candidate for use in a variety of industrial applications, especially for automobile parts, aircraft components, and electronic parts such as supercapacitors, transistors, etc.

  4. Quantificação por NIR/MIR de resina poliuretânica em misturas binárias com nitrocelulose utilizadas em tintas

    Directory of Open Access Journals (Sweden)

    Viviane Cristine Rodrigues

    2014-06-01

    Full Text Available Foi elaborada uma nova metodologia nas regiões do infravermelho médio (MIR e do infravermelho próximo (NIR, usando-se técnicas de Reflexão e/ou Transmissão para a determinação do teor de resina poliuretânica (PU em misturas binárias com nitrocelulose (NC, utilizadas em formulações de tintas. A técnica de Reflexão Total Atenuada Universal (UATR se mostrou útil na região MIR, para tal fim. Após a avaliação de diferentes bandas analíticas, de referência e de linhas de base, a banda relativa (A1541/ A1645 foi escolhida para a elaboração da curva de calibração, com erro de metodologia de 1,42%. As técnicas de Transmissão e Reflexão (DRIFT foram utilizadas na região NIR (banda relativa A5902/ A5262 para validação, apresentando erros de metodologia de 1,42% e 1,60 %, respectivamente. Todos os erros relativos nas metodologias apresentaram-se dentro dos limites de precisão da análise quantitativa FT-IR, para as condições usadas (≤2%. A análise de amostras teste confirmou a precisão das metodologias desenvolvidas, que também apresentam praticidade, baixo custo e tempo reduzido de análise.

  5. Tensile bond srength between composite resin using different adhesive systems Avaliação da resistência à ruptura por tração entre resina composta e diversos adesivos dentinários

    Directory of Open Access Journals (Sweden)

    Patrícia Dias

    2002-11-01

    Full Text Available The aim of this study was evaluate the tensile bond strength (TBS among nine adhesive systems and one composite resin. The groups were made as follows: Single Bond/3M (G1, Etch & Prime 3.0 /Degussa (G2, Bond 1/Jeneric/Pentron (G3, Prime & Bond 2.1/Dentsply (G4, OptiBond FL/Kerr (G5, Stae/SDI (G6, Snap Bond/ Copalite-Cooley & Cooley (G7, Prime & Bond NT/Dentsply (G8, Scotchbond Multi Purpose Plus/3M (G9. The control group (G10 was made only with the composite resin (Z100/3M. One hundred specimens were made, 10 for each group. There were significant differences on TBS among groups. G3 showed the hightest TBS in comparison to other tested groups. G10 presented higher TBS than all groups. O objetivo desta pesquisa foi investigar in vitro a resistência de união entre uma resina composta e nove sistemas adesivos dentinários. Os adesivos estudados foram assim agrupados: Single Bond/3M (G1, Etch & Prime 3.0/ Degussa (G2, Bond 1/Jeneric/Pentron (G3, Prime & Bond 2.1/Dentsply (G4, OptiBond FL/Kerr (G5, Stae/SDI (G6, Snap Bond/Copalite (G7, Prime & Bond NT/Dentsply (G 8, Scotchbond Multi Purpose Plus/3M (G9. O Grupo controle (G10. foi confeccionado somente com a resina composta (Z100/3M. Foram confeccionados 100 espécimes, 10 para cada grupo. Houve diferenças estatísticas significantes entre os grupos. O grupo 3 foi o que mostrou a mais alta resistência em comparação aos nove testados. O grupo controle (G10 apresentou a mais alta resistência entre todos os Grupos.  

  6. Aplicação de FT-MIR e FT-NIR ao estudo de reação de cura de sistemas epoxídicos FT-IR MIR and FT-NIR applied to the study of reaction of epoxy systems

    Directory of Open Access Journals (Sweden)

    Benedita M. V. Romão

    2004-09-01

    Full Text Available A reação de cura entre amostras de resina epoxídica (EP e compostos à base de mercaptana (SH, amino-fenol e amina modificada foi estudada nas regiões espectrais do infravermelho médio (MIR e próximo (NIR. Observou-se, basicamente, que a espectroscopia FT-NIR evidencia melhor as alterações espectrométricas ocorridas durante as reações estudadas, permitindo detectar, inclusive, o agente de cura em menor proporção no sistema epoxídico.The cure reaction of epoxy resin (EP and curing agents based on polymercaptans (SH, amine-phenol and modified amine was studied in the MIR and NIR spectral regions. It was observed that the FT-NIR shows better the spectrometric changes of the reactions studied, which makes it possible to detect the curing agent in lower contents in epoxide systems.

  7. Avaliação clínica de restaurações de resina condensável após dois anos = Two-year clinical evaluation of condensable composite restoration

    Directory of Open Access Journals (Sweden)

    Meireles, Sonia Saeger

    2006-01-01

    Full Text Available O objetivo deste estudo foi avaliar a performance clínica de uma resina condensável, comparada com uma resina microhíbrida e amálgama em restaurações de dentes posteriores após dois anos. Foram confeccionadas 33 restaurações de Classes I e II, em 6 pacientes, alunos da FOUFPel. Cada paciente deveria apresentar, no mínimo, uma restauração de cada material, que seriam aleatoriamente distribuídas. Os critérios para avaliação clínica (USPHS modificado – amálgama e USPHS adaptado – restaurações de resina foram utilizados. As restaurações foram classificadas como clinicamente satisfatórias (Alfa & Bravo e insatisfatórias (Charlie & Delta. A análise estatística foi realizada através dos testes de Friedman e de Kruskal-Wallis. Não foram encontradas diferenças significativas entre os tempos investigados nem entre os materiais testados (p > 0,05. Conclui-se que a maioria das restaurações encontravam-se clinicamente aceitáveis após 2 anos de avaliação clínica

  8. Epoxy resin systems for FGD units

    International Nuclear Information System (INIS)

    Brytus, V.; Puglisi, J.S.

    1984-01-01

    This paper discusses ongoing research work which is directed towards epoxy resins and curing agents which are designed to withstand aggressive environments. This work includes not only a chemical description of the materials involved, but the application testing necessary to verify the usefulness of these systems. It demonstrates that new high performance epoxy systems are superior to those which traditionally come to mind when one thinks epoxy. Finally, it discusses the results of testing designed specifically to screen candidates for use in FGD units

  9. Enhancement of mechanical properties of epoxy/graphene nanocomposite

    Science.gov (United States)

    Berhanuddin, N. I. C.; Zaman, I.; Rozlan, S. A. M.; Karim, M. A. A.; Manshoor, B.; Khalid, A.; Chan, S. W.; Meng, Q.

    2017-10-01

    Graphene is a novel class of nanofillers possessing outstanding characteristics including most compatible with most polymers, high absolute strength, high aspect ratio and cost effectiveness. In this study, graphene was used to reinforce epoxy as a matrix, to enhance its mechanical properties. Two types of epoxy composite were developed which are epoxy/graphene nanocomposite and epoxy/modified graphene nanocomposite. The fabrication of graphene was going through thermal expansion and sonication process. Chemical modification was only done for modified graphene where 4,4’-Methylene diphenyl diisocyanate (MDI) is used. The mechanical properties of both nanocomposite, such as Young’s modulus and maximum stress were investigated. Three weight percentage were used for this study which are 0.5 wt%, 1.0 wt% and 1.5 wt%. At 0.5 wt%, modified and unmodified shows the highest value compared to neat epoxy, where the value were 8 GPa, 6 GPa and 0.675 GPa, respectively. For maximum stress, neat epoxy showed the best result compared to both nanocomposite due to the changes of material properties when adding the filler into the matrix. Therefore, both nanocomposite increase the mechanical properties of the epoxy, however modification surface of graphene gives better improvement.

  10. Adhesion between coating layers based on epoxy and silicone

    DEFF Research Database (Denmark)

    Svendsen, Jacob R.; Kontogeorgis, Georgios; Kiil, Søren

    2007-01-01

    The adhesion between a silicon tie-coat and epoxy primers, used in marine coating systems, has been studied in this work. Six epoxy coatings (with varying chain lengths of the epoxy resins), some of which have shown problems with adhesion to the tie-coat during service life, have been considered....... The experimental investigation includes measurements of the surface tension of the tie-coat and the critical surface tensions of the epoxies, topographic investigation of the surfaces of cured epoxy coatings via atomic force microscopy (AFM), and pull-off tests for investigating the strength of adhesion...... to the silicon/epoxy systems. Calculations for determining the roughness factor of the six epoxy coatings (based on the AFM topographies) and the theoretical work of adhesion have been carried out. The coating surfaces are also characterized based on the van Oss-Good theory. Previous studies on the modulus...

  11. Uso de resíduo industrial a base de resina fenólica como carga para o polipropileno Use of industrial waste based on phenolic resin as filler for polypropylene

    Directory of Open Access Journals (Sweden)

    André P. Cavalcante

    2012-01-01

    Full Text Available O objetivo deste estudo foi analisar a viabilidade técnica do uso de resíduo industrial composto de resina fenólica, lignocelulose, carbonato de cálcio, talco, mica e negro de fumo como carga para o polipropileno (PP. Compósitos de PP com 10, 15 e 20% em massa do resíduo foram processados em extrusora de rosca dupla e moldados por injeção. Os compósitos moldados foram caracterizados por microscopia eletrônica de varredura (MEV, análises térmicas (DSC e TGA, ensaios mecânicos (tração, flexão e impacto e ensaio termo-mecânico (HDT. Os compósitos moldados apresentaram partículas do resíduo com tamanhos inferiores a 500 µm dispersas na matriz de polipropileno. As partículas do resíduo atuaram como agentes de nucleação da cristalização do PP. Os compósitos apresentaram maior resistência à degradação térmica, balanço de rigidez e resistência com aumento do módulo sob flexão e diminuição da resistência à tração, manutenção da resistência ao impacto sob entalhe, e aumento da temperatura de distorção ao calor (HDT. O desempenho dos compósitos demonstrou que o resíduo industrial de resina fenólica pode ser empregado como carga funcional para o PP. Além disso, os compósitos desenvolvidos representam uma alternativa para a reciclagem do resíduo industrial de resina fenólica.The aim of this study was to assess the technical feasibility of using industrial waste composed of phenolic resin, lignocellulose, calcium carbonate, talc, mica and carbon black as filler for polypropylene (PP. Composites of PP with 10, 15 and 20 wt% of the waste were processed in a twin-screw extruder followed by injection molding. Molded composites were characterized by scanning electron microscopy (SEM, thermal analyses (DSC and TGA, mechanical tests (tensile, flexural and impact and thermo-mechanical test (HDT. The composites showed residue particles with sizes less than 500 µm dispersed in the PP matrix. The residue particles

  12. PRODUÇÃO DE CHAPAS DE PARTÍCULAS ORIENTADAS “OSB” DE Eucalyptus grandis COM DIFERENTES TEORES DE RESINA, PARAFINA E COMPOSIÇÃO EM CAMADAS

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2002-10-01

    Full Text Available Este trabalho foi desenvolvido com o objetivo de avaliar a influência dos seguintes parâmetros de processo de produção sobre as propriedades das chapas “OSB”: composição das chapas em camadas cruzadas com proporções face-miolo-face de 30-40-30 e 20-60-20 em relação à composição homogênea; e, quantidades de 3, 4,5 e 6,0% de resina fenol-formaldeído, com incorporação de 0,5 e 1,0% de emulsão de parafina. Os resultados demonstraram que a composição das chapas, com a relação 20-60-20, apresentou melhor balanço das propriedades de flexão estática entre os sentidos de ensaios paralelo e perpendicular ao plano da chapa. A quantidade de 6,0% de resina foi a que resultou em melhores propriedades físico-mecânicas das chapas “OSB”. A produção de chapas “OSB” de Eucalyptus grandis, com 4,5 e 6,0% de resina fenol-formaldeído, superou as exigências mínimas de propriedades mecânicas das chapas “OSB” referendadas pela norma canadense CSA 0437-0 (1993.

  13. Potencial de produção de óleo-resina de copaíba (Copaifera spp de populações naturais do sudoeste da Amazônia Oil resin production potential of Copaifera spp natural populations in the Southwestern Brazilian Amazon

    Directory of Open Access Journals (Sweden)

    Onofra Cleuza Rigamonte-Azevedo

    2006-08-01

    Full Text Available O potencial de produção de óleo-resina extraído de Copaífera spp foi avaliado em duas populações naturais do sudoeste da Amazônia brasileira (municípios de Tarauacá e Xapuri, nos anos de 2000 e 2001. Foram selecionadas 388 árvores adultas de copaíbas das duas populações, sendo identificados em cada árvore o diâmetro à altura do peito (DAP, a produção de óleo-resina, a posição da árvore no relevo local (baixio ou terra firme e a tipologia florestal local (floresta aberta ou densa, além do nome regional da copaíba, com base em características morfológicas da casca: Copaifera reticulata: copaíba-branca, vermelha, amarela e preta e Copaifera paupera: mari-mari. Os resultados indicam que a copaíba mari-mari possui maior proporção de indivíduos produtivos (80%, enquanto os demais morfotipos apresentaram apenas de 22 a 40% de seus indivíduos produtivos. Com relação a todas as árvores amostradas, a produção de óleo-resina variou de 0 a 18 L árvore-1, com a copaíba mari-mari tendo a maior produção média (1,33 L árvore-1, porém sem diferir significativamente dos demais morfotipos. Após excluir da análise as árvores não produtivas, a copaíba-preta apresentou significativamente a maior produção média de óleo-resina (2,92 L árvore-1. A tipologia florestal, posição da árvore no relevo e o DAP não se mostraram relacionados a produção de óleo-resina.The potential for production of oil resin extracted from Copaifera spp natural populations was studied in two natural populations (municipalities of Tarauacá and Xapuri in the Southwestern Brazilian Amazon, in 2000 and 2001. Three hundred and eighty-eight adult trees were selected within these two populations. DBH, oil production, topographic position, regional common names (based on bark appearance; White, Red, Yellow, Black for Copaifera reticulata, and Mari-Mari for C. paupera and forest typology were recorded for each individual. Copaiba Mari

  14. Modification of (DGEBA epoxy resin with maleated depolymerised natural rubber

    Directory of Open Access Journals (Sweden)

    2008-04-01

    Full Text Available In this work, diglycidyl ether of bisphenol A (DEGBA type epoxy resin has been modified with maleated depolymerised natural rubber (MDPR. MDPR was prepared by grafting maleic anhydride onto depolymerised natural rubber. MDPR has been characterized by Fourier transform infrared (FT-IR spectroscopy and nuclear magnetic resonance spectroscopy. MDPR was blended with epoxy resin at three different ratios (97/3, 98/2 and 99/1, by keeping the epoxy resin component as the major phase and maleated depolymerised natural rubber component as the minor phase. The reaction between the two blend components took place between the acid/anhydride group in the MDPR and the epoxide group of the epoxy resin. The proposed reaction schemes were supported by the FT-IR spectrum of the uncured Epoxy/MDPR blends. The neat epoxy resin and Epoxy/MDPR blends were cured by methylene dianiline (DDM at 100°C for three hours. Thermal, morphological and mechanical properties of the neat epoxy and the blends were investigated. Free volume studies of the cured, neat epoxy and Epoxy/MDPR blends were correlated with the morphological and mechanical properties of the same systems using Positron Annihilation Lifetime Studies.

  15. Action of ionizing radiation on epoxy resins

    Energy Technology Data Exchange (ETDEWEB)

    Van de Voorde, M. E.

    1970-12-01

    The resistance of classical and experimental epoxy resins to irradiation was studied. The resistance to irradiation of epoxy resins of diverse compositions as well as the development of resins having a radioresistance that approaches that of certain ceramics are discussed. Sources of irradiation and the techniques of dosimetry used are described. The structures of certain epoxy resins and of hardeners are given. The preparation of these resins and their physical properties is described. The effects of radiation on epoxy resins, as well as conditions of irradiation, and suggested mechanisms for degradation of the irradiated resins are discussed. The relationship between chemical structure of the resins and their physical properties is evaluated. (115 references) (JCB)

  16. Flexural Properties of Activated Carbon Filled Epoxy Nano composites

    International Nuclear Information System (INIS)

    Khalil, H.P.S.A.; Khalil, H.P.S.A.; Alothman, O.Y.; Paridah, M.T.; Zainudin, E.S.

    2014-01-01

    Activated carbon (AC) filled epoxy nano composites obtained by mixing the desired amount of nano AC viz., bamboo stem, oil palm empty fruit bunch, and coconut shell from agricultural biomass with the epoxy resin. Flexural properties of activated carbons filled epoxy nano composites with 1 %, and 5 % filler loading were measured. In terms of flexural strength and modulus, a significant increment was observed with addition of 1 % vol and 5 % vol nano-activated carbon as compared to neat epoxy. The effect of activated carbon treated by two chemical agents (potassium hydroxide and phosphoric acid) on the flexural properties of epoxy nano composites were also investigated. Flexural strength of activated carbon-bamboo stem, activated carbon-oil palm, and activated carbon-coconut shell reinforced epoxy nano composites showed almost same value in case of 5 % potassium hydroxide activated carbon. Flexural strength of potassium hydroxide activated carbon-based epoxy nano composites was higher than phosphoric acid activated carbon. The flexural toughness of both the potassium hydroxide and phosphoric acid activated carbon reinforced composites range between 0.79 - 0.92 J. It attributed that developed activated carbon filled epoxy nano composites can be used in different applications. (author)

  17. Atomistic Modeling of Thermal Conductivity of Epoxy Nanotube Composites

    Science.gov (United States)

    Fasanella, Nicholas A.; Sundararaghavan, Veera

    2016-05-01

    The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for epoxy/single wall carbon nanotube (SWNT) nanocomposites. An epoxy network of DGEBA-DDS was built using the `dendrimer' growth approach, and conductivity was computed by taking into account long-range Coulombic forces via a k-space approach. Thermal conductivity was calculated in the direction perpendicular to, and along the SWNT axis for functionalized and pristine SWNT/epoxy nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. The thermal conductivity of the long, pristine SWNT/epoxy system is equivalent to that of an isolated SWNT along its axis, but there was a 27% reduction perpendicular to the nanotube axis. The functionalized, long SWNT/epoxy system had a very large increase in thermal conductivity along the nanotube axis (~700%), as well as the directions perpendicular to the nanotube (64%). The discontinuous nanotubes displayed an increased thermal conductivity along the SWNT axis compared to neat epoxy (103-115% for the pristine SWNT/epoxy, and 91-103% for functionalized SWNT/epoxy system). The functionalized system also showed a 42% improvement perpendicular to the nanotube, while the pristine SWNT/epoxy system had no improvement over epoxy. The thermal conductivity tensor is averaged over all possible orientations to see the effects of randomly orientated nanotubes, and allow for experimental comparison. Excellent agreement is seen for the discontinuous, pristine SWNT/epoxy nanocomposite. These simulations demonstrate there exists a threshold of the SWNT length where the best improvement for a composite system with randomly oriented nanotubes would transition from pristine SWNTs to functionalized SWNTs.

  18. Halloysite reinforced epoxy composites with improved mechanical properties

    Directory of Open Access Journals (Sweden)

    Saif Muhammad Jawwad

    2016-03-01

    Full Text Available Halloysite nanotubes (HNTs reinforced epoxy composites with improved mechanical properties were prepared. The prepared HNTs reinforced epoxy composites demonstrated improved mechanical properties especially the fracture toughness and flexural strength. The flexural modulus of nanocomposite with 6% mHNTs loading was 11.8% higher than that of neat epoxy resin. In addition, the nanocomposites showed improved dimensional stability. The prepared halloysite reinforced epoxy composites were characterized by thermal gravimetric analysis (TGA. The improved properties are attributed to the unique characteristics of HNTs, uniform dispersion of reinforcement and interfacial coupling.

  19. Shape memory polymers from benzoxazine-modified epoxy

    International Nuclear Information System (INIS)

    Rimdusit, Sarawut; Lohwerathama, Montha; Dueramae, Isala; Hemvichian, Kasinee; Kasemsiri, Pornnapa

    2013-01-01

    Novel shape memory polymers (SMPs) were prepared from benzoxazine-modified epoxy resin. Specimens consisting of aromatic epoxy (E), aliphatic epoxy (N), Jeffamine D230 (D) and BA-a benzoxazine monomer (B) were evaluated. The mole ratio of D/B was used as a mixed curing agent for an epoxy system with a fixed E/N. The effects of BA-a content on the thermal, mechanical and shape memory properties of epoxy-based shape memory polymers (SMPs) were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), flexural test and shape recovery test. The results revealed that the obtained SMPs exhibited a higher flexural strength and flexural modulus than those of the unmodified epoxy-based SMP at room temperature and at 20 ° C above glass transition temperature (T g ). The presence of 1 mol BA-a as a curing agent provided the specimen with the highest T g , i.e. about 72 ° C higher than that of epoxy-based SMP cured by Jeffamine D230. All SMP samples needed only a few minutes to fully recover to their original shape. The samples exhibited high shape fixity (98–99%) and shape recovery ratio (90–100%). In addition, the recovery stress values increased with increasing BA-a mole ratio from 20 to 38 kPa, when BA-a up to 1 mol ratio was added. All of the SMP samples exhibited only minimum change in their flexural strength at the end of a 100 recovery cycles test. (paper)

  20. Influencia de la concentración de pigmento en volumen (CPV en las propiedades de una imprimación epoxi

    Directory of Open Access Journals (Sweden)

    Rodríguez, M. T.

    2005-12-01

    Full Text Available By means of stress-strain tests, electrochemical techniques (EIS and AC/DC/AC and salt spray accelerated tests, the influence of the A=PVC/CPVC parameter (being CPVC the critical pigment volume concentration on mechanical and anticorrosive properties of an anticorrosive epoxy organic primer has been studied. Primers were formulated at different A values (0.73, 0.80, 0.88, 0.93, 0.98, 1.08, 1.15 and 1.24. It was concluded that mechanical and anticorrosive properties of an epoxy coating are greatly affected by the A parameter. The corrosion resistance increases when the PVC decreases. Anticorrosive properties characterized with the different techniques used were very similar, although AC/DC/AC offered the results in a very short time (24 h.

    Mediante ensayos de tracción (tensión-deformación, ensayos electroquímicos (EIS y AC/DC/AC y ensayos acelerados de niebla salina, se ha estudiado el efecto del parámetro A=CPV/CCPV (siendo CCPV la concentración de pigmento en volumen crítica en las propiedades mecánicas y anticorrosivas de una imprimación epoxi. Se formularon imprimaciones con diferentes valores de A (0,73, 0,80, 0,88, 0,93, 0,98, 1,08, 1,15 y 1,24. Se ha observado que las propiedades mecánicas y anticorrosivas de una imprimación epoxi se ven altamente afectadas por el parámetro A, aumentando la resistencia a corrosión al disminuir la CPV. Las conclusiones halladas mediante las diferentes técnicas fueron muy similares, destacando los ensayos AC/DC/AC por su rapidez en la obtención de resultados (24 h.

  1. Chromatographic assessment of two hybrid monoliths prepared via epoxy-amine ring-opening polymerization and methacrylate-based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer.

    Science.gov (United States)

    Wang, Hongwei; Ou, Junjie; Lin, Hui; Liu, Zhongshan; Huang, Guang; Dong, Jing; Zou, Hanfa

    2014-11-07

    Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65°C for 12h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60°C for 12h. Two hybrid monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA-DAD monolith possessed higher column efficiencies (25,000-34,000plates/m) for the separation of alkylbenzenes than the epoxy-MA-EDMA monolith (12,000-13,000plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine monoliths, the epoxy-MA-EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA-DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA-DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA-DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA-EDMA monolith when compared with that on pristine epoxy-MA-EDMA monolith. The enhancement of the column efficiency of epoxy-MA-DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC. Copyright © 2014 Elsevier B.V. All

  2. Atividade antitumoral, antiinflamatória e antiulcerogênica de duas variedades de própolis brasileira

    OpenAIRE

    Cristiana Madjarof

    2009-01-01

    Resumo: A própolis é uma resina coletada por abelhas da espécie Apis mellifera e atualmente esse produto vem se destacando por apresentar propriedades biológicas interessantes, como atividade antimicrobiana, antiinflamatória, antiulcerogênica, antiviral, antioxidante e anticâncer. A própolis brasileira apresenta uma constituição química diferenciada principalmente pela diversidade de espécies vegetais para a retirada de resina; variação esta que aponta para a necessidade de novas investigaçõe...

  3. Avaliação do selamento marginal promovido por sistemas adesivos aplicados em esmalte e dentina

    Directory of Open Access Journals (Sweden)

    Amanda Aguiar

    2015-11-01

    Full Text Available Objetivo: Avaliar o selamento marginal promovido por dois diferentes sistemas adesivos em esmalte e dentina através de microinfiltração. Método: Foram utilizados 20 terceiros molares humanos hígidos. Os sistemas adesivos Adper Single Bond 2 (convencional e Adper SE Plus (autocondicionante foram aplicados em cavidades Classe V, nas faces vestibular e lingual, seguindo-se restauração com resina composta Filtek Z350 na técnica incremental e fotoativação com aparelho de lâmpada halógena (VIP, Bisco, 550mW/cm². Os dentes restaurados permaneceram armazenados em água destilada (24h/37°C, foi feito o acabamento, termociclagem (500 ciclos, 5°/55°C, 30 segundos, impermeabilização dos ápices dentários com resina acrílica e o restante do dente com três camadas de esmalte cosmético, exceto 1 milímetro ao redor da cavidade. Seguiram-se a imersão em solução aquosa de nitrato de prata a 50% (2 h em ambiente escuro, lavagem, imersão em solução reveladora Kodak (8 h sob luz fluorescente e lavagem. As restaurações foram seccionadas pelo centro, no sentido V-L, obtendo-se duas fatias. A microinfiltração foi avaliada por um examinador treinado, em software UTHSCSA Image Tool for Windows 3.0, com dois métodos: qualitativo (escala visual: 0- sem infiltração; 1- infiltração em esmalte; 2- em dentina nas paredes axial e gengival; 3 – idem 3 e em direção à polpa e quantitativo (porcentagem de infiltração de nitrato de prata. Os dados foram submetidos ao teste t de Student (alfa=5%. Resultados: Não foi observada diferença entre os materiais na porcentagem de infiltração de nitrato de prata (p=0,595, nem na avaliação por escala (p=0,408. Houve infiltração em dentina nos dois grupos. Conclusão: os sistemas adesivos testados apresentaram comportamento semelhante.

  4. Characterization and Curing Kinetics of Epoxy/Silica Nano-Hybrids

    Science.gov (United States)

    Yang, Cheng-Fu; Wang, Li-Fen; Wu, Song-Mao; Su, Chean-Cheng

    2015-01-01

    The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC), 29Si nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). To improve the compatibility between the organic and inorganic phases, a coupling agent was used to modify the diglycidyl ether of bisphenol A (DGEBA) epoxy. The sol-gel technique enables the silica to be successfully incorporated into the network of the hybrids, increasing the thermal stability and improving the mechanical properties of the prepared epoxy/silica nano-hybrids. An autocatalytic mechanism of the epoxy/SiO2 nanocomposites was observed. The low reaction rate of epoxy in the nanocomposites is caused by the steric hindrance in the network of hybrids that arises from the consuming of epoxide group in the network of hybrids by the silica. In the nanocomposites, the nano-scale silica particles had an average size of approximately 35 nm, and the particles were well dispersed in the epoxy matrix, according to the TEM images. PMID:28793616

  5. High-performance fiber/epoxy composite pressure vessels

    Science.gov (United States)

    Chiao, T. T.; Hamstad, M. A.; Jessop, E. S.; Toland, R. H.

    1978-01-01

    Activities described include: (1) determining the applicability of an ultrahigh-strength graphite fiber to composite pressure vessels; (2) defining the fatigue performance of thin-titanium-lined, high-strength graphite/epoxy pressure vessel; (3) selecting epoxy resin systems suitable for filament winding; (4) studying the fatigue life potential of Kevlar 49/epoxy pressure vessels; and (5) developing polymer liners for composite pressure vessels. Kevlar 49/epoxy and graphite fiber/epoxy pressure vessels, 10.2 cm in diameter, some with aluminum liners and some with alternation layers of rubber and polymer were fabricated. To determine liner performance, vessels were subjected to gas permeation tests, fatigue cycling, and burst tests, measuring composite performance, fatigue life, and leak rates. Both the metal and the rubber/polymer liner performed well. Proportionately larger pressure vessels (20.3 and 38 cm in diameter) were made and subjected to the same tests. In these larger vessels, line leakage problems with both liners developed the causes of the leaks were identified and some solutions to such liner problems are recommended.

  6. Estudio de eliminación de arsénico con resinas de intercambio iónico en agua potable de Zimapán, Estado de Hidalgo, México

    Directory of Open Access Journals (Sweden)

    Pérez-Moreno, F.

    2006-10-01

    Full Text Available Anionic exchange resins were research with respect its capacity for removal arsenic content in water. Water of well V from Zimapán Hidalgo Mexico was used to make this research, because this water have a mean concentration of 480 ± 11 μg·L-1 of arsenic and it is
    available as drinking water. The exchange resins employed were two strong anionic, one macroreticular (IRA-900 and other gel type (IRA-400, as soon as one third anionic weak macroreticular type (IRA-96. The experiments carried with this resins showing that IRA-900 has highest efficient in the process of arsenic removal from drinking water, because, it showed a treatment capacity of 700 Vagua·Vres-1; while that capacities of IRA-400 e IRA-96 resins were 320 and 52 Vagua·Vres-1 respectively. The mean concentration of arsenic residue in the treatise water was 24 μg·l-1 and it is within the maximum level permissible by Mexican official norm for drinking water.

    Se investigaron resinas de intercambio aniónico con respecto a su capacidad para la eliminación de arsénico contenido en agua. Se utilizó agua del pozo V de Zimapán, Hidalgo, México, cuya concentración promedio es de 480 ± 11 μg·l-1 de arsénico y es utilizada para consumo humano. Se emplearon dos reinas aniónicas fuertes; una, de tipo macro reticular (IRA-900 y la otra de tipo gel (IRA-400, así como una tercera, aniónica débil, de tipo macro reticular (IRA-96. Los experimentos realizados con estas resinas muestran que la IRA-900 es la que mostró la más alta eficiencia en la eliminación de arsénico del agua potable, debido a que presentó una capacidad de tratamiento de 700 Vagua·Vres-1, mientras que las capacidades de las resinas IRA-400 e IRA-96 fueron de 320 y 52 Vagua·Vres-1, respectivamente. La concentración promedio de ars

  7. Viscoelastic properties of graphene-based epoxy resins

    Science.gov (United States)

    Nobile, Maria Rossella; Fierro, Annalisa; Rosolia, Salvatore; Raimondo, Marialuigia; Lafdi, Khalid; Guadagno, Liberata

    2015-12-01

    In this paper the viscoelastic properties of an epoxy resin filled with graphene-based nanoparticles have been investigated in the liquid state, before curing, by means of a rotational rheometer equipped with a parallel plate geometry. Exfoliated graphite was prepared using traditional acid intercalation followed by a sudden treatment at high temperature (900°C). The percentage of exfoliated graphite was found to be 56%. The epoxy matrix was prepared by mixing a tetrafunctional precursor with a reactive diluent which produces a significant decrease in the viscosity of the epoxy precursor so that the dispersion step of nanofillers in the matrix can easily occur. The hardener agent, the 4,4-diaminodiphenyl sulfone (DDS), was added at a stoichiometric concentration with respect to all the epoxy rings. The inclusion of the partially exfoliated graphite (pEG) in the formulated epoxy mixture significantly modifies the rheological behaviour of the mixture itself. The epoxy mixture, indeed, shows a Newtonian behaviour while, at 3 wt % pEG content, the complex viscosity of the nanocomposite clearly shows a shear thinning behaviour with η* values much higher at the lower frequencies. The increase in complex viscosity with the increasing of the partially exfoliated graphite content was mostly caused by a dramatic increase in the storage modulus. All the graphene-based epoxy mixtures were cured by a two-stage curing cycles: a first isothermal stage was carried out at the lower temperature of 125°C for 1 hour while the second isothermal stage was performed at the higher temperature of 200°C for 3 hours. The mechanical properties of the cured nanocomposites show high values in the storage modulus and glass transition temperature.

  8. Estudio cinético del efecto de polifenilsulfona sobre el curado de una resina epoxi/amina mediante calorimetría diferencial de barrido convencional y modulada con temperatura: parte II Kinetic study on the effect of curing polyphenylsulfone epoxy resin/amina by differential calorimetry scanning conventional and modulated temperature: part II

    Directory of Open Access Journals (Sweden)

    Asdrúbal J. Cedeño

    2010-01-01

    Full Text Available En este trabajo se estudió el efecto de la adición del termoplástico lineal polifenilsulfona (PPSU, sobre la cinética de reacción y las propiedades térmicas de una resina epoxídica basada en diglicidil éter de bisfenol - A (DGEBA, curada con diaminodifenilsulfona (DDS. El estudio cinético y la caracterización se realizaron mediante calorimetría diferencial de barrido, DSC estándar y modulado, bajo condiciones isotérmicas y dinámicas. La cinética del curado se discutió en el marco de tres modelos cinéticos: Kissinger, Flynn-Wall-Ozawa y el modelo cinético de orden n. Para describir la reacción de curado en su última etapa, se usó la relación semiempírica propuesta por Chern y Poehlein para considerar la influencia de la difusión sobre la rapidez de reacción. El mecanismo de curado, para todos los sistemas, se ajustó a una cinética de orden n, a pesar del contenido de PPSU, y se observó que éste se hace muy controlado por la difusión conforme aumenta el contenido de PPSU y conforme la temperatura de curado disminuye. El tiempo de vitrificación de los sistemas exhibió una fuerte dependencia con el contenido de PPSU.In this work we studied the effect of the addition of the linear thermoplastic polyphenyl sulfone (PPSU on the cure kinetics and the thermal properties of a resin based on diglycidyl ether of bisphenol-A (DGEBA, cured with 4,4´-diaminodiphenyl sulfone (DDS. The kinetic study and the characterization process have been carried out by using differential scanning calorimetry, DSC, and temperature modulated DSC (TMDSC, under isothermal and dynamic conditions. The curing kinetics was discussed in the framework of three kinetic models: Kissinger, Flynn-Wall-Ozawa, and the model of reaction of order n. To describe the cured reaction in its last stage, we have used the semiempirical relationship proposed by Chern and Poehlein to take into account the influence of diffusion on the reaction rate. The cure mechanism

  9. Epoxy Nanocomposites Containing Zeolitic Imidazolate Framework-8.

    Science.gov (United States)

    Liu, Cong; Mullins, Michael; Hawkins, Spencer; Kotaki, Masaya; Sue, Hung-Jue

    2018-01-10

    Zeolitic imidazole framework-8 (ZIF-8) is utilized as a functional filler and a curing agent in the preparation of epoxy nanocomposites. The imidazole group on the surface of the ZIF-8 initiates epoxy curing, resulting in covalent bonding between the ZIF-8 crystals and epoxy matrix. A substantial reduction in dielectric constant and increase in tensile modulus were observed. The implication of the present study for utilization of metal-organic framework to improve physical and mechanical properties of polymeric matrixes is discussed.

  10. Plasma Treated Multi-Walled Carbon Nanotubes (MWCNTs for Epoxy Nanocomposites

    Directory of Open Access Journals (Sweden)

    Jie Lian

    2011-12-01

    Full Text Available Plasma nanocoating of allylamine were deposited on the surfaces of multi-walled carbon nanotubes (MWCNTs to provide desirable functionalities and thus to tailor the surface characteristics of MWCNTs for improved dispersion and interfacial adhesion in epoxy matrices. Plasma nanocoated MWCNTs were characterized using scanning electron microscopy (SEM, high-resolution transmission electron microscopy (HR-TEM, surface contact angle, and pH change measurements. Mechanical testing results showed that epoxy reinforced with 1.0 wt % plasma coated MWCNTs increased the tensile strength by 54% as compared with the pure epoxy control, while epoxy reinforced with untreated MWCNTs have lower tensile strength than the pure epoxy control. Optical and electron microscopic images show enhanced dispersion of plasma coated MWCNTs in epoxy compared to untreated MWCNTs. Plasma nanocoatings from allylamine on MWCNTs could significantly enhance their dispersion and interfacial adhesion in epoxy matrices. Simulation results based on the shear-lag model derived from micromechanics also confirmed that plasma nanocoating on MWCNTs significantly improved the epoxy/fillers interface bonding and as a result the increased composite strength.

  11. Development of AlN/Epoxy Composites with Enhanced Thermal Conductivity

    Science.gov (United States)

    Xu, Yonggang; Yang, Chi; Li, Jun; Zhang, Hailong; Hu, Song; Wang, Shiwei

    2017-01-01

    AlN/epoxy composites with high thermal conductivity were successfully prepared by infiltrating epoxy into AlN porous ceramics which were fabricated by gelcasting of foaming method. The microstructure, mechanical, and thermal properties of the resulting composites were investigated. The compressive strengths of the AlN/epoxy composites were enhanced compared with the pure epoxy. The AlN/epoxy composites demonstrate much higher thermal conductivity, up to 19.0 W/(m·K), compared with those by the traditional particles filling method, because of continuous thermal channels formed by the walls and struts of AlN porous ceramics. This study demonstrates a potential route to manufacture epoxy-based composites with extremely high thermal conductivity. PMID:29258277

  12. Development of AlN/Epoxy Composites with Enhanced Thermal Conductivity.

    Science.gov (United States)

    Xu, Yonggang; Yang, Chi; Li, Jun; Mao, Xiaojian; Zhang, Hailong; Hu, Song; Wang, Shiwei

    2017-12-18

    AlN/epoxy composites with high thermal conductivity were successfully prepared by infiltrating epoxy into AlN porous ceramics which were fabricated by gelcasting of foaming method. The microstructure, mechanical, and thermal properties of the resulting composites were investigated. The compressive strengths of the AlN/epoxy composites were enhanced compared with the pure epoxy. The AlN/epoxy composites demonstrate much higher thermal conductivity, up to 19.0 W/(m·K), compared with those by the traditional particles filling method, because of continuous thermal channels formed by the walls and struts of AlN porous ceramics. This study demonstrates a potential route to manufacture epoxy-based composites with extremely high thermal conductivity.

  13. Avaliação em MEV da fenda resultante da contração de polimerização da resina composta aplicada sobre diferentes materiais protetores pulpares = A sem evaluation of the gap resulting from the polymerization shrinkage of composite resins applied to different pulp protective materials

    Directory of Open Access Journals (Sweden)

    Unfer, Daniele Taís

    2006-01-01

    Full Text Available Introdução: A resina composta sofre contração como resultado da reação de polimerização que pode deslocar os materiais protetores pulpares, caso estes apresentem deficiente ou nenhuma adesão a dentina. Objetivo: avaliar o comportamento de dois materiais de proteção pulpar (CIV e CaOH2 cement em relação presença de fenda, quando submetidos a estresse de contração da resina composta e avaliar a fenda resultante da contração de polimerização entre dentina e resina composta. Metodologia: Foram confeccionados preparos classe V nas faces vestibular e lingual de 12 dentes molares humanos os quais foram divididos em quatro grupos de estudo, conforme a técnica restauradora e os materiais utilizados: G1 (SA + RC; G2 (HC + SA + RC; G3 (CIV + SA + RC e G4 (HC + CIV + SA + RC. Os corpos de prova foram avaliados em MEV e os dados obtidos foram submetidos análise não-paramétrica. Resultados: Os resultados obtidos mostram que os materiais de proteção pulpar utilizados são deslocados pela contração gerada pela polimerização da resina composta. Os melhores resultados (não presença de fenda foram demonstrados no grupo em que o sistema adesivo foi o único material entre a dentina e a resina composta. Quando do uso do CIV e do HC, associados ou não, foi encontrado o maior percentual de fendas. Conclusão: Os materiais de proteção pulpar continuarão a ser deslocados pela contração de polimerização das resinas compostas enquanto sua união à estrutura dental não apresentar suficiente resistência ou não se evitar a contração da resina composta

  14. Radiation processing of carbon fiber-acrylated epoxy composites

    International Nuclear Information System (INIS)

    Singh, A.; Saunders, C.B.

    1992-01-01

    Advanced composites, specifically carbon fiber reinforced epoxies, are being used for a variety of demanding structural applications, primarily because of their high strength-to-weight and stiffness-to-weight ratios, corrosion resistance, and damage tolerance characteristics. For these composites the key advantages of using electron beam (EB), rather than thermal curing, are curing at ambient temperature, reduced curing times for individual components, improved resin stability, fewer volatiles, and better control of the profile of energy absorption. Epoxy compounds do, however, have to be modified to make them EB curable. The electron beam penetration limit, a function of beam energy, product density, and the thickness of any container required, must also be examined when considering EB processing. Research is being conducted to develop EB-curable carbon fiber-acrylated epoxy composites. The tensile properties of these laminates are comparable to those of thermally cured epoxy laminates. Research is continuing to develop suitable resin formulations and coupling agents to optimize the mechanical properties of EB-cured carbon fiber laminates. In this chapter the EB curing of epoxies, processing considerations, and typical properties of EB-cured carbon fiber-acrylated epoxy laminates are discussed. (orig.)

  15. Polimerização complementar em autoclave, microondas e estufa de um compósito restaurador direto = The effect of post-cure heating in autoclave, microwave oven and conventional oven on direct composite resin

    Directory of Open Access Journals (Sweden)

    Arossi, Guilherme Anziliero

    2007-01-01

    Full Text Available Com o objetivo de tornar o processo de confecção de restaurações indiretas mais acessível, reduzindo seus custos com a resina utilizada e os métodos de polimerização complementar, este estudo testou a possibilidade de se utilizar resinas diretas com métodos de polimerização complementar alternativos. Corpos de prova foram confeccionados com a resina Charisma e fotopolimerizados por 20 segundos. Em seguida as amostras foram submetidas à polimerização complementar em autoclave, microondas e estufa. Foram estabelecidos dois grupos controles: um controle negativo, que consistiu na utilização da resina Charisma fotopolimerizada convencionalmente (20s; e um grupo controle positivo, formado por amostras do compósito restaurador indireto Targis. O ensaio de microdureza Knoop foi realizado após uma semana de armazenagem e os resultados submetidos à análise estatística. Os três métodos de polimerização complementar propostos determinaram um aumento na microdureza do compósito restaurador direto quando comparado ao controle negativo (p 0,05. Conclui-se que, considerando o desenho experimental deste estudo, a polimerização complementar em autoclave, microondas ou estufa aumenta a microdureza da resina Charisma previamente fotopolimerizada

  16. Thermal-mechanical properties of a graphitic-nanofibers reinforced epoxy.

    Science.gov (United States)

    Salehi-Khojin, Amin; Jana, Soumen; Zhong, Wei-Hong

    2007-03-01

    We previously developed a series of reactive graphitic nanofibers (r-GNFs) reinforced epoxy (nano-epoxy) as composite matrices, which have shown good wetting and adhesion properties with continuous fiber. In this work, the thermal-mechanical properties of the nano-epoxy system containing EponTM Resin 828 and Epi-cure Curing Agent W were characterized. Results from three-point bending tests showed that the flexural strength and flexural modulus of this system with 0.30 wt% of reactive nanofibers were increased by 16%, and 21% respectively, over pure epoxy. Fracture toughness increased by ca. 40% for specimens with 0.50 wt% of r-GNFs. By dynamic mechanical analysis (DMA) test, specimens with 0.30 wt% of r-GNFs showed a significant increase in storage modulus E' (by ca. 122%) and loss modulus E" (by ca. 111%) with respect to that of pure epoxy. Also thermo-dilatometry analysis (TDA) was used to measure dimensional change of specimens as a function of temperature, and then, coefficients of thermal expansion (CTE) before and after glass transition temperature (Tg) were obtained. Results implied that nano-epoxy materials had good dimensional stability and reduced CTE values when compared to those of pure epoxy.

  17. Avaliação de fenda marginal, através de microscopia eletrônica de varredura, em restaurações de resina composta com diferentes técnicas adesivas = Scanning electron microscopy evaluation of the marginal gap in composite restorations with different adhesive techniques

    Directory of Open Access Journals (Sweden)

    Coelho-de-Souza, Fábio Herrmann

    2008-01-01

    Full Text Available Objetivo: O propósito deste trabalho foi avaliar a formação de fenda marginal, através de microscopia eletrônica de varredura, em restaurações de resina composta com quatro técnicas adesivas: Prime & Bond 2. 1 (Dentsply sem condicionamento prévio, Prime & Bond 2. 1 com condicionamento convencional com ácido fosfórico, Prime & Bond 2. 1 com condicionamento com ácido poliacrílico a 25% e Clearfil SE Bond (Kuraray. Metodologia: Foram utilizados cinco terceiros molares humanos hígidos, nos quais foram preparadas quatro cavidades, sendo que em cada uma foi utilizada uma técnica adesiva. Todas as cavidades foram restauradas com resina composta Z250 (3M/ESPE. Os dentes foram submetidos à termociclagem por 500 ciclos e observados em microscópio eletrônico de varredura para medição da formação de fenda marginal nas paredes gengivais. Resultados: Não houve diferença estatística de fenda marginal entre os grupos experimentais de técnicas adesivas (ANOVA, P>0,05. Conclusão: Nenhuma das técnicas adesivas foi capaz de evitar a formação de fenda marginal; não houve diferença entre as técnicas adesivas empregadas

  18. Frecuencia de restauraciones plásticas directas en dientes posteriores en tres centros públicos de Asunción

    Directory of Open Access Journals (Sweden)

    Isolde Fischer

    2015-08-01

    Full Text Available En la selección del material de restauración, para rehabilitar una pieza dentaria posterior que ha sufrido una lesión, el operador puede optar entre la amalgama o la resina compuesta, equilibrando las ventajas y desventajas de cada una. Este estudio de enfoque mixto, de diseño descriptivo, retrospectivo y transversal, tuvo como objetivo determinar la frecuencia en el uso de los biomateriales restauradores en dientes posteriores. Se utilizó un cuestionario aplicado a una muestra de 164 sujetos tratados previamente en tres centros públicos de referencia en Asunción en 2.013 y 2.014. El trabajo se complementó con una técnica cualitativa, la entrevista a grupo focal, en dos grupos distintos; por un lado a docentes y por el otro, a comerciantes de artículos dentales. Se observó que la resina es el material de uso más frecuente (77,7% seguido del ionómero de vidrio (18,4%, siendo la amalgama el menos utilizado (4,2%. Docentes y comerciantes entrevistados coincidieron en opinar que la resina es el material más utilizado por el factor estético, y que la amalgama se halla francamente en desuso, sea por su falta de estética o por efectos tóxicos, aunque pocos docentes conocían los criterios actuales sobre los efectos adversos de amalgamas y resinas, emitidos por entes sanitarios internacionales. Se propone tener en cuenta estos resultados para la reorientación del curriculum en la educación odontológica respecto a los biomateriales restauradores si fuese necesario, sobre fundamentos válidos y coherentes con las necesidades del contexto.

  19. Effect of light-activation methods and water storage on the flexural strength of two composite resins and a compomer Efeito da fotoativação e da armazenagem em água na resistência à flexão de duas resinas compostas e um compômero

    Directory of Open Access Journals (Sweden)

    Leonardo Eloy Rodrigues Filho

    2006-04-01

    Full Text Available The present study evaluated the flexural strength of three composite resins recommended for direct esthetic restorations: a polyacid modified composite (Dyract AP, a unimodal composite resin (Filtek Z250 and a hybrid composite resin (Point 4. The variation factors, apart from the type of composite resin, were the light activation method and the water storage period. The composite resins were light-cured in continuous mode (40 s, 500 mW/cm² or in ramp mode (0-800 mW/cm² for 10 s followed by 30 s at 800 mW/cm² and stored for 24 hours or 30 days in distilled water at 37°C. The data were analyzed by ANOVA and Tukey test for multiple comparisons (alpha = 0.05. The composite resin Z250 presented the highest mean flexural strength (166.74 MPa and Dyract AP presented the lowest one (129.76 MPa. The storage for 30 days decreased the flexural strength in ramp mode (24 h: 156.64 MPa; 30 days: 135.58 MPa. The light activation method alone did not lead to different flexural strength values.O presente estudo analisou a resistência à flexão de três compósitos recomendados para restaurações estéticas diretas: um compósito poliácido-modificado (Dyract AP, uma resina composta unimodal (Filtek Z250 e uma resina composta híbrida (Point 4. Os fatores de variação, além do tipo de compósito, foram o método de fotoativação e o período de armazenagem em água. Os materiais foram fotoativados continuamente por 40 s (500 mW/cm² ou com intensidade de luz crescente (0-800 mW/cm² por 10 s seguidos de 30 s a 800 mW/cm². Os períodos de armazenagem foram de 24 horas ou 30 dias em água destilada a 37°C. Os dados foram submetidos à análise de variância e ao teste de Tukey para comparações múltiplas (alfa = 0,05. A resina composta Z250 apresentou a maior média de resistência à flexão (166,74 MPa e a Dyract AP, a menor (129,76 MPa. A armazenagem por 30 dias diminuiu a resistência à flexão para o método de fotoativação crescente (24 h

  20. Green Preparation of Epoxy/Graphene Oxide Nanocomposites Using a Glycidylamine Epoxy Resin as the Surface Modifier and Phase Transfer Agent of Graphene Oxide.

    Science.gov (United States)

    Tang, Xinlei; Zhou, Yang; Peng, Mao

    2016-01-27

    In studies of epoxy/graphene oxide (GO) nanocomposites, organic solvents are commonly used to disperse GO, and vigorous mechanical processes and complicated modification of GO are usually required, increasing the cost and hindering the development and application of epoxy nanocomposites. Here, we report a green, facile, and efficient method of preparing epoxy/GO nanocomposites. When triglycidyl para-aminophenol (TGPAP), a commercially available glycidyl amine epoxy resin with one tertiary amine group per molecule, is used as both the surface modifier and phase transfer agent of GO, GO can be directly and rapidly transferred from water to diglycidyl ether of bisphenol A and other types of epoxy resins by manual stirring under ambient conditions, whereas GO cannot be transferred to these epoxy resins in the absence of TGPAP. The interaction between TGPAP and GO and the effect of the TGPAP content on the dispersion of GO in the epoxy matrix were investigated systematically. Superior dispersion and exfoliation of GO nanosheets and remarkably improved mechanical properties, including tensile and flexural properties, toughness, storage modulus, and microhardness, of the epoxy/GO nanocomposites with a suitable amount of TGPAP were demonstrated. This method is organic-solvent-free and technically feasible for large-scale preparation of high-performance nanocomposites; it opens up new opportunities for exploiting the unique properties of graphene or even other nanofillers for a wide range of applications.

  1. Performance of epoxy-nanocomposite under corrosive environment

    Directory of Open Access Journals (Sweden)

    2007-06-01

    Full Text Available Nanocomposite materials consisting of polymeric matrix materials and natural or synthetic layered minerals like clay are currently an expanding field of study because these new materials often exhibit a wide range of improved properties over their unmodified starting polymers. Epoxy/organoclay nanocomposites have been prepared by intercalating epoxy into the organoclay via direct mixing process. The clay exfoliation was monitored by X-ray diffraction (XRD and transmission electron microscopy (TEM. Water diffusion and sulfuric acid corrosion resistance of epoxy-based nanocomposites were evaluated. Diffusion was studied through epoxy samples containing up to 6 phr (parts per hundred resin of an organically treated montmorillonite. The diffusion of the environmental solution was measured by noting the increase in weight of the samples as a function of immersion time in these solutions at 80°C. The effect of the degree of exfoliation of the organoclay on water barrier and corrosion resistance was specifically studied. The data have been compared to those obtained from the neat epoxy resin to evaluate the diffusion properties of the nanocomposites. The flexural strength of the epoxy/organoclay nanocomposites samples made was examined to compare their mechanical performance under corrosive conditions as a function of immersion time and temperature. It was found, that the organoclay was mainly intercalated with some exfoliation and that addition of the organoclay yields better flexural strength retention under immersion into sulfuric acid.

  2. Bioactivity-Guided Fractionation of the Traditional Chinese Medicine Resina Draconis Reveals Loureirin B as a PAI-1 Inhibitor

    Directory of Open Access Journals (Sweden)

    Yu Jiang

    2017-01-01

    Full Text Available Thrombotic diseases have become a global burden due to morbidity, mortality, and disability. Traditional Chinese medicine has been proven effective in removing blood stasis and promoting blood circulation, but the exact mechanisms remain unclear. Plasminogen activator inhibitor-1 (PAI-1 is a natural inhibitor of tissue-type and urokinase-type plasminogen activators. In this study, we screened four fractions of Resina Draconis (a traditional Chinese medicine extract for PAI-1 inhibitory activity. Bioactivity-guided purification and chromogenic substrate-based assay led to the identification of loureirin B as the major PAI-1 inhibitor, with an IC50 value of 26.10 μM. SDS-PAGE analysis showed that formation of the PAI-1/uPA complex was inhibited by loureirin B, and the inhibitory effect of loureirin B on PAI-1 was also confirmed by clot lysis assay. In vivo studies showed that loureirin B significantly prolonged the tail bleeding time and reduced the weight and size of arterial thrombus, reduced hydroxyproline level, and partly cured liver fibrosis in mice. Taken together, the results revealed loureirin B as a PAI-1 inhibitor, adding a new pharmacological target for loureirin B and uncovering a novel mechanism underlying the antithrombotic property of Resina Draconis, which might be useful in the treatment of cardiovascular diseases such as thrombosis and fibrosis.

  3. In-situ Elevated Temperature Mechanical Performance of MWCNT/epoxy Nanocomposite

    Directory of Open Access Journals (Sweden)

    Bhanu Pratap Singh

    2017-03-01

    Full Text Available The present investigation has been focused on the effects of multi-walled carbon nanotube (MWCNT addition on the mechanical performance of epoxy under different in-service elevated temperature environments. Room temperature flexural test results revealed that addition of 0.1 wt. % MWCNT into epoxy resin resulted in modulus and strength enhancement of 21 % and 9 % respectively. With increase in service temperature, significant decrement in both modulus and strength was noticed for both materials (neat epoxy and MWCNT/epoxy nanocomposite, but the rate of degradation was found to be quite drastic for the nanocomposite. At 90 °C temperature, the CNT/epoxy nanocomposite exhibited inferior modulus and strength, which are 41 % and 59 % lower than neat epoxy respectively. The variation trend in elastic modulus with temperature obtained from both flexural testing and DMA for both these materials was also analyzed. It was found that addition of 0.1 % CNT in the epoxy reduced the glass transition temperature by about 16°C.

  4. Influência do tipo de ponteira condutora de luz na microdureza de uma resina composta Influence of the different light-curing TIPS in the microhardness of a composite resin

    Directory of Open Access Journals (Sweden)

    Máx Dobrovolski

    2010-01-01

    Full Text Available O objetivo desta pesquisa foi avaliar a influência do tipo de ponteira condutora de luz na microdureza de uma resina composta micro-híbrida. Foram confeccionados 14 corpos de prova da resina composta Opallis (FGM com dimensões: 5 x 2 mm, divididos em dois grupos de acordo com a ponteira condutora de luz do aparelho fotoativador de lâmpada halógena Optilight Plus - GNATUS/300 mW.cm-2. GI - ponteira condutora de luz de fibra óptica; GII - ponteira condutora de luz de polímero. Após 24 horas, as medidas de microdureza foram efetuadas com um microdurômetro HMV 2000 (Shimadzu Japão. Cinco penetrações foram efetuadas em cada superfície (topo e base totalizando 10 penetrações para cada corpo de prova. A análise estatística dos resultados realizada por meio do teste de ANOVA não apresentou diferenças significativas entre os tipos de ponta condutora de luz nas superfícies avaliadas. A análise estatística demonstrou diferença significativa nos valores médios de microdureza superficial entre as superfícies de topo e de base, para ambas as ponteiras. Com base nos resultados obtidos, foi possível concluir que as ponteiras de luz não interferem na microdureza da resina composta, e que ambas apresentaram diferenças estatisticamente significativas nos valores de microdureza das superfícies topo e base.The aim of this study is to evaluate the influence of the light-curing tips on the microhardness of a micro-hybrid composite resin. Fourteen samples of Opallis (FGM composite resin with 5 x 2 mm were prepared. The specimens were divided into two groups according to the light-curing tips from a halogen light curing unit (Optilight Plus -GNATUS/300 mW.cm-2: GI - optical fiber light-curing; GII - polymer light-curing. After 24 hours, the microhardness measurements were determined using the HMV 2000 (Shimadzu Japan. Five measurements were made on each surface (top and bottom totalizing 10 indentations for each sample. Statistical analysis

  5. Influência da ciclagem térmica na resistência à flexão de resinas laboratoriais = The effect of thermo-cycling on flexural strength of laboratorial resins

    Directory of Open Access Journals (Sweden)

    Oliveira, Karla Mychellyne Costa

    2007-01-01

    Full Text Available Introdução: Uma nova geração de resinas laboratoriais contendo micro-partículas cerâmicas em sua composição tem sido introduzida no mercado com a finalidade de melhorar suas propriedades mecânicas. Objetivo: O objetivo deste estudo foi avaliar o efeito da termociclagem na resistência à flexão de três resinas laboratoriais. Materiais e método: Foram confeccionadas 48 barras com medidas de 2 mm × 2 mm × 25 mm, utilizando as resinas laboratoriais: G1 - RESILAB MASTER (Wilcos, Brasil, G2 - VITA VM LC (Vita Zanhfabrik, Germany, G3 - VITA ZETA LC (Vita Zanhfabrik, Germany. A metade das barras de cada grupo foi submetida a 3000 ciclos térmicos (5ºC/55ºC ± 1, com banhos de 30 s. Os ensaios mecânicos foram efetuados em máquina de ensaio universal EMIC com capacidade de carga de 100 kg e velocidade de 0,5 mm/min. Resultados: Os dados obtidos foram analisados estatisticamente pelo teste de ANOVA (two-way e Tukey (p < 0,05. As médias (± DP observadas para os grupos sem ciclagem foram: G1(112,6 ± 25,39, G2(116,5 ± 18,51 e G3(136,1 ± 24,34; e para os grupos com ciclagem: G1(91,8 ± 18,86, G2(101,9 ± 20,61 e G3(89,9 ± 23,05. Conclusão: Concluiu-se que a diminuição da resistência à flexão em MPa está diretamente dependente da ciclagem térmica nos grupos testados, sendo que os maiores valores foram obtidos pela resina VITA VM LC. Entretanto, na condição sem ciclagem térmica a VITA ZETA apresentou os maiores valores

  6. Marginal leakage of polyacid-modified composite resin restorations in primary molars: an in vitro study Infiltração marginal em restaurações de resinas compostas modificadas por poliácidos, em molares decíduos: estudo in vitro

    Directory of Open Access Journals (Sweden)

    Cleide Cristina R. Martinhon

    2005-06-01

    Full Text Available The purpose of this in vitro study was to compare the marginal leakage in primary molars restored with 2 polyacid-modified composite resins (Dyract AP - Dentsply and F2000 - 3M and a composite resin (Filtek Z250 - 3M as control. First and second primary molars were used for preparation of cavities on the proximal surfaces, with extension of the gingival margin to the cementoenamel junction. Restorations were accomplished after total etching and application of the respective adhesive system, and were divided into groups according to the restorative system and the number of adhesive layers used. The teeth were stored in distilled water for 7 days, followed by thermocycling with 500 cycles at 5ºC - 55ºC, with one minute in each bath. Thereafter, teeth were prepared for immersion in 0.5% methylene blue solution for four hours. The teeth were sectioned in mesiodistal direction for assessment of dye penetration. According to the results of the Kruskal-Wallis test, the three restorative materials employed did not completely avoid marginal leakage at the gingival margin of primary molars. The marginal leakage of PMCR F2000 (4.06 and 3.95 displayed to be higher than the marginal leakage observed for the materials Dyract AP (2.7 and 2.55 and Filtek Z250 (2.25 and 2.43. The number of adhesive layers did not influence the degree of leakage of the three materials.O estudo in vitro avaliou a infiltração marginal em molares decíduos restaurados com três materiais resinosos: as resinas compostas modificadas por poliácidos (Dyract AP - Dentsply e F2000 - 3M e uma resina composta (Filtek Z 250 como grupo controle. Foram utilizados primeiros e segundos molares decíduos hígidos e as cavidades foram confeccionadas nas faces proximais, estendendo-se até a junção amelo-cementária. As restaurações foram realizadas após o condicionamento ácido total e a aplicação dos sistemas adesivos divididas em grupos de acordo com o sistema restaurador e o n

  7. Prediction of brittle fracture of epoxy-aluminum flanging

    Directory of Open Access Journals (Sweden)

    Korbel J.

    2010-07-01

    Full Text Available This paper presents a fracture mechanical approach for estimation of critical bending load of different types of aluminum-epoxy flanging and comparison with experimental measurements. For this purpose, several designs of the flanges were investigated. The flanges were glued to the epoxy bars and adhesive-epoxy interface was considered as a bi-material notch. Prediction of the failure is based on generalized stress intensity factor and generalized fracture toughness.

  8. Accelerated thermal aging of rubber modified epoxy encapsulants

    International Nuclear Information System (INIS)

    Sayre, J.A.

    1979-01-01

    A program is outlined to enable prediction of physical properties of rubber modified epoxy encapsulants over the life time of the extended life neutron generators. Preliminary results show that the chief aging phenomenon occurring is increased crosslink density of the epoxy matrix. No changes in the rubber phase have been detected. The effect of increased epoxy crosslink density has been higher volume resistivity at 66 0 C, increased tensile strength, and decreased ultimate elongation

  9. Produção de chapas de partículas orientadas “OSB” de Eucalyptus grandis com diferentes teores de resina, parafina e composição em camadas.

    Directory of Open Access Journals (Sweden)

    Setsuo Ivakiri

    2010-08-01

    Full Text Available Este trabalho foi desenvolvido com o objetivo de avaliar a influência dos seguintes parâmetros de processo de produção sobre as propriedades das chapas "OSB": composição das chapas em camadas cruzadas com proporções face-miolo-face de 30-40-30 e 20-60-20 em relação à composição homogênea; e, quantidades de 3, 4,5 e 6,0% de resina fenol-formaldeído, com incorporação de 0,5 e 1,0% de emulsão de parafina. Os resultados demonstraram que a composição das chapas, com a relação 20-60-20, apresentou melhor balanço das propriedades de flexão estática entre os sentidos de ensaios paralelo e perpendicular ao plano da chapa. A quantidade de 6,0% de resina foi a que resultou em melhores propriedades físico-mecânicas das chapas "OSB". A produção de chapas "OSB" de Eucalyptus grandis, com 4,5 e 6,0% de resina fenol-formaldeído, superou as exigências mínimas de propriedades mecânicas das chapas "OSB" referendadas pela norma canadense CSA 0437-0 (1993.

  10. Thermoset epoxy polymers from renewable resources

    Science.gov (United States)

    East, Anthony [Madison, NJ; Jaffe, Michael [Maplewood, NJ; Zhang, Yi [Harrison, NJ; Catalani, Luiz H [Carapicuiba, BR

    2009-11-17

    Novel thermoset epoxy polymers using the bisglycidyl ethers of anhydrosugars, such as isosorbide, isomannide, and isoidide, are disclosed. The bisglycidyl ethers are useful as substitutes for bisphenol A in the manufacture of thermoset epoxy ethers. The anhydrosugars are derived from renewable sources and the bisglycidyl ethers are not xenoestrogenic and the thermoset curing agents are likewise derived form renewable resources.

  11. Síntesis de oxitocina en fase sólida usando derivados de terbutoxicarbonilo y fluorenilmetoxicarbonilo

    OpenAIRE

    Calvo, Julio C; Barrera, Nubia F.; García, Josué A.; Guzman, Fanny; Espejo, Fabiola; Patarroyo, Manuel E.

    2010-01-01

    La oxitocina, péptido cíclico cuya secuencia es CYIQNCPLG, fué el primer péptido de importancia biológica que pudo ser sintetizado. En este trabajo se compara la síntesis de la oxitocina usando resina p metilbenzhidrilamina (MBHA) para la síntesis por estrategia t-Boc y resina Rink p-metilbenzhidrilamina (Rink MBHA) para la síntesis por estrategia Fmoc, con altos rendimientos. El péptido crudo se ciclizó en una disolución acuosa de dimetilsulfóxido al 10%. La caracterización se llevó a cabo p...

  12. Understanding the thermal, mechanical and electrical properties of epoxy nanocomposites

    International Nuclear Information System (INIS)

    Sarathi, R.; Sahu, R.K.; Rajeshkumar, P.

    2007-01-01

    In the present work, the electrical, mechanical and thermal properties of epoxy nanocomposite materials were studied. The electrical insulation characteristics were analyzed through short time breakdown voltage test, accelerated electrical ageing test, and by tracking test. The breakdown voltage increases with increase in nano-clay content up to 5 wt%, under AC and DC voltages. The volume resistivity, permittivity and tan(δ) of the epoxy nanocomposites were measured. The Weibull studies indicate that addition of nanoclay upto 5 wt% enhances the characteristic life of epoxy nanocomposite insulation material. The tracking test results indicate that the tracking time is high with epoxy nanocomposites as compared to pure epoxy. Ageing studies were carried out to understand the surface characteristic variation through contact angle measurement. The hydrophobicity of the insulating material was analysed through contact angle measurement. The diffusion coefficients of the material with different percentage of clay in epoxy nanocomposites were calculated. The exfoliation characteristics in epoxy nanocomposites were analyzed through wide angle X-ray diffraction (WAXD) studies. The thermal behaviour of the epoxy nanocomposites was analyzed by carrying out thermo gravimetric-differential thermal analysis (TG-DTA) studies. Heat deflection temperature of the material was measured to understand the stability of the material for intermittent temperature variation. The dynamic mechanical analysis (DMA) results indicated that storage modulus of the material increases with small amount of clay in epoxy resin. The activation energy of the material was calculated from the DMA results

  13. Modeling and mechanical performance of carbon nanotube/epoxy resin composites

    International Nuclear Information System (INIS)

    Srivastava, Vijay Kumar

    2012-01-01

    Highlights: ► The MWCNT fillers are uniformly dispersed in the epoxy resin, which improved the mechanical properties of epoxy resin. ► Modified Halpin–Tsai model is useful to calculate the Young’s modulus of MWCNT/epoxy resin composite. ► The experimental moduli are within the variation of 27% with the theoretical values. -- Abstract: The effect of multi-walled carbon nanotube (MWCNT) addition on mechanical properties of epoxy resin was investigated to obtain the tensile strength, compressive strength and Young’s modulus from load versus displacement graphs. The result shows that the tensile strength, compressive strength and Young’s modulus of epoxy resin were increased with the addition of MWCNT fillers. The significant improvements in tensile strength, compressive strength and Young’s modulus were obtained due to the excellent dispersion of MWCNT fillers in the epoxy resin. The dispersion of MWCNT fillers in epoxy resin was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Also, Halpin–Tsai model was modified by considering the average diameter of internal/external of multi-walled nanotube and orientation factor (α) to calculate the Young’s modulus of multi-walled carbon nanotubes (MWCNTs)/epoxy resin composite. There was a good correlation between the experimentally obtained Young’s modulus and modified Halpin–Tsai model.

  14. The failure mode of natural silk epoxy triggered composite tubes

    International Nuclear Information System (INIS)

    Eshkour, R A; Ariffin, A K; Zulkifli, R; Sulong, A B; Azhari, C H

    2012-01-01

    In this study the quasi static compression test over natural silk epoxy triggered composite tubes has been carried out, the natural silk epoxy composite tubes consist of 24 layer of woven natural silk as reinforcement and thermoset epoxy resin as matrix which both of them i e natural silk and epoxy have excellent mechanical properties More over the natural silk have better moisture resistance in comparison with other natural reinforcements, the length of tubes are 50, 80 and 120 mm The natural silk epoxy composite tubes are associated with an external trigger which includes 4 steel pieces welded on downside flat plate fixture The hand lay up fabrication method has been used to make the natural silk epoxy composite tubes Instron universal testing machine with 250 KN load capacity has been employed to accomplish this investigation The failure modes of natural silk epoxy triggered composite tubes has been investigated by representative photographs which has been taken by a high resolution camera(12 2 Mp) during the quasi static compression test, from the photographs is observed the failure modes is progressive local buckling

  15. Fracture behaviour of a self-healing microcapsule-loaded epoxy system

    Directory of Open Access Journals (Sweden)

    2011-03-01

    Full Text Available The effect of temperature on the fracture behaviour of a microcapsule-loaded epoxy matrix was investigated. Microencapsulated epoxy and mercaptan-derivative healing agents were incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. Maximum fracture loads were measured using the double-torsion method. Thermal aging at 55 and 110°C for 17 hours [hrs] was applied to heal the pre-cracked samples. The addition of microcapsules appeared to increase significantly the load carrying capacity of the epoxy after healing. Once healed, the composites achieved as much as 93–171% of its virgin maximum fracture load at 18, 55 and 110°C. The fracture behavior of the microcapsule- loaded epoxy matrix was influenced by the healing temperature. The high self-healing efficiency may be attributed to the result of the subsurface micro-crack pinning or deviation, and to a stronger microencapsulated epoxy and mercaptanderivative binder than that of the bulk epoxy. The results show that the healing temperature has a significant effect on recovery of load transferring capability after fracture.

  16. Epoxy/α-alumina nanocomposite with high electrical insulation performance

    Directory of Open Access Journals (Sweden)

    Yun Chen

    2017-10-01

    Full Text Available An experimental study was conducted to improve the electrical insulation of epoxy resin. The effects of boehmite, γ-alumina and α-alumina nanoparticles on the volume resistivity, dielectric strength and glass transition temperature of epoxy nanocomposites were investigated. The results showed that α-alumina nanoparticles displayed obvious advantages in enhancing electrical insulation performance of epoxy nanocomposites, compared to boehmite and γ-alumina nanoparticles. The direct current volume resistivity and breakdown strength of epoxy nanocomposite with 2.0 wt% α-alumina nanoparticles was improved to 2.2 × 1018 Ω cm and 76.1 kV mm−1 respectively. And these improved values of electrical insulation properties are much higher than these of epoxy nanocomposites reported in previous studies. The main reason of these improvements may be that the epoxy/α-alumina interaction zone was enhanced by crosslink. Keywords: Nanocomposite, Epoxy resin, Insulation, α-alumina

  17. Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

    Science.gov (United States)

    Miller, Sandi G (Inventor)

    2013-01-01

    A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

  18. Positron lifetime study of electron-irradiated epoxy resins

    International Nuclear Information System (INIS)

    Suevegh, K.; Vertes, A.; Wojnarovits, L.; Foeldiak, G.; Liszkai, L.; Kajcsos, Zs.

    1990-01-01

    Two bisphenol-A type epoxy resins were irradiated by electron beam and studied afterwards by positron lifetime spectroscopy. An interesting result is that despite of the considerable amount of free-radicals, no inhibition of positronium formation was observed in the two epoxies. Nevertheless, several serious differences were detected between the studied polymers. The results suggest that the radiation-resistant properties of epoxies depend strongly on the amount of the curing agent. (author) 8 refs.; 2 figs

  19. Alternativas técnicas para o controle das alterações dimensionais das resinas acrílicas em prótese total

    OpenAIRE

    GOMEZ Tomas; MORI Matsuyoshi; CORRÊA Gerson de Arruda; MATSON Edmir

    1998-01-01

    Os autores propõem uma nova técnica para diminuição dos problemas provenientes das alterações dimensionais das resinas acrílicas utilizadas na confecção das próteses totais. Com essa proposta, conseguiu-se praticamente eliminar essas alterações dimensionais tão prejudiciais às próteses totais.

  20. Experimental design applied optimization of a state in epoxy clay dispersion; Planejamento de experimentos aplicado a otimizacao do estado de dispersao de argilas em epoxi

    Energy Technology Data Exchange (ETDEWEB)

    Paz, Juliana D' Avila; Bertholdi, Jonas; Folgueras, Marilena Valadares; Pezin, Sergio Henrique; Coelho, Luiz Antonio Ferreira, E-mail: julianadpaz@yahoo.com.b [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas

    2010-07-01

    This paper presents some analysis showed that the exfoliation / intercalation of a montmorillonite clay in epoxy resin such as viscosity, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry (TG). Increasing the viscosity of epoxy resin diglycidyl ether bisphenol A with the addition of clay associated with the sonification system at the time of dispersion is a good indication of exfoliation. The X-ray diffraction already cured composite shows a decrease of crystallinity of clay and EDS microanalysis of SEM, non-uniform dispersion of clay in epoxy resin. Thermal analysis TG composite clay / epoxy shows an increase in thermal stability relative to pure epoxy. (author)

  1. Bio-Based Aromatic Epoxy Monomers for Thermoset Materials

    Directory of Open Access Journals (Sweden)

    Feifei Ng

    2017-01-01

    Full Text Available The synthesis of polymers from renewable resources is a burning issue that is actively investigated. Polyepoxide networks constitute a major class of thermosetting polymers and are extensively used as coatings, electronic materials, adhesives. Owing to their outstanding mechanical and electrical properties, chemical resistance, adhesion, and minimal shrinkage after curing, they are used in structural applications as well. Most of these thermosets are industrially manufactured from bisphenol A (BPA, a substance that was initially synthesized as a chemical estrogen. The awareness on BPA toxicity combined with the limited availability and volatile cost of fossil resources and the non-recyclability of thermosets implies necessary changes in the field of epoxy networks. Thus, substitution of BPA has witnessed an increasing number of studies both from the academic and industrial sides. This review proposes to give an overview of the reported aromatic multifunctional epoxide building blocks synthesized from biomass or from molecules that could be obtained from transformed biomass. After a reminder of the main glycidylation routes and mechanisms and the recent knowledge on BPA toxicity and legal issues, this review will provide a brief description of the main natural sources of aromatic molecules. The different epoxy prepolymers will then be organized from simple, mono-aromatic di-epoxy, to mono-aromatic poly-epoxy, to di-aromatic di-epoxy compounds, and finally to derivatives possessing numerous aromatic rings and epoxy groups.

  2. Thermal conductivity and Kapitza resistance of cyanate ester epoxy mix and tri-functional epoxy electrical insulations at superfluid helium temperature

    CERN Document Server

    Pietrowicz, S; Jones, S; Canfer, S; Baudouy, B

    2012-01-01

    In the framework of the European Union FP7 project EuCARD, two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber have been thermally tested as possible candidates to be the electrical insulation of 13 T Nb$_{3}$Sn high field magnets under development for this program. Since it is expected to be operated in pressurized superfluid helium at 1.9 K and 1 atm, the thermal conductivity and the Kapitza resistance are the most important input parameters for the thermal design of this type of magnet and have been determined in this study. For determining these thermal properties, three sheets of each material with different thicknesses varying from 245 μm to 598 μm have been tested in steady-state condition in the temperature range of 1.6 K - 2.0 K. The thermal conductivity for the tri-functional epoxy (TGPAP-DETDA) epoxy resin insulation is found to be k=[(34.2±5.5).T-(16.4±8.2)]×10-3 Wm-1K-1 and for the cyanate ester epoxy k=[(26.8±4.8).T- (9...

  3. Tensile bond strength between different glass ionomer cement and composite resin using three adhesive systems Avaliação da resistência de união interfacial entre diferentes cimentos de ionômero de vidro e resina composta, usando três sistemas adesivos

    Directory of Open Access Journals (Sweden)

    Patrícia Dias

    2005-10-01

    Full Text Available The purpose of this study was to evaluate the tensile bond strength (TBS among a Composite Resin (Filtek Z250 and six conventional Glass Ionomer Cements, three used for lining (Bioglass F, Vidrion F and Glass Ionomer L.C. and three for restorations (Ketac Fil, Vidrion R and Glass Ionomer type II etched and non etched, using three adhesive systems (Single Bond, Bond 1 and Stae. Thirty-six groups were made, ten samples for each group, totalizing 360 specimens. There were significant differences on TBS among groups. Group 31 (Glass Ionomer Cement type II showed the highest TBS (9.65 MPa in comparison to other tested groups. Group 16 (Glass Ionomer L.C presented the lowest TBS (2.72 MPa in comparison to all the other groups. Therefore, it can be concluded that the acid etching of the Glass Ionomer Cement is not necessary. Foi avaliada, ">in vitro, a resistência de união, por tração, entre uma Resina Composta micro-híbrida (Filtek Z-250 e seis Cimentos de Ionômero de Vidro (CIV convencionais: três utilizados para base/forramento (Bioglass F, Vidrion F e Glass Ionomer Lining Cement e três para restauração (Ketac Fil, Vidrion R e Glass Ionomer Cement type II, sem e com condicionamento ácido ortofosfórico a 37%, usando três sistemas adesivos (Single Bond, Bond 1 e Stae. Foram confeccionados 36 grupos de 10 corpos-de-prova cada, totalizando 360 espécimes. Para análise estatística, foi utilizado o teste de Tukey-Kramer. Dentre os três CIV de base/forramento, os grupos 2 e 5 (Bioglass F apresentaram valores mais altos de adesividade à resina (7,24 e 6,03 MPa respectivamente. Quanto aos três CIV de restauração, todos apresentaram maior resistência de união, superior aos de base/forramento, sendo que o Glass Ionomer Cement type II (Grupo 31 e Vidrion R apresentaram maior força de adesão (9,65 e 7,47 MPa à resina composta. O grupo 16 (Glass Ionomer L.C. mostrou menor adesividade à resina (2,72 MPa. Houve diferenças significantes

  4. Magnetism in graphene oxide induced by epoxy groups

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dongwook, E-mail: dongwookleedl324@gmail.com [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Division of Physics and Applied Physics, Nanyang Technological University, Singapore 637371 (Singapore); Seo, Jiwon, E-mail: jiwonseo@yonsei.ac.kr [Department of Physics and IPAP, Yonsei University, Seoul 120-749 (Korea, Republic of); School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Zhu, Xi; Su, Haibin [Division of Materials Science, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Cole, Jacqueline M. [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Argonne National Laboratory, 9700S Cass Avenue, Argonne, Illinois 60439 (United States)

    2015-04-27

    We have engineered magnetism in graphene oxide. Our approach transforms graphene into a magnetic insulator while maintaining graphene's structure. Fourier transform infrared spectroscopy spectra reveal that graphene oxide has various chemical groups (including epoxy, ketone, hydroxyl, and C-O groups) on its surface. Destroying the epoxy group with heat treatment or chemical treatment diminishes magnetism in the material. Local density approximation calculation results well reproduce the magnetic moments obtained from experiments, and these results indicate that the unpaired spin induced by the presence of epoxy groups is the origin of the magnetism. The calculation results also explain the magnetic properties, which are generated by the interaction between separated magnetic regions and domains. Our results demonstrate tunable magnetism in graphene oxide based on controlling the epoxy group with heat or chemical treatment.

  5. The characteristics of epoxy resin cured by {gamma}-ray and E-beam

    Energy Technology Data Exchange (ETDEWEB)

    Nho, Y.C. E-mail: ycnho@kaeri.re.kr; Kang, Phil Hyun; Park, Jong Seok

    2004-10-01

    Epoxy resins are widely used as high-performance thermosetting resins for many industrial applications. In this study, the effect of an electron beam (E-beam) and {gamma}-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol-A(DGEBA), diglycidyl ether of bisphenol-F(DGEBF) as epoxy resins, triarylsulfonium hexafluoroantimonate(TASHFA), and triarylsulfonium hexafluorophosphate(TASHFP) as initiators were used in this study. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of E-beam and {gamma}-ray irradiation up to 50 kGy in N{sub 2} and air atmosphere. We ascertained the effect of oxygen on the radiation curing of epoxy resin. The thermal properties of cured epoxy were investigated using DMA and TGA. Mechanical properties such as flexural strength were measured. The chemical structures of cured epoxy were characterized by FT-NIR. The gel fraction and the stress at yield of epoxy resins irradiated by E-beam and {gamma}-ray in N{sub 2} atmosphere were also compared with those of epoxy resins irradiated by E-beam and {gamma}-ray in air.

  6. Estudo da cinética de cura de um pré-impregnado de resina epoxídica/fibra de carbono pelo método isoconversional

    Directory of Open Access Journals (Sweden)

    Vanesa C. G. M. Ferrari

    2014-01-01

    Full Text Available Este trabalho tem como objetivo verificar a cinética de cura de um pré-impregnado ("prepreg" de resina epoxídica/fibra de carbono, utilizando a técnica de calorimetria diferencial de varredura (DSC pelo método isoconversional. O método isoconversional analisa a cinética de cura por meio da dependência da energia de ativação durante a conversão (análise isotérmica ou temperatura (análise não-isotérmica e utiliza esta dependência para calcular os parâmetros cinéticos. A avaliação da cinética da reação por DSC baseia-se na quantidade de calor gerado durante as reações exotérmicas. A hipótese de que o calor gerado pela reação química é proporcional à extensão da cura permite obter os parâmetros cinéticos no DSC por meio das análises pelos métodos isotérmicos e não-isotérmicos. Para o método isoconversional isotérmico, a energia de ativação média apresentou valores entre 103 e 72 kJ/mol, e, para o método isoconversional não-isotérmico um valor médio de 80,5 kJ/mol. Estes resultados foram comparados com os obtidos para os métodos ASTM E 2070 e ASTM E 698, cujos valores foram 89±5 kJ/mol e 77,5±2,5 kJ/mol, respectivamente, comprovando a eficiência do método isoconversional.

  7. Corrosion Protection of Steel by Epoxy-Organoclay Nanocomposite Coatings

    OpenAIRE

    Domna Merachtsaki; Panagiotis Xidas; Panagiotis Giannakoudakis; Konstantinos Triantafyllidis; Panagiotis Spathis

    2017-01-01

    The purpose of the present work was to study the corrosion behavior of steel coated with epoxy-(organo) clay nanocomposite films. The investigation was carried out using salt spray exposures, optical and scanning electron microscopy examination, open circuit potential, and electrochemical impedance measurements. The mechanical, thermomechanical, and barrier properties of pristine glassy epoxy polymer and epoxy-clay nanocomposites were examined. The degree of intercalation/exfoliation of clay ...

  8. Análise de peças anatômicas preservadas com resina de poliester para estudo em anatomia humana Analysis of anatomical pieces preservation with polyester resin for human anatomy study

    Directory of Open Access Journals (Sweden)

    Ítalo Martins de Oliveira

    2013-02-01

    Full Text Available OBJETIVO: avaliar o uso da resina de poliéster na preservação de peças anatômicas para estudo da anatomia humana. MÉTODOS: foram utilizadas 150 peças anatômicas, sendo as mesmas não fixadas (frescas, fixadas em formol a 10% e moldes vasculares de órgãos injetados com acetato de vinil e a resina de poliéster. A solução utilizada foi composta de resina de poliéster com seu diluente monômero de estireno e catalisador (peroxol. Foram obtidos, após a inclusão nesta solução, modelos em resina transparente, que permitiam a plena observação das estruturas e conservação da peça utilizada. RESULTADOS: na avaliação das peças, foi observado grau de extrema transparência, promovendo uma completa visualização das estruturas com a perfeita preservação da anatomia. A duração média para a completa finalização da inclusão foi 48 horas. Apenas 14 peças (9,3% foram inutilizadas durante o preparo. CONCLUSÃO: a resina de poliéster pode ser utilizada para a preservação de peças anatômicas para o ensino da anatomia humana, de maneira prática, estética e duradoura.OBJECTIVE: To evaluate the use of polyester resin in preserving anatomical specimens for the study of human anatomy. METHODS: We used 150 anatomical specimens, comprised of unfixed (fresh, fixed in 10% formalin and vascular casts of organs injected with vinyl acetate and polyester resin. The solution used consisted of polyester resin with the diluent styrene monomer and catalyst (peroxol. After embedding in this solution, models in transparent resin were obtained, allowing full observation of structures and conservation of the specimens used. RESULTS: upon evaluation of the specimens, we observed a high degree of transparency, which promoted a complete visualization of structures with perfect preservation of the anatomy. The average time for the completion of the embedding was 48 hours. Only 14 specimens (9.3% were lost during the preparation. CONCLUSION

  9. Effects of Nanofillers on the Thermo-Mechanical Properties and Chemical Resistivity of Epoxy Nanocomposites.

    Science.gov (United States)

    Atchudan, Raji; Pandurangan, Arumugam; Joo, Jin

    2015-06-01

    MWCNTs was synthesized using Ni-Cr/MgO by CVD method and were purified. The purified MWCNT was used as a filler material for the fabrication of epoxy nanocomposites. The epoxy nanocomposites with different amount (wt% = 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0) of nanofillers (CB, SiO2 and MWCNTs) were prepared by casting method. The effects of nanofillers on the properties of neat epoxy matrix were well studied. The thermal properties of nanocomposites were studied using DSC, TGA and flame retardant, and also the mechanical properties such as tensile strength, flexural strength, compressive strength, impact strength, determination of hardness and chemical resistance were studied extensively. Based on the experiment's results, 2 wt% MWCNTs loading in epoxy resin showed the highest improvement in tensile strength, as compared to neat epoxy and to other epoxy systems (CB/epoxy, SiO2/epoxy). Improvements in tensile strength, glass transition temperature and decomposition temperature were observed by the addition of MWCNTs. The mechanical properties of the epoxy nanocomposites were improved due to the interfacial bonding between the MWCNTs and epoxy resin. Strain hardening behavior was higher for MWCNT/epoxy nanocomposites compared with CB/epoxy and SiO2/epoxy nanocomposites. The investigation of thermal and mechanical properties reveals that the incorporation of MWCNTs into the epoxy nanocomposites increases its thermal stability to a great extent. Discrete increase of glass transition temperature of nanocomposites is linearly dependent on MWCNTs content. Due to strong interfacial bonding between MWCNTs and epoxy resin, the chemical resistivity of MWCNT/epoxy nanocomposites is superior to neat epoxy and other epoxy systems.

  10. Silane coupling agent for attaching fusion-bonded epoxy to steel.

    Science.gov (United States)

    Tchoquessi Diodjo, Madeleine R; Belec, Lénaïk; Aragon, Emmanuel; Joliff, Yoann; Lanarde, Lise; Perrin, François-Xavier

    2013-07-24

    We describe the possibility of using γ-aminopropyltriethoxysilane (γ-APS) to increase the durability of epoxy powder coating/steel joints. The curing temperature of epoxy powder coatings is frequently above 200 °C, which is seen so far as a major limitation for the use of the heat-sensitive aminosilane coupling agent. Despite this limitation, we demonstrate that aminosilane is a competitive alternative to traditional chromate conversion to enhance the durability of epoxy powder coatings/steel joints. Fourier-transform reflection-absorption infrared spectroscopy (FT-RAIRS), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) were used to identify the silane deposition conditions that influence the adhesion of epoxy powder coatings on steel. We show that AFM analysis provides highly sensitive measurements of mechanical property development and, as such, the degree of condensation of the silane. The joint durability in water at 60 °C was lower when the pH of the γ-APS solution was controlled at 4.6 using formic acid, rather than that at natural pH (10.6). At the curing temperature of 220 °C, oxidation of the carbon adjacent to the amine headgroup of γ-APS gives amide species by a pseudofirst-order kinetics. However, a few amino functionalities remain to react with oxirane groups of epoxy resin and, thus, strengthen the epoxy/silane interphase. The formation of ammonium formate in the acidic silane inhibits the reaction between silane and epoxy, which consequently decreases the epoxy/silane interphase cohesion. We find that the nanoroughness of silane deposits increases with the cure temperature which is beneficial to the wet stability of the epoxy/steel joints, due to increased mechanical interlocking.

  11. Formación de complejos fármaco-resina usados en preparados de liberación prolongada

    Directory of Open Access Journals (Sweden)

    Susana Alba Delgado

    1998-12-01

    Full Text Available Se estudiaron los tiempos para alcanzar el equilibrio en reacciones de intercambio iónico durante la formación de sales complejas poliestireno divinil-benceno sulfonato, con los fármacos dexanfetamina, metilhomatropina y salbutamol. Se hicieron reaccionar sales de los fármacos en solución con la resina en su forma "sodio", cuantificándose a intervalos la concentración en el sobrenadante, siguiendo el avance de la reacción y determinando el punto de equilibrio. Se propone un estadístico simple que permite seleccionar el tiempo para dar por terminada la reacción, y se encuentran valores inferiores a los informados en la literatura. Se comenta la relación entre dimensión molecular y nivel de saturación del complejo.Time intervals required for reaching the proper balance of ion exchange reactions during the formation of polystirene-dyvinil-benzene-sulphonate complex salts with drugs such as dexamphetamina, metylhomatropine and salbutamol are analyzed. Drug salt solutions were caused to react with resin in "sodium" form, then supernadant concentration was estimated at intervals following the development of the reaction and determining the point of balance. A simple statistical method which makes it possible to determine the time when the reaction shall be finished was proposed, and also values lower than those reported in literature were found. Some comment on the association between molecular dimension and the saturation level of the drug-resine complex are made

  12. Epoxy Nanocomposites filled with Carbon Nanoparticles.

    Science.gov (United States)

    Martin-Gallego, M; Yuste-Sanchez, V; Sanchez-Hidalgo, R; Verdejo, R; Lopez-Manchado, M A

    2018-01-10

    Over the past decades, the development of high performance lightweight polymer nanocomposites and, in particular, of epoxy nanocomposites has become one the greatest challenges in material science. The ultimate goal of epoxy nanocomposites is to extrapolate the exceptional intrinsic properties of the nanoparticles to the bulk matrix. However, in spite of the efforts, this objective is still to be attained at commercially attractive scales. Key aspects to achieve this are ultimately the full understanding of network structure, the dispersion degree of the nanoparticles, the interfacial adhesion at the phase boundaries and the control of the localization and orientation of the nanoparticles in the epoxy system. In this Personal Account, we critically discuss the state of the art and evaluate the strategies to overcome these barriers. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Mechanical Reinforcement of Epoxy Composites with Carbon Fibers and HDPE

    Science.gov (United States)

    He, R.; Chang, Q.; Huang, X.; Li, J.

    2018-01-01

    Silanized carbon fibers (CFs) and a high-density polyethylene with amino terminal groups (HDPE) were introduced into epoxy resins to fabricate high-performance composites. A. mechanical characterization of the composites was performed to investigate the effect of CFs in cured epoxy/HDPE systems. The composites revealed a noticeable improvement in the tensile strength, elongation at break, flexural strength, and impact strength in comparison with those of neat epoxy and cured epoxy/HDPE systems. SEM micrographs showed that the toughening effect could be explained by yield deformations, phase separation, and microcracking.

  14. Functionalizing CNTs for Making Epoxy/CNT Composites

    Science.gov (United States)

    Chen, Jian; Rajagopal, Ramasubramaniam

    2009-01-01

    Functionalization of carbon nanotubes (CNTs) with linear molecular side chains of polyphenylene ether (PPE) has been shown to be effective in solubilizing the CNTs in the solvent components of solutions that are cast to make epoxy/CNT composite films. (In the absence of solubilization, the CNTs tend to clump together instead of becoming dispersed in solution as needed to impart, to the films, the desired CNT properties of electrical conductivity and mechanical strength.) Because the PPE functionalizes the CNTs in a noncovalent manner, the functionalization does not damage the CNTs. The functionalization can also be exploited to improve the interactions between CNTs and epoxy matrices to enhance the properties of the resulting composite films. In addition to the CNTs, solvent, epoxy resin, epoxy hardener, and PPE, a properly formulated solution also includes a small amount of polycarbonate, which serves to fill voids that, if allowed to remain, would degrade the performance of the film. To form the film, the solution is drop-cast or spin-cast, then the solvent is allowed to evaporate.

  15. Preparation and Performance of Amphiphilic Random Copolymer Noncovalently Modified MWCNTs/Epoxy Composite

    Directory of Open Access Journals (Sweden)

    MA Qiang

    2016-09-01

    Full Text Available An amphiphilic random copolymer of polyglycidyl methacrylate-co-N-vinyl carbazole P(GMA-co-NVC was synthesized by free radical polymerization and was used to noncovalently modify multi-walled carbon nanotubes (MWCNTs. The obtained P(GMA-co-NVC/MWCNTs was mixed with epoxy resin and used to reinforce epoxy resin. Polymer modified carbon nanotubes/epoxy resin composites were prepared by a casting molding method. Tensile test, electrical resistivity test and differential scanning calorimeter(DSC analysis were used to study the effect of polymer modified carbon nanotubes on the mechanical, electrical, and thermal properties of epoxy resin. The results show that the epoxy composite reinforced with P(GMA-co-NVC/MWCNTs shows a remarkable enhancement in both tensile strength and elongation at break compared to either the pure epoxy or the pristine MWCNTs/epoxy composites. In addition, the electrical conductivity of epoxy is significantly improved and the volume resistivity decreases from 1014Ω·m to 106Ω·m with 0.25% mass fraction loading of P(GMA-co-NVC/MWCNTs. Moreover, glass transition temperature of the epoxy composite also increases from 144℃ to 149℃.

  16. Sal de iodônio aumenta a resistência coesiva de uma resina adesiva experimental na presença de solvente

    Directory of Open Access Journals (Sweden)

    Fernanda B. Leal

    2013-01-01

    Full Text Available Este estudo avaliou o efeito da concentração de solvente na resistência coesiva de um adesivo experimental contendo um derivado do difeniliodônio. Uma blenda monomérica baseada em Bis-GMA, TEGDMA e HEMA foi utilizada como resina adesiva modelo. Foram avaliados dois sistemas de fotoiniciação: um sistema bináriocanforquinona (CQ e etil 4-dimetilamino benzoato (EDAB] e um sistema ternário [CQ, EDAB e hexafluorfosfato de difeniliodônio (DPI]. Nestas resinas foram adicionadas diferentes concentrações de etanol, 0, 5, 10, 20, 30, 40% e teste de resistência coesiva foi utilizado para investigar o efeito deste solvente sobre as propriedades do material. A presença de solvente reduziu a resistência coesiva do polímero, independentemente do sistema de fotoiniciação utilizado. Além disso, o uso do sal de iodônio no sistema de fotoiniciação aumentou a resistência coesiva quando comparado com o sistema binário, e independentemente da concentração de solvente, a resistência coesiva dos polímeros contendo difeniliodônio foi superior à do sistema binário de fotoiniciação.

  17. Multiscale Modeling of Carbon Nanotube-Epoxy Nanocomposites

    Science.gov (United States)

    Fasanella, Nicholas A.

    Epoxy-composites are widely used in the aerospace industry. In order to improve upon stiffness and thermal conductivity; carbon nanotube additives to epoxies are being explored. This dissertation presents multiscale modeling techniques to study the engineering properties of single walled carbon nanotube (SWNT)-epoxy nanocomposites, consisting of pristine and covalently functionalized systems. Using Molecular Dynamics (MD), thermomechanical properties were calculated for a representative polymer unit cell. Finite Element (FE) and orientation distribution function (ODF) based methods were used in a multiscale framework to obtain macroscale properties. An epoxy network was built using the dendrimer growth approach. The epoxy model was verified by matching the experimental glass transition temperature, density, and dilatation. MD, via the constant valence force field (CVFF), was used to explore the mechanical and dilatometric effects of adding pristine and functionalized SWNTs to epoxy. Full stiffness matrices and linear coefficient of thermal expansion vectors were obtained. The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for the various nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. To obtain continuum-scale elastic properties from the MD data, multiscale modeling was considered to give better control over the volume fraction of nanotubes, and investigate the effects of nanotube alignment. Two methods were considered; an FE based method, and an ODF based method. The FE method probabilistically assigned elastic properties of elements from the MD lattice results based on the desired volume fraction and alignment of the nanotubes. For the ODF method, a distribution function was generated based on the desired amount of nanotube alignment

  18. Microdureza de resina composta: efeito de aparelhos e tempos de polimerização em diferentes profundidades Microhardness of composite resins: effect of photocuring units and polymerization periods in different depths

    Directory of Open Access Journals (Sweden)

    Luciana Aily SANTOS

    2000-03-01

    Full Text Available As propriedades das resinas compostas têm sido estudadas com freqüência, bem como os fatores que podem influenciar seu grau de polimerização. Diante da evolução desses materiais e da necessidade de buscarmos melhora do seu comportamento na cavidade bucal, objetivamos, por meio deste estudo avaliar a eficácia de dois aparelhos fotopolimerizadores do tipo pistola (de alta intensidade de luz, comparando com a de um aparelho a cabo (de baixa intensidade de luz, com tempos de exposição de 20 e de 40 segundos e em profundidades de 1 a 4 milímetros. Os testes avaliaram o grau de polimerização da resina por meio de testes de microdureza Knoop. Os resultados mostraram haver diferença estatisticamente significante entre os tempos, sendo que com 40 segundos a dureza foi maior que com 20 segundos para as 4 diferentes profundidades. Para o fator aparelhos, os dois aparelhos tipo pistola se comportaram superiores ao do tipo cabo Fibralux (Dabi Atlante, e entre eles, o XL 1500 (3M promoveu dureza maior que o Optilight II (Gnatus no tempo de polimerização de 40 segundos. As profundidades de 1, 2, 3 e 4 milímetros mostraram estatisticamente diferença entre si tendo sido encontrada maior dureza para as menores profundidades (p The properties of composite resins have been frequently studied, as well as the factors that might influence the polymerization degree. Considering the evolution of composites and the need to improve their clinical performance, this study intends to evaluate the efficacy of two high-intensity and one low-intensity photocuring units, as a function of exposure time (20 and 40seconds and composite depth (from 1 to 4 millimeters. Composite properties were evaluated via Knoop Microhardness Test. Statistical analysis (1 way ANOVA, p < 0.05 of the obtained results showed that there was statistically significant difference regarding the time factor. The 40-seconds polymerization time showed the best results, for the four depths

  19. Cure monitoring of epoxy resin by using fiber bragg grating sensor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Hyuk [KEPCO, Naju (Korea, Republic of); Kim, Dae Hyun [Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2016-06-15

    In several industrial fields, epoxy resin is widely used as an adhesive for co-curing and manufacturing various structures. Controlling the manufacturing process is required for ensuring robust bonding performance and the stability of the structures. A fiber optic sensor is suitable for the cure monitoring of epoxy resin owing to the thready shape of the sensor. In this paper, a fiber Bragg grating (FBG) sensor was applied for the cure monitoring of epoxy resin. Based on the experimental results, it was demonstrated that the FBG sensor can monitor the status of epoxy resin curing by measuring the strain caused by volume shrinkage and considering the compensation of temperature. In addition, two types of epoxy resin were used for the cure-monitoring; moreover, when compared to each other, it was found that the two types of epoxy had different cure-processes in terms of the change of strain during the curing. Therefore, the study proved that the FBG sensor is very profitable for the cure-monitoring of epoxy resin.

  20. Rapid microwave processing of epoxy nanocomposites using carbon nanotubes

    OpenAIRE

    Luhyna, Nataliia; Inam, Fawad; Winnington, Ian

    2013-01-01

    Microwave processing is one of the rapid processing techniques for manufacturing nanocomposites. There is very little work focussing on the addition of CNTs for shortening the curing time of epoxy nanocomposites. Using microwave energy, the effect of CNT addition on the curing of epoxy nanocomposites was researched in this work. Differential scanning calorimetry (DSC) was used to determine the degree of cure for epoxy and nanocomposite samples. CNT addition significantly reduced the duration ...

  1. Structural and electrical properties of functionalized multiwalled carbon nanotube/epoxy composite

    International Nuclear Information System (INIS)

    Gantayat, S.; Rout, D.; Swain, S. K.

    2016-01-01

    The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increased with increasing concentration of f-MWCNTs.

  2. Experimental design applied optimization of a state in epoxy clay dispersion

    International Nuclear Information System (INIS)

    Paz, Juliana D'Avila; Bertholdi, Jonas; Folgueras, Marilena Valadares; Pezin, Sergio Henrique; Coelho, Luiz Antonio Ferreira

    2010-01-01

    This paper presents some analysis showed that the exfoliation / intercalation of a montmorillonite clay in epoxy resin such as viscosity, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry (TG). Increasing the viscosity of epoxy resin diglycidyl ether bisphenol A with the addition of clay associated with the sonification system at the time of dispersion is a good indication of exfoliation. The X-ray diffraction already cured composite shows a decrease of crystallinity of clay and EDS microanalysis of SEM, non-uniform dispersion of clay in epoxy resin. Thermal analysis TG composite clay / epoxy shows an increase in thermal stability relative to pure epoxy. (author)

  3. Determinants of epoxy allergy in the construction industry: a case-control study.

    Science.gov (United States)

    Spee, Ton; Timmerman, Johan G; Rühl, Reinhold; Kersting, Klaus; Heederik, Dick J J; Smit, Lidwien A M

    2016-05-01

    Workers exposed to epoxy products are at risk of developing allergic contact dermatitis. To compare workers throughout the German construction industry with and without skin allergy to epoxy resins, hardeners, and/or reactive diluents, and to investigate which determinants are related to the development of epoxy allergy. A questionnaire was completed by 179 epoxy allergy cases, and 151 epoxy workers as controls. Crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by the use of backwards stepwise logistic regression analysis. A multiple imputation approach was used to deal with missing data. Epoxy allergy was associated with an unusually high level of exposure to epoxy products [OR 2.13 (95%CI: 1.01-4.51)], wearing short sleeves or short trousers [OR 2.38 (95%CI: 1.03-5.52)], and not always using the correct type of gloves [OR 2.12 (95%CI: 1.12-4.01)]. A monotonic increasing risk was found with increasing exposure hours per week [OR 1.72 (95%CI: 1.39-2.14)]. Not using skin cream was inversely associated with epoxy allergy [OR 0.22 (95%CI: 0.08-0.59)]. Years working with epoxy products were inversely associated with epoxy allergy [OR 0.41 (95%CI: 0.27-0.61) per 10-year increase], suggesting a healthy worker survivor effect. Occupational epoxy allergy may be prevented by improving occupational hygiene behaviour and personal protection. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Molecular Modeling of Aerospace Polymer Matrices Including Carbon Nanotube-Enhanced Epoxy

    Science.gov (United States)

    Radue, Matthew S.

    Carbon fiber (CF) composites are increasingly replacing metals used in major structural parts of aircraft, spacecraft, and automobiles. The current limitations of carbon fiber composites are addressed through computational material design by modeling the salient aerospace matrix materials. Molecular Dynamics (MD) models of epoxies with and without carbon nanotube (CNT) reinforcement and models of pure bismaleimides (BMIs) were developed to elucidate structure-property relationships for improved selection and tailoring of matrices. The influence of monomer functionality on the mechanical properties of epoxies is studied using the Reax Force Field (ReaxFF). From deformation simulations, the Young's modulus, yield point, and Poisson's ratio are calculated and analyzed. The results demonstrate an increase in stiffness and yield strength with increasing resin functionality. Comparison between the network structures of distinct epoxies is further advanced by the Monomeric Degree Index (MDI). Experimental validation demonstrates the MD results correctly predict the relationship in Young's moduli for all epoxies modeled. Therefore, the ReaxFF is confirmed to be a useful tool for studying the mechanical behavior of epoxies. While epoxies have been well-studied using MD, there has been no concerted effort to model cured BMI polymers due to the complexity of the network-forming reactions. A novel, adaptable crosslinking framework is developed for implementing 5 distinct cure reactions of Matrimid-5292 (a BMI resin) and investigating the network structure using MD simulations. The influence of different cure reactions and extent of curing are analyzed on the several thermo-mechanical properties such as mass density, glass transition temperature, coefficient of thermal expansion, elastic moduli, and thermal conductivity. The developed crosslinked models correctly predict experimentally observed trends for various properties. Finally, the epoxies modeled (di-, tri-, and tetra

  5. Epoxy modified bitumen : Chemical hardening and its interpretation

    NARCIS (Netherlands)

    Apostolidis, P.; Pipintakos, G.; van de Ven, M.F.C.; Liu, X.; Erkens, Sandra; Scarpas, Athanasios

    2018-01-01

    Epoxy modified bitumen (EMB) is a promising technology for long lasting paving materials ensuring higher resistance to rutting, oxygen- and moisture-induced damage. In this paper, an analysis of the chemical reactions that take place during the chemical hardening process (curing) of epoxy modified

  6. Thermomechanical Behavior of High Performance Epoxy/Organoclay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Artur Soares Cavalcanti Leal

    2014-01-01

    Full Text Available Nanocomposites of epoxy resin containing bentonite clay were fabricated to evaluate the thermomechanical behavior during heating. The epoxy resin system studied was prepared using bifunctional diglycidyl ether of bisphenol A (DGEBA, crosslinking agent diaminodiphenylsulfone (DDS, and diethylenetriamine (DETA. The purified bentonite organoclay (APOC was used in all experiments. The formation of nanocomposite was confirmed by X-ray diffraction analysis. Specimens of the fabricated nanocomposites were characterized by dynamic mechanical analysis (DMA. According to the DMA results a significant increase in glass transition temperature and storage modulus was evidenced when 1 phr of clay is added to epoxy resin.

  7. Generalized morphea/eosinophilic fasciitis overlap after epoxy exposure

    Directory of Open Access Journals (Sweden)

    Warren H. Chan, MS

    2018-03-01

    Full Text Available Generalized morphea is associated with epoxy resin vapors and is characterized by the development of lesions shortly after exposure. Morphea presenting along with eosinophilic fasciitis (EF, or morphea/EF overlap, is rare and an indicator of poor prognosis and resistance to treatment. Here we present a case of generalized morphea/EF overlap linked to epoxy exposure. Our patient received multiple therapies—ultraviolet A1 phototherapy, prednisone, methotrexate, azathioprine, mycophenolate mofetil, cyclophosphamide, cyclosporine, and rituximab—none of which led to a significant response. The refractory nature of this disease warrants vigilance in its association with epoxy exposure.

  8. Fabrication and characterization of TiO2-epoxy nanocomposite

    International Nuclear Information System (INIS)

    Chatterjee, Amit; Islam, Muhammad S.

    2008-01-01

    A systematic study has been conducted to investigate the matrix properties by introducing nanosize TiO 2 (5-40 nm, 0.5-2% by weight) fillers into an epoxy resin. Ultrasonic mixing process, via sonic cavitations, was employed to disperse the particles into the resin system. The thermal, mechanical, morphology and the viscoelastic properties of the nanocomposite and the neat resin were measured with TGA, DMA, TEM and Instron. The nano-particles are dispersed evenly throughout the entire volume of the resin. The nanofiller infusion improves the thermal, mechanical and viscoelastic properties of the epoxy resin. The nanocomposite shows increase in storage modulus, glass transition temperature, tensile modulus, flexural modulus and short beam shear strength from neat epoxy resin. The mechanical performance and thermal stability of the epoxy nanocomposites are depending on with the dispersion state of the TiO 2 in the epoxy matrix and are correlated with loading (0.0015-0.006% by volume). In addition, the nanocomposite shows enhanced flexural strength. Several reasons to explain these effects in terms of reinforcing mechanisms were discussed

  9. Physical, structural and thermomechanical properties of oil palm nano filler/kenaf/epoxy hybrid nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Saba, N., E-mail: naheedchem@gmail.com [Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products(INTROP), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Paridah, M.T. [Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products(INTROP), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Abdan, K. [Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang Selangor (Malaysia); Ibrahim, N.A. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2016-12-01

    The present research study deals with the fabrication of kenaf/epoxy hybrid nanocomposites by the incorporation of oil palm nano filler, montmorillonite (MMT) and organically modified montmorillonite (OMMT) at 3% loading, through hand lay-up technique. Effect of adding different nano fillers on the physical (density), structural [X-ray diffraction (XRD)] and thermomechanical analysis (TMA) of kenaf/epoxy composites were carried out. Density results revealed that the incorporation of nano filler in the kenaf/epoxy composites increases the density which in turn increases the hardness of the hybrid nanocomposites. XRD analysis confirmed the presence of nano fillers in the structure of their respective fabricated hybrid nanocomposites. All hybrid nanocomposites displayed lower coefficient of thermal expansion (CTE) with respect to kenaf/epoxy composites. Overall results predicted that the properties improvement in nano OPEFB/kenaf/epoxy was quite comparable to MMT/kenaf/epoxy but relatively lesser to OMMT/kenaf/epoxy hybrid nanocomposites and higher with respect to kenaf/epoxy composites. The improvement ascribed due to improved interfacial bonding or cross linking between kenaf fibers and epoxy matrix by addition of nano filler. - Highlights: • Nano OPEFB/kenaf/epoxy hybrid nanocomposites were fabricated by hand lay-up. • Effect of nano OPEFB on density & structure of kenaf/epoxy were investigated. • Thermal expansion coefficients of kenaf/epoxy and hybrid nanocomposites evaluated. • Comparative studies were made with MMT and OMMT kenaf/epoxy hybrid nanocomposites.

  10. Physical, structural and thermomechanical properties of oil palm nano filler/kenaf/epoxy hybrid nanocomposites

    International Nuclear Information System (INIS)

    Saba, N.; Paridah, M.T.; Abdan, K.; Ibrahim, N.A.

    2016-01-01

    The present research study deals with the fabrication of kenaf/epoxy hybrid nanocomposites by the incorporation of oil palm nano filler, montmorillonite (MMT) and organically modified montmorillonite (OMMT) at 3% loading, through hand lay-up technique. Effect of adding different nano fillers on the physical (density), structural [X-ray diffraction (XRD)] and thermomechanical analysis (TMA) of kenaf/epoxy composites were carried out. Density results revealed that the incorporation of nano filler in the kenaf/epoxy composites increases the density which in turn increases the hardness of the hybrid nanocomposites. XRD analysis confirmed the presence of nano fillers in the structure of their respective fabricated hybrid nanocomposites. All hybrid nanocomposites displayed lower coefficient of thermal expansion (CTE) with respect to kenaf/epoxy composites. Overall results predicted that the properties improvement in nano OPEFB/kenaf/epoxy was quite comparable to MMT/kenaf/epoxy but relatively lesser to OMMT/kenaf/epoxy hybrid nanocomposites and higher with respect to kenaf/epoxy composites. The improvement ascribed due to improved interfacial bonding or cross linking between kenaf fibers and epoxy matrix by addition of nano filler. - Highlights: • Nano OPEFB/kenaf/epoxy hybrid nanocomposites were fabricated by hand lay-up. • Effect of nano OPEFB on density & structure of kenaf/epoxy were investigated. • Thermal expansion coefficients of kenaf/epoxy and hybrid nanocomposites evaluated. • Comparative studies were made with MMT and OMMT kenaf/epoxy hybrid nanocomposites.

  11. Enhanced thermal and mechanical properties of epoxy composites by mixing thermotropic liquid crystalline epoxy grafted graphene oxide

    Directory of Open Access Journals (Sweden)

    B. Qi

    2014-07-01

    Full Text Available Graphene oxide (GO sheets were chemically grafted with thermotropic liquid crystalline epoxy (TLCP. Then we fabricated composites using TLCP-g-GO as reinforcing filler. The mechanical properties and thermal properties of composites were systematically investigated. It is found that the thermal and mechanical properties of the composites are enhanced effectively by the addition of fillers. For instance, the composites containing 1.0 wt% of TLCP-g-GO present impact strength of 51.43 kJ/m2, the tensile strength of composites increase from 55.43 to 80.85 MPa, the flexural modulus of the composites increase by more than 48%. Furthermore, the incorporation of fillers is effective to improve the glass transition temperature and thermal stability of the composites. Therefore, the presence of the TLCP-g-GO in the epoxy matrix could make epoxy not only stronger but also tougher.

  12. Predicting the mechanical behaviour of Kevlar/epoxy and carbon/epoxy filament-wound tubes

    Science.gov (United States)

    Cazeneuve, C.; Joguet, P.; Maile, J. C.; Oytana, C.

    1992-11-01

    The axial, hoop and shear moduli and failure conditions of carbon/epoxy and Kevlar/epoxy filament-wound tubes have been determined through respective applications of internal pressure, tension and torsion. The introduction in the laminated plate theory of a gradual reduction in individual moduli makes it possible to overcome the limitations of the theory and enables accurate predictions to be made of the linear and non-linear stress/strain curves of 90 deg +/- 0/90 deg tubes. The existence of a dominant layer in the failure of the multilayered tubes has been shown experimentally. When associated with a failure criterion applied to the dominant layer, the new model permits the prediction of tube failure. Agreement between calculated and experimental data is better than 5 percent.

  13. Optical emission behavior and radiation resistance of epoxy resins

    International Nuclear Information System (INIS)

    Kawanishi, Shunichi; Udagawa, Akira; Hagiwara, Miyuki

    1987-11-01

    To make clear a mechanism of radiation resistance of epoxy resin systems, a role of energy trapping site induced in bisphenol A type epoxy resins cured with 4 kinds of aromatic amines (Φ N ) was studied in comparison with the case of aliphatic amine curing system through a measurement of optical emission. In the system of the epoxy resin cured with DETA, the optical emission from an excited state of bisphenol A unit of epoxy resin and a charge transfer complex was observed. On the other hand, the optical emission from Φ N was observed in the aromatic amine curing system. Their excitation spectrum consists of peaks of absorption spectrum of BA and those of Φ N , showing that the excited state of Φ N is formed through the excitation of both BA and Φ N . Therefore, the excited energy of BA transfers to the excited state of Φ N . Emission intensity of Φ N band was 20 ∼ 100 times as large as that of BA. These results indicate that the radiation energy is effectively released as an optical emission from excited state of Φ N in the epoxy resin when cured with aromatic amine. It can be concluded from the above results that aromatic amine hardeners contribute to enhancement of the radiation resistance of epoxy resin by acting as an energy transfer agent. (author)

  14. Epoxy encapsulant as serendipitous dosimeters during radiological/nuclear events

    Energy Technology Data Exchange (ETDEWEB)

    Barkyoumb, J.H. [Carderock Division, Naval Surface Warfare Center, 9500 MacArthur Blvd., West Bethesda, MD 20817-5700 (United States)], E-mail: jhbarky@earthlink.net; Mathur, V.K. [Carderock Division, Naval Surface Warfare Center, 9500 MacArthur Blvd., West Bethesda, MD 20817-5700 (United States)

    2008-02-15

    The radiation response of a smart chip (embedded integrated circuit) module has been reported earlier using the technique of optically stimulated luminescence (OSL). It was found that a smart chip module could be used to evaluate the personnel exposure in the accident dosimetry range. Through subsequent experiments, the radiation sensitivity of the chip module was traced to the epoxy encapsulant provided to protect the chip from the environment and physical damage and that the radiation sensitivity of the epoxy is due to the silica used as the 'filler' for controlling the thixotropic properties of the epoxy used for 'glob top' or 'dam-and-fill' encapsulation. It is desirable to retain the ability to use the smart chip as an accident dosimeter without requiring a modification of standard manufacturing process for which an infrastructure already exists to avoid additional costs. For this reason, we have investigated commercially available filled and unfilled epoxies both as received from the manufacturer and compared their response with epoxies to which commercial fillers are added. In this work we investigate the OSL response of various epoxies commonly used for potting of electronic circuits with and without various filler materials for their potential to be used as a casualty dosimeter in the exposure range of 0.5-10 Gy.

  15. Evaluation of epoxy resin for cryogenic use by positron annihilation method. Change of characteristics of epoxy resin with cross-linking density and positron lifetime

    International Nuclear Information System (INIS)

    Nishijima, Shigehiro; Honda, Yoshihide; Okada, Toichi; Kobayashi, Yoshinori; Namba, Shingo.

    1994-01-01

    The positron annihilation method has been applied to evaluate unoccupied space in epoxy aiming at the design of the molecular structure for cryogenic use. To confirm the model in which molecular free space is needed in the epoxy for cryogenic use, the molecular weight between cross-linkings in epoxy was changed. The increase of molecular weight between cross-linkings brought an increase of fracture toughness even at liquid helium temperature and the model was found to be confirmed. The increase of molecular weight between cross-linkings was also found to decrease the 3rd lifetime of positrons. It suggested that the epoxy main chains were folded and this was confirmed by the molecular mechanical calculation. (author)

  16. SÍNTESIS DE OXITOCINA EN FASE SÓLIDA USANDO DERIVADOS DE TERBUTOXICARBONILO Y FLUORENILMETOXICARBONILO

    Directory of Open Access Journals (Sweden)

    Julio C Calvo

    2010-08-01

    Full Text Available La oxitocina, péptido cíclico cuya secuencia es CYIQNCPLG, fué el primer péptido de importancia biológica que pudo ser sintetizado. En este trabajo se compara la síntesis de la oxitocina usando resina p metilbenzhidrilamina (MBHA para la síntesis por estrategia t-Boc y resina Rink p-metilbenzhidrilamina (Rink MBHA para la síntesis por estrategia Fmoc, con altos rendimientos. El péptido crudo se ciclizó en una disolución acuosa de dimetilsulfóxido al 10%. La caracterización se llevó a cabo por espectrometría de masas y resonancia magnética nuclear, y se logró detectar la presencia de dos isómeros.

  17. Thermal conductivity of pillared graphene-epoxy nanocomposites using molecular dynamics

    Science.gov (United States)

    Lakshmanan, A.; Srivastava, S.; Ramazani, A.; Sundararaghavan, V.

    2018-04-01

    Thermal conductivity in a pillared graphene-epoxy nanocomposite (PGEN) is studied using equilibrium molecular dynamics simulations. PGEN is a proposed material for advanced thermal management applications because it combines high in-plane conductivity of graphene with high axial conductivity of a nanotube to significantly enhance the overall conductivity of the epoxy matrix material. Anisotropic conductivity of PGEN has been compared with that of pristine and functionalized carbon nanotube-epoxy nanocomposites, showcasing the advantages of the unique hierarchical structure of PGEN. Compared to pure carbon allotropes, embedding the epoxy matrix also promotes a weaker dependence of conductivity on thermal variations. These features make this an attractive material for thermal management applications.

  18. Comportamento de cilindros de carbono/epóxi submetidos a cargas compressivas axiais Mechanical behavior of carbon/epoxy cylinders under axial compressive loads

    Directory of Open Access Journals (Sweden)

    Adriano Gonçalves

    2001-06-01

    Full Text Available Para estruturas utilizadas no setor aeroespacial, os requisitos de baixo peso, alta resistência e rigidez, além de estabilidade dimensional, têm propiciado o aumento da utilização de materiais compósitos nas suas manufaturas. Em particular, cascas cilíndricas ou estruturas construídas pela junção de cilindros de paredes finas, confeccionadas em fibra de carbono e resina epóxi, são amplamente utilizadas neste tipo de aplicação. Neste trabalho, um programa experimental foi desenvolvido para determinar as tensões de falha, os módulos de elasticidade e o modo de falha de 47 cilindros com diâmetro interno de 40 mm e espessura nominal de 0,6 mm (com exceção de 2 corpos de prova, fabricados em carbono/epóxi, quando submetidos a cargas compressivas uniaxiais. Os espécimes testados possuíam diferentes razões entre comprimento e diâmetro (variando de 2,50 a 11,25 e seqüências de laminação variadas (orientações de camadas. Os resultados dos ensaios foram comparados aos obtidos em análises realizadas com programas de elementos finitos e os fatores que influenciaram o comportamento mecânico destes cilindros foram analisados.The requirements of low weight and dimensional stability, combined with high strength and stiffness, for aerospace structures has prompted an increasing use of fiber reinforced materials in manufacturing such structures. In particular, carbon/epoxy cylinders have been widely used in aerospace applications. In this work, an experimental program was developed to determine failure loads, modulus of elasticity and failure modes of 47 carbon/epoxy cylinders shells under compressive loads. The specimens tested had several different length/diameter (from 2.50 to 11.25 ratios and laminate lay-up. These results were compared to the analytical results from finite element code and the most important factors influencing the mechanical behavior of this type of structure were analyzed.

  19. Thermoset Blends of an Epoxy Resin and Polydicyclopentadiene

    Energy Technology Data Exchange (ETDEWEB)

    Rohde, Brian J.; Le, Kim Mai; Krishnamoorti, Ramanan; Robertson, Megan L.

    2016-12-13

    The mechanical properties of two chemically distinct and complementary thermoset polymers were manipulated through development of thermoset blends. The thermoset blend system was composed of an anhydride-cured diglycidyl ether of bisphenol A (DGEBA)-based epoxy resin, contributing high tensile strength and modulus, and polydicyclopentadiene (PDCPD), which has a higher toughness and impact strength as compared to other thermoset polymers. Ultra-small-angle and small-angle X-ray scattering analysis explored the morphology of concurrently cured thermoset blends, revealing a macroscopically phase separated system with a surface fractal structure across blended systems of varying composition. The epoxy resin rich and PDCPD rich phases exhibited distinct glass transitions (Tg’s): the Tg observed at higher temperature was associated with the epoxy resin rich phase and was largely unaffected by the presence of PDCPD, whereas the PDCPD rich phase Tg systematically decreased with increasing epoxy resin content due to inhibition of dicyclopentadiene ring-opening metathesis polymerization. The mechanical properties of these phase-separated blends were in reasonable agreement with predictions by the rule of mixtures for the blend tensile strength, modulus, and fracture toughness. Scanning electron microscopy analysis of the tensile and fracture specimen fracture surfaces showed an increase in energy dissipation mechanisms, such as crazing, shear banding, and surface roughness, as the fraction of the more ductile component, PDPCD, increased. These results present a facile method to tune the mechanical properties of a toughened thermoset network, in which the high modulus and tensile strength of the epoxy resin can be largely retained at high epoxy resin content in the blend, while increasing the fracture toughness.

  20. Self-healing woven glass fabric/epoxy composites with the healant consisting of micro-encapsulated epoxy and latent curing agent

    International Nuclear Information System (INIS)

    Yin Tao; Zhou Lin; Rong Minzhi; Zhang Mingqiu

    2008-01-01

    This paper reports a study of self-healing woven glass fabric reinforced epoxy composites. The healing agent was a two-component one synthesized in the authors' laboratory, which consisted of epoxy-loaded urea-formaldehyde microcapsules as the polymerizable binder and CuBr 2 (2-methylimidazole) 4 (CuBr 2 (2-MeIm) 4 ) as the latent hardener. Both the microcapsules and the matching catalyst were pre-embedded and pre-dissolved in the composites' matrix, respectively. When the microcapsules are split by propagating cracks, the uncured epoxy can be released into the damaged areas and then consolidated under the catalysis of CuBr 2 (2-MeIm) 4 that was homogeneously distributed in the composites' matrix on a molecular scale. As a result, the cracked faces can be bonded together. The influence of the content of the self-healing agent on the composites' tensile properties, interlaminar fracture toughness and healing efficiency was evaluated. It was found that a healing efficiency over 70% relative to the fracture toughness of virgin composites was obtained in the case of 30 wt% epoxy-loaded microcapsules and 2 wt% latent hardener

  1. Development of sealed radioactive sources immobilized in epoxy resin for verification of detectors used in nuclear medicine; Desenvolvimento de fontes radioativas seladas imobilizadas em resina epoxi para verificacao de detectores utilizados em medicina nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Tiezzi, Rodrigo

    2016-07-01

    The radioactive sealed sources are used in verification ionization chamber detectors, which measure the activity of radioisotopes used in several areas, such as in nuclear medicine. The measurement of the activity of radioisotopes must be made with accuracy, because it is administered to a patient. To ensure the proper functioning of the ionization chamber detectors, standardized tests are set by the International Atomic Energy Agency (IAEA) and the National Nuclear Energy Commission using sealed radioactive sources of Barium-133, Cesium-137 and Cobalt-57. The tests assess the accuracy, precision, reproducibility and linearity of response of the equipment. The focus of this work was the study and the development of these radioactive sources with standard Barium-133 and Cesium-137,using a polymer, in case commercial epoxy resin of diglycidyl ether of bisphenol A (DGEBA) and a curing agent based on modified polyamine diethylenetriamine (DETA), to immobilize the radioactive material. The polymeric matrix has the main function of fix and immobilize the radioactive contents not allowing them to leak within the technical limits required by the standards of radiological protection in the category of characteristics of a sealed source and additionally have the ability to retain the emanation of any gases that may be formed during the manufacture process and the useful life of this artifact. The manufacturing process of a sealed source standard consists of the potting ,into bottle standardized geometry, in fixed volume of a quantity of a polymeric matrix within which is added and dispersed homogeneously to need and exact amount in activity of the radioactive materials standards. Accordingly, a study was conducted for the choice of epoxy resin, analyzing its characteristics and properties. Studies and tests were performed, examining the maximum miscibility of the resin with the water (acidic solution, simulating the conditions of radioactive solution), loss of mechanical and

  2. Fabrication and mechanical properties of multi-walled carbon nanotubes/epoxy nanocomposites

    International Nuclear Information System (INIS)

    Yeh, M.-K.; Hsieh, T.-H.; Tai, N.-H.

    2008-01-01

    Carbon nanotubes have better physical and mechanical behavior than the traditional materials. In this study, the multi-walled carbon nanotubes (MWNTs) were added to the epoxy resin as a reinforcement to fabricate MWNTs/epoxy nanocomposites. The pressure and temperature were applied to cure the MWNTs/epoxy compound by hot press method. Mechanical properties such as tensile strength, Young's modulus, and Poisson's ratio were measured. The effect of weight percentages of the MWNTs was investigated. Morphologies of the fracture surface of MWNTs/epoxy nanocomposites were observed by scanning electron microscope

  3. Stronger Fire-Resistant Epoxies

    Science.gov (United States)

    Fohlen, George M.; Parker, John A.; Kumar, Devendra

    1988-01-01

    New curing agent improves mechanical properties and works at lower temperature. Use of aminophenoxycyclotriphosphazene curing agents yields stronger, more heat- and fire-resistant epoxy resins. Used with solvent if necessary for coating fabrics or casting films.

  4. Influence of different kinds of rosins and hydrogenated resins on the setting time of Grossman cements Influência de diferentes tipos de breus e resinas hidrogenadas sobre o tempo de endurecimento dos cimentos do tipo Grossman

    Directory of Open Access Journals (Sweden)

    Manoel Damião SOUSA NETO

    1999-01-01

    Full Text Available In this study, the effect on the setting time by the addition of different kinds of rosin and hydrogenated resin on the Grossman cement powder was evaluated. The experiments were carried out following the American Dental Association’s specification number 57 for root canal sealers. For this analysis, different Grossman cement powders were prepared using different rosins (X, WW and WG and hydrogenated resins (Staybelite and Staybelite ester 10. The study of the physicochemical properties of the Grossman cements obtained the different kinds of rosins and hydrogenated resins interference on the cement’s setting time. The hydrogenated resin, having a higher pH, increased the setting time of the cement when compared to the X, WW and WG rosins.No presente estudo, analisou-se o efeito da adição de diferentes tipos de breus e resinas hidrogenadas ao pó do cimento de GROSSMAN sobre o tempo de endurecimento. Os experimentos foram realizados de acordo com a Especificação 57 para materiais obturadores de canais radiculares da American Dental Association (ADA. Para análise, foram aviados pós do cimento de GROSSMAN com diferentes tipos de breu (X, WW e WG e resinas hidrogenadas (Stabylite e Stabylite éster 10. Os estudos das propriedades físico-químicas dos cimentos tipo GROSSMAN obtidos de diferentes tipos de breus e resinas hidrogenadas interferem no tempo de endurecimento do cimento. A resina hidrogenada, obtida do processo de hidrogenação tem o pH mais alto, provocando um aumento do tempo de endurecimento do cimento em relação aos breus tipo X, WW e WG, que têm pH mais ácido.

  5. Fullerene–epoxy nanocomposites-enhanced mechanical properties at low nanofiller loading

    International Nuclear Information System (INIS)

    Rafiee, Mohammad A.; Yavari, Fazel; Rafiee, Javad; Koratkar, Nikhil

    2011-01-01

    In this study, we characterized the mechanical properties of fullerence (C 60 ) epoxy nanocomposites at various weight fractions of fullerene additives in the epoxy matrix. The mechanical properties measured were the Young’s modulus, ultimate tensile strength, fracture toughness, fracture energy, and the material’s resistance to fatigue crack propagation. All of the above properties of the epoxy polymer were significantly enhanced by the fullerene additives at relatively low nanofiller loading fractions (∼0.1 to 1% of the epoxy matrix weight). By contrast, other forms of nanoparticle fillers such as silica, alumina, and titania nanoparticles require up to an order of magnitude higher weight fraction to achieve comparable enhancement in properties.

  6. Thermal properties of oil palm nano filler/kenaf reinforced epoxy hybrid nanocomposites

    Science.gov (United States)

    Saba, N.; Paridah, M. T.; Abdan, K.; Ibrahim, N. A.

    2016-11-01

    The aim of this research study was to fabricate nano oil palm empty fruit bunch (OPEFB)/kenaf/epoxy hybrid nanocomposites and to make comparative study on the thermal properties of nano OPEFB/kenaf/epoxy hybrid nanocomposites with the montmorillonite (MMT)/kenaf/epoxy hybrid nanocomposites and organically modified MMT (OMMT)/kenaf/epoxy hybrid nanocomposites. Epoxy based kenaf hybrid nanocomposites was prepared by dispersing the nano filler (nano OPEFB filler, MMT, OMMT) at 3% loading through high speed mechanical stirrer followed by hand lay-up technique. Thermal properties of hybrid nanocomposites were analyzed through thermogravimetry analyzer (TGA), and differential scanning calorimetry (DSC). Obtained results specified that addition of nano OPEFB filler improves the thermal stability and char yield of kenaf/epoxy composites. Furthermore, the increase in decomposition temperature by the nano OPEFB filler was quite comparable to the MMT/kenaf/epoxy but relatively less than OMMT/kenaf/epoxy hybrid nanocomposites. We concluded from overall consequences that the nano OPEFB filler can be used as the promising and innovative alternative of existing expensive nano filler, with relatively lesser impact on the environment having marked pronounced impact on the construction, automotive, aerospace, electronics and semiconducting sectors as future industries based on bio-wastes with satisfactory light weight and thermal stability on other side.

  7. Stochastic estimation of acoustic impedance of glass-reinforced epoxy coating 128-134

    Energy Technology Data Exchange (ETDEWEB)

    Kim, No Hyu [School of MechatronicEngineering, Korea University of Technology and Education, Chunan (Korea, Republic of); Nah, Hwan Seon [Structural Engineering Lab., Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2014-04-15

    An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

  8. Stochastic estimation of acoustic impedance of glass-reinforced epoxy coating 128-134

    International Nuclear Information System (INIS)

    Kim, No Hyu; Nah, Hwan Seon

    2014-01-01

    An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

  9. Hansen solubility parameters for a carbon fiber/epoxy composite

    DEFF Research Database (Denmark)

    Launay, Helene; Hansen, Charles M.; Almdal, Kristoffer

    2007-01-01

    In this study, the physical affinity between an epoxy matrix and oxidized, unsized carbon fibers has been evaluated using Hansen solubility (cohesion) parameters (HSP). A strong physical compatibility has been shown, since their respective HSP are close. The use of a glassy carbon substrate...... as a model for unsized carbon fiber has been demonstrated as appropriate for the study of interactions between the materials in composite carbon fiber-epoxy systems. The HSP of glassy carbon are similar to those of carbon fibers and epoxy matrix. (C) 2007 Elsevier Ltd. All rights reserved....

  10. Electrical and Mechanical Properties of 3D-Printed Graphene-Reinforced Epoxy

    Science.gov (United States)

    Compton, Brett G.; Hmeidat, Nadim S.; Pack, Robert C.; Heres, Maximilian F.; Sangoro, Joshua R.

    2018-03-01

    Recent developments in additive manufacturing have demonstrated the potential for thermoset polymer feedstock materials to achieve high strength, stiffness, and functionality through incorporation of structural and functional filler materials. In this work, graphene was investigated as a potential filler material to provide rheological properties necessary for direct-write three-dimensional (3D) printing and electrostatic discharge properties to the printed component. The rheological properties of epoxy/graphene mixtures were characterized, and printable epoxy/graphene inks formulated. Sheet resistance values for printed epoxy/graphene composites ranged from 0.67 × 102 Ω/sq to 8.2 × 103 Ω/sq. The flexural strength of printed epoxy/graphene composites was comparable to that of cast neat epoxy ( 80 MPa), suggesting great potential for these new materials in multifunctional 3D-printed devices.

  11. Degradation of modified carbon black/epoxy nanocomposite coatings under ultraviolet exposure

    International Nuclear Information System (INIS)

    Ghasemi-Kahrizsangi, Ahmad; Shariatpanahi, Homeira; Neshati, Jaber; Akbarinezhad, Esmaeil

    2015-01-01

    Graphical abstract: - Highlights: • Degradation behavior of modified Carbon Black (CB) epoxy coating was studied under UV irradiation using based on EIS technique. • By using SDS as a surfactant, nano particles of CB were uniformly dispersed in an epoxy matrix. • ATR-FTIR analysis showed that the CB coatings were degraded less than epoxy coating. • EIS results showed the coating with 2.5 wt% CB nanoparticles had higher corrosion resistance than neat epoxy. - Abstract: Degradation of epoxy coatings with and without Carbon Black (CB) nanoparticles under ultraviolet (UV) radiation were investigated using electrochemical impedance spectroscopy (EIS). Sodium dodecyl sulfate (SDS) was used to obtain a good dispersion of CB nanoparticles in a polymer matrix. TEM analysis proved a uniform dispersion of modified CB nanoparticles in epoxy coating. The coatings were subjected to UV radiation to study the degradation behavior and then immersed in 3.5 wt% NaCl. The results showed that the electrochemical behavior of neat epoxy coating was related to the formation and development of microcracks on the surface. The occurrence of microcracks on the surface of the coatings and consequently the penetration of ionic species reduced by adding CB nanoparticles into the formulation of the coatings. CB nanoparticles decreased degradation of CB coatings by absorbing UV irradiation. The ATR-FTIR results showed that decrease in the intensity of methyl group as main peak in presence of 2.5 wt% CB was lower than neat epoxy. In addition, the reduction in impedance of neat epoxy coating under corrosive environment was larger than CB coatings. The CB coating with 2.5 wt% nanoparticles had the highest impedance to corrosive media after 2000 h UV irradiation and 24 h immersion in 3.5 wt% NaCl.

  12. Degradation of modified carbon black/epoxy nanocomposite coatings under ultraviolet exposure

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi-Kahrizsangi, Ahmad, E-mail: ahmad_usk@yahoo.com [Corrosion Department, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of); Shariatpanahi, Homeira, E-mail: shariatpanahih@ripi.ir [Coating Research Center, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of); Neshati, Jaber [Corrosion Department, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of); Akbarinezhad, Esmaeil [Coating Research Center, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of)

    2015-10-30

    Graphical abstract: - Highlights: • Degradation behavior of modified Carbon Black (CB) epoxy coating was studied under UV irradiation using based on EIS technique. • By using SDS as a surfactant, nano particles of CB were uniformly dispersed in an epoxy matrix. • ATR-FTIR analysis showed that the CB coatings were degraded less than epoxy coating. • EIS results showed the coating with 2.5 wt% CB nanoparticles had higher corrosion resistance than neat epoxy. - Abstract: Degradation of epoxy coatings with and without Carbon Black (CB) nanoparticles under ultraviolet (UV) radiation were investigated using electrochemical impedance spectroscopy (EIS). Sodium dodecyl sulfate (SDS) was used to obtain a good dispersion of CB nanoparticles in a polymer matrix. TEM analysis proved a uniform dispersion of modified CB nanoparticles in epoxy coating. The coatings were subjected to UV radiation to study the degradation behavior and then immersed in 3.5 wt% NaCl. The results showed that the electrochemical behavior of neat epoxy coating was related to the formation and development of microcracks on the surface. The occurrence of microcracks on the surface of the coatings and consequently the penetration of ionic species reduced by adding CB nanoparticles into the formulation of the coatings. CB nanoparticles decreased degradation of CB coatings by absorbing UV irradiation. The ATR-FTIR results showed that decrease in the intensity of methyl group as main peak in presence of 2.5 wt% CB was lower than neat epoxy. In addition, the reduction in impedance of neat epoxy coating under corrosive environment was larger than CB coatings. The CB coating with 2.5 wt% nanoparticles had the highest impedance to corrosive media after 2000 h UV irradiation and 24 h immersion in 3.5 wt% NaCl.

  13. Adhesive properties and adhesive joints strength of graphite/epoxy composites

    Science.gov (United States)

    Rudawska, Anna; Stančeková, Dana; Cubonova, Nadezda; Vitenko, Tetiana; Müller, Miroslav; Valášek, Petr

    2017-05-01

    The article presents the results of experimental research of the adhesive joints strength of graphite/epoxy composites and the results of the surface free energy of the composite surfaces. Two types of graphite/epoxy composites with different thickness were tested which are used to aircraft structure. The single-lap adhesive joints of epoxy composites were considered. Adhesive properties were described by surface free energy. Owens-Wendt method was used to determine surface free energy. The epoxy two-component adhesive was used to preparing the adhesive joints. Zwick/Roell 100 strength device were used to determination the shear strength of adhesive joints of epoxy composites. The strength test results showed that the highest value was obtained for adhesive joints of graphite-epoxy composite of smaller material thickness (0.48 mm). Statistical analysis of the results obtained, the study showed statistically significant differences between the values of the strength of the confidence level of 0.95. The statistical analysis of the results also showed that there are no statistical significant differences in average values of surface free energy (0.95 confidence level). It was noted that in each of the results the dispersion component of surface free energy was much greater than polar component of surface free energy.

  14. Mechanical properties of multi-walled carbon nanotube/epoxy polysulfide nanocomposite

    International Nuclear Information System (INIS)

    Shirkavand Hadavand, Behzad; Mahdavi Javid, Kimya; Gharagozlou, Mehrnaz

    2013-01-01

    Highlights: ► Preparation of epoxy polysulfide nanocomposite. ► Multi-walled carbon nanotubes have been modified and dispersed in epoxy polysulfide matrix. ► Mechanical properties of MWNT/epoxy polysulfide have been studied. - Abstract: In this research, multi-walled carbon nanotubes (MWCNTs) were modified by acid functionalization (H 2 SO 4 :HNO 3 = 1:3 by volume) and then mechanical properties of reinforced epoxy polysulfide resin by the both pure and treated MWNTs have been evaluated. For achieving this goal, different weight percentages of pure and treated MWCNT (0.1–0.3 wt%) were dispersed in the epoxy polysulfide resin separately and then mixed with curing agent. Experimental results have shown significant difference between acid treated and untreated MWCNTs in mechanical properties of epoxy polysulfide nanocomposites. In nanocomposite with 0.1–0.3% acid treated MWCNTs we observed increase of Young’s modulus from 458 to 723 MPa, tensile strength from 5.29 to 8.83 MPa and fracture strain from 0.16% to 0.25%. For understanding the structure and morphology of nanocomposite, the dispersion states were studied using scanning electron microscopy (SEM) and field emission electron microscopy (FESEM). The results showed better dispersion of modified carbon nanotube than unmodified in polymeric matrix

  15. Thermal and mechanical interfacial properties of epoxy composites based on functionalized carbon nanotubes

    International Nuclear Information System (INIS)

    Jin Fanlong; Ma Changjie; Park, Soo-Jin

    2011-01-01

    Highlights: → CNTs were functionalized by acid and amine treatments. → Epoxy resin/CNT composites were prepared. → T g of the composites increased by about 10 deg. C compared to neat epoxy resins. → Toughness of the composites was significantly improved by the addition of functionalized CNTs. - Abstract: Carbon nanotubes (CNTs) were treated by a mixture of acid and functionalized subsequently by amine treatment to improve interfacial interactions and dispersion of CNTs in epoxy matrix. The thermal stabilities and mechanical interfacial properties of epoxy/CNT composites were investigated using several techniques. The dispersion state of CNTs in the epoxy matrix was observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). As a result, the glass transition temperature of epoxy/CNT composites increased by about 11 deg. C compared to neat epoxy resins. The mechanical interfacial property of the composites was significantly increased by the addition of amine treated CNTs. The SEM and TEM results showed that the separation and uniform dispersion of CNTs in the epoxy matrix.

  16. Kevlar 49/Epoxy COPV Aging Evaluation

    Science.gov (United States)

    Sutter, James K.; Salem, Jonathan L.; Thesken, John C.; Russell, Richard W.; Littell, Justin; Ruggeri, Charles; Leifeste, Mark R.

    2008-01-01

    NASA initiated an effort to determine if the aging of Kevlar 49/Epoxy composite overwrapped pressure vessels (COPV) affected their performance. This study briefly reviews the history and certification of composite pressure vessels employed on NASA Orbiters. Tests to evaluate overwrap tensile strength changes compared 30 year old samples from Orbiter vessels to new Kevlar/Epoxy pressure vessel materials. Other tests include transverse compression and thermal analyses (glass transition and moduli). Results from these tests do not indicate a noticeable effect due to aging of the overwrap materials.

  17. Quantificação do fósforo disponível por extrações sucessivas com diferentes extratores em Latossolo Vermelho distroférrico

    OpenAIRE

    Gatiboni, L. C.; Kaminski, J.; Rheinheimer, D. S.; Saggin, A.

    2002-01-01

    A determinação do fósforo potencialmente disponível por meio dos extratores químicos é dificultada em solos de carga variável, uma vez que existem diversos graus de energia de ligação com os colóides. O objetivo do presente trabalho foi avaliar o número mínimo de extrações sucessivas necessárias para estimar o fósforo potencialmente disponível, com os métodos de Mehlich-1 e Mehlich-3 e resina de troca aniônica (RTA). Foram realizadas treze extrações sucessivas com os três métodos em amostras ...

  18. Fabrication of High Gas Barrier Epoxy Nanocomposites: An Approach Based on Layered Silicate Functionalized by a Compatible and Reactive Modifier of Epoxy-Diamine Adduct

    Directory of Open Access Journals (Sweden)

    Ran Wei

    2018-05-01

    Full Text Available To solve the drawbacks of poor dispersion and weak interface in gas barrier nanocomposites, a novel epoxy-diamine adduct (DDA was synthesized by reacting epoxy monomer DGEBA with curing agent D400 to functionalize montmorillonite (MMT, which could provide complete compatibility and reactivity with a DGEBA/D400 epoxy matrix. Thereafter, sodium type montmorillonite (Na-MMT and organic-MMTs functionalized by DDA and polyether amines were incorporated with epoxy to manufacture nanocomposites. The effects of MMT functionalization on the morphology and gas barrier property of nanocomposites were evaluated. The results showed that DDA was successfully synthesized, terminating with epoxy and amine groups. By simulating the small-angle neutron scattering data with a sandwich structure model, the optimal dispersion/exfoliation of MMT was observed in a DDA-MMT/DGEBA nanocomposite with a mean radius of 751 Å, a layer thickness of 30.8 Å, and only two layers in each tactoid. Moreover, the DDA-MMT/DGEBA nanocomposite exhibited the best N2 barrier properties, which were about five times those of neat epoxy. Based on a modified Nielsen model, it was clarified that this excellent gas barrier property was due to the homogeneously dispersed lamellas with almost exfoliated structures. The improved morphology and barrier property confirmed the superiority of the adduct, which provides a general method for developing gas barrier nanocomposites.

  19. Surface modification of titanium hydride with epoxy resin via microwave-assisted ball milling

    International Nuclear Information System (INIS)

    Ning, Rong; Chen, Ding; Zhang, Qianxia; Bian, Zhibing; Dai, Haixiong; Zhang, Chi

    2014-01-01

    Highlights: • TiH 2 was modified with epoxy resin by microwave-assisted ball milling. • The epoxy ring was opened under the coupling effect of microwave and ball milling. • Microwave-assisted ball milling improved the compatibility of TiH 2 with epoxy. - Abstract: Surface modification of titanium hydride with epoxy resin was carried out via microwave-assisted ball milling and the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and Fourier transform infrared spectroscopy (FT-IR). A sedimentation test was performed to investigate the compatibility of the modified nano titanium hydride with the epoxy resin. The results show that the epoxy resin molecules were grafted on the surface of nano titanium hydride particles during the microwave-assisted ball milling process, which led to the improvement of compatibility between the nanoparticles and epoxy resin. According to the FT-IR, the grafting site was likely to be located around the epoxy group due to the fact that the epoxy ring was opened. However, compared with microwave-assisted ball milling, the conventional ball milling could not realize the surface modification, indicating that the coupling effect of mechanical force and microwave played a key role during the process

  20. Polymerization time for a microwave-cured acrylic resin with multiple flasks Tempo de polimerização de resina acrílica em microondas, utilizando múltiplas muflas

    Directory of Open Access Journals (Sweden)

    Daniela Maffei Botega

    2004-03-01

    Full Text Available This study aimed at establishing the polymerization time of a microwave-cured acrylic resin (AcronTM MC, simultaneously processing 2, 4, and 6 flasks. Required time was measured according to the parameters: monomer release in water, Knoop hardness, and porosity. Samples were made with AcronTM MC in different shapes: rectangular (32 x 10 x 2.5 mm for monomer release and porosity; and half-disc (30 mm in diameter x 4 mm in height for Knoop hardness. There were four experimental groups (n = 24 per group: G1 one flask (control; G2 two flasks; G3 four flasks, and G4 six flasks. At first, polymerization protocol was similar for all groups (3 min/450 W. Time was then adjusted for G2, G3, and G4, based on monomer release evaluation in the control group, obtained by spectrophotometer Beckman DU-70, with emitting wave of 206 nm. Knoop hardness test was performed using a Shimadzu HMV 2000 hardness tester, and 10 indentations were performed on each specimen's surface. Porosity was assessed after specimens were immersed in black ink and the pores counted in a microscope. Results showed that the complete polymerization of the resin occurred in 4.5 min for two flasks (G2; 8.5 min for four flasks (G3; and 13 min for six flasks (G4, all with 450 W. Statistical analysis revealed that the number of flasks does not interfere with polymerization, Knoop hardness, and porosity of the resin. Results showed that polymerization of microwave-curing resin with more than one flask is a viable procedure, as long as polymerization time is adjusted.O objetivo deste estudo foi o de determinar os tempos necessários para a polimerização padrão de uma resina acrílica em microondas, utilizando várias muflas simultaneamente. Os tempos necessários foram aferidos por parâmetros como monômeros liberados em água, dureza Knoop e porosidade. As amostras, confeccionadas em resina AcronTM MC, apresentavam as seguintes dimensões: para os parâmetros monômero residual e porosidade

  1. Epoxy based nanocomposites with fully exfoliated unmodified clay: mechanical and thermal properties.

    Science.gov (United States)

    Li, Binghai; Zhang, Xiaohong; Gao, Jianming; Song, Zhihai; Qi, Guicun; Liu, Yiqun; Qiao, Jinliang

    2010-09-01

    The unmodified clay has been fully exfoliated in epoxy resin with the aid of a novel ultrafine full-vulcanized powdered rubber. Epoxy/rubber/clay nanocomposites with exfoliated morphology have been successfully prepared. The microstructures of the nanocomposites were characterized by means of X-ray diffraction and transmission electron microscopy. It was found that the unmodified clay was fully exfoliated and uniformly dispersed in the resulting nanocomposite. Characterizations of mechanical properties revealed that the impact strength of this special epoxy/rubber/clay nanocomposite increased up 107% over the neat epoxy resin. Thermal analyses showed that thermal stability of the nanocomposite was much better than that of epoxy nanocomposite based on organically modified clay.

  2. Epoxy resin/phosphonium ionic liquid/carbon nanofiller systems: Chemorheology and properties

    Directory of Open Access Journals (Sweden)

    H. Maka

    2014-10-01

    Full Text Available Epoxy nanocomposites with commercial carbon nanotubes (CNT or graphene (GN have been prepared using phosphonium ionic liquid [trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl phosphinate, IL-f]. IL-f served simultaneously as nanofiller dispersing medium and epoxy resin catalytic curing agent. An influence of IL-f/epoxy weight ratio (3, 6 and 9/100, phr, carbon nanofiller type and content on viscosity of epoxy compositions during storage at ambient temperature was evaluated. Curing process was controlled for neat and CNT or GN modified epoxy compositions (0.25-1.0 wt.% load using differential scanning calorimetry and rheometry. Epoxy nanocomposites exhibited slightly increased glass transition temperature values (146 to 149°C whereas tan δ and storage modulus decreased (0.30 to 0.27 and 2087 to 1070 MPa, respectively as compared to reference material. Crosslink density regularly decreased for composites with increasing CNT content (11 094 to 7 020 mol/m3. Electrical volume resistivity of the nanocomposites was improved in case of CNT to 4•101 Ω•m and GN to 2•105 Ω•m (nanofiller content 1 wt.%. Flame retardancy was found for modified epoxy materials with as low GN and phosphorus content as 0.25 and 0.7 wt.%, respectively (increase of limiting oxygen index to 26.5%.

  3. Energy absorption and failure response of silk/epoxy composite square tubes: Experimental

    DEFF Research Database (Denmark)

    Oshkovr, Simin Ataollahi; Taher, Siavash Talebi; A. Eshkoor, Rahim

    2012-01-01

    This paper focuses on natural silk/epoxy composite square tubes energy absorption and failure response. The tested specimens were featured by a material combination of different lengths and same numbers of natural silk/epoxy composite layers in form of reinforced woven fabric in thermosetting epoxy...

  4. Prótese intra-ocular de resina acrílica em cães e gatos Acrylic resin intraocular prosthesis in dogs and cats

    Directory of Open Access Journals (Sweden)

    S.C. Rahal

    2000-08-01

    Full Text Available Foram atendidos no Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Unesp - Campus de Botucatu, 11 animais (oito cães e três gatos, com alterações oftálmicas unilaterais graves que levaram à perda total da função ocular (protrusão de globo com injúria nervosa e estrutural, perfurações de córnea com perda de conteúdo intra-ocular e endoftalmites, entre outras. Os animais, com idades entre dois meses e 10 anos, foram submetidos à evisceração e posterior inclusão de esfera de resina acrílica (metilmetacrilato na capa córneo-escleral ou escleral. As esferas foram previamente confeccionadas e esterilizadas por autoclavagem. No pós-operatório foram utilizados antiinflamatórios e antibioticoterapia tópica combinada ou não a sistêmica. O período de observação variou de 2 meses a 3 anos e os aspectos avaliados foram secreção ocular, blefarospasmo, sinais de desconforto e estética. Obtiveram-se resultados satisfatórios em oito casos. Concluiu-se que a resina acrílica pode ser uma alternativa para uso como inclusão em cavidade anoftálmica.Eleven animals (eight dogs and three cats, aged between two months and ten years were referred to the Veterinary Hospital of Faculty of Veterinary Medicine and Animal Science - Unesp, Botucatu, Brazil. These animals presented severe unilateral ophthalmic changes that lead to a total loss of ocular function, such as prolapsed eyes with nervous and structural injury, corneal damage with loss of intraocular contents or endophthalmitis among others. They were submitted to evisceration followed by the insertion of an acrylic resin prosthesis (methylmethacrylate in the corneoscleral or scleral shell. The spheres were previously made and sterilized by autoclave. The postoperative medical therapy included topical and systemic broad-spectrum antibiotics for seven days and anti-inflammatory drugs. The follow-up time varied from two months to three years. The evaluated

  5. Measurements of print-through in graphite fiber epoxy composites

    Science.gov (United States)

    Jaworske, Donald A.; Jeunnette, Timothy T.; Anzic, Judith M.

    1989-01-01

    High-reflectance accurate-contour mirrors are needed for solar dynamic space power systems. Graphite fiber epoxy composites are attractive candidates for such applications owing to their high modulus, near-zero coefficient of thermal expansion, and low mass. However, mirrors prepared from graphite fiber epoxy composite substrates often exhibit print-through, a distortion of the surface, which causes a loss in solar specular reflectance. Efforts to develop mirror substrates without print-through distortion require a means of quantifying print-through. Methods have been developed to quantify the degree of print-through in graphite fiber epoxy composite specimens using surface profilometry.

  6. Void-free epoxy castings for cryogenic insulators and seals

    International Nuclear Information System (INIS)

    Quirk, J.F.

    1983-01-01

    The design of the Westinghouse Magnet for the Oak Ridge National Laboratory's Large Coil Program (LCP) incorporates a main lead bushing which transmits heat-leak loads by conduction to the supercritical helium stream. The bushing, which consists of epoxy resin cast about a copper conductor, must be electrically insulated, vacuum tight and be capable of withstanding the stresses encountered in cryognic service. The seal design of the bushing is especially important; leakage from either the helium system or the external environment into the vacuum will cause the magnet to quench. Additionally, the epoxy-resin casting must resist mechanical loads caused by the weight of leads attached to the bushing and thermal stresses transmitted to the epoxy via the conductor. The epoxy resin is cast about the conductor in such a way as to provide the required vacuum tight seal. The technique by which this is accomplished is reviewed. Equally important is the elimination of voids in the epoxy which will act as stress-concentrating discontinuities during cooling to or warming from 4K. The types of voids that could be expected and their causes are described. The paper reviews techniques employed to eliminate voids within the cast-resin portion of the bushing

  7. Flexural properties of treated and untreated kenaf/epoxy composites

    International Nuclear Information System (INIS)

    Yousif, B.F.; Shalwan, A.; Chin, C.W.; Ming, K.C.

    2012-01-01

    Graphical abstract: Untreated kenaf fibre/epoxy composites. Treated kenaf fibre/epoxy composites. Highlights: ► Treatment of kenaf fibres with 6% NaOH has improved the flexural properties of epoxy composites. ► Interfacial adhesion of the natural fibres is controlled by the microstructure of the fibres. ► Kenaf fibres have a potential to replace glass fibres for flexural applications. -- Abstract: In the current work, flexural properties of unidirectional long kenaf fibre reinforced epoxy (KFRE) composites are studied. The kenaf fibres were prepared into two types as untreated and treated (with 6% NaOH). The failure mechanism and damage features of the materials were categorized with the surface observation by scanning electron microscope (SEM). The results revealed that reinforcement of epoxy with treated kenaf fibres increased the flexural strength of the composite by about 36%, while, untreated fibres introduced 20% improvement. This was mainly due to the high improvement of the chemical treatment (NaOH) on the interfacial adhesion of the fibres and the porosity of the composites which prevented the debonding, detachments or pull out of fibres. For untreated KFRE, the fracture mechanisms were debonding, tearing, detachments and pull out of fibres. The developed composite exhibited superior properties compared to the previous composites based on natural and synthetic fibres.

  8. Characterization of epoxy hybrid composites filled with cellulose fibers and nano-SiC

    KAUST Repository

    Alamri, H.

    2012-04-06

    Three different approaches have been applied and investigated to enhance the thermal and mechanical properties of epoxy resin. Epoxy system reinforced with either recycled cellulose fibers (RCF) or nanosilicon carbide (n-SiC) particles as well as with both RCF and n-SiC has been fabricated and investigated. The effect of RCF/n-SiC dispersion on the mechanical and thermal properties of these composites has been characterized. The fracture surface morphology and toughness mechanisms were investigated by scanning electron microscopy. The dispersion of n-SiC particles into epoxy nanocomposites was studied by synchrotron radiation diffraction and transmission electron microscopy. Results indicated that mechanical properties increased as a result of the addition of n-SiC. The presence of RCF layers significantly increased the mechanical properties of RCF/epoxy composites when compared with neat epoxy and its nanocomposites. The influence of the addition of n-SiC to RCF/epoxy composites in mechanical properties was found to be positive in toughness properties. At high temperatures, thermal stability of neat epoxy increased due to the presence of either n-SiC particles or RCF layers. However, the presence of RCF accelerated the thermal degradation of neat epoxy as well as the addition of n-SiC to RCF/epoxy samples increased the rate of the major thermal degradation. © 2012 Wiley Periodicals, Inc.

  9. Avaliação in vitro da resistência ao cisalhamento e liberação de flúor de dois cimentos de ionômero de vidro reforçado por resina = In vitro evaluation of shear bond strength and fluoride release from two resin-reinforced glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Pithon, Matheus Melo

    2007-01-01

    Full Text Available O objetivo deste estudo foi avaliar os cimentos de ionômero de vidro reforçados com resina Fuji Ortho LC e Fuji Ortho Band (GC América Corporation, Tokyo, Japan quanto a resistência ao cisalhamento e liberação de flúor. Para avaliação da resistência ao cisalhamento utilizou-se 60 incisivos inferiores permanentes bovinos divididos em três grupos (n = 15. No Grupo 1, 2 e 3, as colagens foram realizadas com Transbond XT, Fuji Ortho LC e Fuji Ortho Band respectivamente. Após a colagem realizou-se o ensaio de cisalhamento de toda amostra à velocidade de 0,5 mm por minuto. A liberação de flúor dos materiais foram medidas durante 28 dias (1h, 24 h, 3, 7, 14, 21 e 28 dias através de eletrodo íon seletivo conectado a um analisador de íons. Os resultados demonstraram que quanto a resistência ao cisalhamento (MPa houve diferenças estatísticas entre os grupos 1 e 3, 2 e 3 (p > 0,05. Quanto a liberação de flúor os resultados evidenciaram diferença estatisticamente significante entre os grupos 1 e 3 e 2 e 3 em todos os tempos (p = 0. 00 e entre os grupos 1 e 2 na avaliação de 3 dias de liberação de flúor (p = 0. 00. Baseado nos resultados obtidos conclui-se que os materiais Transbond XT e Fuji Ortho possuem melhor resistência ao cisalhamento porém menor liberação de flúor quando comparado ao Fuji Ortho Band

  10. Exit Presentation: Infrared Thermography on Graphite/Epoxy

    Science.gov (United States)

    Comeaux, Kayla

    2010-01-01

    This slide presentation reports on the internship project that was accomplished during the summer of 2010. The objectives of the project were to: (1) Simulate Flash Thermography on Graphite/Epoxy Flat Bottom hole Specimen and thin void specimens, (2) Obtain Flash Thermography data on Graphite/Epoxy flat bottom hole specimens, (3) Compare experimental results with simulation results, Compare Flat Bottom Hole Simulation with Thin Void Simulation to create a graph to determine size of IR Thermography detected defects

  11. Realtime 3D stress measurement in curing epoxy packaging

    DEFF Research Database (Denmark)

    Richter, Jacob; Hyldgård, A.; Birkelund, Karen

    2007-01-01

    This paper presents a novel method to characterize stress in microsystem packaging. A circular p-type piezoresistor is implemented on a (001) silicon chip. We use the circular stress sensor to determine the packaging induced stress in a polystyrene tube filled with epoxy. The epoxy curing process...

  12. Enhanced Flexural Strength of Tellurium Nanowires/epoxy Composites with the Reinforcement Effect of Nanowires

    Science.gov (United States)

    Balguri, Praveen Kumar; Harris Samuel, D. G.; Aditya, D. B.; Vijaya Bhaskar, S.; Thumu, Udayabhaskararao

    2018-02-01

    Investigating the mechanical properties of polymer nanocomposite materials has been greatly increased in the last decade. In particular, flexural strength plays a major role in resisting bending and shear loads of a composite material. Here, one dimensional (1D) tellurium nanowires (TeNWs) reinforced epoxy composites have been prepared and the flexural properties of resulted TeNWs/epoxy nanocomposites are studied. The diameter and length of the TeNWs used to make TeNWs/epoxy nanocomposites are 21±2.5 nm and 697±87 nm, respectively. Plain and TeNWs/epoxy nanocomposites are characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). Furthermore, significant enhancement in the flexural strength of TeNWs/epoxy nanocomposite is observed in comparison to plain epoxy composite, i.e. flexural strength is increased by 65% with the addition of very little amount of TeNWs content (0.05 wt.%) to epoxy polymer. Structural details of plain and TeNWs/epoxy at micrometer scale were examined by scanning electron microscopy (SEM). We believe that our results provide a new type of semiconductor nanowires based high strength epoxy polymer nanocomposites.

  13. Behaviour of Epoxy Silica Nanocomposites Under Static and Creep Loading

    Science.gov (United States)

    Constantinescu, Dan Mihai; Picu, Radu Catalin; Sandu, Marin; Apostol, Dragos Alexandru; Sandu, Adriana; Baciu, Florin

    2017-12-01

    Specific manufacturing technologies were applied for the fabrication of epoxy-based nanocomposites with silica nanoparticles. For dispersing the fillers in the epoxy resin special equipment such as a shear mixer and a high energy sonicator with temperature control were used. Both functionalized and unfunctionalized silica nanoparticles were added in three epoxy resins. The considered filling fraction was in most cases 0.1, 0.3 and 0.5 wt%.. The obtained nanocomposites were subjected to monotonic uniaxial and creep loading at room temperature. The static mechanical properties were not significantly improved regardless the filler percentage and type of epoxy resin. Under creep loading, by increasing the stress level, the nanocomposite with 0.1 wt% silica creeps less than all other materials. Also the creep rate is reduced by adding silica nanofillers.

  14. Synthesis and characterization of polyimide-epoxy hybrid films

    International Nuclear Information System (INIS)

    Butt, M.S.; Akhter, Z.; Siddiqi, H.M.

    2011-01-01

    Composites from polyimide and epoxy-amine were prepared aiming for enhancing its thermal and mechanical properties. Polyimide-epoxy-amine hybrid films were prepared by blending of polyimide and epoxy-amine in different ratios whereas, polyimide was prepared by reacting 1,2-di(p-aminophenyloxy)ethylene with 3,3/sub '/4,4/sub '/-benzophenone tetracarboxylic acid dianhydride. The blend systems with Araldite LY564 (1,4-butanediolediglycidyl ether) (BDDE) and Hardener HY2954 (3,3/sub '/-dimethyl-4,4/sub '/-diamino dicyclohexyl)methane (MACM) were investigated in term of thermal, mechanical and viscoelastic measurements. Thermal stability was determined using thermogravimetric analysis. The effect of the polyimide content on the glass transition temperature (Tg) and thermal stability was observed. Viscoelastic measurements showed that the glass transition temperature shifted with the increase of polyimide content. The composites showed higher thermal stability in comparison with neat epoxy-amine matrix for higher polyimide concentration. The effect of polyimide content on the mechanical properties was also investigated. The tensile measurements of the films showed that with the increase of polyimide content the tensile modulus of the films was increased. (author)

  15. Characterization of Hybrid Epoxy Nanocomposites

    Science.gov (United States)

    Simcha, Shelly; Dotan, Ana; Kenig, Samuel; Dodiuk, Hanna

    2012-01-01

    This study focused on the effect of Multi Wall Carbon Nanotubes (MWCNT) content and its surface treatment on thermo-mechanical properties of epoxy nanocomposites. MWCNTs were surface treated and incorporated into two epoxy systems. MWCNT's surface treatments were based on: (a) Titania coating obtained by sol-gel process and (b) a nonionic surfactant. Thermo-mechanical properties improvement was obtained following incorporation of treated MWCNT. It was noticed that small amounts of titania coated MWCNT (0.05 wt %) led to an increase in the glass transition temperature and stiffness. The best performance was achieved adding 0.3 wt % titania coated MWCNT where an increase of 10 °C in the glass transition temperature and 30% in storage modulus were obtained. PMID:28348313

  16. Thermal properties and corrosion resistance of organoclay/epoxy resin film

    Science.gov (United States)

    Baiquni, M.; Soegijono, B.

    2018-03-01

    Hybrid materials organoclay/epoxy resin films were prepared by varying organoclay content in epoxy resin as a matrix. The film were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermal conductivity. TGA and FT-IR results confirmed that the melting temperature shifted to a lower point. The thermal conductivity and corrosion resistant generally increase with increasing organoclay content. The changes on these properties may due to cross link between organoclay and epoxy.

  17. Preparation and Various Characteristics of Epoxy/Alumina Nanocomposites

    Science.gov (United States)

    Kozako, Masahiro; Ohki, Yoshimichi; Kohtoh, Masanori; Okabe, Shigemitsu; Tanaka, Toshikatsu

    Epoxy/ alumina nanocomposites were newly prepared by dispersing 3, 5, 7, and 10 weight (wt) % boehmite alumina nanofillers in a bisphenol-A epoxy resin using a special two-stage direct mixing method. It was confirmed by scanning electron microscopy imaging that the nanofillers were homogeneously dispersed in the epoxy matrix. Dielectric, mechanical, and thermal properties were investigated. It was elucidated that nanofillers affects various characteristics of epoxy resins, when they are nanostructrued. Such nano-effects we obtained are summarized as follows. Partial discharge resistance increases as the filler content increases; e.g. 7 wt% nanofiller content creates a 60 % decrease in depth of PD-caused erosion. Weibull analysis shows that short-time electrical treeing breakdown time is prolonged to 265 % by 5 wt% addition of nanofillers. But there was more data scatter in nanocomposites than in pure epoxy. Permittivity tends to increase from 3.7 to 4.0 by 5 wt% nanofiller addition as opposed to what was newly found in the recent past. Glass transition temperature remains unchanged as 109 °C. Mechanical properties such as flexural strength and flexural modulus increase; e.g. flexural strength and flexural modulus are improved by 5 % and 8 % with 5 wt% content, respectively. Excess addition causes a reverse effect. It is concluded from permittivity and glass transition temperature characteristics that interfacial bonding seems to be more or less weak in the nanocomposite specimens prepared this time, even though mechanical strengths increase. There is a possibility that the nanocomposites specimens will be improved in interfacial quality.

  18. Liquid crystalline epoxy nanocomposite material for dental application.

    Science.gov (United States)

    Tai, Yun-Yuan; Hsu, Sheng-Hao; Chen, Rung-Shu; Su, Wei-Fang; Chen, Min-Huey

    2015-01-01

    Novel liquid crystalline epoxy nanocomposites, which exhibit reduced polymerization shrinkage and effectively bond to tooth structures, can be applied in esthetic dentistry, including core and post systems, direct and indirect restorations, and dental brackets. The purposes of this study were to investigate the properties of liquid crystalline epoxy nanocomposites including biocompatibility, microhardness, and frictional forces of bracket-like blocks with different filler contents for further clinical applications. In this study, we evaluated liquid crystalline epoxy nanocomposite materials that exhibited various filler contents, by assessing their cell activity performance using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and their microhardness with or without thermocycling. We also evaluated the frictional force between bracket-like duplicates and commercially available esthetic bracket systems using Instron 5566. The liquid crystalline epoxy nanocomposite materials showed good biocompatibility. The materials having high filler content demonstrated greater microhardness compared with commercially available bracket materials, before and after the thermocycling treatment. Thus, manufacturing processes are important to reduce frictional force experienced by orthodontic brackets. The microhardness of the bracket-like blocks made by our new material is superior to the commercially available brackets, even after thermocycling. Our results indicate that the evaluated liquid crystalline epoxy nanocomposite materials are of an appropriate quality for application in dental core and post systems and in various restorations. By applying technology to refine manufacturing processes, these new materials could also be used to fabricate esthetic brackets for orthodontic treatment. Copyright © 2014. Published by Elsevier B.V.

  19. The effects of MWNT on thermal conductivity and thermal mechanical properties of epoxy

    Science.gov (United States)

    Ismadi, A. I.; Othman, R. N.

    2017-12-01

    Multiwall nanotube (MWNT) was used as filler in various studies to improve thermal conductivity and mechanical properties of epoxy. Present study varied different weight loading (0, 0.1 %, 0.5 %, 1 %, 1.5 %, 3 % and 5 %) of MWNT in order to observe the effects on the epoxy. Nanocomposite was analyzed by dynamic-mechanical thermal analyser (DMTA) and KD2 pro analyzer. DMTA measured storage modulus (E') and glass transition temperature (Tg) of the nanocomposite. Result showed that Tg value of neat epoxy is higher than all MWNT epoxy nanocomposite. Tg values drop from 81.55 °C (neat epoxy) to 65.03 °C (at 0.1 wt%). This may happen due to the agglomeration of MWNT in the epoxy. However, Tg values increases with the increase of MWNT wt%. Tg values increased from 65.03 °C to 78.53 °C at 1 wt%. Increment of storage modulus (E') at 3 °C (glassy region) was observed as the MWNT loading increases. Maximum value of E' during glassy region was observed to be at 5 wt% with (7.26±0.7) E+08 Pa compared to neat epoxy. On the contrary, there is slight increased and slight decreased with E' values at 100 °C (rubbery region) for all nanocomposite. Since epoxy exhibits low thermal conductivity properties, addition of MWNT has enhanced the properties. Optimum value of thermal conductivity was observed at 3 wt%. The values increased up to 9.03 % compared to neat epoxy. As expected, the result showed decrease value in thermal conductivity at 5 wt% as a result of agglomeration of MWNT in the epoxy.

  20. High Tg and fast curing epoxy-based anisotropic conductive paste for electronic packaging

    Science.gov (United States)

    Keeratitham, Waralee; Somwangthanaroj, Anongnat

    2016-03-01

    Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (Tg) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that Tg obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage by weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (˜90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.

  1. Non-isothermal cure and exfoliation of tri-functional epoxy-clay nanocomposites

    Directory of Open Access Journals (Sweden)

    F. Shiravand

    2015-08-01

    Full Text Available The non-isothermal cure kinetics of polymer silicate layered nanocomposites based on a tri-functional epoxy resin has been investigated by differential scanning calorimetry. From an analysis of the kinetics as a function of the clay content, it can be concluded that the non-isothermal cure reaction can be considered to consist of four different processes: the reaction of epoxy groups with the diamine curing agent; an intra-gallery homopolymerisation reaction which occurs concurrently with the epoxy-amine reaction; and two extra-gallery homopolymerisation reactions, catalysed by the onium ion of the organically modified clay and by the tertiary amines resulting from the epoxy-amine reaction. The final nanostructure displays a similar quality of exfoliation as that observed for the isothermal cure of the same nanocomposite system. This implies that the intra-gallery reaction, which is responsible for the exfoliation, is not significantly inhibited by the extra-gallery epoxy-amine cross-linking reaction.

  2. Tensile properties of compressed moulded Napier/glass fibre reinforced epoxy composites

    Science.gov (United States)

    Fatinah, T. S.; Majid, M. S. Abdul; Ridzuan, M. J. M.; Hong, T. W.; Amin, N. A. M.; Afendi, M.

    2017-10-01

    This paper describes the experimental investigation of the tensile properties of compressed moulded Napier grass fibres reinforced epoxy composites. The effect of treatment 5% sodium hydroxide (NaOH) concentrated solution and hybridization of Napier with CSM E-glass fibres on tensile properties was also studied. The untreated and treated Napier fibres with 25% fibre loading were fabricated with epoxy resin by a cold press process. 7% fibre loading of CSM glass fibre was hybrid as the skin layer for 18% fibre loading of untreated Napier grass fibre. The tensile tests were conducted using Universal Testing Machine in accordance with ASTM D638. The tensile properties of the untreated Napier/epoxy composites were compared with treated Napier/epoxy and untreated Napier/CSM/epoxy composites. The results demonstrated that the tensile performance of untreated Napier fibre composites was significantly improved by both of the modification; alkali treatment and glass fibre hybridization. Napier grass fibres showed promising potentials to be used as reinforcement in the polymer based composites.

  3. Plant Oil-Derived Epoxy Polymers toward Sustainable Biobased Thermosets.

    Science.gov (United States)

    Wang, Zhongkai; Yuan, Liang; Ganewatta, Mitra S; Lamm, Meghan E; Rahman, Md Anisur; Wang, Jifu; Liu, Shengquan; Tang, Chuanbing

    2017-06-01

    Epoxy polymers (EPs) derived from soybean oil with varied chemical structures are synthesized. These polymers are then cured with anhydrides to yield soybean-oil-derived epoxy thermosets. The curing kinetic, thermal, and mechanical properties are well characterized. Due to the high epoxide functionality per epoxy polymer chain, these thermosets exhibit tensile strength over an order of magnitude higher than a control formulation with epoxidized soybean oil. More importantly, thermosetting materials ranging from soft elastomers to tough thermosets can be obtained simply by using different EPs and/or by controlling feed ratios of EPs to anhydrides. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Chemical changes and tensile and electrical properties of epoxy ...

    African Journals Online (AJOL)

    The properties of epoxy rsesin can be improved by the use of nanofiller such as carbon black (CB), The nanocomposite was synthesized by dispersion via sonication and shear mixing. The morphology, surface chemistry and the structure of CB and the epoxy/CB nanocomposites were investigated using XPS, FTIR, FESEM, ...

  5. Education and Public Outreach for NASA's EPOXI Mission.

    Science.gov (United States)

    McFadden, Lucy-Ann A.; Crow, C. A.; Behne, J.; Brown, R. N.; Counley, J.; Livengood, T. A.; Ristvey, J. D.; Warner, E. M.

    2009-09-01

    NASA's EPOXI mission is reusing the Deep Impact (DI) flyby spacecraft to study comets and extra-solar planets around other stars. During the Extrasolar Planetary Observations and Characterization (EPOCh) phase of the mission extrasolar planets transiting their parent stars were observed to gain further knowledge and understanding of planetary systems. Observations of Earth also allowed for characterization of Earth as an extrasolar planet. A movie of a lunar transit of the Earth created from EPOCh images and links to existing planet finding activities from other NASA missions are available on the EPOXI website. The Deep Impact Extended Investigation (DIXI) continues the Deep Impact theme of investigating comet properties and formation by observing comet Hartley 2 in November 2010. The EPOXI Education and Public Outreach (E/PO) program is both creating new materials and updating and modifying existing Deep Impact materials based on DI mission results. Comparing Comets is a new educational activity under development that will guide students in conducting analyses of comet surface features similar to those the DIXI scientists will perform after observing comet Hartley 2. A new story designed to stimulate student creativity was developed in alignment with national educational standards. EPOXI E/PO also funded Family Science Night (FSN), a program bringing together students, families, and educators for an evening at the National Air and Space Museum in Washington, DC. FSN events include time for families to explore the museum, a presentation by a space scientist, and an astronomy themed IMAX film. Nine events were held during the 2008-2009 school year with a total attendance of 3,145 (attendance since inception reached 44,732). Half of attendance is reserved for schools with high percentages of underrepresented minorities. EPOXI additionally offers a bi-monthly newsletter to keep the public, teachers, and space enthusiasts updated on current mission activities. For more

  6. Aging in CTBN modified epoxy resin stocks

    International Nuclear Information System (INIS)

    Creed, K.E. Jr.

    1979-01-01

    The cause of degradation in the glass transition temperature (T/sub G/) of a partially crystallized polymer was investigated. Sample epoxy resin filled capacitors were cured at 90 0 C for 24 hours, then stored at room atmospheric conditions. These showed typical degradation in T/sub G/ after storage for one month. One set of epoxy resin castings was stored at room atmosphere and another set was stored in a dry box at 0% relative humidity and 27 0 C. The samples at room atmospheric conditions showed typical degradation in T/sub G/, while the T/sub G/ for those stored in the dry box increased. Further tests were then made on epoxy resin castings at various curing temperatures and times at both room atmosphere and 0% humidity. Resulting data indicated that absorption of moisture during storage was the predominant cause of T/sub G/ degradation, with stress relaxation another, though smaller, contributing factor

  7. Spall Strength Measurements in Transparent Epoxy Polymers

    Science.gov (United States)

    Pepper, Jonathan; Rahmat, Meysam; Petel, Oren

    2017-06-01

    Polymer nanocomposites are seeing more frequent use in transparent armour applications. The role of the microstructure on the performance of these materials under dynamic tensile loading conditions is of particular interest. In the present study, a series of plate impact experiments was conducted in order to evaluate the dynamic response of an epoxy (EPON 828) cured with two differed hardeners. The purpose was to compare the role of these hardeners on the dynamic performance of the resulting transparent epoxy. The material response was resolved with a multi-channel photonic Doppler velocimeter. This system was used to determine the shock Hugoniot and dynamic tensile (spall) strength of the materials. The experimental results are presented in reference to spall theory and are evaluated against results predicted by an analytical model of the impacts. While varying the hardener did not change the shock Hugoniot of the epoxy, it did have an effect on the measured spall strengths.

  8. Epoxy-silicate nanocomposites: Cure monitoring and characterization

    International Nuclear Information System (INIS)

    Hussain, Farzana; Chen, Jihua; Hojjati, Mehdi

    2007-01-01

    Epoxy-clay nanocomposites were prepared with organically modified layered clay with varying clay contents (1-8 wt.%). Neat resin and nanocomposite were characterized using different techniques. At first, the effect of nanoclay concentration on the cure behaviour was investigated using an on-line dielectric cure monitoring technique. Differential scanning calorimetry (DSC) was used to verify the dielectric measurement results. Furthermore, mechanical and thermal properties were studied using tensile test and Dynamic Mechanical Analysis (DMA), respectively. Experimental results showed that properties of the epoxy were changed evidently because of the nanoclay loading. The tensile modulus of the nanocomposites increased by 47%, however, no improvement in tensile strength and glass transition temperature (T g ) was observed. Fracture surface of the tensile samples were analyzed by Scanning Electron Microscope (SEM). The nanocomposites structures were characterized with Wide Angle X-Ray Diffraction (WAXD) and Transmission Electron Microscopy (TEM), which revealed the intercalated morphology of clay layers in the epoxy resin systems

  9. Radiation curing of γ-Al2O3 filled epoxy resin

    International Nuclear Information System (INIS)

    Kang, Phil Hyun; Kim, Dong Jin; Nho, Young Chang

    2003-01-01

    Epoxy resins are widely utilized as high performance thermosetting resins for many industrial applications but characterized by a relatively low toughness. Recently, the incorporation with rigid inorganic was suggested to improve the mechanical properties of epoxy resins. In the present work, an attempt has been taken to disperse nano-sized γ- Al 2 O 3 particles into diglycidyl ether of bisphenol-A (DGEBA) epoxy resins for improvement of the mechanical properties. These hybrid epoxy-alumina composites were prepared using by the γ-ray curing technique that was conducted with 100kGy under nitrogen at room temperature. The composites were characterized by determining gel content, UTM (Instron model 4443), SEM, FT-IR studies

  10. Documento de Idoneidad Técnica, Granulite CD.U.: 693621 S.F.B. Un 6 - Convalidación n.° 5 Agrément del C.S.T.B. n."2.117 Fecha: 28 de julio de 1965 - revestimiento interior de muros

    Directory of Open Access Journals (Sweden)

    Nadal, J.

    1965-10-01

    Full Text Available Not availableEl revestimiento interior de muros GRANULITE se obtiene por aplicación, sobre la superficie a revestir, de una capa de pasta compuesta de un árido mineral y de im conglomerante constituido por una emulsión acuosa de resina sintética.

  11. Preparations and applications in UV curing coatings of epoxy acrylates containing carboxyl

    International Nuclear Information System (INIS)

    Wu Yu Min

    1999-01-01

    This paper introduces preparations of epoxy acrylates containing carboxyl through the reactions of epoxy acrylates with butanedioic anhydride, pentanedioic anhydride, cis-butenedioic anhydride, phthalic anhydride, tetrabromophthalic anhydride and -tetrahydrophthalic anhydride. These epoxy acrylates containing carboxyl have been applied to UV-curing coatings and their effects on properties of UV-curing coatings have been studied

  12. Efeito higrotérmico em prepregs de fibra de vidro/epóxi por espectroscopia de luminescência Hygrothermal effect in glass fiber/epoxy by luminescence spectroscopy

    Directory of Open Access Journals (Sweden)

    Rita de Cássia M. Sales

    2008-03-01

    Full Text Available O objetivo deste trabalho é o estudo do efeito higrotérmico em pré-impregnados (prepreg não curados de fibra de vidro-resina epoxídica usando a técnica de espectroscopia eletrônica de luminescência em modo estacionário. O método de fluorescência extrínseca foi empregado utilizando-se a sonda 9- ácido antróico (9-AA, cujo comportamento fotofísico depende fortemente da polaridade do meio. As amostras foram submetidas a umidades relativas de 6 e 84% por meio da utilização de soluções aquosas saturadas de hidróxido de sódio a 34,5 °C e cloreto de potássio a 20,0 °C, em recipientes fechados, pelos períodos de tempo de 1 semana, 15 dias e 1 mês. As amostras submetidas à umidade relativa de 6% apresentaram aumento significativo das intensidades relativas dos espectros de fluorescência em relação à amostra referência. Este comportamento fotofísico foi atribuído à presença da forma protonada do 9-AA no meio devido à reticulação da matriz polimérica. Após 1 mês, o espectro de emissão apresenta uma diminuição da intensidade em seu máximo. Isto ocorreu provavelmente devido ao processo de plastificação da matriz polimérica promovido pela presença de água na matriz, confirmado pela análise gravimétrica. Os espectros de fluorescência extrínseca das amostras submetidas à umidade relativa de 84% apresentaram as seguintes modificações espectrais: a decaimento da intensidade de emissão das curvas b e d; b deslocamento da banda de emissão para a região do azul devido ao aumento do teor de água; e c aparecimento de um ombro na banda de emissão em 424 e 472 nm. Este comportamento fotofísico foi atribuído ao deslocamento do equilíbrio químico da forma protonada para a forma ionizada do 9-AA, promovido pela entrada de umidade no material.The work is aimed at studying hygrothermal effects on uncured glass-epoxy fiber prepreg (F-161 - Hexcel Co. using luminescence spectroscopy under steady

  13. ANALISIS ARAH DAN PERLAKUAN SERAT TAPIS SERTA RASIO EPOXY HARDENER TERHADAP SIFAT FISIS DAN MEKANIS KOMPOSIT TAPIS/EPOXY

    Directory of Open Access Journals (Sweden)

    Putu Lokantara

    2012-11-01

    Full Text Available Tapis kelapa (Coconut filter as natural fiber, in this time its resources very copius but no longer be exploited and thrown off hand as waste though in fact its used for other material dissimilar inovatif and high economic valuable that is as one of natural fiber alternative to be composite. The objective of this research is to investigate the behavior changing of physical and mechanical properties of composite tapis kelapa as reinforcement and epoxy 7120 with hardener Versamid 140 as matrix. The fiber is treated with the chemical NaOH and KMnO4 with percentage 0.5%, 1%, and 2% in weight, respectively. The ratio of epoxy and hardener is 7:3 and 6:4, and fiber orientation 0o, 45o, dan 90o. For testing of the speciment in tensile test with ASTM standard D3039 and three point bending test with ASTM standard D790. The result of this research obtained that fiber treatment with KMnO4 give the better effect to machine properties compared to NaOH. Variation of percentage 0.5%, 1%, and 2% NaOH and KMnO4 give the effect in fiber surface which higher percentage make the cleaner of surface, decrease of wax contain, and roughness of fiber surface so that stronger of linkage of fiber and matrix and increase of tensile strength, bending strength, and bending modulus of the composite. The highest tensile strength, modulus of elasticity and bending strength are 70.23 MPa, 446.24 GPa and 97.81 MPa respectively reached at composite with ratio epoxy/hardener 7:3; by 2% KMnO4 and fiber orientation 45o. While the highest modulus of elasticity is 385.48 GPa reached at composite with the ratio epoxy/hardener 6:4; 2% KMnO4 and fiber orientation 90o. Keywords: Tensile Strength, bending strength, ratio of epoxy/hardener, NaOH, KMnO4

  14. Influence of light intensity and curing cycle on microleakage of Class V composite resin restorations Influência da intensidade de luz e métodos de fotoativação no selamento marginal de restaurações classe V em resina composta

    Directory of Open Access Journals (Sweden)

    Maria Jacinta M. Coelho Santos

    2005-06-01

    intuito de situar as margens cavitárias em dentina. Os dentes foram divididos em cinco grupos de acordo com o método de fotoativação. As cavidades, depois de condicionadas, foram tratadas com o sistema adesivo Single Bond (3M Dental e restauradas com a resina composta Z100 (3M Dental pela técnica incremental. A fotoativação foi realizada para cada grupo como descrito a seguir: Grupo I: PAC pelo método de fotoativação constante: 1600mW/cm² - 3s; Grupo II: PAC pelo método de fotoativação por passos (800mW/cm² - 2s, subindo automaticamente para 1600mW/cm² - 4s; Grupo III: QTH pelo método de fotoativação constante: 400 mW/cm² - 40s; Grupo IV: QTH pelo método de fotoativação em rampa: 100 a 600 mW/cm² - 15s, permanecendo a 600mW/cm2 por mais 25s; Grupo V: QTH pelo método de fotoativação por pulso: 200 mW/cm² - 3s, tempo de espera de 3min.e a seguir 600mW/cm² - 30s. Os dentes foram armazenados em água destilada a 37ºC por 30 dias e então submetidos à ciclagem térmica, por 500 ciclos à 5 ºC e 55 ºC. Os ápices dos dentes foram selados com resina composta e os dentes foram cobertos com duas camadas de esmalte para unha, antes da sua imersão em fucsina básica a 0,5%. Os dentes foram seccionados e os cortes foram escaneados para avaliação da área infiltrada por corante por um programa de computador (Image Tools. Os cortes foram também visualizados com lupa para a determinação do grau de penetração do corante na interface dente-restauração por escores. Diferenças estatisticamente significantes foram observadas entre os grupos quanto ao grau e à área de penetração de corante (p < 0,05. Os grupos I e II apresentaram valores significantemente mais altos de infiltração e penetração do corante que os grupos III, IV e V. Em conclusão, o uso da fonte de PAC, no modo constante e por passos, resultou em valores significantemente maiores de infiltração marginal quando comparados com a intensidade de luz média emitida pelos

  15. Análise dos níveis de cinza de 4 resinas compostas micro-híbridas utilizando um sistema de radiografia digital direto =Analisys of the gray scale levels for 4 micro-hibrids composite resins using a radiograph direct digital system

    Directory of Open Access Journals (Sweden)

    Pereira, Ary Salazar Rubim et al.

    2005-01-01

    Full Text Available O objetivo deste estudo foi analisar os diferentes níveis de cinza de quatro resinas compostas micro-híbridas, através do sistema de radiografia digital direto Sens-a-Ray. As resinas utilizadas foram: Concept (Vigodent, Herculite (Sybron/Kerr, IntenS (Ivoclar Vivadent e Z 100 (3MESPE, na cor A2. Foram confeccionadas 3 placas de acrílico para cada espessura 2, 3 e 4 mm que possuíam dimensões de um filme periapical. Em todas as placas foram feitos quatro orifícios eqüidistantes com 4 mm de diâmetro onde as resinas compostas foram inseridas, esses orifícios apresentavam 4mm de diâmetro. As amostras foram radiografadas a 30 cm de distância foco-filme do sistema Sens-a-Ray por 0,8 segundo com aparelho de Raios-X (Dabi Atlante de 70 kV e 10 mA. A quantidade dos níveis de cinza, das resinas, foi aferida em pixels pelo sistema Sens-a-Ray. Foram obtidas as seguintes médias: Concept – 2 mm com 79,6; 3 mm com 85,4 e 4 mm com 96,7; Herculite – 2 mm com 65,1; 3 mm com 72,5 e 4 mm com 85,4; IntenS – 2 mm com 138,5; 3 mm com 147,3 e 4 mm com 153,7; Z 100 – 2 mm com 133,5; 3 mm com 143,8 e 4 mm com 150,6. Após os resultados foram submetidos ao teste estatístico ANOVA-Tukey com um nível de significância (p 0,05. A colorimetria foi utilizada para ilustrar a densidade óptica dos compósitos, com cores vermelho, verde e azul, representando, respectivamente do mais radiopaco para o menos radiopaco. Podemos concluir que na medida em que aumentou a espessura das placas os níveis de cinza também aumentaram. A resina Herculite apresentou os menores níveis de cinza, diferindo estatisticamente das demais. As resinas IntenS e Z 100 apresentaram maiores níveis de cinza que as demais. The aim of this study was analysed the different gray scale levels for 4 micro-hybrids composite resins, throught the direct digital radiography device, Sens-a-Ray. The composites used in this study were: Concept (Vigodent, Herculite (Sybron/Kerr, IntenS (Ivoclar

  16. Epoxy-resin adhesive and method for bonding using such an epoxy resin adhesive

    NARCIS (Netherlands)

    Bhowmik, S.; Poulis, J.A.; Benedictus, R.

    2008-01-01

    The invention relates to an epoxy resin adhesive comprising a dotation of nano-substances, wherein the nano- substances are selected from the group comprising carbon-fibre nanotubes, carbon nano-fibres, silicate nano powders, and wherein the nano-substances are dispersed in the adhesive with a

  17. Preparation and Properties of Epoxy Resin-Coated Micro-Sized Ferrosilicon Powder

    OpenAIRE

    Ku,Jiangang; Chen,Huihuang; He,Kui; Yan,Quanxiang

    2016-01-01

    Ferrosilicon powder surface coated with a dense epoxy resin membrane was prepared via coating precipitation methods using silane coupling agents as the modifier and epoxy resin as the coating agent. FTIR, FESEM, MPMS-XL, and TG-DSC were used to analyze the morphology, surface composition, magnetic property and thermostability of ferrosilicon powder before and after the modification and coating. The experimental results indicate that epoxy resin membranes of a certain thickness were successful...

  18. Endogenous or exogenous spreading of HIV-1 in Nordrhein-Westfalen, Germany, investigated by phylodynamic analysis of the RESINA Study cohort.

    Science.gov (United States)

    Lawyer, Glenn; Schülter, Eugen; Kaiser, Rolf; Reuter, Stefan; Oette, Mark; Lengauer, Thomas

    2012-08-01

    HIV's genetic instability means that sequence similarity can illuminate the underlying transmission network. Previous application of such methods to samples from the United Kingdom has suggested that as many as 86% of UK infections arose outside of the country, a conclusion contrary to usual patterns of disease spread. We investigated transmission networks in the Resina cohort, a 2,747 member sample from Nordrhein-Westfalen, Germany, sequenced at therapy start. Transmission networks were determined by thresholding the pairwise genetic distance in the pol gene at 96.8% identity. At first blush the results concurred with the UK studies. Closer examination revealed four large and growing transmission networks that encompassed all major transmission groups. One of these formed a supercluster containing 71% of the sex with men (MSM) subjects when the network was thresholded at levels roughly equivalent to those used in the UK studies, though methodological differences suggest that this threshold may be too generous in the current data. Examination of the endo- versus exogenesis hypothesis by testing whether infections that were exogenous to Cologne or to Dusseldorf were endogenous to the greater region supported endogenous spread in MSM subjects and exogenous spread in the endemic transmission group. In intravenous drug using group subjects, it depended on viral strain, with subtype B sequences appearing to have origin exogenous to the Resina data, while non-B sequences (primarily subtype A) were almost completely endogenous to their local community. These results suggest that, at least in Germany, the question of endogenous versus exogenous linkages depends on subject group.

  19. Impact Damage In Carbon/Epoxy And Carbon/PEEK Composites

    Science.gov (United States)

    Nettles, A. T.; Magold, N. J.

    1991-01-01

    Report describes results of drop-weight impact testing of specimens of carbon-fiber/epoxy and carbon-fiber/polyetheretherketone (PEEK) composite materials. Panels made of these materials assembled into lightweight, strong, stiff structures useful in automobiles, aircraft, sporting goods, and many other products. PEEK specimens showed less delamination than epoxy specimens at given impact energy.

  20. Effect of epoxy resin and hardener containing microcapsules on healing efficiency of epoxy adhesive based metal joints

    International Nuclear Information System (INIS)

    Khan, Nazrul Islam; Halder, Sudipta; Goyat, M.S.

    2016-01-01

    Dual component microcapsules of epoxy resin and polyamine hardener with polymethyl methacrylate (PMMA) shell were synthesized using a water-oil-water emulsion solvent evaporation method. The high concentration of sodium dodecyl sulfate (SDS) was used to reduce the thickness of shell wall of dual component microcapsules. The dual microcapsules of 1:1 weight ratio were introduced in the epoxy adhesive to study the healing effect. The morphology, chemical structure and thermal characteristics of the microcapsules were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), respectively. The insertion of dual component microcapsules in epoxy matrix reduced the lap shear strength of adhesive joints, which may be attributed to the generation of stress concentration cites because of micron sized capsules. However, the extension and absorbed failure energy of adhesive joints under uniaxial loading increased with the increase of concentration of dual microcapsules. The viscoelastic nature of the dual microcapsules may be responsible for this enhancement. Significant enhancement in the healing efficiency (90.93%) of the joints was achieved for 10 wt% of dual microcapsules. The crack pinning and crack blunting mechanisms at the vicinity of the crack path adjacent to the microcapsules were found responsible for significant enhancement in the healing efficiency of the adhesive joints. - Highlights: • High SDS concentration was used to control the dual component microcapsules shell wall thickness. • Self-healing performance of dual component microcapsules reinforced epoxy adhesive based single lap joints was studied. • 90.93% of the damage healing was achieved for self-healing adhesive based single lap joints. • Increase in concentration of microcapsules reduces the lap shear properties of the self-healing joints.

  1. Effect of epoxy resin and hardener containing microcapsules on healing efficiency of epoxy adhesive based metal joints

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Nazrul Islam [Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar 788010, Assam (India); Halder, Sudipta, E-mail: shalder@nits.ac.in [Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar 788010, Assam (India); Goyat, M.S. [Department of Physics, University of Petroleum & Energy Studies, Dehradun, Uttarakhand 248007 (India)

    2016-03-01

    Dual component microcapsules of epoxy resin and polyamine hardener with polymethyl methacrylate (PMMA) shell were synthesized using a water-oil-water emulsion solvent evaporation method. The high concentration of sodium dodecyl sulfate (SDS) was used to reduce the thickness of shell wall of dual component microcapsules. The dual microcapsules of 1:1 weight ratio were introduced in the epoxy adhesive to study the healing effect. The morphology, chemical structure and thermal characteristics of the microcapsules were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), respectively. The insertion of dual component microcapsules in epoxy matrix reduced the lap shear strength of adhesive joints, which may be attributed to the generation of stress concentration cites because of micron sized capsules. However, the extension and absorbed failure energy of adhesive joints under uniaxial loading increased with the increase of concentration of dual microcapsules. The viscoelastic nature of the dual microcapsules may be responsible for this enhancement. Significant enhancement in the healing efficiency (90.93%) of the joints was achieved for 10 wt% of dual microcapsules. The crack pinning and crack blunting mechanisms at the vicinity of the crack path adjacent to the microcapsules were found responsible for significant enhancement in the healing efficiency of the adhesive joints. - Highlights: • High SDS concentration was used to control the dual component microcapsules shell wall thickness. • Self-healing performance of dual component microcapsules reinforced epoxy adhesive based single lap joints was studied. • 90.93% of the damage healing was achieved for self-healing adhesive based single lap joints. • Increase in concentration of microcapsules reduces the lap shear properties of the self-healing joints.

  2. Utilização de uma resina preparada pelo método da solução líquida de citratos como ligante durante a preparação de filtros cerâmicos à base de alumina

    OpenAIRE

    Gouvêa,D.; Savaglia Neto,W. A.; Capocchi,J. D. T.

    1999-01-01

    Este trabalho propõe a preparação de filtros cerâmicos macroporosos pela técnica da impregnação de espumas de poliuretano e utilização de uma resina preparada pelo método Pechini contendo íons alumínio e manganês como ligante. Nas temperaturas inferiores à de combustão da resina a parte orgânica age com ligante. Após a decomposição térmica, o produto da combustão, ou seja, alumina contendo íons Mn, passa a ser um ligante inorgânico mas apresentando composição química semelhante à do filtro. O...

  3. Improvement in electrical, thermal and mechanical properties of epoxy by filling carbon nanotube

    Directory of Open Access Journals (Sweden)

    2008-01-01

    Full Text Available In this study, electrical, thermal and mechanical properties of multi-walled carbon nanotubes (CNTs reinforced Epon 862 epoxy have been evaluated. Firstly, 0.1, 0.2, 0.3, and 0.4 wt% CNT were infused into epoxy through a high intensity ultrasonic liquid processor and then mixed with EpiCure curing agent W using a high speed mechanical agitator. Electric conductivity, dynamic mechanical analysis (DMA, three point bending tests and fracture tests were then performed on unfilled, CNT-filled epoxy to identify the loading effect on the properties of materials. Experimental results show significant improvement in electric conductivity. The resistivity of epoxy decreased from 1014 Ω•m of neat epoxy to 10 Ω•m with 0.4% CNT. The experimental results also indicate that the frequency dependent behavior of CNT/epoxy nanocomposite can be modeled by R-C circuit, permittivity of material increase with increasing of CNT content. DMA studies revealed that filling the carbon nanotube into epoxy can produce a 90% enhancement in storage modulus and a 17°C increase in Tg. Mechanical test results showed that modulus increased with higher CNT loading percentages, but the 0.3 wt% CNT-infusion system showed the maximum strength and fracture toughness enhancement. The decrease in strength and fracture toughness in 0.4% CNT/epoxy was attributed to poor dispersions of nanotubes in the composite.

  4. Resinas de intercambio iónico para prolongar la liberación de los fármacos

    Directory of Open Access Journals (Sweden)

    Héctor M Alfonso Zerquera

    2000-12-01

    Full Text Available Se realizó el estudio de las resinas de intercambio iónico como sistemas para liberación prolongada con atención a los factores que afectan la formación de los resinatos o complejos fármacoresina. También se estudió la liberación de los principios activos a partir de los complejos y de las formas terminadas que los contienen, evaluándose los factores que afectan dicho proceso y las cinéticas a las que se ajusta. Se revisaron las combinaciones de procesos tecnológicos (principalmente la formación de complejos iónicos y su recubrimiento que potencian la utilidad de los resinatos para prolongar la liberación a través de mecanismos combinados de intercambio iónico y difusión a través de membranas, combinaciones dirigidas a reducir las limitaciones inherentes a cada proceso por separado y conseguir un control eficaz de la liberación de fármacos iónicos.The study of the ion exchange resins as systems for the prolonged release was conducted, making emphasis on the factors affecting the formation of resinates or drug-resin complexes. The release of the active principles was also studied starting from the complexes and the finished forms containing them. The factors affecting this process and the kinetics to which it is adjusted were evaluated, too. The combinations of technological processes (mainly the formation of ion complexes and their coating potentiating the usefulness of resinates to prolong the release by combined mechanisms of ion exchange and difussion through membranes, combinations directed to reduce the limitations inherent to each process separately and to achieve an efficient control of the release of ion drugs, were reviewed.

  5. A study of thermal diffusivity of carbon-epoxy and glass-epoxy composites using the modified pulse method

    Directory of Open Access Journals (Sweden)

    Terpiłowski Janusz

    2014-09-01

    Full Text Available Transient heat transfer is studied and compared in two planeparallel composite walls and one EPIDIAN 53 epoxy resin wall acting as a matrix for both composites. The first of the two walls is made of carbonepoxy composite; the other wall is made of glass-epoxy composite, both with comparable thickness of about 1 mm and the same number of carbon and glass fabric layers (four layers. The study was conducted for temperatures in the range of 20-120 °C. The results of the study of thermal diffusivity which characterizes the material as a heat conductor under transient conditions have a preliminary character. Three series of tests were conducted for each wall. Each series took about 24 h. The results from the three series were approximated using linear functions and were found between (0.7-1.35×10−7m2/s. In the whole range of temperature variation, the thermal diffusivity values for carbon-epoxy composite are from 1.2 to 1.5 times higher than those for the other two materials with nearly the same thermal diffusivity characteristics.

  6. The influence of stiffeners on axial crushing of glass-fabric-reinforced epoxy composite shells

    Directory of Open Access Journals (Sweden)

    A. Vasanthanathan

    2017-01-01

    Full Text Available A generic static and impact experimental procedure has been developed in this work aimed at improving the stability of glass fabric reinforced epoxy shell structures by bonding with axial stiffeners. Crashworthy structures fabricated from composite laminate with stiffeners would offer energy absorption superior to metallic structures under compressive loading situations. An experimental material characterisation of the glass fabric reinforced epoxy composite under uni-axial tension has been carried out in this study. This work provides a numerical simulation procedure to describe the static and dynamic response of unstiffened glass fabric reinforced epoxy composite shell (without stiffeners and stiffened glass fabric reinforced epoxy composite shell (with axial stiffeners under static and impact loading using the Finite Element Method. The finite element calculation for the present study was made with ANSYS®-LS-DYNA® software. Based upon the experimental and numerical investigations, it has been asserted that glass fabric reinforced epoxy shells stiffened with GFRP stiffeners are better than unstiffened glass fabric reinforced epoxy shell and glass fabric reinforced epoxy shell stiffened with aluminium stiffeners. The failure surfaces of the glass fabric reinforced epoxy composite shell structures tested under impact were examined by SEM.

  7. Synthesis and characterization of rubbery epoxy/organoclay hectorite nanocomposites

    Directory of Open Access Journals (Sweden)

    2007-12-01

    Full Text Available The present research investigates the morphology, the mechanical, and the viscoelastic properties of rubbery epoxy/clay nanocomposites synthesized by in situ polymerisation of a prepolymer diglycidyl ether of bisphenol-A crosslinked with an aliphatic diamine based on a polyoxypropylene backbone. The inorganic phase was hectorite, exchanged with octadecylammonium ions in order to give organophilic properties to the phyllosilicate. An ultrasonicator was used to disperse the silicate clay layer into epoxy-amine matrix. The morphology of epoxy-hectorite nanocomposites examined by transmission electron microscopy (TEM showed that mixed delamination or intercalation or microdispersion could occur depending on type of organoclay. Moreover, the mechanical and viscoelastic properties were found to be improved with only the treated hectorite.

  8. Epoxy coatings for anticorrosion challenges: a link between chemistry and performance?

    Energy Technology Data Exchange (ETDEWEB)

    Sauvant-Moynot, Valerie; Schweitzer, Sylvie; Grenier, Jacky; Duval, Sebastien [Institut Francais du Petrole, 1 et 4 avenue Bois Preau, 92450 Rueil-Malmaison (France)

    2004-07-01

    Epoxy coatings have been used extensively for pipeline protection in the oil and gas industries over the past decades. Thank to their outstanding adhesive properties, epoxy resins are classically used for external coating of offshore pipelines although cathodic protection is applied. They provide corrosion protection while being used as neat coating or as primer layer in a three-layer coating. Protection of internal pipelines devoted to gas transport is another application of epoxy coatings. Whatever the case, the choice of the right epoxy formulation should be adapted to the service conditions, namely exposition medium and temperature, in order to provide efficient and sustainable corrosion protection. Epoxy resins constitute a wide family and classical formulations may not fulfill the requirements of today's challenges: as pipelines are require d to operate in more and more difficult conditions, coatings are expected to function in higher temperature conditions; additionally, practical conditions such as temporary injection of methanol make the environmental exposure of the epoxy coating harsher. Therefore, there is a need of a better knowledge of technical performance and limitations of high temperature epoxy resins. This paper examined the influence of the epoxy network architecture on their protection properties and durability while exposed to distilled / sea water at 110 deg. C and to methanol at room temperature. The objective was to investigate the link between resin chemistry and final performance with respect to anticorrosion applications. Five epoxy resin formulations mixed in stoichiometric proportions were cured and post-cured to infinite extent in order to achieve densely cross-linked networks exhibiting controlled and reproducible architectures. Gravimetric and pressurised differential scanning calorimetry (DSC) measurements were performed to evaluate the plasticization effect of both water and methanol on formulations under study. The related

  9. Flame resistant hybrid epoxy composites

    Czech Academy of Sciences Publication Activity Database

    Śliwa, R.; Oleksy, M.; Heneczkowski, M.; Oliwa, R.; Budzik, G.; Kozik, B.; Markowska, O.; Strachota, Adam

    2015-01-01

    Roč. 60, č. 10 (2015), s. 667-670 ISSN 0032-2725 Institutional support: RVO:61389013 Keywords : epoxy resin * quaternary phosphonium salts * modified bentonite Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.718, year: 2015

  10. Characterization and analysis of epoxy/clay nanotubes composites; Cacaterizacao e analise de compositos de epoxi, argila e nanotubos de carbono

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    An DGEBA epoxy matrix was used aiming to achieve a nanocomposite material, through the dispersion of (CNT) via mechanical stirring followed by sonication. In this work the following characterization were performed: mechanical characterization, differential scanning calorimetry (DSC), wide angle X-ray diffraction (WXRD) and scanning electron microscopy (SEM). The addition of CNT and modified clays promoted the increase of modulus of the epoxy matrix, and a synergistic effect between CNT and both clays could be presumed. SEM images of the fracture surface show the difference between the fracture surface area and the presence of clusters among the samples, allowing a correlation with the modulus of elasticity. X-ray diffractograms from 2{Theta} = 5 deg showed no peaks for modified clay samples, however it is possible to affirm that modified clay platelets are forming a less organized structure compared to the structure of the clay as natural in epoxy. (author)

  11. Novel epoxy activated hydrogels for solving lactose intolerance.

    Science.gov (United States)

    Elnashar, Magdy M M; Hassan, Mohamed E

    2014-01-01

    "Lactose intolerance" is a medical problem for almost 70% of the world population. Milk and dairy products contain 5-10% w/v lactose. Hydrolysis of lactose by immobilized lactase is an industrial solution. In this work, we succeeded to increase the lactase loading capacity to more than 3-fold to 36.3 U/g gel using epoxy activated hydrogels compared to 11 U/g gel using aldehyde activated carrageenan. The hydrogel's mode of interaction was proven by FTIR, DSC, and TGA. The high activity of the epoxy group was regarded to its ability to attach to the enzyme's -SH, -NH, and -OH groups, whereas the aldehyde group could only bind to the enzyme's -NH2 group. The optimum conditions for immobilization such as epoxy chain length and enzyme concentration have been studied. Furthermore, the optimum enzyme conditions were also deliberated and showed better stability for the immobilized enzyme and the Michaelis constants, K m and V max, were doubled. Results revealed also that both free and immobilized enzymes reached their maximum rate of lactose conversion after 2 h, albeit, the aldehyde activated hydrogel could only reach 63% of the free enzyme. In brief, the epoxy activated hydrogels are more efficient in immobilizing more enzymes than the aldehyde activated hydrogel.

  12. Electrically Conductive Epoxy Adhesives

    Directory of Open Access Journals (Sweden)

    Lan Bai

    2011-02-01

    Full Text Available Conductive adhesives are widely used in electronic packaging applications such as die attachment and solderless interconnections, component repair, display interconnections, and heat dissipation. The effects of film thickness as functions of filler volume fraction, conductive filler size, shape, as well as uncured adhesive matrix viscosity on the electrical conduction behavior of epoxy-based adhesives are presented in this work. For this purpose, epoxy-based adhesives were prepared using conductive fillers of different size, shape, and types, including Ni powder, flakes, and filaments, Ag powder, and Cu powder. The filaments were 20 μm in diameter, and 160 or 260 μm in length. HCl and H3PO4 acid solutions were used to etch and remove the surface oxide layers from the fillers. The plane resistance of filled adhesive films was measured using the four-point method. In all cases of conductive filler addition, the planar resistivity levels for the composite adhesive films increased when the film thickness was reduced. The shape of resistivity-thickness curves was negative exponential decaying type and was modeled using a mathematical relation. The relationships between the conductive film resistivities and the filler volume fractions were also derived mathematically based on the experimental data. Thus, the effects of surface treatment of filler particles, the type, size, shape of fillers, and the uncured epoxy viscosity could be included empirically by using these mathematical relations based on the experimental data. By utilizing the relations we proposed to model thickness-dependent and volume fraction-dependent conduction behaviors separately, we were able to describe the combined and coupled volume fraction-film thickness relationship mathematically based on our experimental data.

  13. Electroactive polymer gels based on epoxy resin

    Science.gov (United States)

    Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

    2007-04-01

    Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

  14. Quantitative Study of Interface/Interphase in Epoxy/Graphene-Based Nanocomposites by Combining STEM and EELS.

    Science.gov (United States)

    Liu, Yu; Hamon, Ann-Lenaig; Haghi-Ashtiani, Paul; Reiss, Thomas; Fan, Benhui; He, Delong; Bai, Jinbo

    2016-12-14

    A quantitative study of the interphase and interface of graphene nanoplatelets (GNPs)/epoxy and graphene oxide (GO)/epoxy was carried out by combining scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). The interphase regions between GNPs and epoxy matrix were clearly identified by the discrepancy of the plasmon peak positions in the low energy-loss spectra due to different valence electron densities. The spectrum acquisitions were carried out along lines across the interface. An interphase thickness of 13 and 12.5 nm was measured for GNPs/epoxy and GO/epoxy, respectively. The density of the GNPs/epoxy interphase was 2.89% higher than that of the epoxy matrix. However, the density of the GO/epoxy interphase was 1.37% lower than that of the epoxy matrix. The interphase layer thickness measured in this work is in good agreement with the transition layer theory, which proposed an area with modulus linearly varying across a finite width. The results provide an insight into the interphase for carbon-based polymer composites that can help to design the functionalization of nanofillers to improve the composite properties.

  15. Photocured epoxy/graphene nanocomposites with enhanced water vapor barrier properties

    Science.gov (United States)

    Periolatto, M.; Sangermano, M.; Spena, P. Russo

    2016-05-01

    A transparent, water vapor barrier film made of an epoxy resin and graphene oxide (GO) was synthesized by photopolymerization process. The epoxy/GO film with just 0.05 wt% GO gives a 93% WVTR reduction with respect to the pristine polymer, reaching barrier properties better than other polymer composites containing higher amounts of graphene. The excellent water vapor barrier is attributed to the good dispersion of GO in the polymer matrix. Moreover, GO significantly enhances the toughness and the damping capacity of the epoxy resins. The hybrid film can have potential applications in anticorrosive coatings, electronic devices, pharmaceuticals and food packaging.

  16. Photocured epoxy/graphene nanocomposites with enhanced water vapor barrier properties

    Energy Technology Data Exchange (ETDEWEB)

    Periolatto, M.; Spena, P. Russo [Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, Bolzano (Italy); Sangermano, M. [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino (Italy)

    2016-05-18

    A transparent, water vapor barrier film made of an epoxy resin and graphene oxide (GO) was synthesized by photopolymerization process. The epoxy/GO film with just 0.05 wt% GO gives a 93% WVTR reduction with respect to the pristine polymer, reaching barrier properties better than other polymer composites containing higher amounts of graphene. The excellent water vapor barrier is attributed to the good dispersion of GO in the polymer matrix. Moreover, GO significantly enhances the toughness and the damping capacity of the epoxy resins. The hybrid film can have potential applications in anticorrosive coatings, electronic devices, pharmaceuticals and food packaging.

  17. Photocured epoxy/graphene nanocomposites with enhanced water vapor barrier properties

    International Nuclear Information System (INIS)

    Periolatto, M.; Spena, P. Russo; Sangermano, M.

    2016-01-01

    A transparent, water vapor barrier film made of an epoxy resin and graphene oxide (GO) was synthesized by photopolymerization process. The epoxy/GO film with just 0.05 wt% GO gives a 93% WVTR reduction with respect to the pristine polymer, reaching barrier properties better than other polymer composites containing higher amounts of graphene. The excellent water vapor barrier is attributed to the good dispersion of GO in the polymer matrix. Moreover, GO significantly enhances the toughness and the damping capacity of the epoxy resins. The hybrid film can have potential applications in anticorrosive coatings, electronic devices, pharmaceuticals and food packaging.

  18. Synthesis of cuprous oxide epoxy nanocomposite as an environmentally antimicrobial coating.

    Science.gov (United States)

    M El Saeed, Ashraf; Abd El-Fattah, M; Azzam, Ahmed M; Dardir, M M; Bader, Magd M

    2016-08-01

    Cuprous oxide is commonly used as a pigment; paint manufacturers begin to employ cuprous oxide as booster biocides in their formulations, to replace the banned organotins as the principal antifouling compounds. Epoxy coating was reinforced with cuprous oxide nanoparticles (Cu2O NPs). The antibacterial as well as antifungal activity of Cu2O epoxy nanocomposite (Cu2O EN) coating films was investigated. Cu2O NPs were also experimented for antibiofilm and time-kill assay. The thermal stability and the mechanical properties of Cu2O EN coating films were also investigated. The antimicrobial activity results showed slowdown, the growth of organisms on the Cu2O EN coating surface. TGA results showed that incorporating Cu2O NPs into epoxy coating considerably enhanced the thermal stability and increased the char residue. The addition of Cu2O NPs at lower concentration into epoxy coating also led to an improvement in the mechanical resistance such as scratch and abrasion. Cu2O NPs purity was confirmed by XRD. The TEM photograph demonstrated that the synthesized Cu2O NPs were of cubic shape and the average diameter of the crystals was around 25nm. The resulting perfect dispersion of Cu2O NPs in epoxy coating revealed by SEM ensured white particles embedded in the epoxy matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. The non-isothermal DSC kinetics of polyethylene tereftalate–epoxy compatible blends

    International Nuclear Information System (INIS)

    Zvetkov, V.L.; Djoumaliisky, S.; Simeonova-Ivanova, E.

    2013-01-01

    Highlights: ► The non-isothermal DSC kinetics of the reaction of DGEBA with DDS, in particular in the presence of phase separating PET, has been studied. ► The specific features in the kinetics of PET formulations in comparison to the pure system have been discussed. ► The fast pre-curing of the epoxy phase allows supposing sub-micro phase separation of PET and efficient toughening of the epoxy matrix. - Abstract: Polyethylene tereftalate has been dissolved in an epoxy resin based on diglycidyl ether of bisphenol-A, DGEBA, and the epoxy component has been cross-linked with the aid of two diamine hardeners. Two series of samples have been tested at the epoxy-amine stoichiometry applying the differential scanning calorimetry, DSC, in scanning mode. One of the series of samples was pre-cured at low temperatures with the aid of an aliphatic diamine hardener near the gel point and post-cured with diaminodiphenyl sulfone, DDS. The other series of samples contained the higher temperature hardener only. Consequently, the experimental data obtained in this study on both systems relate to the non-isothermal curing of DGEBA with DDS. The kinetics has been estimated applying preferably isoconversional (model free) methods. It has been established that the fast pre-curing allows performing a sub-micro phase separation and efficient toughening of the epoxy matrix

  20. The non-isothermal DSC kinetics of polyethylene tereftalate–epoxy compatible blends

    Energy Technology Data Exchange (ETDEWEB)

    Zvetkov, V.L., E-mail: zvetval@yahoo.com [Institute of Mechanics, Bulgarian Academy of Sciences, bl. I, Sofia 1113 (Bulgaria); Djoumaliisky, S.; Simeonova-Ivanova, E. [Institute of Mechanics, Bulgarian Academy of Sciences, bl. I, Sofia 1113 (Bulgaria)

    2013-02-10

    Highlights: ► The non-isothermal DSC kinetics of the reaction of DGEBA with DDS, in particular in the presence of phase separating PET, has been studied. ► The specific features in the kinetics of PET formulations in comparison to the pure system have been discussed. ► The fast pre-curing of the epoxy phase allows supposing sub-micro phase separation of PET and efficient toughening of the epoxy matrix. - Abstract: Polyethylene tereftalate has been dissolved in an epoxy resin based on diglycidyl ether of bisphenol-A, DGEBA, and the epoxy component has been cross-linked with the aid of two diamine hardeners. Two series of samples have been tested at the epoxy-amine stoichiometry applying the differential scanning calorimetry, DSC, in scanning mode. One of the series of samples was pre-cured at low temperatures with the aid of an aliphatic diamine hardener near the gel point and post-cured with diaminodiphenyl sulfone, DDS. The other series of samples contained the higher temperature hardener only. Consequently, the experimental data obtained in this study on both systems relate to the non-isothermal curing of DGEBA with DDS. The kinetics has been estimated applying preferably isoconversional (model free) methods. It has been established that the fast pre-curing allows performing a sub-micro phase separation and efficient toughening of the epoxy matrix.

  1. Colorless triphenylamine-based aliphatic thermoset epoxy for multicolored and near-infrared electrochromic applications.

    Science.gov (United States)

    Chuang, Ya-Wen; Yen, Hung-Ju; Wu, Jia-Hao; Liou, Guey-Sheng

    2014-03-12

    In this study, two novel colorless thermoset epoxy resins with anodically electrochromism were prepared from the thermal curing of two triphenylamine-based diamine monomers, 4,4'-diamino-4″-methoxytriphenylamine (1) and N,N'-bis(4-aminophenyl)-N,N'-di(4-methoxylphenyl)-1,4-phenylenediamine (2) with aliphatic epoxy triglycidyl isocyanurate, respectively. The resulting thermoset epoxy resins showed excellent softening temperature (Ts, 270 and 280 °C) due to the rigid structure and highly crosslinking density. In addition, novel colorless epoxy resin films revealed good reversible electrochemical oxidation and interesting multi-electrochromic behavior with high contrast ratio both in visible and near-infrared regions. The aliphatic thermoset epoxy resins also exhibited high transparency in visible region as colorless and great potential for practical electrochromic applications.

  2. Damage detection and conductivity evolution in carbon nanofiber epoxy via electrical impedance tomography

    International Nuclear Information System (INIS)

    Tallman, T N; Wang, K W; Gungor, S; Bakis, C E

    2014-01-01

    Utilizing electrically conductive nanocomposites for integrated self-sensing and health monitoring is a promising area of structural health monitoring (SHM) research wherein local changes in conductivity coincide with damage. In this research we conduct proof of concept investigations using electrical impedance tomography (EIT) for damage detection by identifying conductivity changes and by imaging conductivity evolution in a carbon nanofiber (CNF) filled epoxy composite. CNF/epoxy is examined because fibrous composites can be manufactured with a CNF/epoxy matrix thereby enabling the entire matrix to become self-sensing. We also study the mechanisms of conductivity evolution in CNF/epoxy through electrical impedance spectroscopy (EIS) testing. The results of these tests indicate that thermal expansion is responsible for conductivity evolution in a CNF/epoxy composite. (paper)

  3. Nanoindentation study of interphases in epoxy/amine thermosetting systems modified with thermoplastics.

    Science.gov (United States)

    Ramos, Jose Angel; Blanco, Miren; Zalakain, Iñaki; Mondragon, Iñaki

    2009-08-15

    The characterization of a mixture of epoxy/amine with different stoichiometric ratios was carried out by means of nanoindentation. The epoxy system was composed by diglycidyl ether of bisphenol-A and 4,4'-methylene bis-(3-chloro 2,6-diethylaniline). Diffusion through interface formed by epoxy/amine system in stoichiometric ratio and several thermoplastic polymers was also analyzed by means of stiffness analysis, as studied by atomic force microscopy (AFM) and coupled nanoindentation tests. Used thermoplastics were an amorphous, atactic polystyrene, and two semicrystalline, syndiotactic polystyrene and poly(phenylene sulfide). Larger range diffusion was obtained in epoxy/amine systems modified with atactic polystyrene while the study of the influence of stoichiometric ratio suggests that the excess of epoxy generated stiffer material. In addition, larger indentation loads resulted in higher apparent stiffness because of the more number of polymer chains that had to re-accommodate owing to the increase in contact area.

  4. E-Beam-Cured Layered-Silicate and Spherical Silica Epoxy Nanocomposites (Preprint)

    National Research Council Canada - National Science Library

    Chen, Chenggang; Anderson, David P

    2007-01-01

    .... The nanofillers can be two dimensional (layered-silicate) and zero dimensional (spherical silica). Both the spherical silica epoxy nanocomposite and the layered-silicate epoxy nanocomposite can be cured to a high degree of curing...

  5. UV absorption by cerium oxide nanoparticles/epoxy composite thin films

    International Nuclear Information System (INIS)

    Dao, Ngoc Nhiem; Luu, Minh Dai; Nguyen, Quang Khuyen; Kim, Byung Sun

    2011-01-01

    Cerium oxide (CeO 2 ) nanoparticles have been used to modify properties of an epoxy matrix in order to improve the ultra-violet (UV) absorption property of epoxy thin films. The interdependence of mechanical properties, UV absorption property and the dispersed concentration of CeO 2 nanoparticles was investigated. Results showed that, by increasing the dispersed concentration of CeO 2 nanoparticles up to 3 wt%, tensile modulus increases while two other mechanical properties, namely tensile strength and elongation, decrease. The UV absorption peak and the absorption edges of the studied thin films were observed in the UV-Vis absorption spectra. By incorporating CeO 2 nanoparticles into the epoxy matrix, an absorption peak appears at around 318 nm in UV-Vis spectra with increasing CeO 2 concentration from 0.1 to 1.0 wt%. Scanning electron microscopy (SEM) images revealed that a good dispersion of nanoparticles in the epoxy matrix by an ultrasonic method was achieved

  6. Improvement of Mechanical and Dielectric Properties of Epoxy Resin Using CNTs/ZnO Nanocomposite.

    Science.gov (United States)

    Vu, Pham Gia; Truc, Trinh Anh; Chinh, Nguyen Thuy; Tham, Do Quang; Trung, Tran Huu; Oanh, Vu Ke; Hang, To Thi Xuan; Olivier, Marjorie; Hoang, Thai

    2018-04-01

    In this study, carbon nanotubes (CNTs)/ZnO composites had been prepared using the sol-gel method and then incorporated into an epoxy resin for reinforcement of mechanical and electrical properties. Fourier Transform Infrared (FTIR), X-ray diffraction (XRD) Field Emission Scanning Electron Microscope (FE-SEM) analyses show that the ZnO nanoparticles deposited on CNTs were crystallized in a hexagonal wurtzite structure. Average particle size of ZnO deposited on the CNT was about 8 nm. The mechanical and dielectric properties of epoxy containing CNTs/ZnO were investigated in comparison to epoxy resin and epoxy resin containing only CNT or ZnO nanoparticles. The results indicated that tensile strength and elongation at break of the nanocomposite were substantially improved with the presence of CNTs/ZnO at the equal volume. The DSC analysis associate with the dielectric results shows that the behavior of epoxy/CNTs/ZnO is identical to epoxy/ZnO composite, and the CNTs is essential to the distributed arrangement of ZnO in the epoxy resin.

  7. Epoxy-based broadband antireflection coating for millimeter-wave optics.

    Science.gov (United States)

    Rosen, Darin; Suzuki, Aritoki; Keating, Brian; Krantz, William; Lee, Adrian T; Quealy, Erin; Richards, Paul L; Siritanasak, Praween; Walker, William

    2013-11-20

    We have developed epoxy-based, broadband antireflection coatings for millimeter-wave astrophysics experiments with cryogenic optics. By using multiple-layer coatings where each layer steps in dielectric constant, we achieved low reflection over a wide bandwidth. We suppressed the reflection from an alumina disk to 10% over fractional bandwidths of 92% and 104% using two-layer and three-layer coatings, respectively. The dielectric constants of epoxies were tuned between 2.06 and 7.44 by mixing three types of epoxy and doping with strontium titanate powder required for the high dielectric mixtures. At 140 K, the band-integrated absorption loss in the coatings was suppressed to less than 1% for the two-layer coating, and below 10% for the three-layer coating.

  8. DEGRADATION OF MAGNET EPOXY AT NSLS X-RAY RING.

    Energy Technology Data Exchange (ETDEWEB)

    HU,J.P.; ZHONG,Z.; HAAS,E.; HULBERT,S.; HUBBARD,R.

    2004-05-24

    Epoxy resin degradation was analyzed for NSLS X-ring magnets after two decades of 2.58-2.8 GeV continuous electron-beam operation, based on results obtained from thermoluminescent dosimeters irradiated along the NSLS ring and epoxy samples irradiated at the beamline target location. A Monte Carlo-based particle transport code, MCNP, was utilized to verify the dose from synchrotron radiation distributed along the axial- and transverse-direction in a ring model, which simulates the geometry of a ring quadrupole magnet and its central vacuum chamber downstream of the bending-magnet photon ports. The actual life expectancy of thoroughly vacuum baked-and-cured epoxy resin was estimated from radiation tests on similar polymeric materials using a radiation source developed for electrical insulation and mechanical structure studies.

  9. Protection of Steel Rebar in Salt-Contaminated Cement Mortar Using Epoxy Nanocomposite Coatings

    Directory of Open Access Journals (Sweden)

    The Huu Nguyen

    2018-01-01

    Full Text Available Epoxy reinforced with two kinds of nanoparticles dealing with nano-SiO2 and nano-Fe2O3 was coated on steel rebar embedded in a chloride contaminated cement mortar. NaCl was added to the fresh Portland cement paste (at 0.3% and 0.5% by weight of cement to simulate the chloride contamination at the critical level. The effect of incorporating nanoparticles on the corrosion resistance of epoxy-coated steel rebar was investigated by linear potentiodynamic polarization and electrochemical impedance spectroscopy. For the 0.3 wt.% chloride mortars, the electrochemical monitoring of the coated steel rebars during immersion for 56 days in 0.1 M NaOH solutions suggested the beneficial role of nano-Fe2O3 particles in significantly improving the corrosion resistance of the epoxy-coated rebar. After 56 days of immersion, the nano-Fe2O3 reduced the corrosion current of epoxy-coated rebar by a factor of 7.9. When the chloride concentration in the cement mortar was 0.5 wt.%, the incorporation of nanoparticles into the epoxy matrix did not enhance the corrosion resistance of epoxy coating for the rebar. At this critical level, chloride ions initiated rebar corrosion through nanoparticles at the epoxy/rebar interface.

  10. Effect of Thermally Reduced Graphene Oxide on Mechanical Properties of Woven Carbon Fiber/Epoxy Composite

    Directory of Open Access Journals (Sweden)

    Nitai Chandra Adak

    2018-02-01

    Full Text Available Thermally reduced graphene oxide (TRGO was incorporated as a reinforcing filler in the epoxy resin to investigate the effect on the mechanical properties of carbon fiber (CF/epoxy composites. At first, the epoxy matrix was modified by adding different wt % of TRGO from 0.05 to 0.4 wt % followed by the preparation of TRGO/CF/epoxy composites througha vacuum-assisted resin transfer molding process. The prepared TRGO was characterized by using Fourier transform infrared spectroscopy, Raman Spectroscopy and field emission scanning electron microscopy (FE-SEM techniques. It was observed that the wrinkled structure of synthesized TRGO may be helpful to interlock with the epoxy resin and CF.The inter-laminar shear strength, in-plane fracture toughness and impact strength increased by ~67%, 62% and 93% at 0.2 wt % of TRGO loading in the CF/epoxy composites as compared to the CF reinforced epoxy. The mechanical properties of the hybrid composites decreased beyond the 0.2 wt % of TRGO incorporation in the epoxy resin. The fracture surfaces of the hybrid composites were studied by FE-SEM image analysis to investigate the synergistic effect of TRGO in the CF/epoxy composite. This study suggested that TRGO could be used asgood nanofiller to resist the matrix and fiber fracture.

  11. Characterization and analysis of epoxy/clay nanotubes composites

    International Nuclear Information System (INIS)

    Sene, Tarcisio S.; Kock, Thyago; Coelho, Luiz A.F.; Becker, Daniela

    2011-01-01

    An DGEBA epoxy matrix was used aiming to achieve a nanocomposite material, through the dispersion of (CNT) via mechanical stirring followed by sonication. In this work the following characterization were performed: mechanical characterization, differential scanning calorimetry (DSC), wide angle X-ray diffraction (WXRD) and scanning electron microscopy (SEM). The addition of CNT and modified clays promoted the increase of modulus of the epoxy matrix, and a synergistic effect between CNT and both clays could be presumed. SEM images of the fracture surface show the difference between the fracture surface area and the presence of clusters among the samples, allowing a correlation with the modulus of elasticity. X-ray diffractograms from 2Θ = 5 deg showed no peaks for modified clay samples, however it is possible to affirm that modified clay platelets are forming a less organized structure compared to the structure of the clay as natural in epoxy. (author)

  12. Mechanical Properties of Epoxy and Its Carbon Fiber Composites Modified by Nanoparticles

    Directory of Open Access Journals (Sweden)

    Fang Liu

    2017-01-01

    Full Text Available Compressive properties are commonly weak parts in structural application of fiber composites. Matrix modification may provide an effective way to improve compressive performance of the composites. In this work, the compressive property of epoxies (usually as matrices of fiber composites modified by different types of nanoparticles was firstly investigated for the following study on the compressive property of carbon fiber reinforced epoxy composites. Carbon fiber/epoxy composites were fabricated by vacuum assisted resin infusion molding (VARIM technique using stitched unidirectional carbon fabrics, with the matrices modified with nanosilica, halloysite, and liquid rubber. Testing results showed that the effect of different particle contents on the compressive property of fiber/epoxy composites was more obvious than that in epoxies. Both the compressive and flexural results showed that rigid nanoparticles (nanosilica and halloysite have evident strengthening effects on the compression and flexural responses of the carbon fiber composite laminates fabricated from fabrics.

  13. Hydrothermal ageing of glass/epoxy composites for wind turbine blades

    NARCIS (Netherlands)

    Rocha, I.B.C.M.; Raijmaekers, S.; Nijssen, R.P.L.; Van der Meer, F.P.

    2015-01-01

    In this work, a glass/epoxy material system commonly applied in wind turbine design was used to evaluate damage processes brought by water ingression during service life. Composite short-beams and neat epoxy beams and dog-bones were conditioned by water immersion at 50º until saturation and tested

  14. Nickel-catalyzed regio- and enantioselective aminolysis of 3,4-epoxy alcohols.

    Science.gov (United States)

    Wang, Chuan; Yamamoto, Hisashi

    2015-04-08

    The first catalytic regio- and enantioselective aminolysis of 3,4-epoxy alcohols has been accomplished. Under the catalysis of Ni(ClO4)2·6H2O, the C4 selective ring opening of various 3,4-epoxy alcohols proceeded in a stereospecific manner with high regioselectivities. Furthermore, with the Ni-BINAM catalytic system the enantioselective ring opening of 3,4-epoxy alcohols furnished various γ-hydroxy-δ-amino alcohols as products with complete regiocontrol and high enantioselectivities (up to 94% ee).

  15. Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

    OpenAIRE

    Maria Elena Arce; Miguel Angel Alvarez Feijoo; Andres Suarez Garcia; Claudia C. Luhrs

    2018-01-01

    This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the sa...

  16. Creep behavior of an epoxy resin and an epoxy-based FRP in condition of simultaneous supply of radiation and stress at cryogenic temperatures

    International Nuclear Information System (INIS)

    Nishiura, Tetsuya; Nishijima, Shigehiro; Okada, Toichi

    1995-01-01

    Creep tests of an epoxy resin and an epoxy-based FRP in bending under irradiation condition have been carried out, to investigate the synergistic effects of radiation and stress on mechanical properties of FRP. Simultaneous supply of stress and irradiation on the epoxy resin and the FRP enhanced creep rates in comparison with that supply of the stress on a post-irradiated one did. ESR spectra measurement was also carried out to study the change of molecule of the resin irradiated. Increase of molecular weight between crosslinks was found out to be enhanced by the synergistic effect of radiation and stress. The mechanism of increased damage of FRP induced by the effects of simultaneous stress and irradiation is discussed. (author)

  17. Determination of Young's modulus of epoxy coated polyethylene micro-cantilever using phase-shift shadow moiré method

    Science.gov (United States)

    Lim, J. H.; Ratnam, M. M.; Azid, I. A.; Mutharasu, D.

    2011-11-01

    Young's moduli of various epoxy coated polyethylene terephthalate (PET) micro-cantilevers were determined from the deflection results obtained using the phase-shift shadow moiré (PSSM) method. The filler materials for epoxy coatings were aluminum and graphite powders that were mixed with epoxy at various percentages. Young's moduli were calculated from theory based on the deflection results. The PET micro-cantilever coated with aluminum-epoxy coating showed increasing value of Young's modulus when the ratios of the aluminum-epoxy were increased. The graphite-epoxy coating on the PET micro-cantilever also showed the same trend. The experimental results also show that Young's modulus of the graphite-epoxy coating is higher than aluminum-epoxy coating in comparison at the same mixing ratio.

  18. Preparation, Characterization, and Modeling of Carbon Nanofiber/Epoxy Nanocomposites

    Directory of Open Access Journals (Sweden)

    Lan-Hui Sun

    2011-01-01

    Full Text Available There is a lack of systematic investigations on both mechanical and electrical properties of carbon nanofiber (CNF-reinforced epoxy matrix nanocomposites. In this paper, an in-depth study of both static and dynamic mechanical behaviors and electrical properties of CNF/epoxy nanocomposites with various contents of CNFs is provided. A modified Halpin-Tsai equation is used to evaluate the Young's modulus and storage modulus of the nanocomposites. The values of Young's modulus predicted using this method account for the effect of the CNF agglomeration and fit well with those obtained experimentally. The results show that the highest tensile strength is found in the epoxy nanocomposite with a 1.0 wt% CNFs. The alternate-current (AC electrical properties of the CNF/epoxy nanocomposites exhibit a typical insulator-conductor transition. The conductivity increases by four orders of magnitude with the addition of 0.1 wt% (0.058 vol% CNFs and by ten orders of magnitude for nanocomposites with CNF volume fractions higher than 1.0 wt% (0.578 vol%. The percolation threshold (i.e., the critical CNF volume fraction is found to be at 0.057 vol%.

  19. Tailored SWCNT functionalization optimized for compatibility with epoxy matrices

    International Nuclear Information System (INIS)

    Martinez-Rubi, Y; Kingston, C T; Daroszewska, M; Barnes, M; Simard, B; Gonzalez-Dominguez, J M; Ansón-Casaos, A; Martinez, M T; Hubert, P; Cattin, C

    2012-01-01

    We have modified single walled carbon nanotubes (SWCNTs) with well defined matrix-based architectures to improve interface interaction in SWCNT/epoxy composites. The hardener and two pre-synthesized oligomers containing epoxy and hardener moieties were covalently attached to the SWCNT walls by in situ diazonium or carboxylic coupling reactions. In this way, SWCNTs bearing amine or epoxide-terminated fragments of different molecular weights, which resemble the chemical structure of the cured resin, were synthesized. A combination of characterization techniques such as Raman and infrared absorption (FTIR) spectroscopy, elemental analysis and coupled thermogravimetry-FTIR spectroscopy were used to identify both the functional groups and degree of functionalization of SWCNTs synthesized by the laser ablation and arc-discharge methods. Depending on the type of reaction employed for the chemical functionalization and the molecular weight of the attached fragment, it was possible to control the degree of functionalization and the electronic properties of the functionalized SWCNTs. Improved dispersion of SWCNTs in the epoxy matrix was achieved by direct integration without using solvents, as observed from optical microscopy and rheology measurements of the SWCNT/epoxy mixtures. Composite materials using these fillers are expected to exhibit improved properties while preserving the thermosetting architecture. (paper)

  20. AC electrical breakdown phenomena of epoxy/layered silicate nanocomposite in needle-plate electrodes.

    Science.gov (United States)

    Park, Jae-Jun; Lee, Jae-Young

    2013-05-01

    Epoxy/layered silicate nanocomposite for the insulation of heavy electric equipments were prepared by dispersing 1 wt% of a layered silicate into an epoxy matrix with a homogenizing mixer and then AC electrical treeing and breakdown tests were carried out. Wide-angle X-ray diffraction (WAXD) analysis and transmission electron microscopy (TEM) observation showed that nano-sized monolayers were exfoliated from a multilayered silicate in the epoxy matrix. When the nano-sized silicate layers were incorporated into the epoxy matrix, the breakdown rate in needle-plate electrode geometry was 10.6 times lowered than that of the neat epoxy resin under the applied electrical field of 520.9 kV/mm at 30 degrees C, and electrical tree propagated with much more branches in the epoxy/layered silicate nanocomposite. These results showed that well-dispersed nano-sized silicate layers retarded the electrical tree growth rate. The effects of applied voltage and ambient temperature on the tree initiation, growth, and breakdown rate were also studied, and it was found that the breakdown rate was largely increased, as the applied voltage and ambient temperature increased.

  1. Curing behaviors and properties of an extrinsic toughened epoxy/anhydride system and an intrinsic toughened epoxy/anhydride system

    International Nuclear Information System (INIS)

    Fan, Mengjin; Liu, Jialin; Li, Xiangyuan; Cheng, Jue; Zhang, Junying

    2013-01-01

    Highlights: ► Two curing systems (ETRS and ITRS) with similar chemical composite were prepared. ► The curing kinetics of the ETRS and the novel ITRS were comparatively studied. ► Crosslinking density can affect the kinetic schemes of the two curing systems. ► Their mechanical properties and thermal stabilities were also comparatively studied. ► Crosslinking density may play an influential role in mechanical properties. - Abstract: The curing kinetics of an extrinsic toughened epoxy (mixture of diglycidyl ether of bisphenol-A and 1,4-butanediol epoxy resin, DGEBA/DGEBD) and an intrinsic toughened epoxy (ethoxylated bisphenol-A epoxy resin with two oxyethylene units, DGEBAEO-2) using hexahydrophthalic anhydride (HHPA) as curing agent and tris-(dimethylaminomethyl) phenol (DMP-30) as accelerator were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TGA, respectively. The results showed that Šesták–Berggren model can generally simulate well the reaction rates of these two systems. The activation energy of DGEBA/DGEBD/HHPA/DMP-30 at high fractional conversion changed much higher than that of DGEBAEO-2/HHPA/DMP-30, indicating the increased steric hindrance mainly affected the reaction kinetic scheme of DGEBA/DGEBD/HHPA/DMP-30. The T g and storage moduli of cured DGEBAEO-2/HHPA/DMP-30 were lower than those of cured DGEBA/DGEBD/HHPA/DMP-30 according to DMTA while TGA showed that the thermal stabilities of these two cured systems were similar

  2. Curing behaviors and properties of an extrinsic toughened epoxy/anhydride system and an intrinsic toughened epoxy/anhydride system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Mengjin; Liu, Jialin; Li, Xiangyuan [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Cheng, Jue, E-mail: chengjue@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Junying, E-mail: zjybuct@gmail.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China)

    2013-02-20

    Highlights: ► Two curing systems (ETRS and ITRS) with similar chemical composite were prepared. ► The curing kinetics of the ETRS and the novel ITRS were comparatively studied. ► Crosslinking density can affect the kinetic schemes of the two curing systems. ► Their mechanical properties and thermal stabilities were also comparatively studied. ► Crosslinking density may play an influential role in mechanical properties. - Abstract: The curing kinetics of an extrinsic toughened epoxy (mixture of diglycidyl ether of bisphenol-A and 1,4-butanediol epoxy resin, DGEBA/DGEBD) and an intrinsic toughened epoxy (ethoxylated bisphenol-A epoxy resin with two oxyethylene units, DGEBAEO-2) using hexahydrophthalic anhydride (HHPA) as curing agent and tris-(dimethylaminomethyl) phenol (DMP-30) as accelerator were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TGA, respectively. The results showed that Šesták–Berggren model can generally simulate well the reaction rates of these two systems. The activation energy of DGEBA/DGEBD/HHPA/DMP-30 at high fractional conversion changed much higher than that of DGEBAEO-2/HHPA/DMP-30, indicating the increased steric hindrance mainly affected the reaction kinetic scheme of DGEBA/DGEBD/HHPA/DMP-30. The T{sub g} and storage moduli of cured DGEBAEO-2/HHPA/DMP-30 were lower than those of cured DGEBA/DGEBD/HHPA/DMP-30 according to DMTA while TGA showed that the thermal stabilities of these two cured systems were similar.

  3. The Effect of Nanoparticles Percentage on Mechanical Behavior of Silica-Epoxy Nanocomposites

    International Nuclear Information System (INIS)

    Islam, M.S.; Masoodi, R.; Rostami, H.

    2013-01-01

    Silica-epoxy nanocomposites are very common among nanocomposites, which makes them very important. Several researchers have studied the effect of nanoparticle’s size, shape, and loading on mechanical behavior of silica-epoxy nanocomposites. This paper reviews the most important research done on the effect of nanoparticle loading on mechanical properties of silica-epoxy nanocomposites. While the main focus is the tensile behavior of nanocomposite, the compressive behavior and flexural behavior were also reviewed. Finally, some of the published experimental data were combined in the graphs, using dimensionless parameters. Later, the best fitted curves were used to derive some empirical formulas for mechanical properties of silica-epoxy nanocomposites as functions of weight or volume fraction of nanoparticles.

  4. Novel Epoxy Activated Hydrogels for Solving Lactose Intolerance

    Directory of Open Access Journals (Sweden)

    Magdy M. M. Elnashar

    2014-01-01

    Full Text Available “Lactose intolerance” is a medical problem for almost 70% of the world population. Milk and dairy products contain 5–10% w/v lactose. Hydrolysis of lactose by immobilized lactase is an industrial solution. In this work, we succeeded to increase the lactase loading capacity to more than 3-fold to 36.3 U/g gel using epoxy activated hydrogels compared to 11 U/g gel using aldehyde activated carrageenan. The hydrogel’s mode of interaction was proven by FTIR, DSC, and TGA. The high activity of the epoxy group was regarded to its ability to attach to the enzyme’s –SH, –NH, and –OH groups, whereas the aldehyde group could only bind to the enzyme’s –NH2 group. The optimum conditions for immobilization such as epoxy chain length and enzyme concentration have been studied. Furthermore, the optimum enzyme conditions were also deliberated and showed better stability for the immobilized enzyme and the Michaelis constants, Km and Vmax, were doubled. Results revealed also that both free and immobilized enzymes reached their maximum rate of lactose conversion after 2 h, albeit, the aldehyde activated hydrogel could only reach 63% of the free enzyme. In brief, the epoxy activated hydrogels are more efficient in immobilizing more enzymes than the aldehyde activated hydrogel.

  5. Interlaminar fracture in woven carbon/epoxy laminates

    Directory of Open Access Journals (Sweden)

    Paulo N.B. Reis

    2014-10-01

    Full Text Available This paper describes an experimental study developed to characterize the mode I and mode II fracture toughness of carbon/epoxy woven composites, using DCB and ENF tests, respectively. The laminates were manufactured using an epoxy resin and twelve woven balanced bi-directional layers of carbon fibres, all of them with the same orientation (0/90º. Significant instantaneous delaminations were observed particularly for the DCB specimen, which were responsible for an oscillatory behaviour of GI versus crack length. The maximum values obtained for GIC and GIIC were 281 and 1800 J/m2, respectively.

  6. Control of pore size in epoxy systems.

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Patricia Sue; Lenhart, Joseph Ludlow (North Dakota State University, Fargo, ND); Lee, Elizabeth (North Dakota State University, Fargo, ND); Kallam, Alekhya (North Dakota State University, Fargo, ND); Majumdar, Partha (North Dakota State University, Fargo, ND); Dirk, Shawn M.; Gubbins, Nathan; Chisholm, Bret J. (North Dakota State University, Fargo, ND); Celina, Mathias C.; Bahr, James (North Dakota State University, Fargo, ND); Klein, Robert J.

    2009-01-01

    Both conventional and combinatorial approaches were used to study the pore formation process in epoxy based polymer systems. Sandia National Laboratories conducted the initial work and collaborated with North Dakota State University (NDSU) using a combinatorial research approach to produce a library of novel monomers and crosslinkers capable of forming porous polymers. The library was screened to determine the physical factors that control porosity, such as porogen loading, polymer-porogen interactions, and polymer crosslink density. We have identified the physical and chemical factors that control the average porosity, pore size, and pore size distribution within epoxy based systems.

  7. Preparation of a bio-based epoxy with comparable properties to those of petroleum-based counterparts

    Directory of Open Access Journals (Sweden)

    X. Q. Liu

    2012-04-01

    Full Text Available In this paper a bio-based epoxy with outstanding thermal and mechanical properties was synthesized using a rosin-based epoxy monomer and a rosin-based curing agent. The chemical structures of rosin based epoxy monomer and curing agent were confirmed by Nuclear Magnetic Resonance (NMR and Fourier Transform Infrared (FT-IR spectra. The flexural mechanical and dynamic mechanical properties as well as thermal stability of the cured epoxy were investigated. The results showed that the cured epoxy exhibited a glass transition temperature (Tg of 164°C and its flexural strength and modulus were as high as 70 and 2200 MPa, respectively. This indicated that a wholly bio-based epoxy resin possessing high performance was successfully obtained.

  8. Wear Behavior of Woven Roving Aramid / Epoxy Composite under Different Conditions

    Directory of Open Access Journals (Sweden)

    Asad A. Khalid

    2012-09-01

    Full Text Available Wear behavior studies of aramid woven roving /epoxy composite has been conducted. Sliding the material against smooth steel counter face under dry and  lubricated with oil conditions has been investigated. Powder of Silicon carbide has been mixed with the epoxy resin and tested also. The powder was mixed in a volumetric fraction of 10% with the epoxy resin. Four Laminates of six layers were fabricated by hand lay up  method. A pin on disc apparatus has been fabricated to conduct the sliding wear tests on specimens of (4 mm   4 mm   12 mm in size have been cut from the four laminates. The effect of sliding condition including dry, lubricated, dry with additives and lubricated with additives have been studied. Wear rate tests have been conducted at different sliding speeds and loads. Results show that the wear characteristics are influenced by the operating conditions and the construction of the composite material used. It was also found that the wear of aramid /epoxy composite onto the steel counter face were significantly reduced by using lubricant and additives but still took place.Keywords: Wear, Composite materials, Woven roving aramid, Epoxy, Additives, Lubricant.

  9. Development of a new composite system: fire resistant and highly structural

    Directory of Open Access Journals (Sweden)

    González, J.

    2010-06-01

    Full Text Available Infrastructure and rail sectors share two singularities in terms of materials: highly structural performance and strict fire requirements. Moreover, there is a common growing interest in both sectors: the use of organic matrix composite materials due to their high performance, lightweight and in-service behavior. Traditionally, fire fillers have been added to the matrix, decreasing its mechanical performance in a critical way. A study about composite materials formed by three different matrices and four different carbon fibers will be presented in this paper. A number of laminates have been manufactured by using these composite materials in order to analyze both the resin processing and the compatibility of the different matrices and fibers. This study is a need due to the fact that these matrices are fire-related and therefore further problems may arise in comparison with standard matrices.

    Los sectores de la construcción y del ferrocarril tienen dos aspectos en común en el ámbito de los materiales: la utilización de materiales altamente estructurales y la aplicación de estrictos requerimientos de fuego. Asimismo, en ambos sectores existe un interés creciente en el uso de materiales compuestos de matriz orgánica por sus excelentes prestaciones, ligereza y comportamiento en servicio. Tradicionalmente, se han aplicado cargas anti-fuego a la matriz orgánica, disminuyendo sus propiedades mecánicas de forma importante. En este artículo se presentará un estudio de materiales compuestos formados por tres matrices orgánicas diferentes y cuatro tipos de fibras de carbono. Con estos constituyentes se han fabricado diferentes laminados para analizar, por un lado, la procesabilidad de estas resinas, y, por otro, la compatibilidad de estas resinas con las fibras de refuerzo utilizadas. Este estudio es necesario debido a que al tratarse de resinas formuladas con características frente a fuego y humos, su fabricabilidad puede

  10. Estudo do comportamento térmico de laminados carbono/epóxi submetidos a múltiplos ciclos térmicos

    Directory of Open Access Journals (Sweden)

    Christiane Sales Reis de Souza

    2016-01-01

    Full Text Available Resumo Este trabalho apresenta um estudo comparativo dos comportamentos térmicos de três famílias de laminados de fibra de carbono/resina epóxi, submetidas a múltiplos ciclos térmicos, via análises termogravimétricas e dinâmico-mecânicas. Este estudo procura aliar a possibilidade de utilização de retalhos de pré-impregnados de fibra de carbono com resina epóxi - um material nobre na indústria aeronáutica, por meio da comparação do comportamento térmico de um laminado preparado com retalhos de pré-impregnados (laminado R, com outros dois laminados, sendo um manufaturado com prepreg comercial (laminado A e um terceiro obtido por impregnação manual de reforço seco de fibra de carbono com resina epóxi (laminado B. Os laminados curados a 180 °C foram submetidos a múltiplos ciclos térmicos, totalizando 40, 100 e 300 h de exposição na temperatura máxima de 180 °C. As análises termogravimétricas mostram que os laminados submetidos às múltiplas ciclagens apresentam estabilidade térmica na temperatura de 180 °C, com perda de massa relativa à umidade absorvida pelos laminados. As análises dinâmico-mecânicas evidenciam que as múltiplas ciclagens térmicas afetam pouco ou até aumentam as temperaturas de transição vítrea dos sistemas de resinas epóxis estudados. A partir dos resultados obtidos pode-se afirmar que os laminados submetidos às múltiplas ciclagens térmicas apresentam estabilidade térmica suficiente para serem utilizados, por exemplo, em ferramentais de cura de componentes aeronáuticos.

  11. The thermal properties of a carbon nanotube-enriched epoxy: Thermal conductivity, curing, and degradation kinetics

    KAUST Repository

    Ventura, Isaac Aguilar

    2013-05-31

    Multiwalled carbon nanotube-enriched epoxy polymers were prepared by solvent evaporation based on a commercially available epoxy system and functionalized multiwalled carbon nanotubes (COOH-MWCNTs). Three weight ratio configurations (0.05, 0.5, and 1.0 wt %) of COOH-MWCNTs were considered and compared with neat epoxy and ethanol-treated epoxy to investigate the effects of nano enrichment and processing. Here, the thermal properties of the epoxy polymers, including curing kinetics, thermal conductivity, and degradation kinetics were studied. Introducing the MWCNTs increased the curing activation energy as revealed by differential scanning calorimetry. The final thermal conductivity of the 0.5 and 1.0 wt % MWCNT-enriched epoxy samples measured by laser flash technique increased by up to 15% compared with the neat material. The activation energy of the degradation process, investigated by thermogravimetric analysis, was found to increase with increasing CNT content, suggesting that the addition of MWCNTs improved the thermal stability of the epoxy polymers. © 2013 Wiley Periodicals, Inc.

  12. Effect of electron beam irradiation on thermal and mechanical properties of aluminum based epoxy composites

    Science.gov (United States)

    Visakh, P. M.; Nazarenko, O. B.; Sarath Chandran, C.; Melnikova, T. V.; Nazarenko, S. Yu.; Kim, J.-C.

    2017-07-01

    The epoxy resins are widely used in nuclear and aerospace industries. The certain properties of epoxy resins as well as the resistance to radiation can be improved by the incorporation of different fillers. This study examines the effect of electron beam irradiation on the thermal and mechanical properties of the epoxy composites filled with aluminum nanoparticles at percentage of 0.35 wt%. The epoxy composites were exposed to the irradiation doses of 30, 100 and 300 kGy using electron beam generated by the linear electron accelerator ELU-4. The effects of the doses on thermal and mechanical properties of the aluminum based epoxy composites were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The results revealed that the studied epoxy composites showed good radiation resistance. The thermal and mechanical properties of the aluminum based epoxy composites increased with increasing the irradiation dose up to 100 kGy and decreased with further increasing the dose.

  13. Bilirrubina covalente : estudio en las enfermedades hepatobiliares

    OpenAIRE

    Ruiz Cabello Jiménez, Miguel

    2011-01-01

    Una cuarta bilirrubina ha sido identificada, llamada bilirrubinacovalente, delta o biliproteina, la cual esta constituida por bilirrubina conjugada unida por enlace probablemente covalente a la albumina. para estudiar su importancia cl??nica hemos determinado la bilirrubina covalente en 499 muestras de 226 individuos mediante cromatografia con resina intercambiadora de aniones, m??todo ideado por seligson. en sujetos normales, en pacientes con hiperbilirrubinemia indirecta excluidos aquellos ...

  14. Modificación de grafeno con cadenas de polisulfona e incorporación a matrices poliméricas. Evaluación de las propiedades y de la biocompatibilidad de los nanocomposites

    OpenAIRE

    Peña Bahamonde, Janire

    2017-01-01

    Mención Internacional en el título de doctor La presente tesis trata del estudio y diseño de nanocomposites de grafeno empleando como matrices poliméricas polisulfona y una mezcla de polímeros de polisulfona y resina epoxi. En el diseño de estos nanocomposites juega un papel muy importante la interfase del nanomaterial; ya que una buena interacción entre la nanopartícula y la matriz en la región interfacial podría mejorar la estabilidad y despersabilidad de los nanorrefuerzo...

  15. Materiales compuestos biodegradables con usos agronómicos a partir de raíces tuberosas

    OpenAIRE

    Versino, Florencia

    2017-01-01

    Los materiales poliméricos abarcan un amplio abanico de compuestos tanto naturales (proteínas, almidones, etc.) como sintéticos (polietilenos, poliuretanos, resinas epoxy, etc.) cuya versatilidad y fácil procesamiento los ha vuelto adecuados para un gran número de aplicaciones industriales. A raíz de la creciente necesidad de mitigar las emisiones de gases de efecto invernadero, reducir la acumulación de residuos sólidos y disminuir el consumo de recursos no renovables, el interés en el desar...

  16. Design and analysis of MEMS MWCNT / epoxy strain sensor using ...

    Indian Academy of Sciences (India)

    Gaurav Sapra

    2017-06-20

    Jun 20, 2017 ... In this paper, highly sensitive MEMS-based multi- walled (MWCNT)/epoxy strain sensor has been designed using ... This paper also discusses the process flow for fabricating MWCNT/epoxy thin film ... stone bridge, i.e., connected to the gold metal pad of the sensor. The change in resistance with respect to.

  17. Morphological Study on Room-Temperature-Cured PMMA-Grafted Natural Rubber-Toughened Epoxy/Layered Silicate Nanocomposite

    OpenAIRE

    Yuhana, N. Y.; Ahmad, S.; Kamal, M. R.; Jana, S. C.; Bahri, A. R. Shamsul

    2012-01-01

    A morphological study was conducted on ternary systems containing epoxy, PMMA-grafted natural rubber, and organic chemically modified montmorillonite (Cloisite 30B). Optical microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and wide-angle X-ray diffraction (WAXD) analysis were used. The following four materials were prepared at room temperature: cured unmodified epoxy, cured toughened epoxy, cured unmodified epoxy/Cloisite 3...

  18. Improvement of the piezoelectric properties of glass fiber-reinforced epoxy composites by poling treatment

    International Nuclear Information System (INIS)

    Oh, S M; Hwang, H Y

    2013-01-01

    Recently, a new non-destructive method has been proposed for damage monitoring of glass fiber-reinforced polymer composite materials using the piezoelectric characteristics of a polymeric matrix. Several studies of the piezoelectric properties of unidirectional glass fiber epoxy composites and damage monitoring of double-cantilever beams have supported the claim that the piezoelectric method is feasible and powerful enough to monitor the damage of glass fiber epoxy composites. Generally, conventional piezoelectric materials have higher piezoelectric characteristics through poling treatment. In this work, we investigated the change of the piezoelectric properties of glass fiber-reinforced epoxy composites before and after poling treatment. The piezoelectric constants (d 33 ) of glass fiber-reinforced epoxy composites increased by more than 400%. Also, x-ray diffraction tests revealed that poling treatment changed the degree of crystallinity of the epoxy matrix, and this led to the improvement of the piezoelectric characteristics of glass fiber-reinforced epoxy composites. (paper)

  19. UV curing silicon-containing epoxy resin and its glass cloth reinforced composites

    International Nuclear Information System (INIS)

    Yang Guang; Tang Zhuo; Huang Pengcheng

    2007-01-01

    A UV-curable cationic silicon-containing epoxy resin formulation was developed. The gel conversion of the cured resin after 10-min UV irradiation reached 80% in the presence of 5% diaryliodonium salt photoinitiator and 5.5% polyol chain transfer agent by cationic ring-opening polymerization. The glass cloth-reinforced composites were fabricated with the silicon-containing epoxy resin using the wet lay-up technique and UV irradiation. The mechanical properties of the composites were evaluated. Compared with glass cloth reinforced bisphenol A epoxy resin matrix composites, the silicon-containing epoxy resin matrix composites possessed higher tensile strength and interlayer shear strength which was 158.5MPa and 9.9MPa respectively while other mechanical properties such as flexural property and tensile modulus were similar. (authors)

  20. Velocity Measurement of ultrasonic for evaluation of aging epoxy coating in containment structure of nuclear power plant

    International Nuclear Information System (INIS)

    Eun, Gil Soo; Kim, Noh Yu; Nah, Hwan Seon; Song, Young Chol

    2001-01-01

    Relative variation of ultrasonic velocity in aging epoxy coating in nuclear plant is measured for evaluation of the degradation of the epoxy coating. Time delay for ultrasound to travel through the epoxy film due to change of ultrasonic velocity is measured indirectly using ultrasonic interferometry which compares two reflection waves from the same point of coating surface at two different distances. Magnitude of the difference of two waves increases or decreases depending on change of the time of flight of ultrasound in the epoxy film caused by heat damage in the epoxy coating. Based on the transfer functions of the wedge and the epoxy coating in frequency domain, the reflection wave is analyzed and related to the velocity of ultrasound in the epoxy coating. A specially designed conical wedge is adopted to minimize the waviness effect of the surface of the epoxy coating. Epoxy films are fabricated, degraded under the accelerated aging conditions and tested to evaluate the change of ultrasonic velocity in the films. The experimental results show that the method can be applied to evaluate quantitatively the sealing quality of the epoxy coating.

  1. Evaluation and Control of Thiol-ene/Thiol-epoxy Hybrid Networks.

    Science.gov (United States)

    Carioscia, Jacquelyn A; Stansbury, Jeffrey W; Bowman, Christopher N

    2007-03-08

    The development of thiol-ene/thiol-epoxy hybrid networks offers the advantage of tailorable polymerization kinetics while producing a highly crosslinked, high T(g) polymer that has significantly reduced shrinkage stress. Stoichiometric mixtures of pentaerythritol tetra(3-mercaptopropionate) (PETMP)/triallyl-1,3,5-triazine-2,4,6-trione (TATATO) (thiol-ene, mixture 1) and PETMP/bisphenol a diglycidyl ether (BADGE) (thiol-epoxy, mixture 2) were prepared and hybrid mixtures of 75/25, 50/50, 25/75, and 10/90 w/w of mixtures 1 and 2 were polymerized using a combination of both radical and anionic initiation. The light exposure timing and the relative initiation conditions of the two types were used to control the order and relative rates of the radical and anionic polymerizations. The 50/50 w/w thiol-ene/thiol-epoxy hybrid material exhibited a final stress of only 0.2 MPa, which is 90 % lower than the stress developed in a control dimethacrylate resin. Kinetic analysis indicates composition affects network development in thiol-ene/thiol-epoxy hybrid networks and produces materials with robust mechanical properties.

  2. Syntheses and characterization of novel P/Si polysilsesquioxanes/epoxy nanocomposites

    International Nuclear Information System (INIS)

    Chiu Yiechan; Liu Fangyi; Ma, C.-C.M.; Chou, I.-C.; Riang Linawati; Chiang, C.-L.; Yang, J.-C.

    2008-01-01

    Phosphorus-containing polysilsesquioxane (PSSQ) was introduced into diglycidyl ether of bisphenol A epoxy (DGEBA) to generate a novel P/Si PSSQ nanocomposite. A series of nanocomposites was fabricated by changing the content of the 2-(diphenylphosphino)ethyltriethoxysilane (DPPETES) monomer or P/Si PSSQ cured with DGEBA epoxy and modified epoxy. The structure, thermal properties and flame-retardancy of the P/Si PSSQ nanocomposites were characterized by FT-IR, solid-state 29 Si NMR, thermogravimetric analysis (TGA) and limited oxygen index (LOI) instruments. The nano-sizes of the particles in P/Si PSSQ were approximately 30-50 nm, and the polarity of nanocomposites might generate the nanophase-separated structure from transmission electron microscopy (TEM). The urethane-like side group of the modified epoxy and the fabrication of oligomers in the curing reaction affected the T d5 values of nanocomposites. TGA and LOI results indicated that the char yield (29 wt%) increased and the nanocomposites were not very flammable (LOI = 30). The hybrid materials also exhibited high thermal stability, good flame-retardance and a lack of phase separation

  3. Mechanical, Thermal, and Electrical Properties of Graphene-Epoxy Nanocomposites—A Review

    Directory of Open Access Journals (Sweden)

    Rasheed Atif

    2016-08-01

    Full Text Available Monolithic epoxy, because of its brittleness, cannot prevent crack propagation and is vulnerable to fracture. However, it is well established that when reinforced—especially by nano-fillers, such as metallic oxides, clays, carbon nanotubes, and other carbonaceous materials—its ability to withstand crack propagation is propitiously improved. Among various nano-fillers, graphene has recently been employed as reinforcement in epoxy to enhance the fracture related properties of the produced epoxy–graphene nanocomposites. In this review, mechanical, thermal, and electrical properties of graphene reinforced epoxy nanocomposites will be correlated with the topographical features, morphology, weight fraction, dispersion state, and surface functionalization of graphene. The factors in which contrasting results were reported in the literature are highlighted, such as the influence of graphene on the mechanical properties of epoxy nanocomposites. Furthermore, the challenges to achieving the desired performance of polymer nanocomposites are also suggested throughout the article.

  4. Seawater infiltration effect on thermal degradation of fiber reinforced epoxy composites

    Science.gov (United States)

    Ibrahim, Mohd Haziq Izzuddin bin; Hassan, Mohamad Zaki bin; Ibrahim, Ikhwan; Rashidi, Ahmad Hadi Mohamed; Nor, Siti Fadzilah M.; Daud, Mohd Yusof Md

    2018-05-01

    Seawater salinity has been associated with the reduction of polymer structure durability. The aim of this study is to investigate the change in thermal degradation of fiber reinforced epoxy composite due to the presence of seawater. Carbon fiber, carbon/kevlar, fiberglass, and jute that reinforced with epoxy resin was laminated through hand-layup technique. Initially, these specimen was sectioned to 5×5 mm dimension, then immersed in seawater and distilled water at room temperature until it has thoroughly saturated. Following, the thermal degradation analysis using Differential Scanning Calorimetry (DSC), the thermic changes due to seawater infiltration was defined. The finding shows that moisture absorption reduces the glass transition temperature (Tg) of fiber reinforced epoxy composite. However, the glass transition temperature (Tg) of seawater infiltrated laminate composite is compareable with distilled water infiltrated laminate composite. The carbon fiber reinfored epoxy has the highest glass transition temperature out of all specimen.

  5. Interfacial Strength and Physical Properties of Functionalized Graphene - Epoxy Nanocomposites

    Science.gov (United States)

    Miller, Sandi G.; Heimann, Paula; Scheiman, Daniel; Adamson, Douglas H.; Aksay, Iihan A.; Prud'homme, Robert K.

    2006-01-01

    The toughness and coefficient of thermal expansion of a series of functionalized graphene sheet - epoxy nanocomposites are investigated. Functionalized graphene sheets are produced by splitting graphite oxide into single graphene sheets through a rapid thermal expansion process. These graphene sheets contain approx. 10% oxygen due to the presence of hydroxide, epoxide, and carboxyl functional groups which assist in chemical bond formation with the epoxy matrix. Intrinsic surface functionality is used to graft alkyl amine chains on the graphene sheets, and the addition of excess hardener insures covalent bonding between the epoxide matrix and graphene sheets. Considerable improvement in the epoxy dimensional stability is obtained. An increase in nanocomposite toughness is observed in some cases.

  6. The removal of toxic metals from liquid effluents by ion exchange resins. Part IV: Chromium(III)/H+ /Lewatit SP112; La eliminación de metales tóxicos presentes en efluentes líquidos mediante resinas de cambio iónico. Parte IV: cromo(III)/H+/Lewatit SP112

    Energy Technology Data Exchange (ETDEWEB)

    Alguacil, F.J.

    2017-09-01

    This investigation presented results on the removal of chromium(III), from aqueous solution in the 0-5 pH range, using Lewatit SP112 cationic exchange resin. Several aspects affecting the ion exchange process were evaluated, including: the influence of the stirring speed, temperature, pH of the solution, resin dosage and aqueous ionic strength. The selectivity of the system was tested against the presence of other metals in the aqueous solution, whereas the removal of chromium(III) from solutions was compared with results obtained using multiwalled carbon nanotubes as adsorbents. From the batch experimental data, best fit of the results is obtained with the Langmuir model, whereas the ion exchange process is best explained by the pseudo-second order model, moreover, experimental data responded well to the film-diffusion controlled model. Elution of the chromium(III) loaded into the resin is well accomplished by the use of sodium hydroxide solutions. [Spanish] En este trabajo se presentan los resultados obtenidos en la eliminación de cromo(III) de disoluciones acuosas (pH 0-5) mediante la resina de intercambio catiónico Lewatit SP112. Se han investigado algunas variables que pueden afectar al sistema: influencia de la agitación, temperatura, pH y fuerza iónica del medio acuoso y cantidad de resina; también se ha investigado acerca de la selectividad del sistema cuando otros metales están presentes en el medio acuoso, comparándose los resultados de la eliminación del cromo(III) usando la resina con los resultados obtenidos cuando se emplea otro adsorbente como son los nanotubos de carbono de pared múltiple. Los resultados experimentales indican que la carga del cromo(III) en la resina responde mejor al modelo de Langmuir, mientras que los modelos cinéticos indican que la carga del metal en la resina responde al modelo de pseudo-segundo orden y difusión en la capa límite. La elución del cromo(III) se realiza con disoluciones de hidróxid.

  7. Mechanical properties of ramie fiber reinforced epoxy lamina composite for socket prosthesis

    Directory of Open Access Journals (Sweden)

    Tresna Soemardi

    2010-10-01

    Full Text Available This paper presents an investigation into the application of natural fiber composite especially ramie fiber reinforced epoxy lamina composite for socket prosthesis. The research focuses on the tensile and shear strength from ramie fiber reinforced epoxy lamina composite which will be applied as alternative material for socket prosthesis. The research based on American Society for Testing Material (ASTM standard D 3039/D 3039M for tensile strength and ASTM D 4255/D 4255M-83 for shear strength. The ramie fiber applied is a fiber continue 100 % Ne14'S with Epoxy Resin Bakelite EPR 174 as matrix and Epoxy Hardener V-140 as hardener. The sample composite test made by hand lay up method. Multiaxial characteristic from ramie fiber reinforced epoxy composite will be compared with ISO standard for plastic/polymer for health application and refers strength of material application at Prosthetics and Orthotics. The analysis was completed with the mode of the failure and the failure criterion observation by using Scanning Electron Microscope (SEM. Based on results of the research could be concluded that ramie fiber reinforced epoxy composite could be developed further as the alternative material for socket prosthesis on Vf 40-50%. Results of the research will be discussed in more detail in this paper.

  8. Occupational contact dermatitis caused by aniline epoxy resins in the aircraft industry.

    Science.gov (United States)

    Pesonen, Maria; Suuronen, Katri; Jolanki, Riitta; Aalto-Korte, Kristiina; Kuuliala, Outi; Henriks-Eckerman, Maj-Len; Valtanen, Ilona; Alanko, Kristiina

    2015-08-01

    Tetraglycidyl-4,4'-methylenedianiline (TGMDA) is an aniline epoxy resin used in, for example, resin systems of pre-impregnated composite materials (prepregs) of the aircraft industry. Allergic contact dermatitis caused by TGMDA in prepregs has been described previously. To report on 9 patients with occupational allergic contact dermatitis caused by TGMDA in epoxy glues used in helicopter assembly. The patients were examined with patch testing at the Finnish Institute of Occupational Health in 2004-2009. The first patient was diagnosed by testing both components of two epoxy glues from the workplace, and was also tested with glue ingredients, including TGMDA. The following patients were tested with the glues and TGMDA. The resin parts of the glues were analysed for their epoxy compounds, including TGMDA. All of the patients had a patch test reaction to one or both of the resin parts of the TGMDA-containing glues. Eight of them had a strong allergic reaction to TGMDA, and one had a doubtful reaction to TGMDA. Two of the patients also had an allergic reaction to triglycidyl-p-aminophenol (TGPAP), another aniline epoxy resin, which was not present in the TGMDA-containing glues. In aircraft industry workers with suspected occupational dermatitis, aniline epoxy resins should be considered and patch tested as possible contact allergens. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

    Science.gov (United States)

    Alvarez Feijoo, Miguel Angel

    2018-01-01

    This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (phase combination (PCM + epoxy resin + hardener + thickening agent) presents great potential as a heat-absorbing material at the temperatures employed. PMID:29373538

  10. Synthesis and characterisation of epoxy resins reinforced with carbon nanotubes and nanofibers.

    Science.gov (United States)

    Prolongo, S G; Gude, M R; Ureña, A

    2009-10-01

    Epoxy nanocomposites were fabricated using two kinds of nanofiller, amino-functionalized multi-walled carbon nanotubes (CNTs) and non-treated long carbon nanofibers (CNFs). The non-cured mixtures were analysed through viscosity measurements. The effect of the nanoreinforcement on the curing process was determined by differential scanning calorimetry. Finally, the characterisation of cured nanocomposites was carried out studying their thermo-mechanical and electrical behaviour. At room temperature, the addition of CNTs causes a viscosity increase of epoxy monomer much more marked than the introduction of CNFs due to their higher specific area. It was probed that in that case exists chemical reaction between amino-functionalized CNTs and the oxirane rings of epoxy monomer. The presence of nanoreinforcement induces a decrease of curing reaction rate and modifies the epoxy conversion reached. The glass transition temperature of the nanocomposites decreases with the contents of CNTs and CNFs added, which could be related to plasticization phenomena of the nanoreinforcements. The storage modulus of epoxy resin significantly increases with the addition of CNTs and CNFs. This augment is higher with amino-functionalized CNTs due, between other reasons, to the stronger interaction with the epoxy matrix. The electrical conductivity is greatly increased with the addition of CNTs and CNFs. In fact, the percolation threshold is lower than 0.25 wt% due to the high aspect ratio of the used nanoreinforcements.

  11. Adhesion of epoxy primer to hydrotalcite conversion coated AA2024

    Science.gov (United States)

    Leggat, Robert Benton, III

    Hydrotalcite-based (HT) conversion coatings are being developed as an environmentally benign alternative to chromate conversion coatings (CCC). Accelerated exposure tests were conducted on epoxy primed, HT-modified AA2024 to gauge service performance. HT-based conversion coatings did not perform as well as the CCC when used with an epoxy primer. The current HT chemistries are optimized for stand-alone corrosion protection, however additional research into the primer/HT interactions is necessary before they can be implemented within a coating scheme. The relative contribution of mechanical and physico-chemical interactions in controlling adhesion has been investigated in this study. Practical adhesion tests were used to assess the dry and wet bond strength of epoxy primer on HT coatings using the pull-off tensile strength (POTS) as the figure of merit. The practical adhesion of HT coated samples generally fell between that observed for the CCC and bare AA2024. Laboratory testing was done to assess the physical and chemical properties of HT coatings. Contact angle measurements were performed using powders representative of different HT chemistries to evaluate the dispersive and acid-base character of the surface. The wet POTS correlated with the electrodynamic (dipole + dispersive) parameter of the surface tension. The HT surfaces were found to be predominantly basic. Given the basicity of epoxy, these results indicate that increasing the acidic character of HT coatings may increase the adhesion performance. This was supported by electrokinetic measurements in which the dry POTS was found to increase with decreasing conversion coating iso-electric point. The correlations with the dry and wet state adhesion are interpreted as indicating that dry state adhesion is optimized by minimizing unfavorable polar interactions between the basic epoxy and HT interfaces. Wet state adhesion, where polar interactions are disrupted, is dictated by non-polar bonding. FTIR

  12. Fabrication of tough epoxy with shape memory effects by UV-assisted direct-ink write printing.

    Science.gov (United States)

    Chen, Kaijuan; Kuang, Xiao; Li, Vincent; Kang, Guozheng; Qi, H Jerry

    2018-03-07

    3D printing of epoxy-based shape memory polymers with high mechanical strength, excellent thermal stability and chemical resistance is highly desirable for practical applications. However, thermally cured epoxy in general is difficult to print directly. There have been limited numbers of successes in printing epoxy but they suffer from relatively poor mechanical properties. Here, we present an ultraviolet (UV)-assisted 3D printing of thermally cured epoxy composites with high tensile toughness via a two-stage curing approach. The ink containing UV curable resin and epoxy oligomer is used for UV-assisted direct-ink write (DIW)-based 3D printing followed by thermal curing of the part containing the epoxy oligomer. The UV curable resin forms a network by photo polymerization after the 1st stage of UV curing, which can maintain the printed architecture at an elevated temperature. The 2nd stage thermal curing of the epoxy oligomer yields an interpenetrating polymer network (IPN) composite with highly enhanced mechanical properties. It is found that the printed IPN epoxy composites enabled by the two-stage curing show isotropic mechanical properties and high tensile toughness. We demonstrated that the 3D-printed high-toughness epoxy composites show good shape memory properties. This UV-assisted DIW 3D printing via a two-stage curing method can broaden the application of 3D printing to fabricate thermoset materials with enhanced tensile toughness and tunable properties for high-performance and functional applications.

  13. Improving Fracture Toughness of Epoxy Nanocomposites by Silica Nanoparticles

    Directory of Open Access Journals (Sweden)

    Seyed Reza Akherati Sany

    2017-04-01

    Full Text Available An epoxy resin was modified by silica nanoparticles and cured with an anhydride. The particles with different batches of 12, 20, and 40 nm sizes were each distributed into the epoxy resin ultrasonically. Electron microscopy images showed that the silica particles were well dispersed throughout the resin. Tensile test results showed that Young’s modulus and tensile strength increased with the volume fraction and surface area of the silica particles. The simultaneous use of two average sizes of 20 and 40 nm diameter silica particles still increased these mechanical properties but other combinations of silica particles were unsuccessful. A three-point bending test on each pre-cracked specimen was performed to measure the mode I fracture toughness energy. The fracture energy increased from 283 J/m2 for the unmodified epoxy to about 740 J/m2 for the epoxy with 4.5 wt% of 12 nm diameter silica nanoparticles. The fracture energy of smaller particles was greater because of their higher surface to volume ratio. The fracture energy results showed also that the combined nanoparticles has a synergic effect on the fracture toughness of nanocomposites. Simultaneous use of 10 and 20 nm particles increased the fracture energy to about 770 J/m2. Finally, crack-opening displacement was calculated and found to be in the range of several micrometers which was much larger than the sizes of particles studied. Thus, the toughening mechanisms of crack pinning and crack deflection have a negligible effect on improvement of toughness, nevertheless, the plastic deformation and plastic void growth are dominant mechanisms in epoxy toughening by nanoparticles.

  14. Preparation and optical properties of indium tin oxide/epoxy nanocomposites with polyglycidyl methacrylate grafted nanoparticles.

    Science.gov (United States)

    Tao, Peng; Viswanath, Anand; Schadler, Linda S; Benicewicz, Brian C; Siegel, Richard W

    2011-09-01

    Visibly highly transparent indium tin oxide (ITO)/epoxy nanocomposites were prepared by dispersing polyglycidyl methacrylate (PGMA) grafted ITO nanoparticles into a commercial epoxy resin. The oleic acid stabilized, highly crystalline, and near monodisperse ITO nanoparticles were synthesized via a nonaqueous synthetic route with multigram batch quantities. An azido-phosphate ligand was synthesized and used to exchange with oleic acid on the ITO surface. The azide terminal group allows for the grafting of epoxy resin compatible PGMA polymer chains via Cu(I) catalyzed alkyne-azide "click" chemistry. Transmission electron microscopy (TEM) observation shows that PGMA grafted ITO particles were homogeneously dispersed within the epoxy matrix. Optical properties of ITO/epoxy nanocomposites with different ITO concentrations were studied with an ultraviolet-visible-near-infrared (UV-vis-NIR) spectrometer. All the ITO/epoxy nanocomposites show more than 90% optical transparency in the visible light range and absorption of UV light from 300 to 400 nm. In the near-infrared region, ITO/epoxy nanocomposites demonstrate low transmittance and the infrared (IR) transmission cutoff wavelength of the composites shifts toward the lower wavelength with increased ITO concentration. The ITO/epoxy nanocomposites were applied onto both glass and plastic substrates as visibly transparent and UV/IR opaque optical coatings.

  15. Immobilization of spent resin with epoxy resin

    International Nuclear Information System (INIS)

    Gultom, O.; Suryanto; Sayogo; Ramdan

    1997-01-01

    immobilization of spent resin using epoxy resin has been conducted. The spent resin was mixtured with epoxy resin in variation of concentration, i.e., 30, 40, 50, 60, 70 weight percent of spent resin. The mixture were pour into the plastic tube, with a diameter of 40 mm and height of 40 mm. The density, compressive strength and leaching rate were respectively measured by quanta chrome, paul weber apparatus and gamma spectrometer. The results showed that the increasing of waste concentration would be decreased the compressive strength, and increased density by immobilized waste. The leaching rate of 137 Cs from waste product was not detected in experiment (author)

  16. High T{sub g} and fast curing epoxy-based anisotropic conductive paste for electronic packaging

    Energy Technology Data Exchange (ETDEWEB)

    Keeratitham, Waralee, E-mail: waralee.ke@student.chula.ac.th; Somwangthanaroj, Anongnat, E-mail: anongnat.s@chula.ac.th [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, 10330 (Thailand)

    2016-03-09

    Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (T{sub g}) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that T{sub g} obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage by weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (∼90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.

  17. Nanocellulose composites with enhanced interfacial compatibility and mechanical properties using a hybrid-toughened epoxy matrix.

    Science.gov (United States)

    Kuo, Pei-Yu; Barros, Luizmar de Assis; Yan, Ning; Sain, Mohini; Qing, Yan; Wu, Yiqiang

    2017-12-01

    Although there is a growing interest in utilizing nanocellulose fibres (NCFs) based composites for achieving a higher sustainability, mechanical performance of these composites is limited due to the poor compatibility between fibre reinforcement and polymer matrices. Here we developed a bio-nanocomposite with an enhanced fibre/resin interface using a hybrid-toughened epoxy. A strong reinforcing effect of NCFs was achieved, demonstrating an increase up to 88% in tensile strength and 298% in tensile modulus as compared to neat petro-based P-epoxy. The toughness of neat P-epoxy was improved by 84% with the addition of 10wt% bio-based E-epoxy monomers, which also mitigated the amount of usage of bisphenol A (BPA). The morphological analyses showed that the hybrid epoxy improved the resin penetration and fibre distribution significantly in the resulting composites. Thus, our findings demonstrated the promise of developing sustainable and high performance epoxy composites combing NCFs with a hybrid petro-based and bio-based epoxy resin system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Evaluation of Carbon Composite Overwrap Pressure Vessels Fabricated Using Ionic Liquid Epoxies

    Data.gov (United States)

    National Aeronautics and Space Administration — In terms of "Innovation" this is a unique epoxy with unique properties, and NASA co-holds the patent. This epoxy is being exclusively formulated for cryogenic use....

  19. Effect of Montmorillonite Nanogel Composite Fillers on the Protection Performance of Epoxy Coatings on Steel Pipelines.

    Science.gov (United States)

    Atta, Ayman M; El-Saeed, Ashraf M; Al-Lohedan, Hamad A; Wahby, Mohamed

    2017-06-02

    Montmorillonite (MMT) clay mineral is widely used as filler for several organic coatings. Its activity is increased by exfoliation via chemical modification to produce nanomaterials. In the present work, the modification of MMT to form nanogel composites is proposed to increase the dispersion of MMT into epoxy matrices used to fill cracks and holes produced by the curing exotherms of epoxy resins. The dispersion of MMT in epoxy improved both the mechanical and anti-corrosion performance of epoxy coatings in aggressive marine environments. In this respect, the MMT surfaces were chemically modified with different types of 2-acrylamido-2-methyl propane sulfonic acid (AMPS) nanogels using a surfactant-free dispersion polymerization technique. The effect of the chemical structure, nanogel content and the interaction with MMT surfaces on the surface morphology, surface charges and dispersion in the epoxy matrix were investigated for use as nano-filler for epoxy coatings. The modified MMT nanogel epoxy composites showed excellent resistance to mechanical damage and salt spray resistance up to 1000 h. The interaction of MMT nanogel composites with the epoxy matrix and good response of AMPS nanogel to sea water improve their ability to act as self-healing materials for epoxy coatings for steel.

  20. Degradation of modified carbon black/epoxy nanocomposite coatings under ultraviolet exposure

    Science.gov (United States)

    Ghasemi-Kahrizsangi, Ahmad; Shariatpanahi, Homeira; Neshati, Jaber; Akbarinezhad, Esmaeil

    2015-10-01

    Degradation of epoxy coatings with and without Carbon Black (CB) nanoparticles under ultraviolet (UV) radiation were investigated using electrochemical impedance spectroscopy (EIS). Sodium dodecyl sulfate (SDS) was used to obtain a good dispersion of CB nanoparticles in a polymer matrix. TEM analysis proved a uniform dispersion of modified CB nanoparticles in epoxy coating. The coatings were subjected to UV radiation to study the degradation behavior and then immersed in 3.5 wt% NaCl. The results showed that the electrochemical behavior of neat epoxy coating was related to the formation and development of microcracks on the surface. The occurrence of microcracks on the surface of the coatings and consequently the penetration of ionic species reduced by adding CB nanoparticles into the formulation of the coatings. CB nanoparticles decreased degradation of CB coatings by absorbing UV irradiation. The ATR-FTIR results showed that decrease in the intensity of methyl group as main peak in presence of 2.5 wt% CB was lower than neat epoxy. In addition, the reduction in impedance of neat epoxy coating under corrosive environment was larger than CB coatings. The CB coating with 2.5 wt% nanoparticles had the highest impedance to corrosive media after 2000 h UV irradiation and 24 h immersion in 3.5 wt% NaCl.

  1. Physical and chemical durability of cement impregnated epoxy resin

    International Nuclear Information System (INIS)

    Suryantoro

    1997-01-01

    Immobilization of simulation radioactive waste contains Cs and Sr with cement impregnated epoxy resin has been done. Low level liquid waste in 30% weight mixed cement homogeneously and then set in its curing time about 28 days. Waste from was impregnated with epoxy resin (Bisphenol-A-diglycidylether) and use Triethylenteramin as catalyst. the sample of cement impregnated epoxy resin 2.5 cm x 2.5 cm in diameter and length was tested by Paul Weber. The compressive strength was obtained of 4.08 kN.cm - 2. The sochxlet apparatus was run on flow rate of 300 ml/hour at 100 o C and during 24 hours. The leaching rate of Cs was round on 5.5 x 10 - 4 g.cm - 2.d - 1 and Sr was 6.1 x 10 - 4 g.cm - 2.d - 1 (author)

  2. Synthesis and Antimicrobial Activity of Long-Chain 3,4-Epoxy-2-alkanones

    OpenAIRE

    Wood, William F.

    2010-01-01

    3,4-Epoxy-2-dodecanone, a major component in the preorbital gland of the African grey duiker (Sylvicapra grimmia), showed antimicrobial activity in preliminary tests. The C11 to C17 homologues of this compound were prepared and their activity against several pathogenic dermal bacteria and fungi was tested. 3,4-Epoxy-2-dodecanone and 3,4-epoxy-2-tridecanone inhibited the growth of Trichophyton mentagrophytes at 25 μg/mL. Moderate inhibition of the growth of the bacteria Propionibacterium acnes...

  3. Elaboration, structural and optical investigations of ZnO/epoxy nanocomposites

    Science.gov (United States)

    Moussa, S.; Namouchi, F.; Guermazi, H.

    2015-07-01

    Hybrid nanocomposites were elaborated by incorporating ZnO nanoparticles into a transparent epoxy polymer matrix, using the direct dispersion method. The effect of the nanoparticles on the structural and optical properties of the polymer matrix was investigated using Fourier transform infrared (FTIR), Raman and UV-Visible spectroscopies. Nanocomposites FTIR spectra showed a variation of band intensities attributed to nanoparticles agglomeration within the polymer. The UV-Visible measurements showed a redshift on the band gap energy of the nanocomposites differently from neat epoxy resin, caused by interactions between ZnO NPs and polymer chains. Raman spectra confirm these interactions and the formation of hydrogen bonds in the nanocomposites. The UV-Visible transmittance spectra revealed that addition of a very low concentration (0.2wt%) of ZnO nanoparticles to a transparent epoxy matrix would maintain high visible-light transparency. The decrease of transmittance with increasing ZnO percentage is due to light scattering which originates from the agglomeration of nanoparticles in the matrix, the mismatch between the refractive index of ZnO and that of the epoxy matrix, and the increase of the surface roughness of the nanocomposite with increasing ZnO addition. Moreover, the UV-vis absorption spectra revealed that adding more than 1wt% ZnO leads to the improvement of the UV shielding properties of the nanocomposites. These results prove that the elaborated ZnO/epoxy nanocomposites can be used as UV shielding materials.

  4. Radiochemical ageing of epoxy coating for nuclear plants

    International Nuclear Information System (INIS)

    Queiroz, D.P.R.; Fraisse, F.; Fayolle, B.; Kuntz, M.; Verdu, J.

    2010-01-01

    The degradation of an epoxy-amine network exposed to gamma irradiation in oxygen atmosphere has been studied by using a variety of analytical methods, including infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and sol-gel analysis. Results show that the oxidation of epoxy systems grows with the irradiation dose. Hydroperoxides, which are species resulting from oxidation, were identified and quantified by DSC. As indicated by the sol-gel analysis, the mechanism of degradation of chain scission seems to be predominant over crosslinking. The modifications induced by irradiation reflect in a greater capacity of water absorption.

  5. Utilization of ilmenite/epoxy composite for neutrons and gamma rays attenuation

    Energy Technology Data Exchange (ETDEWEB)

    El-Sayed Abdo, A. E-mail: attiaabdo11@hotmail.com; El-Sarraf, M.A.; Gaber, F.A

    2003-01-01

    This work deals with the study of ilmenite/epoxy composite as an injecting mortar for cracks developed in biological concrete shields, as well as, neutrons and gamma rays attenuation. Effects of the particle size on the mechanical strengths have been studied for epoxy resin filled with crushed ilmenite with different maximum particle sizes ranging from 32 to 500 {mu}m. Thermal neutrons and gamma rays attenuation in ilmenite/epoxy composites with 75 and 80 wt.% of ilmenite concentration have been investigated. The total mass attenuation coefficients {mu}/{rho} (cm{sup 2} g{sup -1}) of gamma ray for five ilmenite/epoxy composites have been calculated using the XCOM program (version 3.1) at energies from 10 keV to 100 MeV. Also, the total mass attenuation coefficients ({mu}/{rho}) have estimated based on the measured total linear attenuation coefficients ({mu}) and compared with the calculated results where, a reasonable agreement was found.

  6. Hearing loss in workers exposed to epoxy adhesives and noise: a cross-sectional study.

    Science.gov (United States)

    Yang, Hsiao-Yu; Shie, Ruei-Hao; Chen, Pau-Chung

    2016-02-18

    Epoxy adhesives contain organic solvents and are widely used in industry. The hazardous effects of epoxy adhesives remain unclear. The objective of this study was to investigate the risk of hearing loss among workers exposed to epoxy adhesives and noise. Cross-sectional study. For this cross-sectional study, we recruited 182 stone workers who were exposed to both epoxy adhesives and noise, 89 stone workers who were exposed to noise only, and 43 workers from the administrative staff who had not been exposed to adhesives or noise. We obtained demographic data, occupational history and medical history through face-to-face interviews and arranged physical examinations and pure-tone audiometric tests. We also conducted walk-through surveys in the stone industry. A total of 40 representative noise assessments were conducted in 15 workplaces. Air sampling was conducted at 40 workplaces, and volatile organic compounds were analysed using the Environmental Protection Agency (EPA) TO-15 method. The mean sound pressure level was 87.7 dBA (SD 9.9). The prevalence of noise-induced hearing loss was considerably increased in the stone workers exposed to epoxy adhesives (42%) compared with the stone workers who were not exposed to epoxy adhesives (21%) and the administrative staff group (9.3%). A multivariate logistic regression analysis revealed that exposure to epoxy adhesives significantly increased the risk of hearing loss between 2 and 6 kHz after adjusting for age. Significant interactions between epoxy adhesives and noise and hearing impairment were observed at 3, 4 and 6 kHz. Epoxy adhesives exacerbate hearing impairment in noisy environments, with the main impacts occurring in the middle and high frequencies. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  7. Fractografia de compósito estrutural aeronáutico submetido à caracterização de tenacidade à fratura interlaminar em modo I Fractography of aeronautical composite structures submitted to mode I interlaminar fracture toughness characterization

    Directory of Open Access Journals (Sweden)

    Geraldo Maurício Cândido

    2012-01-01

    Full Text Available Muitos componentes das modernas aeronaves estão sendo manufaturados em compósitos poliméricos. Laminados de resina epóxi modificada reforçada com fibras de carbono contínuas são empregados em estruturas primárias e secundárias para reduzir o peso e melhorar o desempenho operacional. Porém, se ocorrer uma falha circunstancial, o processo de fratura desses laminados é complexo e pode envolver mecanismos de danos interlaminares. A delaminação é a descontinuidade interlaminar que pode se propagar de forma catastrófica com a aplicação de cargas mecânicas. O ensaio de corpos de prova denominado de Double Cantilever Beam (DCB é o método mais utilizado para determinar a tenacidade à fratura em Modo I de compósitos estruturais. Neste trabalho, amostras preparadas de um laminado de tecido bidirecional, estilo plain weave, foram submetidas ao carregamento estático de delaminação em Modo I, à temperatura ambiente. A análise fractográfica das superfícies delaminadas foi realizada por microscopia eletrônica de varredura. Os resultados mostram que o processo de fratura se inicia nas bolsas de resina após um inserto de Teflon® e se propaga ao longo das regiões ricas em resina posicionadas nos interstícios de entrelaçamento das mechas da trama e da urdidura. Os principais aspectos fractográficos revelados são identificados, documentados e discutidos neste trabalho.Many components of modern aircrafts are now manufactured from polymer composites. Reinforced laminates with continuous carbon fibers and modified epoxy resin are employed in primary and secondary structures to reduce weight and improve the aircraft performance. However, if a circumstantial failure happens, the complex fracture process of the laminates may involve interlaminar damage mechanisms. The delamination is the interlaminar discontinuity which may propagate catastrophically with the application of mechanical loads. The Double Cantilever Beam (DCB is the most

  8. Modification of the Interfacial Interaction between Carbon Fiber and Epoxy with Carbon Hybrid Materials

    Directory of Open Access Journals (Sweden)

    Kejing Yu

    2016-05-01

    Full Text Available The mechanical properties of the hybrid materials and epoxy and carbon fiber (CF composites were improved significantly as compared to the CF composites made from unmodified epoxy. The reasons could be attributed to the strong interfacial interaction between the CF and the epoxy composites for the existence of carbon nanomaterials. The microstructure and dispersion of carbon nanomaterials were characterized by transmission electron microscopy (TEM and optical microscopy (OM. The results showed that the dispersion of the hybrid materials in the polymer was superior to other carbon nanomaterials. The high viscosity and shear stress characterized by a rheometer and the high interfacial friction and damping behavior characterized by dynamic mechanical analysis (DMA indicated that the strong interfacial interaction was greatly improved between fibers and epoxy composites. Remarkably, the tensile tests presented that the CF composites with hybrid materials and epoxy composites have a better reinforcing and toughening effect on CF, which further verified the strong interfacial interaction between epoxy and CF for special structural hybrid materials.

  9. Epoxy – the hub for the most versatile polymer with exceptional combination of superlative features

    OpenAIRE

    Inam, Fawad

    2014-01-01

    Epoxy resins and epoxy based materials have experienced significant advancement since their beginning in 1936, when Dr. Castan of Switzerland and Dr. Greenlee of USA succeeded in synthesizing the very first bisphenol-A-based epoxy resins. Whether it is the new carbon fiber composite of Boeing’s Dreamliner or the thin set terrazzo flooring, epoxy has always been the ideal choice because of its superlative properties and unique chemical composition. Belonging to thermoset family, it is certainl...

  10. Effect of Thermally Reduced Graphene Oxide on Mechanical Properties of Woven Carbon Fiber/Epoxy Composite

    OpenAIRE

    Nitai Chandra Adak; Suman Chhetri; Naresh Chandra Murmu; Pranab Samanta; Tapas Kuila

    2018-01-01

    Thermally reduced graphene oxide (TRGO) was incorporated as a reinforcing filler in the epoxy resin to investigate the effect on the mechanical properties of carbon fiber (CF)/epoxy composites. At first, the epoxy matrix was modified by adding different wt % of TRGO from 0.05 to 0.4 wt % followed by the preparation of TRGO/CF/epoxy composites througha vacuum-assisted resin transfer molding process. The prepared TRGO was characterized by using Fourier transform infrared spectroscopy, Raman Spe...

  11. Enhancing Mechanical and Thermal Properties of Epoxy Nanocomposites via Alignment of Magnetized SiC Whiskers.

    Science.gov (United States)

    Townsend, James; Burtovyy, Ruslan; Aprelev, Pavel; Kornev, Konstantin G; Luzinov, Igor

    2017-07-12

    This research is focused on the fabrication and properties of epoxy nanocomposites containing magnetized SiC whiskers (MSiCWs). To this end, we report an original strategy for fabrication of magnetically active SiCWs by decorating the whiskers with magnetic (iron oxide) nanoparticles via polymer-polymer (poly(acrylic acid)/poly(2-vinyl pyridine)) complexation. The obtained whiskers demonstrated a substantial magnetic response in the polymerizing epoxy resin, with application of only a 20 mT (200 G) magnetic field. We also found that the whiskers chemically reacted with the epoxy resin, causing formation of an extended interphase near the boundary of the whiskers. The SiC whiskers oriented with the magnetic field demonstrated positive effects on the behavior of epoxy-based nanocomposites. Namely, the aligned MSiCWs enhanced the thermomechanical properties of the materials significantly above that of the neat epoxy and epoxy nanocomposite, with randomly oriented whiskers.

  12. Enhancing the Heat Transfer Efficiency in Graphene-Epoxy Nanocomposites Using a Magnesium Oxide-Graphene Hybrid Structure.

    Science.gov (United States)

    Du, Fei-Peng; Yang, Wen; Zhang, Fang; Tang, Chak-Yin; Liu, Sheng-Peng; Yin, Le; Law, Wing-Cheung

    2015-07-08

    Composite materials, such as organic matrices doped with inorganic fillers, can generate new properties that exhibit multiple functionalities. In this paper, an epoxy-based nanocomposite that has a high thermal conductivity and a low electrical conductivity, which are required for the use of a material as electronic packaging and insulation, was prepared. The performance of the epoxy was improved by incorporating a magnesium oxide-coated graphene (MgO@GR) nanomaterial into the epoxy matrix. We found that the addition of a MgO coating not only improved the dispersion of the graphene in the matrix and the interfacial bonding between the graphene and epoxy but also enhanced the thermal conductivity of the epoxy while preserving the electrical insulation. By adding 7 wt % MgO@GR, the thermal conductivity of the epoxy nanocomposites was enhanced by 76% compared with that of the neat epoxy, and the electrical resistivity was maintained at 8.66 × 10(14) Ω m.

  13. Synthesis and Characterization of Modified Epoxy Resins by Silicic Acid Tetraethyl Ester and Nano-SiO2

    Institute of Scientific and Technical Information of China (English)

    李海燕; 张之圣

    2004-01-01

    A kind of modified epoxy resins was obtained by condensation of epoxy resin with silicic acid tetraethyl ester(TEOS) and nano-SiO2. The reactions were performed with hydrochloric acid as a catalyst at 63 °C.The structure, thermal stability and morphological characteristics of the modified epoxy resins were studied through infrared spectra(FT-IR) analysis, thermogravimetric (TG) analysis and scanning electron microscopy respectively. It has been found from the IR and TG study that modified epoxy resins have greater thermal stability than epoxy resins, and its thermal stability has been improved by the formation of inter-crosslinked network structure. The modified epoxy resins exhibit heterogeneous morphology and heterogeneity increases with more TEOS feeding, which in turn confirms the formation of inter-crosslinked network structure in modified epoxy resins.

  14. Radiation curing of {gamma}-Al{sub 2}O{sub 3} filled epoxy resin

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Phil Hyun; Kim, Dong Jin; Nho, Young Chang [KAERI, Taejon (Korea, Republic of)

    2003-10-01

    Epoxy resins are widely utilized as high performance thermosetting resins for many industrial applications but characterized by a relatively low toughness. Recently, the incorporation with rigid inorganic was suggested to improve the mechanical properties of epoxy resins. In the present work, an attempt has been taken to disperse nano-sized {gamma}- Al{sub 2}O{sub 3} particles into diglycidyl ether of bisphenol-A (DGEBA) epoxy resins for improvement of the mechanical properties. These hybrid epoxy-alumina composites were prepared using by the {gamma}-ray curing technique that was conducted with 100kGy under nitrogen at room temperature. The composites were characterized by determining gel content, UTM (Instron model 4443), SEM, FT-IR studies.

  15. Tensile Mechanical Property of Oil Palm Empty Fruit Bunch Fiber Reinforced Epoxy Composites

    Science.gov (United States)

    Ghazilan, A. L. Ahmad; Mokhtar, H.; Shaik Dawood, M. S. I.; Aminanda, Y.; Ali, J. S. Mohamed

    2017-03-01

    Natural, short, untreated and randomly oriented oil palm empty fruit bunch fiber reinforced epoxy composites were manufactured using vacuum bagging technique with 20% fiber volume composition. The performance of the composite was evaluated as an alternative to synthetic or conventional reinforced composites. Tensile properties such as tensile strength, modulus of elasticity and Poisson’s ratio were compared to the tensile properties of pure epoxy obtained via tensile tests as per ASTM D 638 specifications using Universal Testing Machine INSTRON 5582. The tensile properties of oil palm empty fruit bunch fiber reinforced epoxy composites were lower compared to plain epoxy structure with the decrement in performances of 38% for modulus of elasticity and 61% for tensile strength.

  16. Mechanical and Thermal Properties of Epoxy Composites Containing Zirconia-Impregnated Halloysite Nanotubes with Different Loadings.

    Science.gov (United States)

    Kim, Suhyun; Kim, Moon Il; Shon, Minyoung; Seo, Bongkuk; Lim, Choongsun

    2018-09-01

    Epoxy resins are widely used in various industrial fields due to their low cost, good workability, heat resistance, and good mechanical strength. However, they suffer from brittleness, an issue that must be addressed for further applications. To solve this problem, additional fillers are needed to improve the mechanical and thermal properties of the resins; zirconia is one such filler. However, it has been reported that aggregation may occur in the epoxy composites as the amount of zirconia increases, preventing enhancement of the mechanical strength of the epoxy composites. Herein, to reduce the aggregation, zirconia was well dispersed on halloysite nanotubes (HNTs), which have high thermal and mechanical strength, by a conventional wet impregnation method. The HNTs were impregnated with zirconia at different loadings using zirconyl chloride octahydrate as a precursor. The mechanical and thermal strengths of the epoxy composites with these fillers were investigated. The zirconia-impregnated HNTs (Zr/HNT) were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and tunneling electron microscopy (TEM). The hardening conditions of the epoxy composites were analyzed by differential scanning calorimetry (DSC). The thermal strength of the epoxy composites was studied by thermomechanical analysis (TMA) and micro-calorimetry and the mechanical strength of the epoxy composites (flexural strength and tensile strength) was studied by using a universal testing machine (UTM). The mechanical and thermal strengths of the epoxy composites with Zr/HNT were improved compared to those of the epoxy composite with HNT, and also increased as the zirconia loading on HNT increased.

  17. Noncovalently Functionalized Tungsten Disulfide Nanosheets for Enhanced Mechanical and Thermal Properties of Epoxy Nanocomposites.

    Science.gov (United States)

    Sahu, Megha; Narashimhan, Lakshmi; Prakash, Om; Raichur, Ashok M

    2017-04-26

    In the present study, noncovalently functionalized tungsten disulfide (WS 2 ) nanosheets were used as a toughening agent for epoxy nanocomposites. WS 2 was modified with branched polyethyleneimine (PEI) to increase the degree of interaction of nanosheets with the epoxy matrix and prevent restacking and agglomeration of the sheets in the epoxy matrix. The functionalization of WS 2 sheets was confirmed through Fourier transform infrared spectroscopy and thermogravimetric analysis. The exfoliation of the bulk WS 2 was confirmed through X-ray diffraction and various microscopic techniques. Epoxy nanocomposites containing up to 1 wt % of WS 2 -PEI nanosheets were fabricated. They showed a remarkable improvement in fracture toughness (K IC ). K IC increased from 0.94 to 1.72 MPa m -1/2 for WS 2 -PEI nanosheet loadings as low as 0.25 wt %. Compressive and flexural properties also showed a significant improvement as incorporation of 0.25 wt % of WS 2 -PEI nanosheets resulted in 43 and 65% increase in the compressive and flexural strengths of epoxy nanocomposites, respectively, compared with neat epoxy. Thermal stability and thermomechanical properties of the WS 2 -PEI-modified epoxy also showed a significant improvement. The simultaneous improvement in the mechanical and thermal properties could be attributed to the good dispersion of WS 2 -PEI nanosheets in the matrix, intrinsic high strength and thermal properties of the nanosheets, and improved interaction of the WS 2 nanosheets with the epoxy matrix owing to the presence of PEI molecules on the surface of the WS 2 nanosheets.

  18. Modified silyl-terminated polyether polymer blends with bisphenol A diglycidyl ether epoxy for adhesive applications

    International Nuclear Information System (INIS)

    Bitenieks, J; Meri, R Merijs; Zicans, J; Berzins, R; Umbraško, J; Rekners, U

    2016-01-01

    Modified silyl-terminated polyether polymer (MS Polymer) was blended with bisphenol A diglycidyl ether (DGEBPA) epoxy at MS Polymer/epoxy ratio from 30/70 to 70/30. MS Polymer/epoxy systems were examined for two-component adhesive formulation with additional fillers. Applicability of the MS Polymer/epoxy system at the ratio of the components 60/40 is demonstrated for the development of adhesive formulation. Rheological analysis of the components A and B shows suitable viscosity values for development of two- component adhesives formulation. Curing dynamics as well as tensile stress-strain properties and Shore A hardness of the chosen adhesive formulation are reasonable for the development of MS Polymer/epoxy type adhesive. (paper)

  19. Effect of Hygrothermal Aging on the Mechanical Properties of Fluorinated and Nonfluorinated Clay-Epoxy Nanocomposites.

    Science.gov (United States)

    Hamim, Salah U; Singh, Raman P

    2014-01-01

    Hydrophilic nature of epoxy polymers can lead to both reversible and irreversible/permanent changes in epoxy upon moisture absorption. The permanent changes leading to the degradation of mechanical properties due to combined effect of moisture and elevated temperature on EPON 862, Nanomer I.28E, and Somasif MAE clay-epoxy nanocomposites are investigated in this study. The extent of permanent degradation on fracture and flexural properties due to the hygrothermal aging is determined by drying the epoxy and their clay-epoxy nanocomposites after moisture absorption. Significant permanent damage is observed for fracture toughness and flexural modulus, while the extent of permanent damage is less significant for flexural strength. It is also observed that permanent degradation in Somasif MAE clay-epoxy nanocomposites is higher compared to Nanomer I.28E clay-epoxy nanocomposites. Fourier transform infrared (FTIR) spectroscopy revealed that both clays retained their original chemical structure after the absorption-desorption cycle without undergoing significant changes. Scanning electron microscopy (SEM) images of the fracture surfaces provide evidence that Somasif MAE clay particles offered very little resistance to crack propagation in case of redried specimens when compared to Nanomer I.28E counterpart. The reason for the observed higher extent of permanent degradation in Somasif MAE clay-epoxy system has been attributed to the weakening of the filler-matrix interface.

  20. Avaliação do processo de cura da borracha nitrílica (NBR pela resina fenólica através do cálculo da constante de cura Evaluation of phenolic resin vulcanization of nitrile rubber (NBR through determination of the cure constant

    Directory of Open Access Journals (Sweden)

    Ana Maria Furtado

    2001-03-01

    Full Text Available O processo de cura envolve reações de múltiplos mecanismos e sua investigação pode ser feita por meio de várias técnicas. Este trabalho apresenta a comparação entre dois métodos que utilizam parâmetros reométricos para o cálculo da constante cinética de cura (k relacionada com a cura da borracha nitrílica com a resina fenólica, tendo o policloropreno e o óxido de zinco como sistema ativador. Foi utilizado o planejamento de experimentos fatorial completo (2³ + ponto central como base para a preparação das formulações e análise dos resultados. Os resultados obtidos identificaram a influência da temperatura, da quantidade de cada um dos componentes das formulações e da adequação dos métodos de avaliação para o processo de cura da borracha nitrílica pela resina fenólica.The cure process involves reactions with multiple mechanisms and its investigation can be followed by using different techniques. This work compares two methods in which rheometric parameters are used to calculate the cure rate constant (k, related to the cure of nitrile rubber with phenolic resin and having polychloroprene and zinc oxide as the activators. A complete factorial (2³ + central point experimental design was used as base to prepare the formulations and to analyse the results. The results obtained identified the influence of the temperature, the amount of each component in the formulation and the suitability of the evaluation methods for the cure process of nitrile rubber with phenolic resin.

  1. Epoxy Nanocomposites - Curing Rheokinetics, Wetting and Adhesion to Fibers

    International Nuclear Information System (INIS)

    Ilyin, S. O.; Kotomin, S. V.; Kulichikhin, V. G.

    2010-01-01

    Epoxy nanocomposites considered as challenging polymeric matrix for advanced reinforced plastics. Nanofillers change rheokinetics of epoxy resin curing, affect wetting and adhesion to aramid and carbon fibers. In all cases extreme dependence of adhesive strength vs filler content in the binder was observed. New experimental techniques were developed to study wettability and fiber-matrix adhesion interaction, using yarn penetration path length, aramid fiber knot pull-up test and electrical admittance of the fracture surface of CFRP.

  2. Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

    Directory of Open Access Journals (Sweden)

    Maria Elena Arce

    2018-01-01

    Full Text Available This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a inorganic PCMs (hydrated salts, epoxy resins and aluminum particulates or (b organic PCM (paraffin, epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (<10 wt %; however, given its mass, the enthalpy detected in the composites was reduced as their loading further increased. The conductive phase combination (PCM + epoxy resin + hardener + thickening agent presents great potential as a heat-absorbing material at the temperatures employed.

  3. Fabrication of carbon nanotube/epoxy nanocomposite and characterization of its mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Mubin, Muhammad Shamsul Huda

    2007-02-15

    In this study, carbon nanotube polymer nanocomposites have been fabricated incorporating single walled carbon nantubes (SWNTs) or multiwalled carbon nanotubes (MWNTs) in a thermosetting polymer matrix, epoxy resin. Nanoindentation measurements showed that elastic modulus of epoxy polymer matrix has changed from 3.5 GPa to 4.0 GPa (∼ 15 % increase) only for 0.005 wt% single walled carbon nanotubes loading. The hardness of the single walled carbon nanotube incorporated epoxy nanocomposites remained nearly unchanged for 0.005 wt % nanotube loading. Multiwalled carbon nanotube incorporated epoxy nanocomposites showed deterioration of both the hardness, from 0.2 GPa to 0.08 GPa (∼factor 2.5), and elastic modulus, from 3.5 GPa to 2.1 GPa (∼ factor 1.6), for 0.02 wt % nanotube loading. Homogeneity study using continuous stiffness measurement (CSM) mode of indentation techniques revealed the lack in homogeneity of the fabricated nancomposite may be responsible for deteriorating mechanical properties. High resolution scanning electronic microscopic (SEM) images taken from cross section of carbon nanotubes incorporated epoxy nanocomposites showed several poorly attached thin layers of nanocomposites staked on each other which may be another cause of property deterioration.

  4. Fabrication of carbon nanotube/epoxy nanocomposite and characterization of its mechanical properties

    International Nuclear Information System (INIS)

    Mubin, Muhammad Shamsul Huda

    2007-02-01

    In this study, carbon nanotube polymer nanocomposites have been fabricated incorporating single walled carbon nantubes (SWNTs) or multiwalled carbon nanotubes (MWNTs) in a thermosetting polymer matrix, epoxy resin. Nanoindentation measurements showed that elastic modulus of epoxy polymer matrix has changed from 3.5 GPa to 4.0 GPa (∼ 15 % increase) only for 0.005 wt% single walled carbon nanotubes loading. The hardness of the single walled carbon nanotube incorporated epoxy nanocomposites remained nearly unchanged for 0.005 wt % nanotube loading. Multiwalled carbon nanotube incorporated epoxy nanocomposites showed deterioration of both the hardness, from 0.2 GPa to 0.08 GPa (∼factor 2.5), and elastic modulus, from 3.5 GPa to 2.1 GPa (∼ factor 1.6), for 0.02 wt % nanotube loading. Homogeneity study using continuous stiffness measurement (CSM) mode of indentation techniques revealed the lack in homogeneity of the fabricated nancomposite may be responsible for deteriorating mechanical properties. High resolution scanning electronic microscopic (SEM) images taken from cross section of carbon nanotubes incorporated epoxy nanocomposites showed several poorly attached thin layers of nanocomposites staked on each other which may be another cause of property deterioration

  5. IMPACT OF THERMAL FATIGUE ON YOUNG’S MODULUS OF EPOXY ADHESIVES

    Directory of Open Access Journals (Sweden)

    Mariusz Kłonica

    2015-11-01

    Full Text Available The following paper presents a comparative analysis of two epoxy-based adhesives: Hysol 9466 and Hysol 3421, prior to and after thermal shock testing. The tests focused on determining Young’s modulus. Epoxy-based materials are among the most widespread adhesive materials used as universal structural adhesives. The prepared epoxy samples (Hysol 9466 and Hysol 3421 were subjected to thermal shock cycling tests, according to a specified programme, in a thermal shock testing chamber, at a temperature range –40 °C to +60 °C and in the number of 200 cycles. Conclusions from the tests are presented at the final stage of the paper.

  6. Mechanical, thermal and microstructural characteristics of cellulose fibre reinforced epoxy/organoclay nanocomposites

    KAUST Repository

    Alamri, H.

    2012-10-01

    Epoxy nanocomposites reinforced with recycled cellulose fibres (RCFs) and organoclay platelets (30B) have been fabricated and investigated in terms of WAXS, TEM, mechanical properties and TGA. Results indicated that mechanical properties generally increased as a result of the addition of nanoclay into the epoxy matrix. The presence of RCF significantly enhanced flexural strength, fracture toughness, impact strength and impact toughness of the composites. However, the inclusion of 1 wt.% clay into RCF/epoxy composites considerably increased the impact strength and toughness. The presence of either nanoclay or RCF accelerated the thermal degradation of neat epoxy, but at high temperature, thermal stability was enhanced with increased char residue over neat resin. The failure micromechanisms and energy dissipative processes in these nanocomposites were discussed in terms of microstructural observations. © 2012 Published by Elsevier Ltd. All rights reserved.

  7. Thermomechanical response and toughening mechanisms of a carbon nano bead reinforced epoxy composite

    Energy Technology Data Exchange (ETDEWEB)

    Goyat, M.S., E-mail: goyatmanjeetsingh@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India); Suresh, Sumit; Bahl, Sumit [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India); Halder, Sudipta [Department of Mechanical Engineering, National Institute of Technology, Silchar, 788010, Assam (India); Ghosh, P.K. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India)

    2015-09-15

    The current research on carbon nano beads (CNB) is focused on various applications such as high strength nanocomposites, electronic devices, lubricants, semiconductors, and high-performance batteries, etc. The commercial uses of CNB are yet juvenile for the market. Only limited results have been published so far on CNB reinforced polymers [1]. This study highlights the synthesis of uniform size, spherical CNB using chemical vapour deposition (CVD) method. The synthesized CNB are introduced into epoxy matrix by ultrasonic dual mode mixing route to produce CNB/epoxy nanocomposite. The CNB are characterized by X-ray diffraction, Energy dispersive X-ray analysis and field emission scanning electron microscope (FESEM). Morphology, thermal and mechanical properties of the CNB/epoxy nanocomposites is characterized by FESEM, Thermo-gravimetric analyzer and tensile and bending tests respectively. A noticeable improvement in thermal and mechanical properties of CNB reinforced epoxy matrix with low nanofiller content is observed. Several toughening mechanisms such as particle pull out, crack deflection, particle bridging, crack pinning, shear yielding or plastic deformation, and microcracking are identified. But, only the crack deflection, particle bridging and shear yielding or plastic deformations are recognized as the leading toughening mechanisms for CNB/epoxy nanocomposite. These results can be considered as symptomatic of a potential CNB espousal in new composites. - Highlights: • Synthesis of uniform size, spherical CNB using chemical vapour deposition method. • Fabrication of CNB/epoxy nanocomposites by ultrasonic dual mode mixing route. • Significant enhancement in thermomechanical properties of CNB/epoxy nanocomposite. • Main toughening mechanisms: Crack deflection, particle bridging and shear yielding.

  8. Thermomechanical response and toughening mechanisms of a carbon nano bead reinforced epoxy composite

    International Nuclear Information System (INIS)

    Goyat, M.S.; Suresh, Sumit; Bahl, Sumit; Halder, Sudipta; Ghosh, P.K.

    2015-01-01

    The current research on carbon nano beads (CNB) is focused on various applications such as high strength nanocomposites, electronic devices, lubricants, semiconductors, and high-performance batteries, etc. The commercial uses of CNB are yet juvenile for the market. Only limited results have been published so far on CNB reinforced polymers [1]. This study highlights the synthesis of uniform size, spherical CNB using chemical vapour deposition (CVD) method. The synthesized CNB are introduced into epoxy matrix by ultrasonic dual mode mixing route to produce CNB/epoxy nanocomposite. The CNB are characterized by X-ray diffraction, Energy dispersive X-ray analysis and field emission scanning electron microscope (FESEM). Morphology, thermal and mechanical properties of the CNB/epoxy nanocomposites is characterized by FESEM, Thermo-gravimetric analyzer and tensile and bending tests respectively. A noticeable improvement in thermal and mechanical properties of CNB reinforced epoxy matrix with low nanofiller content is observed. Several toughening mechanisms such as particle pull out, crack deflection, particle bridging, crack pinning, shear yielding or plastic deformation, and microcracking are identified. But, only the crack deflection, particle bridging and shear yielding or plastic deformations are recognized as the leading toughening mechanisms for CNB/epoxy nanocomposite. These results can be considered as symptomatic of a potential CNB espousal in new composites. - Highlights: • Synthesis of uniform size, spherical CNB using chemical vapour deposition method. • Fabrication of CNB/epoxy nanocomposites by ultrasonic dual mode mixing route. • Significant enhancement in thermomechanical properties of CNB/epoxy nanocomposite. • Main toughening mechanisms: Crack deflection, particle bridging and shear yielding.

  9. Synthesis and antimicrobial activity of long-chain 3,4-Epoxy-2-alkanones.

    Science.gov (United States)

    Wood, William F

    2010-01-01

    3,4-Epoxy-2-dodecanone, a major component in the preorbital gland of the African grey duiker (Sylvicapra grimmia), showed antimicrobial activity in preliminary tests. The C(11) to C(17) homologues of this compound were prepared and their activity against several pathogenic dermal bacteria and fungi was tested. 3,4-Epoxy-2-dodecanone and 3,4-epoxy-2-tridecanone inhibited the growth of Trichophyton mentagrophytes at 25 Îg/mL. Moderate inhibition of the growth of the bacteria Propionibacterium acnes and the lipophilic yeast, Pityrosporum ovale, was seen for several of the homologues.

  10. Silica Treatments: A Fire Retardant Strategy for Hemp Fabric/Epoxy Composites

    Directory of Open Access Journals (Sweden)

    Francesco Branda

    2016-08-01

    Full Text Available In this paper, for the first time, inexpensive waterglass solutions are exploited as a new, simple and ecofriendly chemical approach for promoting the formation of a silica-based coating on hemp fabrics, able to act as a thermal shield and to protect the latter from heat sources. Fourier Transform Infrared (FTIR and solid-state Nuclear Magnetic Resonance (NMR analysis confirm the formation of –C–O–Si– covalent bonds between the coating and the cellulosic substrate. The proposed waterglass treatment, which is resistant to washing, seems to be very effective for improving the fire behavior of hemp fabric/epoxy composites, also in combination with ammonium polyphosphate. In particular, the exploitation of hemp surface treatment and Ammonium Polyphosphate (APP addition to epoxy favors a remarkable decrease of the Heat Release Rate (HRR, Total Heat Release (THR, Total Smoke Release (TSR and Specific Extinction Area (SEA (respectively by 83%, 35%, 45% and 44% as compared to untreated hemp/epoxy composites, favoring the formation of a very stable char, as also assessed by Thermogravimetric Analysis (TGA. Because of the low interfacial adhesion between the fabrics and the epoxy matrix, the obtained composites show low strength and stiffness; however, the energy absorbed by the material is higher when using treated hemp. The presence of APP in the epoxy matrix does not affect the mechanical behavior of the composites.

  11. Characterization of Low Density Glass Filled Epoxies

    National Research Council Canada - National Science Library

    Quesenberry, Matthew

    2003-01-01

    This report discusses the experimental determination and modeling of several thermophysical and mechanical properties of glass filled epoxy composite systems for potential use as electronic potting compounds...

  12. Determinants of epoxy allergy in the construction industry : a case-control study

    NARCIS (Netherlands)

    Spee, Ton; Timmerman, Johan G; Rühl, Reinhold; Kersting, Klaus; Heederik, Dick J J; Smit, Lidwien A M

    2016-01-01

    BACKGROUND: Workers exposed to epoxy products are at risk of developing allergic contact dermatitis. OBJECTIVES: To compare workers throughout the German construction industry with and without skin allergy to epoxy resins, hardeners, and/or reactive diluents, and to investigate which determinants

  13. Improvement of fatigue resistance of epoxy composite with microencapsulated epoxy-SbF5 self-healing system

    Directory of Open Access Journals (Sweden)

    X. J. Ye

    2017-11-01

    Full Text Available Rapid retardation and arresting of fatigue crack are successfully realized in the epoxy composite containing microencapsulated epoxy and ethanol solution of antimony pentafluoride-ethanol complex (SbF5·HOC2H5/HOC2H5. The effects of (i microcapsules induced-toughening, (ii hydrodynamic pressure crack tip shielding offered by the released healing agent, and (iii polymeric wedge and adhesive bonding of cured healing agent account for extension of fatigue life of the material. The two components of the healing agent can quickly react with each other soon after rupture of the microcapsules, and reconnect the crack only 20 seconds as of the test. The applied stress intensity range not only affects the healing efficiency, but also can be used to evaluate the healing speed. The present work offers a very fast healing system, and sets up a framework for characterizing speed of self-healing.

  14. High performance, rapid thermal/UV curing epoxy resin for additive manufacturing of short and continuous carbon fiber epoxy composites

    Science.gov (United States)

    Lewicki, James

    2018-04-17

    An additive manufacturing resin system including an additive manufacturing print head; a continuous carbon fiber or short carbon fibers operatively connected to the additive manufacturing print head; and a tailored resin operatively connected to the print head, wherein the tailored resin has a resin mass and wherein the tailored resin includes an epoxy component, a filler component, a catalyst component, and a chain extender component; wherein the epoxy component is 70-95% of the resin mass, wherein the filler component is 1-20% of the resin mass, wherein the catalyst component is 0.1-10% of the resin mass, and wherein the chain extender component is 0-50% of the resin mass.

  15. Pristine and γ-irradiated halloysite reinforced epoxy nanocomposites - Insight study

    Science.gov (United States)

    Saif, Muhammad Jawwad; Naveed, Muhammad; Zia, Khalid Mahmood; Asif, Muhammad

    2016-10-01

    The present study focuses on development of epoxy system reinforced with naturally occurring halloysite nanotubes (HNTs). A comparative study is presented describing the performance of pristine and γ-irradiated HNTs in an epoxy matrix. The γ-irradiation treatment was used for structural modification of natural pristine HNTs under air sealed environment at different absorbed doses and subsequently these irradiated HNTs were incorporated in epoxy resin with various wt% loadings. The consequences of γ-irradiation on HNTs were studied by FTIR and X-ray diffraction analysis (XRD) in terms of changes in functional groups and crystalline characteristics. An improvement is observed in mechanical properties and crack resistance of composites reinforced with γ-irradiated HNTs. The irradiated HNTs imparted an improved flexural and tensile strength/modulus along with better thermal performance.

  16. Exploring biomass based carbon black as filler in epoxy composites: Flexural and thermal properties

    International Nuclear Information System (INIS)

    Abdul Khalil, H.P.S.; Firoozian, P.; Bakare, I.O.; Akil, Hazizan Md.; Noor, Ahmad Md.

    2010-01-01

    Carbon blacks (CB), derived from bamboo stem (BS-CB), coconut shells (CNS-CB) and oil palm empty fiber bunch (EFB-CB), were obtained by pyrolysis of fibers at 700 o C, characterized and used as filler in epoxy composites. The results obtained showed that the prepared carbon black possessed well-developed porosities and are predominantly made up of micropores. The BS-CB, CNS-CB and EFB-CB filled composites were prepared and characterized using scanning electron microscope (SEM) and thermogravimetric analyzer (TGA). The SEM showed that the fractured surface of the composite indicates its high resistance to fracture. The CBs-epoxy composites exhibited better flexural properties than the neat epoxy, which was attributed to better adhesion between the CBs and the epoxy resin. TGA showed that there was improvement in thermal stability of the carbon black filled composites compared to the neat epoxy resin.

  17. Static and Dynamic Mechanical Properties of Graphene Oxide-Incorporated Woven Carbon Fiber/Epoxy Composite

    Science.gov (United States)

    Adak, Nitai Chandra; Chhetri, Suman; Kim, Nam Hoon; Murmu, Naresh Chandra; Samanta, Pranab; Kuila, Tapas

    2018-03-01

    This study investigates the synergistic effects of graphene oxide (GO) on the woven carbon fiber (CF)-reinforced epoxy composites. The GO nanofiller was incorporated into the epoxy resin with variations in the content, and the CF/epoxy composites were manufactured using a vacuum-assisted resin transfer molding process and then cured at 70 and 120 °C. An analysis of the mechanical properties of the GO (0.2 wt.%)/CF/epoxy composites showed an improvement in the tensile strength, Young's modulus, toughness, flexural strength and flexural modulus by 34, 20, 83, 55 and 31%, respectively, when compared to the CF/epoxy composite. The dynamic mechanical analysis of the composites exhibited an enhancement of 56, 114 and 22% in the storage modulus, loss modulus and damping capacity (tan δ), respectively, at its glass transition temperature. The fiber-matrix interaction was studied using a Cole-Cole plot analysis.

  18. Grafting of polyethylenimine onto cellulose nanofibers for interfacial enhancement in their epoxy nanocomposites.

    Science.gov (United States)

    Zhao, Jiangqi; Li, Qingye; Zhang, Xiaofang; Xiao, Meijie; Zhang, Wei; Lu, Canhui

    2017-02-10

    Cellulose nanofibers (CNFs) were surface-modified with polyethyleneimine (PEI), which brought plentiful amine groups on the surface of CNFs, leading to a reduced hydrogen bond density between CNFs and consequently less CNFs agglomerates. The amine groups could also react with the epoxy as an effective curing agent that could increase the interfacial crosslinking density and strengthen interfacial adhesion. The tensile strength and Young's modulus of CNFs-PEI/Epoxy nanocomposites were 88.1% and 237.6% higher than those of neat epoxy, respectively. The tensile storage modulus of the nanocomposites also increased significantly at the temperature either below or above the Tg. The coefficient of thermal expansion for the CNFs-PEI/Epoxy nanocomposites was 22.2ppmK -1 , much lower than that of the neat epoxy (88.6ppmK -1 ). In addition, the thermal conductivity of the nanocomposites was observed to increase as well. The exceptional and balanced properties may provide the nanocomposites promising applications in automotive, construction and electronic devices. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Enhanced mechanical properties of epoxy nanocomposites by mixing noncovalently functionalized boron nitride nanoflakes.

    Science.gov (United States)

    Lee, Dongju; Song, Sung Ho; Hwang, Jaewon; Jin, Sung Hwan; Park, Kwang Hyun; Kim, Bo Hyun; Hong, Soon Hyung; Jeon, Seokwoo

    2013-08-12

    The influence of surface modifications on the mechanical properties of epoxy-hexagonal boron nitride nanoflake (BNNF) nanocomposites is investigated. Homogeneous distributions of boron nitride nanoflakes in a polymer matrix, preserving intrinsic material properties of boron nitride nanoflakes, is the key to successful composite applications. Here, a method is suggested to obtain noncovalently functionalized BNNFs with 1-pyrenebutyric acid (PBA) molecules and to synthesize epoxy-BNNF nanocomposites with enhanced mechanical properties. The incorporation of noncovalently functionalized BNNFs into epoxy resin yields an elastic modulus of 3.34 GPa, and 71.9 MPa ultimate tensile strength at 0.3 wt%. The toughening enhancement is as high as 107% compared to the value of neat epoxy. The creep strain and the creep compliance of the noncovalently functionalized BNNF nanocomposite is significantly less than the neat epoxy and the nonfunctionalized BNNF nanocomposite. Noncovalent functionalization of BNNFs is effective to increase mechanical properties by strong affinity between the fillers and the matrix. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Graphene-epoxy flexible transparent capacitor obtained by graphene-polymer transfer and UV-induced bonding.

    Science.gov (United States)

    Sangermano, Marco; Chiolerio, Alessandro; Veronese, Giulio Paolo; Ortolani, Luca; Rizzoli, Rita; Mancarella, Fulvio; Morandi, Vittorio

    2014-02-01

    A new approach is reported for the preparation of a graphene-epoxy flexible transparent capacitor obtained by graphene-polymer transfer and UV-induced bonding. SU8 resin is employed for realizing a well-adherent, transparent, and flexible supporting layer. The achieved transparent graphene/SU8 membrane presents two distinct surfaces: one homogeneous conductive surface containing a graphene layer and one dielectric surface typical of the epoxy polymer. Two graphene/SU8 layers are bonded together by using an epoxy photocurable formulation based on epoxy resin. The obtained material showed a stable and clear capacitive behavior. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Effect of thermally reduced graphene oxide on dynamic mechanical properties of carbon fiber/epoxy composite

    Science.gov (United States)

    Adak, Nitai Chandra; Chhetri, Suman; Murmu, Naresh Chandra; Samanta, Pranab; Kuila, Tapas

    2018-03-01

    The Carbon fiber (CF)/epoxy composites are being used in the automotive and aerospace industries owing to their high specific mechanical strength to weight ratio compared to the other conventional metal and alloys. However, the low interfacial adhesion between fiber and polymer matrix results the inter-laminar fracture of the composites. Effects of different carbonaceous nanomaterials i.e., carbon nanotubes (CNT), graphene nanosheets (GNPs), graphene oxide (GO) etc. on the static mechanical properties of the composites were investigated in detail. Only a few works focused on the improvement of the dynamic mechanical of the CF/epoxy composites. Herein, the effect of thermally reduced grapheme oxide (TRGO) on the dynamic mechanical properties of the CF/epoxy composites was investigated. At first, GO was synthesized using modified Hummers method and then reduced the synthesized GO inside a vacuum oven at 800 °C for 5 min. The prepared TRGO was dispersed in the epoxy resin to modify the epoxy matrix. Then, a number of TRGO/CF/epoxy laminates were manufactured incorporating different wt% of TRGO by vacuum assisted resin transfer molding (VARTM) technique. The developed laminates were cured at room temperature for 24 h and then post cured at 120 °C for 2 h. The dynamic mechanical analyzer (DMA 8000 Perkin Elmer) was used to examine the dynamic mechanical properties of the TRGO/CF/epoxy composites according to ASTM D7028. The dimension of the specimen was 44×10×2.4 mm3 for the DMA test. This test was carried out under flexural loading mode (duel cantilever) at a frequency of 1 Hz and amplitude of 50 μm. The temperature was ramped from 30 to 200 °C with a heating rate of 5 °C min-1. The dynamic mechanical analysis of the 0.2 wt% TRGO incorporated CF/epoxy composites showed ~ 96% enhancement in storage modulus and ~ 12 °C increments in glass transition temperature (Tg) compared to the base CF/epoxy composites. The fiber-matrix interaction was studied by Cole

  2. Avaliação in vitro da força de união, através de teste de tração, de porcelana feldspática com diversos tratamentos superficiais à resina composta In vitro evaluation of the bonding strength of the composite resin to feldspathic porcelain with several surface treatments, applying a tensile strength test

    Directory of Open Access Journals (Sweden)

    Américo Mendes CARNEIRO JUNIOR

    1999-07-01

    Full Text Available Na busca da reprodução do aspecto dental, a porcelana se destaca entre os materiais restauradores. Desse modo, a utilização do material vem atualmente crescendo cada vez mais, e, com ela, a probabilidade de fraturas. Porém, uma falha nem sempre exige a troca da restauração: existe a possibilidade de um reparo com resina composta. Este trabalho se propôs a avaliar, in vitro, a força de união da resina composta à porcelana feldspática, quando efetuados os seguintes tratamentos superficiais na porcelana: asperização com instrumento cortante rotatório diamantado ou jateamento com óxido de alumínio de 50 micra, em aplicação isolada ou associada a condicionamento com ácido fosfórico, por 15 segundos, ou com ácido fluorídrico, por 1 ou por 4 minutos. Todos os espécimes foram previamente regularizados com lixa nº 220. Após os tratamentos superficiais, receberam o sistema de união adesivo para porcelana Scotchbond Multi-Purpose Plus Dental Adhesive System (3M. Feita a união com a resina composta (Restaurador Z100, 3M, foram armazenados em água destilada a 37ºC, em estufa, por 7 dias, e termociclados (600 ciclos de 1 minuto, entre 5 e 55ºC, sendo então submetidos a teste de tração. Pelos resultados obtidos, pôde-se concluir que ocorreu melhora na resistência à tração com todos os tratamentos propostos (em comparação ao observado no grupo controle, sem nenhum tratamento superficial. O jateamento produziu maior resistência de união que a asperização com instrumento cortante rotatório diamantado; mas, quando associados ao condicionamento com qualquer dos ácidos selecionados, independente do tempo de aplicação, não houve diferença estatística entre esses tratamentos.In the search for the recovery of the dental aspect, the porcelain stands out among restoring materials. The use of this material has increased considerably over the last years, therefore increasing the probability of fractures. Even so, not

  3. Thermal conductive epoxy enhanced by nanodiamond-coated carbon nanotubes

    Science.gov (United States)

    Zhao, Bo; Jiang, Guohua

    2017-11-01

    Nanodiamond (ND) particles were coated on the surface of carbon nanotubes (CNTs) by chemical reactions. Reliable bonding was formed by the combination of acyl chloride on NDs and amine group on CNTs. ND coated CNTs (CNT-ND) were dispersed into epoxy to fabricate thermal conductive resins. The results show that the surface energy of CNTs is decreased by the coated NDs, which is contributed to the excellent dispersion of CNT-NDs in the epoxy matrix. The heat-transfer channels were built by the venous CNTs cooperating with the coated NDs, which not only plays an effective role of heat conduction for CNTs and NDs, but also avoids the electrical leakage by the protection of NDs surrounding outside of CNTs. Electrical and thermal conductance measurements demonstrate that the influence of the CNT-ND incorporation on the electrical conductance is minor, however, the thermal conductivity is improved significantly for the epoxy filled with CNT-ND.[Figure not available: see fulltext.

  4. Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

    Science.gov (United States)

    Pour-Ali, Sadegh; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

    2016-07-01

    An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

  5. Influence of hematite nanorods on the mechanical properties of epoxy resin

    Directory of Open Access Journals (Sweden)

    Bogdanović Gordana

    2017-01-01

    Full Text Available The mechanical properties of nanocomposites obtained by incorporation of fairly uniform hematite nanorods (α-Fe2O3 NRs into epoxy resin were studied as a function of the content of the inorganic phase. A thorough microstructural characterization of the α-Fe2O3 NRs and the nanocomposites was performed using transmission electron microscopy (TEM and atomic force microscopy (AFM. The TEM measurements revealed rod-like morphology of the nanofiller with a uniform size distribution (8.5 nm×170 nm, diameter×length. High-magnification TEM and AFM measurements indicated agglomeration of α-Fe2O3 NRs embedded in the epoxy resin. Stress at break, strain at break, elastic modulus and tensile toughness of the nanocomposites were compared with the data obtained for pure epoxy resin. Significant influence of nanofiller on the mechanical properties of epoxy resin, as well as on the glass transition temperature, could be noticed for samples with low contents of the inorganic phase (up to 1 wt. %. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45020

  6. Strengthening Performance of PALF-Epoxy Composite Plate on Reinforced Concrete Beams

    Science.gov (United States)

    Chin, Siew C.; Tong, Foo S.; Doh, Shu I.; Gimbun, Jolius; Ong, Huey R.; Serigar, Januar P.

    2018-03-01

    This paper presents the effective strengthening potential of pineapple leaves fiber (PALF)-epoxy composite plate on reinforced concrete (RC) beam. At first the PALF is treated with alkali (NaOH) and its morphology is observed via scanning electron microscope (SEM). The composite plates made of PALF and epoxy with fiber loading ranging from 0.1 to 0.4 v/v was tested for its flexural behaviour. The composite was then used for external RC beam strengthening. The structural properties of RC beams were evaluated and all the beams were tested under four-point bending. It was found that the flexural strength increased as the fiber volume ratio increases. The maximum flexural strength (301.94 MPa) was obtained at the fiber volume ratio of 40%. The beam strengthened with PALF-epoxy composite plate has a 7% higher beam capacity compared to the control beam. Cracks formed at the edge of the plate of PALF-strengthened beams resulted in diagonal cracking. Result from this work shows that the PALF-epoxy composite plate has the potential to be used as external strengthening material for RC beam.

  7. Adhesion of pineapple-leaf fiber to epoxy matrix: The role of surface treatments

    Directory of Open Access Journals (Sweden)

    Yusran Payae

    2009-07-01

    Full Text Available Natural fibers are considered to have potential use as reinforcing agents in polymer composite materials because of their principle benefits: moderate strength and stiffness, low cost, and be an environmental friendly, degradable, and renewablematerial. Due to their inherently hydrophilic nature, they are prone to absorb moisture, which can plasticise or weaken theadhesion of fibers to the surrounding matrix and by this affect the performance of composites used in atmospheric humidity,particularly at elevated temperatures. The surface treatments are often applied to the fiber to improve the bond strengthbetween the fibers and matrix. This work discussed the effect of sodium hydroxide (NaOH treatment and epoxy resin as acompatibilizing agent on interface properties of pineapple leaf fiber (PALF-epoxy composites. A single-fiber fragmentationtest coupled with data reduction technique was employed to assess interface quality in terms of apparent interfacial shearstrength (IFSS or a of untreated, NaOH, and epoxy resin treated PALFs-epoxy composites. Tensile properties of untreatedand treated PALFs were also examined. It was found that both treatments substantially increase a, corresponding to animproved level of adhesion. The improvement in the level of adhesion for the alkali and epoxy treated fiber composites wasdue to an increase in the physical bonding between the alkali treated fibers and the matrix, and due to a promoted compatibilitybetween the epoxy treated fibers and matrix, respectively.

  8. Ionic Liquid Epoxy Composite Cryotanks, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this work is to determine the optimal process for manufacturing lightweight linerless cryogenic storage tanks using ionic liquid epoxy composite...

  9. Synthesis, structure and properties of novel epoxy and rubber-modified epoxy impregnated Y-Ba-Cu-O superconductors

    International Nuclear Information System (INIS)

    Low, I.M.; Lim, F.W.; Chisholm, W.

    1992-01-01

    This paper reports the synthesis, structure and properties of novel YBa 2 Cu 3 O 6+x (123) - polymer composites. The polymers used were epoxy and rubber-modified epoxy resins. Superconducting composites with good strength, toughness, hardness and chemical resistance have been successfully fabricated. The presence of polymer(s) does not appear to affect the superconducting (T c ) of about 90 K. Levitation experiments show that the height (z) of the levitating magnet depends on sample thickness, and mass and pole strength of the magnet. A simple image force model best describes the observed dependence of z on the mass and pole strength. Atomic absorption and pH measurements in the corrosion study show that the polymer coating provides an impermeable barrier to the ingress of solvents and a concomitant resistance to phase decomposition. 12 refs., 2 tabs., 5 figs

  10. Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite.

    Science.gov (United States)

    Hsu, Sheng-Hao; Chen, Rung-Shu; Chang, Yuan-Ling; Chen, Min-Huey; Cheng, Kuo-Chung; Su, Wei-Fang

    2012-11-01

    Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70-100 nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42 vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility

  11. Morphological Study on Room-Temperature-Cured PMMA-Grafted Natural Rubber-Toughened Epoxy/Layered Silicate Nanocomposite

    Directory of Open Access Journals (Sweden)

    N. Y. Yuhana

    2012-01-01

    Full Text Available A morphological study was conducted on ternary systems containing epoxy, PMMA-grafted natural rubber, and organic chemically modified montmorillonite (Cloisite 30B. Optical microscopy, transmission electron microscopy (TEM, scanning electron microscopy (SEM, energy dispersive X-ray (EDX, and wide-angle X-ray diffraction (WAXD analysis were used. The following four materials were prepared at room temperature: cured unmodified epoxy, cured toughened epoxy, cured unmodified epoxy/Cloisite 30B nanocomposites, and cured toughened epoxy/Cloisite 30B nanocomposites. Mixing process was performed by mechanical stirring. Poly(etheramine was used as the curing agent. The detailed TEM images revealed co-continuous and dispersed spherical rubber in the epoxy-rubber blend, suggesting a new proposed mechanism of phase separation. High-magnification TEM analysis showed good interactions between rubber and Cloisite 30B in the ternary system. Also, it was found that rubber particles could enhance the separation of silicates layers. Both XRD and TEM analyses confirmed that the intercalation of Cloisite 30B was achieved. No distinct exfoliated silicates were observed by TEM. Aggregates of layered silicates (tactoids were observed by SEM and EDX, in addition to TEM at low magnification. EDX analysis confirmed the presence of organic and inorganic elements in the binary and ternary epoxy systems containing Cloisite 30B.

  12. Effective functionalization of carbon nanotubes for bisphenol F epoxy matrix composites

    Directory of Open Access Journals (Sweden)

    Zhe Wang

    2012-08-01

    Full Text Available A brand-new type of multifunctional nanocomposites with high DC conductivity and enhanced mechanical strength was fabricated. Ionic liquid functionalized Carbon Nanotubes (CNTs-IL were embedded into epoxy matrix with covalent bonding by the attached epoxy groups. The highest DC conductivity was 8.38 x 10-3 S.m-1 with 1.0 wt. (% loading of CNTs-IL and the tensile strength was increased by 36.4% only at a 0.5 wt. (% concentration. A mixing solvent was used to disperse CNTs-IL in the epoxy monomer. The dispersion and distribution of CNTs-IL in the polymer matrix were measured by utilizing both optical microscopy and scanning electron microscopy, respectively.

  13. Carbon black reinforced C8 ether linked bismaleimide toughened electrically conducting epoxy nanocomposites

    International Nuclear Information System (INIS)

    Mandhakini, M.; Chandramohan, A.; Jayanthi, K.; Alagar, M.

    2014-01-01

    Highlight: • The toughness of the epoxy is improved with C8e-BMI. • Conduction through ohmic contact chain takes the leading mechanism for electrical conduction instead of tunneling with 5 wt% CB. • The phase segregation between epoxy/C8 e-BMI improves the toughness of the nanocomposite. • Both toughening and flexibilization effect is responsible for improvement in impact strength. • The largest challenge of appropriate balance between the electrical conductivity and mechanical behavior is attained in a cost effective manner. - Abstract: The present work deals with the toughening of brittle epoxy matrix with C8 ether linked bismaleimide (C8 e-BMI) and then study the reinforcing effect of carbon black (CB) in enhancing the conducting properties of insulating epoxy matrix. The Fourier transform infrared spectroscopy (FTIR) and Raman analysis indicate the formation of strong covalent bonds between CB and C8 e-BMI/epoxy matrix. The X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) analysis indicate the event of phase separation in 5 wt% CB loaded epoxy C8 e-BMI nanocomposites. The impact strength increased up to 5 wt% of CB loading with particle pull and crack deflection to be driving mechanism for enhancing the toughness of the nanocomposite and beyond 5 wt% the impact strength started to decrease due to aggregation of CB. The dynamic mechanical analysis (DMA) also indicates the toughness of the nanocomposites was improved with 5 wt% of CB loading due to the phase segregation between epoxy and C8 e-BMI in the presence of CB. The electrical conductivity was also increased with 5 wt% of CB due to classical conduction by ohmic chain contact

  14. Comportamiento a fractura de polímeros envejecidos

    Directory of Open Access Journals (Sweden)

    Argüelles, A.

    2001-04-01

    Full Text Available The dynamic fracture behaviour of three types of composite materials was studied. Two of the composites were manufactured from the same thermoplastic resin, reinforced with glass or carbon fibre fabric, respectively; the other one, was manufactured with an epoxy resin, reinforced with carbon fibre fabric. The composites were subjected to accelerated ageing effect on a climatic test chamber, under humidity and temperature control, for different notch-Width ratios. The dynamic fracture behaviour was analysed by applying the ASTM E 24.03.03 Standard proposal to Charpy instrumented test results with the goal of validating this testing procedure for composite materials.

    Se estudia aquí el comportamiento a fractura en régimen dinámico de tres tipos de materiales compuestos: dos de ellos fabricados a partir de una misma resina termoplástica reforzada con tejido de fibra de vidrio o de carbono y el otro a partir de una resina de tipo epoxi reforzada con tejido de fibra de carbono. Todos ellos fueron sometidos a envejecimiento acelerado en cámara climática con control de humedad y de temperatura, para diferentes relaciones entre longitud de fisura y ancho de la probeta. El comportamiento a fractura se analizó en régimen dinámico a partir de los datos obtenidos de ensayos Charpy instrumentados, aplicando la propuesta de norma ASTM E 24.03.03, con el objetivo último de validar esta metodología de ensayo sobre materiales compuestos.

  15. Analysis and Testing of Bisphenol A-Free Bio-Based Tannin Epoxy-Acrylic Adhesives

    OpenAIRE

    Jahanshahi , Shayesteh; Pizzi , Antonio; Abdulkhani , Ali; Shakeri , Alireza

    2016-01-01

    International audience; A tannin-based epoxy acrylate resin was prepared from glycidyl ether tannin (GET) and acrylic acid. The influence of the reaction condition for producing tannin epoxy acrylate was studied by FT-MIR, C-13-NMR, MALDI-TOF spectroscopy and shear strength. The best reaction conditions for producing tannin epoxy acrylate resin without bisphenol A was by reaction between GET and acrylic acid in the presence of a catalyst and hydroquinone at 95 degrees C for 12 h. FT-MIR, C-13...

  16. Experimental and theoretical investigation of mechanical disturbances in epoxy-impregnated superconducting coils

    International Nuclear Information System (INIS)

    Iwasa, Y.; Bobrov, E.S.; Tsukamoto, O.; Takaghi, T.; Fujita, H.; Massachusetts Inst. of Tech., Cambridge

    1985-01-01

    The theoretical correlation between shear stress and epoxy resin fracture developed in an earlier paper was verified experimentally using a series of epoxy-impregnated, thin-walled superconducting test coils. In test coils with both ends rigidly clamped, cracks occurred as transport current was increased; during a training sequence the test was terminated by a premature quench. Using acoustic emission and voltage signals, each premature quench was linked directly to a crack occurring near one of the ends. Test coils which had both ends unsupported, giving the winding freedom to expand radially, did not experience epoxy fracture and showed no premature quenches. (author)

  17. Facile fabrication of superhydrophobic films with fractal structures using epoxy resin microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Yun-Yun; Zhang, Li-Zhi, E-mail: lzzhang@scut.edu.cn

    2014-02-15

    A simple method has been developed to fabricate superhydrophobic surfaces with fractal structures with epoxy resin microspheres (ERMs). The ERMs is produced by phase separation in an epoxy-amine curing system with a silica sol (SS) dispersant. The transparent epoxy solution becomes cloudy and turns into epoxy suspension (ES) in this process. The fractal structure (two tier structure) generated by synthetic epoxy resin microspheres (ERMs) and deposited nanoincrutations on the surfaces of these ERMs, which have been observed by scanning electron microscope (SEM). The curing time of ES is an important condition to obtain films with good comprehensive performances. Superhydrophobic films can be prepared by adding extra SS into ES with a curing time longer than 5 h. The optimal curing time is 10 h to fabricate a film with good mechanical stability and high superhydrophobicity. In addition, a surface with anti-wetting property of impacting microdroplets can be fabricated by prolonging the curing time of ES to 24 h. The gradually decreased hydrophilic groups resulted from a longer curing time enable the surface to have smaller surface adhesions to water droplets, which is the main reason to keep its superhydrophobicity under impacting conditions. The coated surface is highly hydrophobic and the impacting water droplets are bounced off from the surface.

  18. Novel Formulations of Phase Change Materials-Epoxy Composites for Thermal Energy Storage.

    Science.gov (United States)

    Arce, Maria Elena; Alvarez Feijoo, Miguel Angel; Suarez Garcia, Andres; Luhrs, Claudia C

    2018-01-26

    This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (material at the temperatures employed.

  19. Facile fabrication of superhydrophobic films with fractal structures using epoxy resin microspheres

    Science.gov (United States)

    Quan, Yun-Yun; Zhang, Li-Zhi

    2014-02-01

    A simple method has been developed to fabricate superhydrophobic surfaces with fractal structures with epoxy resin microspheres (ERMs). The ERMs is produced by phase separation in an epoxy-amine curing system with a silica sol (SS) dispersant. The transparent epoxy solution becomes cloudy and turns into epoxy suspension (ES) in this process. The fractal structure (two tier structure) generated by synthetic epoxy resin microspheres (ERMs) and deposited nanoincrutations on the surfaces of these ERMs, which have been observed by scanning electron microscope (SEM). The curing time of ES is an important condition to obtain films with good comprehensive performances. Superhydrophobic films can be prepared by adding extra SS into ES with a curing time longer than 5 h. The optimal curing time is 10 h to fabricate a film with good mechanical stability and high superhydrophobicity. In addition, a surface with anti-wetting property of impacting microdroplets can be fabricated by prolonging the curing time of ES to 24 h. The gradually decreased hydrophilic groups resulted from a longer curing time enable the surface to have smaller surface adhesions to water droplets, which is the main reason to keep its superhydrophobicity under impacting conditions. The coated surface is highly hydrophobic and the impacting water droplets are bounced off from the surface.

  20. Thermoplastic impact property improvement in hybrid natural fibre epoxy composite bumper beam

    International Nuclear Information System (INIS)

    Davoodi, M M; Sapuan, S M; Ali, Aidy; Ahmad, D; Khalina, A

    2010-01-01

    Utilization of thermoset resin as a bumper beam composite matrix is currently more dominated in car manufacturer suppliers, because of availability, easy processing, low material cost and production equipment investment. Moreover, low viscosity, shrinkage and excellent flow facilitate better fibre impregnation and proper surface resin wetting. Three-dimensional cross linking curing increase impact, creep and environmental stress cracking resistance properties. Low impact properties of natural fibre epoxy composite, are main issues in its employment for automotive structural components. Impact properties in epoxy composite bumper beam could be increased by modifying the resin, reinforcement and manufacturing process as well as geometry parameters such as cross section, thickness, added ribs and fixing method optimizations could strengthen impact resistance. There are two main methods, flexibilisation and toughening, as modifying the resin in order to improve the impact properties of epoxy composite, which form single phase or two-phase morphology to make modifier as epoxy or from separate phase to keep the thermo-mechanical properties. Liquid rubber, thermoplastic, core shell particle and rigid particle are different methods of toughening improvements. In this research, thermoplastic toughening has used to improve impact properties in hybrid natural fibre epoxy composite for automotive bumper beam and has achieved reasonable impact improvements.

  1. Corrosion study of the graphene oxide and reduced graphene oxide-based epoxy coatings

    Science.gov (United States)

    Ghauri, Faizan Ali; Raza, Mohsin Ali; Saad Baig, Muhammad; Ibrahim, Shoaib

    2017-12-01

    This work aims to determine the effect of graphene oxide (GO) and reduced graphene oxide (rGO) incorporation as filler on the corrosion protection ability of epoxy coatings in saline media. GO was derived from graphite powder following modified Hummers’ method, whereas rGO was obtained after reduction of GO with hydrazine solution. About 1 wt.% of GO or rGO were incorporated in epoxy resin by solution mixing process followed by ball milling. GO and rGO-based epoxy composite coatings were coated on mild steel substrates using film coater. The coated samples were characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests after 1 and 24 h immersion in 3.5% NaCl. The results suggested that GO-based epoxy composite coatings showed high impedance and low corrosion rate.

  2. Thermal expansion of epoxy-fiberglass composite specimens

    International Nuclear Information System (INIS)

    McElroy, D.L.; Weaver, F.J.; Bridgman, C.

    1986-01-01

    The thermal expansion behavior of three epoxy-fiberglass composite specimens was measured from 20 to 120 0 C (70 to 250 0 F) using a fused quartz push-rod dilatometer. Billets produced by vacuum impregnating layers of two types of fiberglass cloth with an epoxy resin were core-drilled to produce cylindrical specimens. These were used to study expansion perpendicular and parallel to the fiberglass layers. The dilatometer is held at a preselected temperature until steady-state is indicated by stable length and temperature data. Before testing the composite specimens, a reliability check of the dilatometer was performed using a copper secondary standard. This indicated thermal expansion coefficient (α) values within +-2% of expected values from 20 to 200 0 C

  3. Imidazolium Ionic Liquid Modified Graphene Oxide: As a Reinforcing Filler and Catalyst in Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Qing Lyu

    2017-09-01

    Full Text Available Surface modification of graphene oxide (GO is one of the most important issues to produce high performance GO/epoxy composites. In this paper, the imidazole ionic liquid (IMD-Si was introduced onto the surface of GO sheets by a cheap and simple method, to prepare a reinforcing filler, as well as a catalyst in epoxy resin. The interlayer spacing of GO sheets was obviously increased by the intercalation of IMD-Si, which strongly facilitated the dispersibility of graphene oxide in organic solvents and epoxy matrix. The addition of 0.4 wt % imidazolium ionic liquid modified graphene oxide (IMD-Si@GO, yielded a 12% increase in flexural strength (141.3 MPa, a 26% increase in flexural modulus (4.69 GPa, and a 52% increase in impact strength (18.7 kJ/m2, compared to the neat epoxy. Additionally the IMD-Si@GO sheets could catalyze the curing reaction of epoxy resin-anhydride system significantly. Moreover, the improved thermal conductivities and thermal stabilities of epoxy composites filled with IMD-Si@GO were also demonstrated.

  4. Characterization of the flexural behavior of a reactive graphitic nanofibers reinforced epoxy using a non-linear damage model

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Soumen [Department of Mechanical Engineering and Applied Mechanics, North Dakota State University, Fargo, ND 58105 (United States); Zhong Weihong [Department of Mechanical Engineering and Applied Mechanics, North Dakota State University, Fargo, ND 58105 (United States)]. E-mail: Katie.zhong@ndsu.edu; Gan, Yong X. [Department of Mechanical Engineering, Albert Nerken School of Engineering, Cooper Union for the Advancement of Science and Art, 51 Astor Place, New York City, NY 10003 (United States)

    2007-02-15

    In our previous work, a nano-epoxy was developed based on the preparation of reactive graphitic nanofibers (r-GNFs). The objective of this work is to study the effect of the r-GNFs in an epoxy resin on the mechanical properties of the resulting nano-epoxy composites. Three-point bending tests were carried out for the pure epoxy and nano-epoxy materials with 0.15, 0.2, 0.3, 0.5 wt% r-GNFs to obtain the flexural behaviors. The nano-epoxy composite containing 0.3 wt% of r-GNFs showed the best flexural properties including highest flexural strength, modules and ductility values among all the tested materials. Non-linear fracture mechanics (NLFM) was applied to analyze the phenomena occurred during the bending tests. A non-linear damage model was used to interpret the flexural stress-strain relationships of the tested materials, which showed agreement with the testing results. The fracture surfaces of the nano-epoxy composites were examined with scanning electron microscopy (SEM), and the morphological features on the SEM images also reveals that the nano-epoxy composites are tougher than the pure epoxy resin.

  5. Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers.

    Science.gov (United States)

    Domun, Nadiim; Paton, Keith R; Hadavinia, Homayoun; Sainsbury, Toby; Zhang, Tao; Mohamud, Hibaaq

    2017-10-19

    In this work the fracture toughness of epoxy resin has been improved through the addition of low loading of single part and hybrid nanofiller materials. Functionalised multi-walled carbon nanotubes (f-MWCNTs) was used as single filler, increased the critical strain energy release rate, G IC , by 57% compared to the neat epoxy, at only 0.1 wt% filler content. Importantly, no degradation in the tensile or thermal properties of the nanocomposite was observed compared to the neat epoxy. When two-dimensional boron nitride nanosheets (BNNS) were added along with the one-dimensional f-MWCNTs, the fracture toughness increased further to 71.6% higher than that of the neat epoxy. Interestingly, when functionalised graphene nanoplatelets (f-GNPs) and boron nitride nanotubes (BNNTs) were used as hybrid filler, the fracture toughness of neat epoxy is improved by 91.9%. In neither of these hybrid filler systems the tensile properties were degraded, but the thermal properties of the nanocomposites containing boron nitride materials deteriorated slightly.

  6. Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers

    Directory of Open Access Journals (Sweden)

    Nadiim Domun

    2017-10-01

    Full Text Available In this work the fracture toughness of epoxy resin has been improved through the addition of low loading of single part and hybrid nanofiller materials. Functionalised multi-walled carbon nanotubes (f-MWCNTs was used as single filler, increased the critical strain energy release rate, GIC, by 57% compared to the neat epoxy, at only 0.1 wt% filler content. Importantly, no degradation in the tensile or thermal properties of the nanocomposite was observed compared to the neat epoxy. When two-dimensional boron nitride nanosheets (BNNS were added along with the one-dimensional f-MWCNTs, the fracture toughness increased further to 71.6% higher than that of the neat epoxy. Interestingly, when functionalised graphene nanoplatelets (f-GNPs and boron nitride nanotubes (BNNTs were used as hybrid filler, the fracture toughness of neat epoxy is improved by 91.9%. In neither of these hybrid filler systems the tensile properties were degraded, but the thermal properties of the nanocomposites containing boron nitride materials deteriorated slightly.

  7. Photochemical studies on aromatic γ,δ-epoxy ketones: efficient synthesis of benzocyclobutanones and indanones.

    Science.gov (United States)

    Shao, Yutian; Yang, Chao; Gui, Weijun; Liu, Yang; Xia, Wujiong

    2012-04-11

    Irradiation of terminal aromatic γ,δ-epoxy ketones with a 450 W UV lamp led to Norrish type II cyclization/semi-pinacol rearrangement cascade reaction which formed the benzocyclobutanones containing a full-carbon quaternary center, whereas irradiation of substituted aromatic γ,δ-epoxy ketones led to the indanones through a photochemical epoxy rearrangement and 1,5-biradicals cyclization tandem reaction. This journal is © The Royal Society of Chemistry 2012

  8. Study on Concrete Containing Recycled Aggregates Immersed in Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Adnan Suraya Hani

    2017-01-01

    Full Text Available In recent decades, engineers have sought a more sustainable method to dispose of concrete construction and demolition waste. One solution is to crush this waste concrete into a usable gradation for new concrete mixes. This not only reduces the amount of waste entering landfills but also alleviates the burden on existing sources of quality natural concrete aggregates. There are too many kinds of waste but here constructions waste will be the priority target that should be solved. It could be managed by several ways such as recycling and reusing the concrete components, and the best choice of these components is the aggregate, because of the ease process of recycle it. In addition, recycled aggregates and normal aggregates were immersed in epoxy resin and put in concrete mixtures with 0%, 5%, 10% and 20% which affected the concrete mixtures properties. The strength of the concrete for both normal and recycled aggregates has increased after immersed the aggregates in epoxy resin. The percentage of water absorption and the coefficient of water permeability decreased with the increasing of the normal and the recycled aggregates immersed in epoxy resin. Generally the tests which have been conducted to the concrete mixtures have a significant results after using the epoxy resin with both normal and recycled aggregates.

  9. Characterization of fracture toughness of epoxy resin after hygrothermal aging

    KAUST Repository

    Quispe, Gustavo Q.

    2013-07-01

    Characterization of fracture toughness of epoxy resin after hygrothermal ageing Gustavo Quino Quispe The aim of this work is to characterize the e ects of hygrothermal aging in the plain strain fracture toughness of the epoxy system composed by cycloaliphatic epoxy resin and diglycidyl ether of bisphenol-A (DGEBA). For this, after having been under hygrothermal aging in a climatic chamber, epoxy samples were studied using ASTM D5045 fracture toughness test, and micrography and roughness measurements of the fracture surface. It is reported a rapid decrease of GIc and KIc during the rst 2 days. Moreover, a numerical model [13] was used to simulate and see with more detail the water absorption in the aged samples. From that, it was observed the heterogeneous distribution of water. Accordingly, it was proposed that the results should be correlated with the water content at the vicinity of the crack tip. Consequently, it was possible to obtain, by quasi-static simulations, the ideal load-displacement curves of crack propagation in the heterogeneous samples. Finally, another contribution of this work is the study of the fracture surface, that gives a clue of the relationship among the fracture energy, the appearance of microcracks in the fracture surface, and the roughness (Ra).

  10. Influência da relação estequiométrica resina/endurecedor em propriedades mecânicas de compósitos ternários hierárquicos resina - epóxi/tecido de fibra de carbono/nanotubos de carbono

    Directory of Open Access Journals (Sweden)

    Kássio André Lacerda

    2014-01-01

    Full Text Available A produção de materiais que apresentem alto desempenho em suas aplicações exige avanços tecnológicos e científicos. Os elevados valores de resistência à tração e módulo de elasticidade, aliados à flexibilidade, baixa densidade e alta razão de aspecto, fazem dos nanotubos de carbono excepcionais candidatos para reforçar compósitos poliméricos. Preparamos por laminação sistemas compósitos ternários à base de resina epóxi/tecidos de fibra de carbono (para os binários, acrescendo nanotubos de carbono para os sistemas ternários. Os parâmetros estequiométricos do sistema epoxídico (valor de Phr e concentração de nanotubos de carbono empregado nos sistemas compósitos tiveram avaliadas suas morfologias (MEV, propriedades térmicas (TG e mecânicas (ASTM D790. Embora o sistema epoxídico com Phr 10,0 tenha apresentado uma maior estabilidade térmica, os compósitos ternários produzidos a partir do sistema com Phr 26,6 mostraram valores de tensão máxima e módulo de elasticidade até 8 vezes maiores que aqueles produzidos com o sistema Phr 10. A adição de nanotubos de carbono aos compósitos com Phr 26,6 resultou em ganhos adicionais de aproximadamente 38 e 15% na tensão máxima e no módulo de elasticidade, respectivamente. Esses resultados revelaram a limitação nos métodos de integralização de nanoestruturas a sistemas compósitos, onde as dispersões estão limitadas a uma série de fatores inerentes a interação química e/ou física durante a fabricação dos compósitos nanoestruturados.

  11. Resinas termofixas e a produção de refratários contendo carbono: base teórica e insights para futuros desenvolvimentos Thermosetting resins and the production of carbon containing refractories: theoretic basis and insights for future developments

    Directory of Open Access Journals (Sweden)

    C. S. Bitencourt

    2013-03-01

    Full Text Available Por suas diversas vantagens em relação ao piche de alcatrão convencional, o uso das resinas termofixas fenólicas vem se expandindo na produção dos refratários contendo carbono. Contudo, apesar desta tendência, ainda se verificam poucos trabalhos publicados no meio acadêmico que se proponham a investigar como alterações nas características desses polímeros podem afetar e beneficiar o processamento e as propriedades dos refratários. Algumas pesquisas reportam os efeitos dessas alterações sobre a pirólise do termofixo isolado. Entretanto, empregar plenamente as suas conclusões nos estudos em refratários pode não ser adequado, visto que os demais componentes e os próprios métodos de processamento desses materiais podem ter uma importante influência sobre o comportamento do termofixo. Assim, procurando verificar os caminhos mais promissores para desenvolver resinas fenólicas que apresentem um desempenho otimizado para essa aplicação específica, este artigo faz uma revisão geral sobre a química desses termofixos e suas conseqüências para o processamento do refratário e para a geração de carbono. Também serão revisados alguns aditivos capazes de auxiliar a resina a alcançar tal desempenho superior, entre eles os chamados agentes grafitizantes, que teriam a função de induzir a cristalização do carbono produzido pelo termofixo, um fenômeno antes exclusivo de fontes de carbono grafitizáveis como os piches.Based on the many advantages over the conventional coal tar pitch, the application of thermosetting phenolic resins has been expanding for the production of carbon containing refractories. Nevertheless, despite this trend, it is noticeable that there are few published technical and scientific papers aiming to investigate how modifications in these polymers characteristics could affect and benefit the refractories processing and properties. There are studies in the literature analyzing the effects of these

  12. Preparation of epoxy/zirconia hybrid materials via in situ polymerization using zirconium alkoxide coordinated with acid anhydride

    International Nuclear Information System (INIS)

    Ochi, Mitsukazu; Nii, Daisuke; Harada, Miyuki

    2011-01-01

    Highlights: → Novel epoxy/zirconia hybrid materials were synthesized via in situ polymerization using zirconium alkoxide coordinated with acid anhydride. → The half-ester compound of acid anhydride desorbed from zirconium played as curing agent of epoxy resin. → The zirconia was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale by synchronizing the epoxy curing and sol-gel reactions. → The refractive indices of the hybrid materials significantly improved with an increase in the zirconia content. - Abstract: Novel epoxy/zirconia hybrid materials were synthesized using a bisphenol A epoxy resin (diglycidyl ether of bisphenol A; DGEBA), zirconium(IV)-n-propoxide (ZTNP), and hexahydrophthalic anhydride (HHPA) via in situ polymerization. HHPA played two roles in this system: it acted as a modifier to control the hydrolysis and condensation reactions of zirconium alkoxide and also as a curing agent - the half-ester compound of HHPA desorbed from zirconium reacted with the epoxy resin to form the epoxy network. As a result, both the sol-gel reaction and epoxy curing occurred simultaneously in a homogeneous solution, and organic-inorganic hybrid materials were readily obtained. Further, the zirconia produced by the in situ polymerization was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale; thus, hybrid materials that exhibited excellent optical transparency were obtained. Furthermore, the heat resistance of the hybrid materials could be improved by hybridization with zirconia. And, the refractive indices of the hybrid materials significantly improved with an increase in the zirconia content.

  13. Morphology and parameters of crystallization the blend PE/Epoxy/PE-co-PEG; Morfologia e parametros de cristalizacao da blenda PE/epoxi/PE-co-PEG

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Daniela; Coelho, Luiz Antonio Ferreira; Nack, Fernanda; Silva, Bruna Louise, E-mail: dep2db@joinville.udesc.br [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas

    2014-07-01

    This study aims to evaluate the morphology and crystallization parameters of high density polyethylene (HDPE) with different concentrations of epoxy (DGEBA / OTBG), and the compatibility of this system was used and the copolymer polyethylene-block-poly (ethylene glycol) (PEG-co-PE). The blends were obtained by mechanical mixing on a torque rheometer (Haake). Determined the crystallization parameters of the test matrix differential scanning calorimetry (DSC) and by X-ray diffraction (XRD). The morphology of the system was analyzed by transmission electron microscopy (TEM). It was observed by XRD analysis that the addition of compatibilizer and epoxy resins do not interfere with the crystal structure of HDPE, indicating that the increase in crystallinity associated with the crystallization kinetics. It was observed that the compatibilizing helped the adhesion, reducing the size of the dispersed phase becomes a more stable morphology and obtaining a distribution of the dispersed epoxy phase. (author)

  14. Novel epoxy-benzoxazine water-based emulsions with reactive benzoxazine surfactants for coatings

    Directory of Open Access Journals (Sweden)

    M. Krajnc

    2014-08-01

    Full Text Available Novel epoxy-benzoxazine emulsions designed for water-based coatings were prepared and investigated. Bisphenol A-based epoxy resins with molar weights of 340, 377 and 1750 g/mol along with epoxidized soybean oil were emulsified using mono- and bi-functional benzoxazine surfactants, which are able to react with epoxy resins at their cure temperature. The structure of synthesized surfactants carrying one or two polyether chains was confirmed using Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance and differential scanning calorimetry. Stability of emulsions was verified by particle diameters measurements. Coatings, made directly from emulsions, were dried and cured at elevated temperature using 3,3'-dimetoxybenzidine as curing agent to ensure a highly cross-linked structure of thermosetting films. Curing process, thermal properties and hardness of cured films were investigated. It was found that benzoxazine molecules were well incorporated into the epoxy network upon curing, which ensures no void structure of cured copolymer and enhanced coating properties.

  15. ‘Containers’ for self-healing epoxy composites and coating: Trends and advances

    Directory of Open Access Journals (Sweden)

    P. Vijayan

    2016-06-01

    Full Text Available The introduction of self-healing functionality into epoxy matrix is an important and challenging topic. Various micro/nano containers loaded self-healing agents are developed and incorporated into epoxy matrix to impart self-healing ability. The current report reviews the major findings in the area of self-healing epoxy composites and coatings with special emphasis on these containers. The preparation and use of polymer micro/nano capsules, polymer fibers, hollow glass fibers/bubbles, inorganic nanotubes, inorganic meso- and nano-porous materials, carbon nanotubes etc. as self-healing containers are outlined. The nature of the container and its response to the external stimulations greatly influence the self-healing performance. The self-healing mechanism associated with each type of container and the role of container parameters on self-healing performance of self-healing epoxy systems are reviewed. Comparison of the efficiency offered by different types of containers is introduced. Finally, the selection of containers to develop cost effective and green self-healing systems are mentioned.

  16. Composites of Graphene Nanoribbon Stacks and Epoxy for Joule Heating and Deicing of Surfaces.

    Science.gov (United States)

    Raji, Abdul-Rahman O; Varadhachary, Tanvi; Nan, Kewang; Wang, Tuo; Lin, Jian; Ji, Yongsung; Genorio, Bostjan; Zhu, Yu; Kittrell, Carter; Tour, James M

    2016-02-10

    A conductive composite of graphene nanoribbon (GNR) stacks and epoxy is fabricated. The epoxy is filled with the GNR stacks, which serve as a conductive additive. The GNR stacks are on average 30 nm thick, 250 nm wide, and 30 μm long. The GNR-filled epoxy composite exhibits a conductivity >100 S/m at 5 wt % GNR content. This permits application of the GNR-epoxy composite for deicing of surfaces through Joule (voltage-induced) heating generated by the voltage across the composite. A power density of 0.5 W/cm(2) was delivered to remove ∼1 cm-thick (14 g) monolith of ice from a static helicopter rotor blade surface in a -20 °C environment.

  17. Characterization of epoxy hybrid composites filled with cellulose fibers and nano-SiC

    KAUST Repository

    Alamri, H.; Low, I. M.

    2012-01-01

    Three different approaches have been applied and investigated to enhance the thermal and mechanical properties of epoxy resin. Epoxy system reinforced with either recycled cellulose fibers (RCF) or nanosilicon carbide (n-SiC) particles as well

  18. Latent Hardeners for the Assembly of Epoxy Composites

    Science.gov (United States)

    Palmieri, Frank; Wohl, Christopher J.; Connell, John W.; Mercado, Zoar; Galloway, Jordan

    2016-01-01

    Large-scale composite structures are commonly joined by secondary bonding of molded-and-cured thermoset components. This approach may result in unpredictable joint strengths. In contrast, assemblies made by co-curing, although limited in size by the mold, result in stable structures, and are certifiable for commercial aviation because of structural continuity through the joints. Multifunctional epoxy resins were prepared that should produce fully-cured subcomponents with uncured joining surfaces, enabling them to be assembled by co-curing in a subsequent out-of-autoclave process. Aromatic diamines were protected by condensation with a ketone or aldehyde to form imines. Properties of the amine-cured epoxy were compared with those of commercially available thermosetting epoxy resins and rheology and thermal analysis were used to demonstrate the efficacy of imine protection. Optimum conditions to reverse the protecting chemistry in the solid state using moisture and acid catalysis were determined. Alternative chemistries were also investigated. For example, chain reaction depolymerization and photoinitiated catalysts would be expected to minimize liberation of volatile organic content upon deprotection and avoid residual reactive species that could damage the resin. Results from the analysis of protected and deprotected resins will be presented.

  19. Evaluation and Control of Thiol-ene/Thiol-epoxy Hybrid Networks

    OpenAIRE

    Carioscia, Jacquelyn A.; Stansbury, Jeffrey W.; Bowman, Christopher N.

    2007-01-01

    The development of thiol-ene/thiol-epoxy hybrid networks offers the advantage of tailorable polymerization kinetics while producing a highly crosslinked, high Tg polymer that has significantly reduced shrinkage stress. Stoichiometric mixtures of pentaerythritol tetra(3-mercaptopropionate) (PETMP)/triallyl-1,3,5-triazine-2,4,6-trione (TATATO) (thiol-ene, mixture 1) and PETMP/bisphenol a diglycidyl ether (BADGE) (thiol-epoxy, mixture 2) were prepared and hybrid mixtures of 75/25, 50/50, 25/75, ...

  20. Epoxy composites based on inexpensive tire waste filler

    Science.gov (United States)

    Ahmetli, Gulnare; Gungor, Ahmet; Kocaman, Suheyla

    2014-05-01

    Tire waste (TW) was recycled as raw material for the preparation of DGEBA-type epoxy composite materials. The effects of filler amount and epoxy type on the mechanical properties of the composites were investigated. Tensile strength and Young's modulus of the composites with NPEL were generally higher than composites with NPEF. The appropriate mass level for TW in both type composites was found to be 20 wt%. The equilibrium water sorption of NPEL/TW and NPEF/TW composites for 14-day immersion was determined as 0.10 % and 0.21 %, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for characterization of the composites.

  1. Epoxy composites based on inexpensive tire waste filler

    International Nuclear Information System (INIS)

    Ahmetli, Gulnare; Gungor, Ahmet; Kocaman, Suheyla

    2014-01-01

    Tire waste (TW) was recycled as raw material for the preparation of DGEBA-type epoxy composite materials. The effects of filler amount and epoxy type on the mechanical properties of the composites were investigated. Tensile strength and Young’s modulus of the composites with NPEL were generally higher than composites with NPEF. The appropriate mass level for TW in both type composites was found to be 20 wt%. The equilibrium water sorption of NPEL/TW and NPEF/TW composites for 14-day immersion was determined as 0.10 % and 0.21 %, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for characterization of the composites

  2. Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

    International Nuclear Information System (INIS)

    Pour-Ali, Sadegh; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

    2016-01-01

    Highlights: • Preparing mild steel surface with ultrafine grains by wire brushing process. • Performance of a smart coating on micro- and nano-crystalline surfaces. • Corrosion evaluation, surface analysis and ac/dc electrochemical measurements. • Ultrafine surface grains improve protective behavior of epoxy/PANI-CSA coating. - Abstract: An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

  3. Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

    Energy Technology Data Exchange (ETDEWEB)

    Pour-Ali, Sadegh, E-mail: pourali2020@ut.ac.ir; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

    2016-07-15

    Highlights: • Preparing mild steel surface with ultrafine grains by wire brushing process. • Performance of a smart coating on micro- and nano-crystalline surfaces. • Corrosion evaluation, surface analysis and ac/dc electrochemical measurements. • Ultrafine surface grains improve protective behavior of epoxy/PANI-CSA coating. - Abstract: An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

  4. 78 FR 4792 - Epoxy Polymer; Exemption From the Requirement of a Tolerance

    Science.gov (United States)

    2013-01-23

    ... ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 180 [EPA-HQ-OPP-2012-0615; FRL-9364-6] Epoxy Polymer... residues of polymers of one or more diglycidyl ethers of bisphenol A, resorcinol, glycerol... and 1,2,3,6-tetrahydrophthalic anhydride; also referred to as epoxy polymer, when used as an inert...

  5. Effect of pretreatment with epoxy compounds on the mechanical properties of bovine pericardial bioprosthetic materials.

    Science.gov (United States)

    Xi, T; Liu, F; Xi, B

    1992-07-01

    Early failures of bovine pericardial heart valves are due to leaflet perforation, tearing and calcification. Since glutaraldehyde fixation has been shown to produce marked changes in leaflet mechanics and has been linked to development of calcification, bovine pericardium fixed with the four hydrophilic epoxy formulations and their mechanical properties are studied in this paper. We measured the thicknesses, shrinkage temperatures, stress relaxations and stress-strain curves of bovine pericardiums after different treatments with (1) non-treatment (fresh), (2) glutaraldehyde (GA), (3) epoxy compounds followed by the posttreatment with GA (EP 1#, EP 2#), and (4) epoxy compounds (EP 3# and EP 4#). Results of this study showed that the hydrophilic epoxy compounds are good crosslinking agents. There are no significant differences of shrinkage temperature and ultimate tensile stress among all tissue samples pretreated with GA, EP 1# and EP 2#. However, the stress relaxations of tissue-samples pretreated with epoxy compounds followed by the posttreatment with GA (EP 1# and EP 2#) are significantly slower than that pretreated with GA, and the strains at fracture of EP 1# and EP 2# are also significantly larger than that of GA or epoxy compounds. These facts show that the bovine pericardium pretreated with the epoxy compound followed by the posttreatment with GA (EP 1# and EP 2#) possesses greater tenacity and potential durability in dynamic stress.

  6. Mechanical properties of short random oil palm fibre reinforced epoxy composites

    International Nuclear Information System (INIS)

    Mohd Zuhri Mohamed Yusoff; Mohd Sapuan Salit; Napsiah Ismail; Riza Wirawan

    2010-01-01

    This paper presents the study of mechanical properties of short random oil palm fibre reinforced epoxy (OPF/epoxy) composites. Empty fruit bunch (EFB) was selected as the fibre and epoxy as the matrix. Composite plate with four different volume fractions of oil palm fibre was fabricated, (5 vol %, 10 vol %, 15 vol % and 20 vol %). The fabrication was made by hand-lay up techniques. The tensile and flexural properties showed a decreasing trend as the fibre loading was increased. The highest tensile properties was obtained for the composite with fibre loading of 5 vol % and there were no significant effect for addition of more than 5 vol % to the flexural properties. Interaction between fibre and matrix was observed from the scanning electron microscope (SEM) micrograph. (author)

  7. Development and characterization of woven kevlar reinforced epoxy matrix composite materials

    International Nuclear Information System (INIS)

    Imran, A.; Alam, S.; Irfan, S.; Iftikhar, F.; Raza, M.A.

    2006-01-01

    Composite materials are actually well established materials that have demonstrated their promising advantages among the light weight structural materials used for aerospace and advanced applications. A great effort is now being made to develop and characterize the Kevlar Epoxy Composite Materials by changing the % age composition of curing agent in epoxy matrix. In order to study the phenomenon; how the change in composition of curing agent effect the composite material and which optimum composition can give the optimum properties of the material, when Kevlar reinforced to Epoxy Matrix by Hand Lay-up process. It was ensured that factors which can .affect the experiment remained the same for each experiment. The composite produced were subjected to mechanical tests to analyze the performance, to optimize the material. (author)

  8. Compatibility of anhydride cured epoxies with hexanitroazobenzene (HNAB) and hexanitrostilbene (HNS)

    International Nuclear Information System (INIS)

    Massis, T.M.; Wischmann, K.B.

    1985-01-01

    The explosives HNAB (hexanitroazobenzene) and HNS (hexanitrostilbene) have compatibility problems with amine-cured epoxy systems. A program was instituted to find compatible polymeric substitutes for use with these explosives. These polymeric materials must have rigid structures after curing for both adhesive and encapsulant applications. A promising class of epoxy materials using anhydride curing agents with various catalysts to trigger the cure reaction were developed. These polymeric systems have very good compatibility with HNS. Of those tested with HNAB, the anhydride epoxy system that used uranyl nitrate as the catalyst was found to be marginally compatible while the others were incompatible. These results indicated further studies are needed. The CRT (chemical reactivity test) was used to evaluate the compatibility of these materials. 6 references, 2 figures, 5 tables

  9. Scheming of microwave shielding effectiveness for X band considering functionalized MWNTs/epoxy composites

    Science.gov (United States)

    Bal, S.; Saha, S.

    2016-02-01

    Present typescript encompasses anextraordinary electrical and mechanical behaviors of carboxylic (-COOH) functionalized multiwall carbon nanotube (MWNTs)/epoxy composites at low wt.% (0,5, 0,75, 1wt.%). Functionalization on the surface of the nanotube assists MWNTs in dispersing it into epoxy polymer in a respectable manner, Fabricated composites are exposed to different characterization techniques in order to examine the overall physical properties, Microwave shielding effectiveness (SE) for X band (8-12 GHz) and the flexural properties have been premeditated to predict the electrical and mechanical performances. It was found that the total SE of the nanocomposites was increased with the positive gradient of MWNT contents, The best result was recorded for 1 wt.% MWNT loading (SE of about 51,72 dB).In addition, incorporation of nanofillers enhanced the flexural modulus, flexural strength and micro-hardness of the resulting composites while comparing with neat epoxy, Nanocomposites with 0,75 wt,% MWNT loading demonstrated an incrementof 101% in modulus than that of neat epoxy, Theincrement in mechanical properties was due to achievement of good dispersion quality, effective bonding between MWNTs and epoxy polymer analyzed by micrographs of fracture surfaces

  10. Scheming of microwave shielding effectiveness for X band considering functionalized MWNTs/epoxy composites

    International Nuclear Information System (INIS)

    Bal, S; Saha, S

    2016-01-01

    Present typescript encompasses anextraordinary electrical and mechanical behaviors of carboxylic (-COOH) functionalized multiwall carbon nanotube (MWNTs)/epoxy composites at low wt.% (0,5, 0,75, 1wt.%). Functionalization on the surface of the nanotube assists MWNTs in dispersing it into epoxy polymer in a respectable manner, Fabricated composites are exposed to different characterization techniques in order to examine the overall physical properties, Microwave shielding effectiveness (SE) for X band (8-12 GHz) and the flexural properties have been premeditated to predict the electrical and mechanical performances. It was found that the total SE of the nanocomposites was increased with the positive gradient of MWNT contents, The best result was recorded for 1 wt.% MWNT loading (SE of about 51,72 dB).In addition, incorporation of nanofillers enhanced the flexural modulus, flexural strength and micro-hardness of the resulting composites while comparing with neat epoxy, Nanocomposites with 0,75 wt,% MWNT loading demonstrated an incrementof 101% in modulus than that of neat epoxy, Theincrement in mechanical properties was due to achievement of good dispersion quality, effective bonding between MWNTs and epoxy polymer analyzed by micrographs of fracture surfaces (paper)

  11. Nanostructure of tetrafunctional epoxy resins and composites: Correlation to moisture absorption properties

    Science.gov (United States)

    Bolan, Brett Andrew

    The effect that changes in network topology, while maintaining a constant network polarity (i.e. thermodynamic driving force was kept constant), had upon the moisture absorption properties of an aerospace grade tetrafunctional epoxy (TGMDA) cured with multifunctional amines were investigated. Utilizing Positron Annihilation Lifetime Spectroscopy (PALS) to characterize the nanoscale structure of these epoxies, it was found that as the "static" hole volume (a measurement of packing defects at 0K) increased so did the equilibrium uptake. PALS studies of one of these resins cured to varying extents, found that this static amount increased with degree of cure indicating that the network becomes more open as a direct consequence of crosslinking. Polar groups, which are the attractive force for diffusion, are in the vicinity of these crosslinks, therefore it is believed that the increase in static hole volume results in exposing more polar groups for absorption. The diffusion coefficient, which is representative of the kinetic aspect of diffusion, was also investigated. It was discovered that the amount of nanohole volume in the polymer; whether the total, the static, or dynamic (i.e. thermally activated) does not correlate to the diffusion coefficient in anyway. Furthermore, at an isotherm the diffusion coefficients for all these materials were relatively constant. From this it is hypothesized that it is the similar sub-Tsb{g} motions of these resins which is the rate limiting step in diffusion. This was bolstered by the fact that the activation energy for diffusion and for the sub-Tsb{g} motions for these epoxies are of the same order of magnitude. The nanostructure of fiber reinforced epoxy composites (i.e. a boron/epoxy and a graphite/epoxy) were probed with the bulk PALS technique as well. It was observed that for the graphite/epoxy composite and its flash (i.e. no fibers present) cured under identical conditions, that the nanoholes in the composite were larger than

  12. Corrosion performance of epoxy-coated reinforcement in aggressive environments

    Science.gov (United States)

    Vaca Cortes, Enrique

    The objective of this research was to investigate the integrity and corrosion performance of epoxy-coated reinforcement in aggressive environments. A series of experimental studies were conducted: (a) hot water immersion and knife adhesion testing for assessment of coating adhesion; (b) materials and procedures for repairing coating damage; (c) degree of mechanical damage caused during concrete placement when using metal head and rubber head vibrators; (d) accelerated corrosion of coated bars embedded in macrocell and beam specimens placed in a corrosive environment for more than four years. The effects of coating condition and amount of damage, repaired vs. unrepaired damage, bar fabrication, and concrete cracking were studied. Regardless of coating condition, the performance of epoxy-coated bars was better than that of uncoated bars. Unlike black bars, coated bars did not exhibit deep pitting or substantial loss of cross section at crack locations. Damage to epoxy coating was the most significant factor affecting corrosion performance. Bars with coating in good condition, without any visible damage, performed best. The greater the size and frequency of damage, the more severe and extensive the amount of corrosion. The performance of bars that were fabricated or bent after coating was worse than that of coated straight bars. Mixing coated and uncoated bars in the same concrete member led to undesirable performance. Patching damaged coating reduced but did not prevent corrosion, particularly at bar ends. The most important factor in coating repair was the type and properties of the patching material. Surface preparation prior to coating had little effect. The absence of cracks in the concrete delayed, but did not prevent the onset of corrosion of coated bars. During consolidation of concrete, rubber head vibrators caused less damage to epoxy-coated reinforcement than did comparable metal heads. Hot water and adhesion tests were useful and practical for evaluating

  13. Electron beam processed plasticized epoxy coatings for surface protection

    International Nuclear Information System (INIS)

    Ibrahim, Mervat S.; Mohamed, Heba A.; Kandile, Nadia G.; Said, Hossam M.; Mohamed, Issa M.

    2011-01-01

    Highlights: · Coating formulations with EA 70%, HD 20%, and castor oil 10% under 1 Mrad pass -1 irradiation dose showed the best adhesion and passed bending tests. · The prepared EP-SF-An adduct improve anti-corrosion properties of coatings without any significant effect on physical, mechanical and chemical properties of the cured film. The optimum amount of aniline adduct as corrosion inhibitor was found to be 0.4 g for 100 g of coating formulation. · The corrosion inhibition efficiency of the prepared adduct competed the commercial efficiency. - Abstract: Epoxy acrylate oligomer (EA) was plasticized by adding different plasticizers such as epoxidized soybean oil, glycerol and castor oil and cured by electron beam (EB). Different irradiation doses (1, 2.5 and 5 Mrad pass -1 ) were used in the curing process. The effect of both different irradiation doses and plasticizers on the end use performance properties of epoxy acrylate coating namely, pencil hardness, bending test, adhesion test, acid and alkali resistance test were studied. It was observed that incorporation of castor oil in epoxy acrylate diluted by 1,6-hexanediol diacrylate (HD) monomer with a ratio (EA 70%, HD 20%, castor oil 10%) under 1 Mrad pass -1 irradiation dose improved the physical, chemical and mechanical properties of cured films than the other plasticizer. Sunflower free fatty acid was epoxidized in situ under well established conditions. The epoxidized sunflower free fatty acids (ESFA) were subjected to react with aniline in sealed ampoules under inert atmosphere at 140 deg. C. The produced adducts were added at different concentrations to epoxy acrylate coatings under certain EB irradiation dose and then evaluated as corrosion inhibitors for carbon steel surfaces in terms of weight loss measurements and corrosion resistance tests. It was found that, addition of 0.4 g of aniline adduct to 100 g epoxy acrylate formula may give the best corrosion protection for carbon steel and compete the

  14. Improvement of Thermal and Electrical Conductivity of Epoxy/boron Nitride/silver Nanoparticle Composite

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seungyong; Lim, Soonho [Korea Institute of Science and Technology, Wanju (Korea, Republic of)

    2017-06-15

    In this study, we investigated the effect of BN (boron nitride) on the thermal and the electrical conductivity of composites. In case of epoxy/BN composites, the thermal conductivity was increased as the BN contents were increased. Epoxy/AgNP (Ag nanoparticle) nanocomposites exhibited a slight change of thermal conductivity and showed a electrical percolation threshold at 20 vol% of Ag nanoparticles. At the fixed Ag nanoparticle content below the electrical percolation threshold, increasing the amount of BN enhanced the electrical conductivity as well as thermal conductivity for the epoxy/AgNP/BN composites.

  15. Self-Sensing of Single Carbon Fiber/Carbon Nanotube-Epoxy Composites Using Electro-Micromechanical Techniques and Acoustic Emission

    International Nuclear Information System (INIS)

    Park, Joung Man; Jang, Jung Hoon; Wang, Zuo Jia; Kwon, Dong Jun; Park, Jong Kyu; Lee, Woo Il

    2010-01-01

    Self-sensing on micro-failure, dispersion degree and relating properties, of carbon nanotube(CNT)/epoxy composites, were investigated using wettability, electro-micromechanical technique with acoustic emission(AE). Specimens were prepared from neat epoxy as well as composites with untreated and acid-treated CNT. Degree of dispersion was evaluated comparatively by measuring volumetric electrical resistivity and its standard deviation. Apparent modulus containing the stress transfer was higher for acid-treated CNT composite than for the untreated case. Applied cyclic loading responded well for a single carbon fiber/CNT-epoxy composite by the change in contact resistivity. The interfacial shear strength between a single carbon fiber and CNT-epoxy, determined in a fiber pullout test, was lower than that between a single carbon fiber and neat epoxy. Regarding on micro-damage sensing using electrical resistivity measurement with AE, the stepwise increment in electrical resistivity was observed for a single carbon fiber/CNT-epoxy composite. On the other hand, electrical resistivity increased infinitely right after the first carbon fiber breaks for a single carbon fiber/neat epoxy composite. The occurrence of AE events of added CNT composites was much higher than the neat epoxy case, due to microfailure at the interfaces by added CNTs

  16. Glycolysis of carbon fiber-epoxy unidirectional mat catalysed by sodium hydroxide

    Science.gov (United States)

    Zaini, Mariana Binti Mohd; Badri, Khairiah Haji

    2014-09-01

    This study was conducted to recycle carbon fibre-epoxy (CFRP) composite in woven sheet/ mat form. The CFRP was recycled through glycolysis with polyethlyene glycol (PEG 200) as the solvent. The CFRP was loaded into the solvent at a ratio of 4:1 (w/w). PEG200 was diluted with water to a ratio of 80:20 (v/v). This reaction was catalysed by sodium hydroxide (NaOH) solution with varying concentrations at 1.5, 1.7 and 1.9% (w/v). The glycolysis was conducted at 180-190 °C. The recovered CF (rCF) was analysed using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) while the degraded solution was analysed using FTIR and the epoxy content was determined. The FTIR spectrum of the rCF exhibited the disappearance of the COC peak belonged to epoxy and supported by the SEM micrographs that showed clear rCF. On the other hand, the analysed filtrate detected the disappearance of oxygen peak element in the EDX spectrum for all rCF samples. This gave an indication that the epoxy resin has been removed from the surface of the carbon fiber.

  17. Glycolysis of carbon fiber-epoxy unidirectional mat catalysed by sodium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Zaini, Mariana Binti Mohd [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Badri, Khairiah Haji [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia and Polymer Research Center, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43 (Malaysia)

    2014-09-03

    This study was conducted to recycle carbon fibre-epoxy (CFRP) composite in woven sheet/ mat form. The CFRP was recycled through glycolysis with polyethlyene glycol (PEG 200) as the solvent. The CFRP was loaded into the solvent at a ratio of 4:1 (w/w). PEG200 was diluted with water to a ratio of 80:20 (v/v). This reaction was catalysed by sodium hydroxide (NaOH) solution with varying concentrations at 1.5, 1.7 and 1.9% (w/v). The glycolysis was conducted at 180-190 °C. The recovered CF (rCF) was analysed using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) while the degraded solution was analysed using FTIR and the epoxy content was determined. The FTIR spectrum of the rCF exhibited the disappearance of the COC peak belonged to epoxy and supported by the SEM micrographs that showed clear rCF. On the other hand, the analysed filtrate detected the disappearance of oxygen peak element in the EDX spectrum for all rCF samples. This gave an indication that the epoxy resin has been removed from the surface of the carbon fiber.

  18. Preparation, Characterization, and Modeling of Carbon Nano fiber/Epoxy Nano composites

    International Nuclear Information System (INIS)

    Sun, L.H.; Yang, Z.G.; Ounaies, Z.; Whalen, C.A.; Gao, X.L.

    2011-01-01

    There is a lack of systematic investigations on both mechanical and electrical properties of carbon nano fiber (CNF)-reinforced epoxy matrix nano composites. In this paper, an in-depth study of both static and dynamic mechanical behaviors and electrical properties of CNF/epoxy nano composites with various contents of CNFs is provided. A modified Halpin-Tsai equation is used to evaluate the Young's modulus and storage modulus of the nano composites. The values of Young's modulus predicted using this method account for the effect of the CNF agglomeration and fit well with those obtained experimentally. The results show that the highest tensile strength is found in the epoxy nano composite with a 1.0 wt % CNFs. The alternate-current (AC) electrical properties of the CNF/epoxy nano composites exhibit a typical insulator-conductor transition. The conductivity increases by four orders of magnitude with the addition of 0.1 wt % (0.058 vol %) CNFs and by ten orders of magnitude for nano composites with CNF volume fractions higher than 1.0 wt % (0.578 vol %). The percolation threshold (i.e., the critical CNF volume fraction) is found to be at 0.057 vol %.

  19. Epoxy-based broadband anti-reflection coating for millimeter-wave optics

    OpenAIRE

    Rosen, Darin; Suzuki, Aritoki; Keating, Brian; Krantz, William; Lee, Adrian T.; Quealy, Erin; Richards, Paul L.; Siritanasak, Praween; Walker, William

    2013-01-01

    We have developed epoxy-based, broadband anti-reflection coatings for millimeter-wave astrophysics experiments with cryogenic optics. By using multiple-layer coatings where each layer steps in dielectric constant, we achieved low reflection over a wide bandwidth. We suppressed the reflection from an alumina disk to 10% over fractional bandwidths of 92% and 104% using two-layer and three-layer coatings, respectively. The dielectric constants of epoxies were tuned between 2.06 and 7.44 by mixin...

  20. Influence of the reaction stoichiometry on the mechanical and thermal properties of SWCNT-modified epoxy composites

    International Nuclear Information System (INIS)

    Ashrafi, Behnam; Johnston, Andrew; Martinez-Rubi, Yadienka; Kingston, Christopher T; Simard, Benoit; Khoun, Lolei; Yourdkhani, Mostafa; Hubert, Pascal

    2013-01-01

    Previous studies suggest that carbon nanotubes (CNTs) have a considerable influence on the curing behavior and crosslink density of epoxy resins. This invariably has an important effect on different thermal and mechanical properties of the epoxy network. This work focuses on the important role of the epoxy/hardener mixing ratio on the mechanical and thermal properties of a high temperature aerospace-grade epoxy (MY0510 Araldite as an epoxy and 4,4′-diaminodiphenylsulfone as an aromatic hardener) modified with single-walled carbon nanotubes (SWCNTs). The effects of three different stoichiometries (stoichiometric and off-stoichiometric) on various mechanical and thermal properties (fracture toughness, tensile properties, glass transition temperature) of the epoxy resin and its SWCNT-modified composites were obtained. The results were also supported by Raman spectroscopy and scanning electron microscopy (SEM). For the neat resin, it was found that an epoxy/hardener molar ratio of 1:0.8 provides the best overall properties. In contrast, the pattern in property changes with the reaction stoichiometry was considerably different for composites reinforced with unfunctionalized SWCNTs and reduced SWCNTs. A comparison among composites suggests that a 1:1 molar ratio considerably outperforms the other two ratios examined in this work (1:0.8 and 1:1.1). This composition at 0.2 wt% SWCNT loading provides the highest overall mechanical properties by improving fracture toughness, ultimate tensile strength and ultimate tensile strain of the epoxy resin by 40%, 34%, 54%, respectively. (paper)