WorldWideScience

Sample records for plastics resins based

  1. SABIC Innovative Plastics: Be the World Best Plastic Resin Manufacturer

    Institute of Scientific and Technical Information of China (English)

    Jenny Du

    2007-01-01

    @@ "SABIC Innovative Plastics is a global supplier of plastic resins, manufacturing and compounding polycarbonate, ABS, SAN, ASA, PPE, PC/ABS, PBT and PEI resins, as well as the LNP* line of high performance specialty compounds," said Hiroshi Yoshida, the Global Market Director for Electronics of SABIC Innovative Plastics based in Tokyo at the press conference held by SABIC Innovative Plastics, November 8th 2007, Shanghai.

  2. 77 FR 54930 - Carlyle Plastics and Resins, Formerly Known as Fortis Plastics, A Subsidiary of Plastics...

    Science.gov (United States)

    2012-09-06

    ... Employment and Training Administration Carlyle Plastics and Resins, Formerly Known as Fortis Plastics, A... plastic parts. New information shows that Fortis Plastics is now called Carlyle Plastics and Resins. In... of Carlyle Plastics and Resins, formerly known as Fortis Plastics, a subsidiary of...

  3. [Contact allergy to epoxy resins plastics based on materials collected by the Nofer Institute of Occupational Medicine].

    Science.gov (United States)

    Kieć-Swierczyńska, Marta; Krecisz, Beata

    2003-01-01

    Of the 5604 patients examined in 1984-2001 for suspected occupational dermatitis, 160 persons (2.8%) showed allergy to epoxy resins plastics. Allergy was more frequent in men (4.9%) than in women (1.2%); in 154 persons, allergy was of occupational etiology (in a group of 160 patients with allergy to epoxy resins, the following proportions were observed: bricklayers, platelayers--17.5%; fitters, turners, machinist millers--13.8%; plastics molders--13.1%; laminators--11.3%; electrical equipment assemblers--10.6%; painters--10.0%). Having compared the frequency of allergy to components of epoxy resins in the years 1984-1993 and 1994-2001, it was found that allergy to resin, reactive diluents and plasticizers was on increase, whereas allergy to amines and acid anhydrides hardeners was on decrease. In a group of 13 chemical compounds entering into the composition of epoxy resins, epoxy resin contributed to the largest number of positive patch tests (77.5% of epoxy-allergic persons). This was followed by triethylenetetramine (23.1%), ethylenediamine (13.1%), phthalic anhydride (8.1%), diethylenetetramine (6.9%) and phenylglycidylether (6.2%). In addition, three patients reacted to both epoxy resin and cycloaliphatic resin.

  4. Modification of polyester resins during molding of glass-fiber-reinforced plastics

    Science.gov (United States)

    Yakushin, V.; Jansons, J.; Bulmanis, V.; Cabulis, U.; Bulmanis, A.

    2013-11-01

    The effect of addition of two new urethane prepolymers on the mechanical properties of unsaturated polyester resins and glass-fiber-reinforced plastics based on them is investigated. The effect of concentration of these additives on the elastic modulus, elongation at break, and flexural strength of hardened orthophthalic resins is evaluated. A significant increase in the strength of the binders and glass-fiber-reinforced plastics (GFRPs) based on them is observed upon adding urethane prepolymers to the resins. The properties of laminated and randomly reinforced glass-fiber plastics with the modified orthophthalic resins are compared with those of similar GFRPs based on popular brands of industrial resins.

  5. Resin injection in clays with high plasticity

    Science.gov (United States)

    Nowamooz, Hossein

    2016-11-01

    Regarding the injection process of polyurethane resins in clays with high plasticity, this paper presents the experimental results of the pressuremeter and cone penetration tests before and after injection. A very important increase in pressure limit or in soil resistance can be observed for all the studied depths close to the injection points. An analytical analysis for cylindrical pore cavity expansion in cohesive frictional soils obeying the Mohr-Coulomb criterion was then used to reproduce the pressuremeter tests before and after injection. The model parameters were calibrated by maintaining constant the elasticity parameters as well as the friction angel before and after injection. A significant increase in cohesion was observed because of soil densification after resin expansion. The estimated undrained cohesions, derived from the parameters of the Mohr-Coulomb criterion, were also compared with the cone penetration tests. Globally, the model predictions show the efficiency of resin injection in clay soils with high plasticity.

  6. The Creep of Laminated Synthetic Resin Plastics

    Science.gov (United States)

    Perkuhn, H

    1941-01-01

    The long-time loading strength of a number of laminated synthetic resin plastics was ascertained and the effect of molding pressure and resin content determined. The best value was observed with a 30 to 40 percent resin content. The long-time loading strength also increases with increasing molding pressure up to 250 kg/cm(exp 2); a further rise in pressure affords no further substantial improvement. The creep strength is defined as the load which in the hundredth hour of loading produces a rate of elongation of 5 X 10(exp -4) percent per hour. The creep strength values of different materials were determined and tabulated. The effect of humidity during long-term tests is pointed out.

  7. System for removing contaminants from plastic resin

    Science.gov (United States)

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2010-11-23

    A resin recycling system that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The system includes receiving the resin in container form. A grinder grinds the containers into resin particles. The particles are exposed to a solvent in one or more solvent wash vessels, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. A separator is used to separate the resin particles and the solvent. The resin particles are then placed in solvent removing element where they are exposed to a solvent removing agent which removes any residual solvent remaining on the resin particles after separation.

  8. Microscopic Approaches to Decomposition and Burning Processes of a Micro Plastic Resin Particle under Abrupt Heating

    Science.gov (United States)

    Ohiwa, Norio; Ishino, Yojiro; Yamamoto, Atsunori; Yamakita, Ryuji

    To elucidate the possibility and availability of thermal recycling of waste plastic resin from a basic and microscopic viewpoint, a series of abrupt heating processes of a spherical micro plastic particle having a diameter of about 200 μm is observed, when it is abruptly exposed to hot oxidizing combustion gas. Three ingenious devices are introduced and two typical plastic resins of polyethylene terephthalate and polyethylene are used. In this paper the dependency of internal and external appearances of residual plastic embers on the heating time and the ingredients of plastic resins is optically analyzed, along with appearances of internal micro bubbling, multiple micro explosions and jets, and micro diffusion flames during abrupt heating. Based on temporal variations of the surface area of a micro plastic particle, the apparent burning rate constant is also evaluated and compared with those of well-known volatile liquid fuels.

  9. Method of removing contaminants from plastic resins

    Science.gov (United States)

    Bohnert,George W.; Hand,Thomas E.; Delaurentiis,Gary M.

    2007-08-07

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  10. Method for removing contaminants from plastic resin

    Science.gov (United States)

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2008-12-30

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  11. Production of the Large-area Plastic Scintillator for Beta-ray Detection using Epoxy Resin

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Jong Soo; Choi, Yong Seok; Hong, Sang Bum; Seo, Bum Kyung; Moon, Jei Kwon; Choi, Jong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In this study, we prepared a plastic scintillator whose manufacturing process is simple and can be freely shaped. A thin plate of the plastic scintillator was manufactured using epoxy resin as a polymer. The plastic scintillator was made by mixing epoxy resin and organic scintillators under various conditions. The optimal mixture ratio to prepare the plastic scintillator was derived from the above results. Using the derived results, we made the large-area plastic scintillator which can quickly measure the contamination site and evaluated characteristics of the large-area plastic scintillator in the laboratory. A thin plate of a plastic scintillator with a simple preparation process can be freely shaped using epoxy resin and organic scintillators such as PPO and POPOP. PPO emits scintillation of light in the ultraviolet range, and POPOP is a wave shifter for moving the wavelength responsible for the PMT. The mixture ratio of PPO and POPOP was determined using their emission spectra. The optimal weight percentage of PPO and POPOP in an organic scintillator was determined to be 0.2 wt%:0.01 wt%. Based on the above results, the large-area plastic scintillator of the window size of a typical pancake-type αβ surface contamination counter was prepared. We want to evaluate the characteristics of the large-area plastic scintillator. However, there were the difficulties in evaluating characteristics of the large-area plastic scintillator. The cross-sectional area of the large-area plastic scintillator is significantly different to PMT.

  12. An Investigation on Thermal Recycling of Recycled Plastic Resin

    Science.gov (United States)

    Yamakita, Ryuji; Miura, Katsuya; Ishino, Yojiro; Ohiwa, Norio

    Thermal recycling of recycled plastic resin is focused in this investigation. Fine grinding of plastic resin and preparation of high temperature oxidizing atmosphere are indispensable for effective and successful burn-up of plastic resin. Polyethylene terephthalate resin powder is employed and high temperature oxidizing atmosphere is generated downstream an annular burner. Through a circular nozzle set coaxially in the closed bottom end of the annular burner, PET-powder and propane-air mixture are issued vertically upward into the high temperature oxidizing atmosphere. Temperature and O2 concentration fields downstream the annular burner are first examined by varying the circular jet equivalence ratio with the air flow rate kept constant and without PET-powder supply. PET-powder having a mass-median diameter of either 89.7µm or 145µm is then issued into the high temperature region along with propane-air mixture by varying the PET-powder mass flow rate. Appearances of the PET-powder flame are observed using a high-speed CCD video camera and unburnt PET particles are traced during their passages in the high temperature region. Variation of O2 concentration fields due to PET-powder combustion is also measured in the PET flame. According to the results, overall limit conditions for effective burn-up of PET-powder are finally discussed.

  13. 竹粉用量对呋喃树脂基木塑复合材料性能的影响%Effect of Content of Bamboo Powder on Properties of Furan Resin-based Wood-plastic Composites

    Institute of Scientific and Technical Information of China (English)

    郝建淦; 贾润礼; 闫赫

    2012-01-01

    采用呋喃树脂和竹粉作原料,用传统的热压成型方法来制备呋喃树脂基木塑复合材料.研究了竹粉用量对木塑复合材料性能的影响.结果表明:当竹粉用量为40%时,材料各方面的性能达到最佳.%The furan resin-based wood-plastic composites were prepared through hot pressing method with furan resin and bamboo powder as raw material.The effects of bamboo powder content on performances of wood-plastic composites were researched.The results show that: when the bamboo powder content is 40%,the comprehensive performances of composites are the best.

  14. Interaction between vegetable oil based plasticizer molecules and polyvinyl chloride, and their plasticization effect

    Science.gov (United States)

    Haryono, Agus; Triwulandari, Evi; Jiang, Pingping

    2017-01-01

    Plasticizer molecules are low molecular weight compounds that are widely used in polymer industries especially in polyvinyl chloride (PVC) resin. As an additive in PVC resin, the important role of plasticizer molecules is to improve the flexibility and processability of PVC by lowering the glass transition temperature (Tg). However, the commercial plasticizer like di(2-ethylhexyl)phthalate (DEHP) is known to cause liver cancer, at least in laboratory rats. DEHP can leach out from PVC into blood, certain drug solutions and fatty foods, which has been detected in the bloodstream of patients undergoing transfusion. Vegetable oil based plasticizers have some attractive properties such as non-toxic, bio-degradable, good heat and light stability, renewable resources, and environmentally friendly. Here we discussed the main results and development of vegetable oil based plasticizer, and especially palm oil based plasticizer. The interaction between plasticizer and polymer was discussed from the properties of the plasticized polymeric material.

  15. PHENOLIC RESINS AND THE PLASTICS INDUSTRY: YESTERDAY, TODAY, AND TOMORROW%PHENOLIC RESINS AND THE PLASTICS INDUSTRY:YESTERDAY,TODAY,AND TOMORROW

    Institute of Scientific and Technical Information of China (English)

    Louis Pilato

    2010-01-01

    During 2010,Phenolic Resins celebrate 100years of existence.Dr.Leo Baekeland began commercial production of phenolic resins in May 1910 in Germany and October 1910 in the United States.This activity launched the Plastics Industry as it is recognized today.It is estimated that about 255 million tons of plastics will be produced worldwide in 2010 and consist of thermoplastic,thermosetting and elastomeric materials.Some of these polymeric materials are further transformed into fiber reinforced plastics (FRP) utilizing fibers such as carbon fiber,glass fiber,and organic fibers such as Kevlar,Spectra (ultrahigh molecular weight polyethylene) and others.

  16. Tensile Properties of Unsaturated Polyester and Epoxy Resin Reinforced with Recycled Carbon-Fiber-Reinforced Plastic

    Science.gov (United States)

    Okayasu, Mitsuhiro; Kondo, Yuta

    2017-08-01

    To better understand the mechanical properties of recycled carbon-fiber-reinforced plastic (rCFRP), CFRP crushed into small pieces was mixed randomly in different proportions (0-30 wt%) with two different resins: unsaturated polyester and epoxy resin. Two different sizes of crushed CFRP were used: 0.1 mm × 0.007 mm (milled CFRP) and 30 mm × 2 mm (chopped CFRP). The tensile strength of rCFRP was found to depend on both the proportion and the size of the CFRP pieces. It increased with increasing proportion of chopped CFRP, but decreased with increasing proportion of milled CFRP. There was no clear dependence of the tensile strength on the resin that was used. A low fracture strain was found for rCFRP samples made with chopped CFRP, in contrast to those made with milled CFRP. The fracture strain was found to increase with increasing content of milled CFRP up to 20 wt%, at which point, coalescence of existing microvoids occurred. However, there was a reduction in fracture strain for rCFRP with 30 wt% of milled CFRP, owing to the formation of defects (blow holes). Overall, the fracture strain was higher for rCFRPs based on epoxy resin than for those based on unsaturated polyester with the same CFRP content, because of the high ductility of the epoxy resin. The different tensile properties reflected different failure characteristics, with the use of chopped CFRP leading to a complicated rough fracture surface and with milled CFRP causing ductile failure through the presence of tiny dimple-like fractures. However, for a high content of milled CFRP (30 wt%), large blow holes were observed, leading to low ductility.

  17. [Dimensional accuracy of microwave-cured denture base resin].

    Science.gov (United States)

    Uchida, K; Okamoto, F; Ogata, K; Sato, T

    1989-02-01

    Recently, microwave-cured denture base resin was developed, and the resin solved the problem of internal porosity which had been generated by curing the conventional denture base resins with microwave irradiation. In this study, the dimensional accuracy of microwave-cured denture base resin was compared with that of other denture base resins, such as pour-type resin, heat-cured resin and heat-shock resin. From the experiment, the following results were obtained. 1. Dimensional accuracy of microwave-cured denture base resin was better than that of heat-cured resin and heat-shock resin, and was similar to that of pour-type resin. 2. Dimensional accuracy of microwave-cured denture base resin by slow cooling method and rapid cooling method was almost the same. Those findings suggest that microwave-cured denture base resin is valuable in clinic.

  18. A study on compound contents for plastic injection molding products of metallic resin pigment

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young Whan; Kwak, Jae Seob [Dept. of Mechanical Engineering, Pukyong National University, Busan (Korea, Republic of); Lee, Gyu Sang [Alliance Molding Engineering TeamLG Electronics Inc., Osan (Korea, Republic of)

    2016-12-15

    Injection molding process is widely used for producing most plastic products. In order to make a metal-colored plastic product especially in modern luxury home alliances, metallic pigments which are mixed to a basic resin material for injection molding are available. However, the process control for the metal-colored plastic product is extremely difficult due to non-uniform melt flow of the metallic resin pigments. To improve the process efficiency, a rapid mold cooling method by a compressed cryogenic fluid and electricity mold are also proposed to decrease undesired compound contents within a molded plastic product. In this study, a quality of the metal-colored plastic product is evaluated with process parameters; injection speed, injection pressure, and pigment contents, and an influence of the rapid cooling and heating system is demonstrated.

  19. Reinforcement of Denture Base Resins

    Directory of Open Access Journals (Sweden)

    T Nejatiant

    2005-10-01

    Full Text Available Introduction: PMMA has been the most popular denture base material because of its advantages including good aesthetics, accurate fit, stability in the oral environment, easy laboratory and clinical manipulation and inexpensive equipments since the 1930’s. However, its fracture resistance is not satisfactory. Aim: The aim of this study is to improve the fracture resistance of denture bases made of PMMA by assessing the effect of resin type, packing and processing variables on biaxial flexural strength (BFS. Materials & methods: 930 discs, 12 mm diameter and 2 mm thick were prepared with the following variables: a. Veined (V and Plain (P PMMA. b. 5 different powder/liquid ratios by volume (1.5:1, 2:1, 2.5:1, 3:1, 3.5:1. c. Conventional (C and Injection packing methods (I. d. Dry heat (D Water bath (W; and e. different curing times. The discs were trimmed and stored in 37°C tap water for 50 hours before carrying out BFS test, according to BS EN ISO 1567: 2001. BFS test was carried out using a tensile-testing machine (Lloyd LRX, Lloyd instruments Ltd (Figure.1 b, with a x-head speed of 1mm/min. ONE-WAY ANOVA analysis and TUKEY’S comparison were carried out (MINITAB. The temperature within the curing baths and inside of curing resin was evaluated by using a thermocouple. Results: BFS of Powder/liquid ratio of 1.5:1 is significantly lower than the other four ratios. Among the last four ratios, 2.5:1 was the strongest one although the difference was not significant. BFS of the plain type of PMMA is significantly higher than the veined type.• BFS of conventionally packed PMMA discs was greater than the injectional packed ones and the difference is significant. Water bath cured resin showed a significant higher BFS compared with dry heat curing. • Changing the curing time in the dry heat bath from 7h @ 75º C and 2hrs @ 95º C to 5hrs @ 75º C and 3hrs @ 95º C and then 2hrs @ 95º C improves BFS of PMMA. In the water bath the trend is identical

  20. Novel silica-based ion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-11-01

    Eichrom`s highly successful Diphonixo resin resembles a conventional ion exchange resin in its use of sulfonic acid ligands on a styrene- divinylbenzene matrix. Diphonix resin exhibits rapid exchange kinetics that allow economical operation of ion exchange systems. Unlike conventional resins, Diphonix resin contains chelating ligands that are diphosphonic acid groups that recognize and remove the targeted metals and reject the more common elements such as sodium, calcium and magnesium. This latter property makes Diphonix ideal for many industrial scale applications, including those involving waste treatment. For treatment of low-level, transuranic (TRU) and high- level radioactive wastes, Diphonix`s polystyrene backbone hinders its application due to radiolytic stability of the carbon-hydrogen bonds and lack of compatibility with expected vitrification schemes. Polystyrene-based Diphonix is approximately 60% carbon- hydrogen. In response to an identified need within the Department of Energy for a resin with the positive attributes of Diphonix that also exhibits greater radiolytic stability and final waste form compatibility, Eichrom has successfully developed a new, silica-based resin version of Diphonix. Target application for this new resin is for use in environmental restoration and waste management situations involving the processing of low-level, transuranic and high-level radioactive wastes. The resin can also be used for processing liquid mixed waste (waste that contains low level radioactivity and hazardous constituents) including mixed wastes contaminated with organic compounds. Silica-based Diphonix is only 10% carbon-hydrogen, with the bulk of the matrix silica.

  1. Novel silica-based ion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Gula, M.; Harvey, J.

    1996-12-31

    Shortcomings of chelating resins have been addressed by a new class of ion exchange resins called dual mechanism bifunctional polymers (DMBPs). DMBPs use hydrophilic cation exchange ligands with rapid uptake kinetics and use chelating ligands for selectivity for one or more metals; result is a resin that quickly recognizes and removes targeted metals from waste, remediation, and process streams. Eichrom`s Diphonix {reg_sign} resin is the first DMBP to be widely released as a commercial product; it is polystyrene based. Objective of this work is to synthesize commercial quantities of a silica-based ion exchange resin with the same or better metal ion selectivity, metal uptake kinetics, and acid stability as Diphonix. Feasibility was determined, however the process needs to be optimized. Studies at Eichrom and ANL of the performance of Diphonix resin over a broad range of HNO3 and HCl conditions and inorganic salt loadings are discussed together with the proposed method of incorporating similar characteristics into a silica-based resin. The new, silica-based resin functionalized with diphosphonic acid ligands can be used in environmental restoration and waste management situations involving processing of low-level, transuranic, and high-level radioactive wastes; it can also be used for processing liquid mixed waste including wastes contaminated with organic compounds.

  2. Plastic deformation mechanisms in polyimide resins and their semi-interpenetrating networks

    Science.gov (United States)

    Jang, Bor Z.

    1990-01-01

    High-performance thermoset resins and composites are critical to the future growth of space, aircraft, and defense industries in the USA. However, the processing-structure-property relationships in these materials remain poorly understood. In the present ASEE/NASA Summer Research Program, the plastic deformation modes and toughening mechanisms in single-phase and multiphase thermoset resins were investigated. Both thermoplastic and thermoset polyimide resins and their interpenetrating networks (IPNs and semi-IPNs) were included. The fundamental tendency to undergo strain localization (crazing and shear banding) as opposed to a more diffuse (or homogeneous) deformation in these polymers were evaluated. Other possible toughening mechanisms in multiphase thermoset resins were also examined. The topological features of network chain configuration/conformation and the multiplicity of phase morphology in INPs and semi-IPNs provide unprecedented opportunities for studying the toughening mechanisms in multiphase thermoset polymers and their fiber composites.

  3. Biocompatibility of Resin-based Dental Materials

    OpenAIRE

    Keyvan Moharamzadeh; Ian M. Brook; Richard van Noort

    2009-01-01

    Oral and mucosal adverse reactions to resin-based dental materials have been reported. Numerous studies have examined thebiocompatibility of restorative dental materials and their components, and a wide range of test systems for the evaluation of the biological effects of these materials have been developed. This article reviews the biological aspects of resin-based dental materials and discusses the conventional as well as the new techniques used for biocompatibility assessment of dental mat...

  4. Luminous Efficient Compositions Based on Epoxy Resin

    Directory of Open Access Journals (Sweden)

    R.S. Palaiah

    2006-07-01

    Full Text Available Magnesium/sodium nitrate illuminating compositions with epoxy resin - E 605 have beenstudied for luminosity and luminous efficiency by varying fuel oxidizer ratio and binder content.The compositions have been evaluated for impact and friction sensitivities, burn rate, thermalcharacteristics, and mechanical properties. Flame temperature and combustion products areevaluated theoretically by using REAL program. Experimental results show that, luminosity,burn rate, and calorimetric value are higher for polyester resin-based compositions. The highluminous efficiency composition is achieved with magnesium/sodium nitrate ratio of 70/30 with4 per cent epoxy resin.

  5. In vitro mechanical properties comparsion of four room temperature curing denture base resin:

    Institute of Scientific and Technical Information of China (English)

    LI Zhian; XIA Xuetong; Xiao Qun

    2001-01-01

    @@ The room temperature curing denture base resin has low mechanical properties,so it was limited in clinical application. It had previously disscused that reinfored maehinical properties with metal fiber, glass fiber,plastic fiber and by adding the fracture resistance substances in powderThe aim of this study was to determined the mechanical properities of four roomtemperature curing denture base resin which had been modified performance withhigh boil point methacrylate.

  6. The effect of bulk-resin CNT-enrichment on damage and plasticity in shear-loaded laminated composites

    KAUST Repository

    Ventura, Isaac Aguilar

    2013-07-01

    One way to improve multi functionality of epoxy-based laminated composites is to dope the resin with carbon nanotubes. Many investigators have focused on the elastic and fracture behavior of such nano-modified polymers under tensile loading. Yet, in real structural applications, laminated composites can exhibit plasticity and progressive damage initiated mainly by shear loading. We investigated the damage and plasticity induced by the addition of carbon nanotubes to the matrix of a glass fiber/epoxy composite system. We characterized both the modified epoxy resin and the associated modified laminates using classical mesoscale analysis. We used dynamic mechanical analysis, scanning electron microscopy, atomic force microscopy and classical mechanical testing to characterize samples with different concentrations of nanofillers. Since the samples were prepared using the solvent evaporation technique, we also studied the influence of this process. We found that in addition to the global increase in elastic regime properties, the addition of carbon nanotubes also accelerates the damage process in both the bulk resin and its associated glass-fiber composite. © 2013 Elsevier Ltd.

  7. Persistent organic pollutants carried on plastic resin pellets from two beaches in China.

    Science.gov (United States)

    Zhang, Weiwei; Ma, Xindong; Zhang, Zhifeng; Wang, Yan; Wang, Juying; Wang, Jing; Ma, Deyi

    2015-10-15

    Microplastics provide a mechanism for the long-range transport of hydrophobic chemical contaminants to remote coastal and marine locations. In this study, plastic resin pellets were collected from Zhengmingsi Beach and Dongshan Beach in China. The collected pellets were analyzed for PAHs, PCBs, HCHs, DDTs, chlordane, heptachlor, endosulfan, aldrin, dieldrin and endrin. The total concentration of PCBs ranged from 34.7-213.7 ng g(-1) and from 21.5-323.2 ng g(-1) in plastic resin pellets for Zhengmingsi Beach and Dongshan Beach respectively. The highest concentrations of PCBs were observed for congeners 44, 110, 138, 155 and 200. The total concentration of PAHs ranged from 136.3-1586.9 ng g(-1) and from 397.6-2384.2 ng g(-1) in the plastic pellets, whereas DDTs concentration ranged from 1.2-101.5 ng g(-1) and from 1.5-127.0 ng g(-1) for the two beaches. The elevated concentrations of pollutants appear to be related to extensive industrial development, agricultural activity and the use of coal in the area.

  8. FDI report on adverse reactions to resin-based materials.

    Science.gov (United States)

    Fan, P L; Meyer, D M

    2007-02-01

    Resin-based restorative materials are considered safe for the vast majority of dental patients. Although constituent chemicals such as monomers, accelerators and initiators can potentially leach out of cured resin-based materials after placement, adverse reactions to these chemicals are rare and reaction symptoms commonly subside after removal of the materials. Dentists should be aware of the rare possibility that patients could have adverse reactions to constituents of resin-based materials and be vigilant in observing any adverse reactions after restoration placement. Dentists should also be cognisant of patient complaints about adverse reactions that may result from components of resin-based materials. To minimise monomer leaching and any potential risk of dermatological reactions, resin-based materials should be adequately cured. Dental health care workers should avoid direct skin contact with uncured resin-based materials. Latex and vinyl gloves do not provide adequate barrier protection to the monomers in resin-based materials.

  9. Dental repair material: a resin-modified glass-ionomer bioactive ionic resin-based composite.

    Science.gov (United States)

    Croll, Theodore P; Berg, Joel H; Donly, Kevin J

    2015-01-01

    This report documents treatment and repair of three carious teeth that were restored with a new dental repair material that features the characteristics of both resin-modified glass-ionomer restorative cement (RMGI) and resin-based composite (RBC). The restorative products presented are reported by the manufacturer to be the first bioactive dental materials with an ionic resin matrix, a shock-absorbing resin component, and bioactive fillers that mimic the physical and chemical properties of natural teeth. The restorative material and base/liner, which feature three hardening mechanisms, could prove to be a notable advancement in the adhesive dentistry restorative materials continuum.

  10. [Antibacterial actions of denture base resin on oral bacteria].

    Science.gov (United States)

    Yamauchi, M; Nigauri, A; Yamamoto, K; Nakazato, G; Kawano, J; Kimura, K

    1989-06-01

    Antibacterial action of various denture base resins on thirteen species of bacteria were studied in vitro. Antibacterial effect of 5% tannin-fluoride preparation, 5% tannic acid and 5% chlorhexidine added to resins on these thirteen bacterial species were also investigated using heat-curing denture base resins. Fresh microwave-curing resin and pour-type resin each showed an antibacterial action on one bacterial strain. Fresh self-curing resins had antibacterial actions on several bacterial strains. However, after storage in water at 37 degrees C for one week, antibacterial action of microwave-curing and pour-type resin were diminished and self-curing resins partially lost their antibacterial actions. Denture base resin containing tannin-fluoride preparation or tannic acid showed an antibacterial effect on one bacterial strain. On the other hand, denture base resin containing chlorhexidine had an antibacterial action on eleven bacterial strains. However, color and mechanical properties of the drug-containing resins were not satisfactory.

  11. The effect of biobased plastic resins containing chichen feather fibers on the growth and flowering of Begonia boliviensis

    Science.gov (United States)

    This study was conducted to evaluate growth and flowering of Begoniaboliviensis A. DC. 'Bonfire' when grown in medium mixed with pellets made from biobased plastic resins containing chicken feather fibers. We also analyzed macro- and macro-elements in soil and leaf tissues during different develope...

  12. Synthesis and Characterizations of Melamine-Based Epoxy Resins

    Directory of Open Access Journals (Sweden)

    Raffaele Cioffi

    2013-09-01

    Full Text Available A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I or by adding a silane derivative (resin II. The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials.

  13. Synthesis and characterizations of melamine-based epoxy resins.

    Science.gov (United States)

    Ricciotti, Laura; Roviello, Giuseppina; Tarallo, Oreste; Borbone, Fabio; Ferone, Claudio; Colangelo, Francesco; Catauro, Michelina; Cioffi, Raffaele

    2013-09-05

    A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I) or by adding a silane derivative (resin II). The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials.

  14. Graphite Nanoplatelet Modified Epoxy Resin for Carbon Fibre Reinforced Plastics with Enhanced Properties

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-01-01

    Full Text Available A simple approach to deliver graphene or graphite nanoplatelets (GNPs into carbon fibre reinforced plastic (CFRPs to enhance the multifunctional properties of carbon/epoxy laminates was demonstrated. GNPs improved the typically low interlaminar mechanical, thermal, and electrical properties of CFRPs after direct vacuum infusion of GNP doped resin obtained via in situ exfoliation by three-roll milling (TRM. Compared to high shear mixing or probe ultrasonication, TRM produces higher shear rates and stresses to exfoliate and finely disperse GNP particles within an epoxy matrix. This environmentally friendly and industrial scalable process does not require the use of solvents, additives, or chemical treatments. The flexural modulus and interlaminar shear strength (ILSS of CFRPs was increased by 15% and by 18%, respectively, with the addition of 5 wt.% in situ exfoliated GNP in the doped epoxy resin. Out-of-plane electrical and thermal conductivity, at the same filler content, were, respectively, improved by nearly two orders of magnitude and 50%.

  15. 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

  16. Has resin-based composite replaced amalgam?

    Science.gov (United States)

    Christensen, Gordon J; Child, Paul L

    2010-02-01

    The major health organizations in the world continue to accept amalgam use, but the "amalgam war" of the 1800s is still going on. The end is not in sight. There is little disagreement that amalgam serves well and, although controversial, it appears to have minimal to no health hazards. There is a wide variation in the relative amount of amalgam placed in developed countries, and many dentists in North America do not use it. However, amalgam is still being used at least some of the time by the majority of practitioners in North America, and most of those practitioners also place resin-based composite in Class II locations. The evolution from amalgam to tooth-colored restorations has been a slow and tumultuous journey. The acceptability of resin-based composite in Class II locations continues to be a question for some dentists, while others have concluded that amalgam is "dead." It would be highly desirable if some of dentists using the alleged poisonous properties of amalgam as a "practice building" ploy would find more legitimate methods to increase their practice activity.

  17. The creep behavior of acrylic denture base resins.

    Science.gov (United States)

    Sadiku, E R; Biotidara, F O

    1996-01-01

    The creep behavior of acrylic dental base resins, at room temperature and at different loading conditions, has been examined. The behaviors of these resins are similar to that of "commercial perspex" at room temperature over a period of 1000 seconds. The pseudo-elastic moduli of the blends of PMMA VC show a significant increase compared with PMMA alone. The addition of the PVC powder to the heat-cured acrylic resin increased the time-dependent elastic modulus. This increase in elastic modulus is advantageous in the production of denture based resins of improv mechanical properties.

  18. Sorption kinetics of ethanol/water solution by dimethacrylate-based dental resins and resin composites.

    Science.gov (United States)

    Sideridou, Irini D; Achilias, Dimitris S; Karabela, Maria M

    2007-04-01

    In the present investigation the sorption-desorption kinetics of 75 vol % ethanol/water solution by dimethacrylate-based dental resins and resin composites was studied in detail. The resins examined were made by light-curing of bisphenol A glycol dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), bisphenol A ethoxylated dimethacrylate (Bis-EMA), and mixtures of these monomers. The resin composites were prepared from two commercial light-cured restorative materials (Z100 MP and Filtek Z250), the resin matrix of which is based on copolymers of the above-mentioned monomers. Ethanol/water sorption/desorption was examined in both equilibrium and dynamic conditions in two adjacent sorption-desorption cycles. For all the materials studied, it was found that the amount of ethanol/water sorbed or desorbed was always larger than the corresponding one reported in literature in case of water immersion. It was also observed that the chemical structure of the monomers used for the preparation of the resins directly affects the amount of solvent sorbed or desorbed, as well as sorption kinetics, while desorption rate was nearly unaffected. In the case of composites studied, it seems that the sorption/desorption process is not influenced much by the presence of filler. Furthermore, diffusion coefficients calculated for the resins were larger than those of the composites and were always higher during desorption than during sorption. Finally, an interesting finding concerning the rate of ethanol/water sorption was that all resins and composites followed Fickian diffusion kinetics during almost the whole sorption curve; however, during desorption the experimental data were overestimated by the theoretical model. Instead, it was found that a dual diffusion-relaxation model was able to accurately predict experimental data during the whole desorption curve. Kinetic relaxation parameters, together with diffusion coefficients, are reported

  19. Acrylic Resin Cytotoxicity for Denture Base--Literature Review.

    Science.gov (United States)

    Goiato, Marcelo C; Freitas, Emily; dos Santos, Daniela; de Medeiros, Rodrigo; Sonego, Mariana

    2015-01-01

    Acrylic resin is a widely used material in clinical practice, and a satisfactory biocompatibility is essential. When the resin polymerization reaction is incomplete, residual monomers are released into the oral cavity. The aim of this study was to evaluate, through a literature review, the cytotoxicity caused by the denture base acrylic resin used, and its components. The selection of published studies was performed on the Pubmed database from January 2008 to July 2013. The keywords used were: "cytotoxicity and acrylic resins", "cytotoxicity and denture base resins" and "cytotoxicity and oral prosthesis". Inclusion criteria were: in vitro studies and literature reviews published in English that evaluated the acrylic resin cytotoxicity for denture base and its components. Studies with no reference to the search strategy were excluded. A total of 182 articles were found. Among these, only 13 were included for writing this review. The MTT test is the most common test used to evaluate acrylic resin cytotoxicity. Auto-polymerized resin is more cytotoxic than heat-polymerized resin because of its higher quantity of residual monomers which cause cell and tissue changes in the oral mucosa. However, more studies are necessary for the development of biocompatible materials.

  20. Curing depth of a resin-modified glass ionomer and two resin-based luting agents.

    Science.gov (United States)

    Sigemori, Ricardo Massao; Reis, André Figueiredo; Giannini, Marcelo; Paulillo, Luís Alexandre M S

    2005-01-01

    The degree of conversion of resin-based luting agents used for retention of prefabricated posts has been questioned due to the difficulty of light penetration into the resin-filled root canal. This study evaluated the depth of cure of a resin-modified glass ionomer cement (Rely X--3M ESPE) and two resin-based luting agents (Rely X ARC--3M ESPE and Enforce-Dentsply). Twenty-four 14x2x2mm3 specimens were prepared in a Teflon split mold with the three luting agents (n=8). After preparation, the specimens were stored at 37 degrees C in a dark box for 24 hours prior to microhardness testing. Measurements of Knoop hardness were performed at three different depths: superficial, medium and deep thirds. The results (KHN) were statistically analyzed by repeated measures ANOVA and Tukey test (0.05), which showed that resin-based luting agents presented the highest Knoop hardness values within the superficial third. Within the medium third, there were no significant differences among luting materials. However, within the deep third, Rely X presented the highest values. KHN values of resin-based luting agents decreased remarkably as depth increased.

  1. Posterior resin-based composite: review of the literature.

    Science.gov (United States)

    Burgess, J O; Walker, Richard; Davidson, J M

    2002-01-01

    The use of direct posterior resin-based composite has increased primarily due to patient esthetic desires and product improvements. Other factors (substantiated or not) contributing to increased use of resin-based composite are environmental and health concerns with dental amalgam. New visible light cured resin-based composite products are introduced yearly, as manufacturers continue to improve this tooth-colored restorative material. This paper will characterize current posterior resin-based composite materials (hybrid, microfill, flowable, and packable), review recent in vitro and clinical research, and recommend indications for these materials. In addition, the literature on compomers will be reviewed and recommendation made for their use. The data indicates that composite resin is a technique sensitive restorative material that can be used in large preparations if proper manipulation and isolation can be maintained. Compomers may also be used as an esthetic posterior restorative if proper isolation is provided.

  2. Temporal and spatial changes in persistent organic pollutants in Vietnamese coastal waters detected from plastic resin pellets.

    Science.gov (United States)

    Le, Dung Quang; Takada, Hideshige; Yamashita, Rei; Mizukawa, Kaoruko; Hosoda, Junki; Tuyet, Dao Anh

    2016-08-15

    Plastic resin pellets collected at Minh Chau island and Ba Lat estuary between 2007 and 2014 in Vietnam were analyzed for dichloro-diphenyl-trichloroethanes (DDTs), polychlorinated biphenyls (PCBs) and hexachlorocyclohexanes (HCHs). The study was carried out as part of the International Pellet Watch program for monitoring the global distribution of persistent organic pollutants (POPs). Higher levels of DDTs compared to PCBs indicated agricultural inputs rather than industrial discharges in the region. Most POP concentrations on both beaches decreased over the period, with the exception of HCH isomers. Though the concentration of DDTs showed a drastic decline on both beaches between 2007/2008 and 2014, DDTs accounted for 60-80% of total DDTs, suggesting that there is still a fresh input of these chemicals in the region. This study strongly recommends further investigations to track temporal and spatial patterns of POP levels in the marine environment using plastic resin pellets.

  3. Attribute based selection of thermoplastic resin for vacuum infusion process

    DEFF Research Database (Denmark)

    Prabhakaran, R.T. Durai; Lystrup, Aage; Løgstrup Andersen, Tom

    2011-01-01

    The composite industry looks toward a new material system (resins) based on thermoplastic polymers for the vacuum infusion process, similar to the infusion process using thermosetting polymers. A large number of thermoplastics are available in the market with a variety of properties suitable...... for different engineering applications, and few of those are available in a not yet polymerised form suitable for resin infusion. The proper selection of a new resin system among these thermoplastic polymers is a concern for manufactures in the current scenario and a special mathematical tool would...... be beneficial. In this paper, the authors introduce a new decision making tool for resin selection based on significant attributes. This article provides a broad overview of suitable thermoplastic material systems for vacuum infusion process available in today’s market. An illustrative example—resin selection...

  4. LPG based all plastic pressure sensor

    DEFF Research Database (Denmark)

    Bundalo, Ivan-Lazar; Lwin, R.; Leon-Saval, S.

    2015-01-01

    A prototype all-plastic pressure sensor is presented and characterized for potential use as an endoscope. The sensor is based on Long Period Gratings (LPG) inscribed with a CO2 laser in 6-ring microstructured PMMA fiber. Through a latex coated, plastic 3D-printed transducer pod, external pressure...

  5. Repair of dental resin-based composites.

    Science.gov (United States)

    Baur, Veronika; Ilie, Nicoleta

    2013-03-01

    The study analyzed the reparability and compatibility of light-curing resin-based composites (RBCs) of the categories "microhybrid," "nanohybrid," and "packable." Six RBCs with different matrix and filler formulation--purely methacrylate-based composites (MBCs), ormocer-based composites (OBCs), and silorane-based composites (SBCs)--were used for the specimens. Every material was combined with itself and with the other five RBCs, resulting in a total of 36 combination groups (n = 20). The specimens were polymerized, aged for 8 weeks in distilled water at 37 °C, and then repaired by means of a repair kit. Shear bond strength and fracture mode were measured after aging of the specimens, undergoing storage for 24 h in distilled water at 37 °C followed by thermocycling (5,000 cycles, 5-55 °C) and an additional 4-week storage in distilled water at 37 °C. Data were statistically analyzed using ANOVA with TUKEY HSD post hoc test (α = 0.05). On average, the OBC Admira reached the highest value as a substrate material (30.41 MPa), and the SBC Filtek Silorane reached the lowest value (8.14 MPa). Filtek Silorane was identified as the repair material with the highest bond strength value (28.70 MPa), while a packable composite reached the lowest bond strength value (15.55 MPa). The analysis of the break modes showed that adhesive breaks are typical when strength is at its lowest (6.27 MPa). A large number of cohesive fractures are conspicuous when identical materials are used for repair, except Filtek Silorane (2 % cohesive fractures). The study demonstrated that the effect of the different materials on bond strength varies strongly, depending on whether the material is used as filling or as repair material. It is generally advisable but not compulsory to combine identical RBCs.

  6. Cytotoxicity evaluation of methacrylate- and silorane-based composite resins

    Directory of Open Access Journals (Sweden)

    Gulsah Goktolga Akin

    2012-10-01

    Full Text Available

    Objectives: The objective of this study was to investigate and compare the cytotoxic effects of four composite resin materials with different content.

    Material and Methods: Two traditional methacrylate-based (Clearfil AP-X, RefleXions, as well as a self-adhering methacrylate-based (Vertise Flow and a silorane-based (Filtek Silorane composite resin were tested in the experiment. Ten cylindrical specimens were made of each material, using a mould (2mm. thick and 8 mm. in diameter. An agar diffusion method was employed, and cytotoxicity rankings were determined using lysis index scores. For statistical analysis, Kruskal-Wallis and Mann-Whitney U-tests were used.

    Results: Amongst the composite resins, the silorane-based composite was found to be less cytotoxic than the methacrylate-based composite resins, which all had the same cytotoxicity ranking.

    Conclusions: The silorane-based composite resin was considered more biocompatible than the methacrylate-based composite resins.

  7. Polymerization shrinkage of flowable resin-based restorative materials

    OpenAIRE

    Stavridakis, Minos M; Dietschi, Didier; Krejci, Ivo

    2005-01-01

    This study measured the linear polymerization displacement and polymerization forces induced by polymerization shrinkage of a series of flowable resin-based restorative materials. The materials tested were 22 flowable resin-based restorative materials (Admira Flow, Aelite Flow, Aeliteflow LV, Aria, Crystal Essence, Definite Flow, Dyract Flow, Filtek Flow, FloRestore, Flow-it, Flow-Line, Freedom, Glacier, OmegaFlo, PermaFlo, Photo SC, Revolution 2, Star Flow, Synergy Flow, Tetric Flow, Ultrase...

  8. Field based plastic contamination sensing

    Science.gov (United States)

    The United States has a long-held reputation of being a dependable source of high quality, contaminant-free cotton. Recently, increased incidence of plastic contamination from sources such as shopping bags, vegetable mulch, surface irrigation tubing, and module covers has threatened the reputation o...

  9. Resin-based composites and compomers in primary molars.

    Science.gov (United States)

    García-Godoy, F

    2000-07-01

    Resin-based composite resins and polyacid-modified resin-based composites (compomers) have become popular for the restoration of primary anterior and posterior teeth. In some European countries, resin-based composites or glass-ionomers are the materials of choice for primary teeth because of the controversy over dental amalgam and its alleged adverse health effects resulting from the release of mercury, although a clear correlation between amalgam restorations and health has not been determined. Another reason for the worldwide increased use of resin-based composites and glass-ionomers in pediatric dentistry could be attributed to the growing demand from parents to provide esthetic restorations to their children. More conservative preparations can be performed maintaining more tooth structure because of the adhesive properties of the composites and compomers. The most conservative treatment planning and meticulous care in the placement of the resin-based composites and compomers would produce long-term satisfactory results. These restorations should be placed in patients with low-to-moderate caries risk, and after placement the restorations should be monitored carefully to avoid complications mainly produced by recurrent caries and wear.

  10. The effect of resin thickness on polymerization characteristics of silorane-based composite resin

    Directory of Open Access Journals (Sweden)

    Sung-Ae Son

    2014-11-01

    Full Text Available Objectives This study examined the influence of the resin thickness on the polymerization of silorane- and methacrylate-based composites. Materials and Methods One silorane-based (Filtek P90, 3M ESPE and two methacrylate-based (Filtek Z250 and Z350, 3M ESPE composite resins were used. The number of photons were detected using a photodiode detector at the different thicknesses (thickness, 1, 2 and 3 mm specimens. The microhardness of the top and bottom surfaces was measured (n = 15 using a Vickers hardness with 200 gf load and 15 sec dwell time conditions. The degree of conversion (DC of the specimens was determined using Fourier transform infrared spectroscopy (FTIR. Scratched powder of each top and bottom surface of the specimen dissolved in ethanol for transmission FTIR spectroscopy. The refractive index was measured using a Abbe-type refractometer. To measure the polymerization shrinkage, a linometer was used. The results were analyzed using two-way ANOVA and Tukey's test at p < 0.05 level. Results The silorane-based resin composite showed the lowest filler content and light attenuation among the specimens. P90 showed the highest values in the DC and the lowest microhardness at all depth. In the polymerization shrinkage, P90 showed a significantly lower shrinkage than the rest two resin products (p < 0.05. P90 showed a significantly lower refractive index than the remaining two resin products (p < 0.05. Conclusions DC, microhardness, polymerization rate and refractive index linearly decreased as specimen thickness linearly increased. P90 showed much less polymerization shrinkage compared to other specimens. P90, even though achieved the highest DC, showed the lowest microhardness and refractive index.

  11. A comparison of shear bond strength of ceramic and resin denture teeth on different acrylic resin bases.

    Science.gov (United States)

    Corsalini, Massimo; Di Venere, Daniela; Pettini, Francesco; Stefanachi, Gianluca; Catapano, Santo; Boccaccio, Antonio; Lamberti, Luciano; Pappalettere, Carmine; Carossa, Stefano

    2014-01-01

    The purpose of this study is to compare the shear bond strength of different resin bases and artificial teeth made of ceramic or acrylic resin materials and whether tooth-base interface may be treated with aluminium oxide sandblasting. Experimental measurements were carried on 80 specimens consisting of a cylinder of acrylic resin into which a single tooth is inserted. An ad hoc metallic frame was realized to measure the shear bond strength at the tooth-base interface. A complete factorial plan was designed and a three-way ANalysis Of VAriance (ANOVA) was carried out to investigate if shear bond strength is affected by the following factors: (i) tooth material (ceramic or resin); (ii) base material (self-curing or thermal-curing resin); (iii) presence or absence of aluminium oxide sandblasting treatment at the tooth-base interface. Tukey post hoc test was also conducted to evaluate any statistically significant difference between shear strength values measured for the dif-ferently prepared samples. It was found from ANOVA that the above mentioned factors all affect shear strength. Furthermore, post hoc analysis indi-cated that there are statistically significant differences (p-value=0.000) between measured shear strength values for: (i) teeth made of ceramic material vs. teeth made of acrylic resin material; (ii) bases made of self-curing resin vs. thermal-curing resin; (iii) specimens treated with aluminium oxide sandblasting vs. untreated specimens. Shear strength values measured for acryl-ic resin teeth were on average 70% higher than those measured for ceramic teeth. The shear bond strength was maximized by preparing samples with thermal-curing resin bases and resin teeth submitted to aluminium oxide sandblasting.

  12. Resistance of particleboard panels made of agricultural residues and bonded with synthetic resins or PVC plastic to wood-rotting fungi

    Directory of Open Access Journals (Sweden)

    Divino Eterno Teixeira

    2009-12-01

    Full Text Available This study aims to evaluate the resistance of three types of particleboard panel to biodeterioration, two of which bonded with synthetic resins and one bonded with PVC plastic. Composite panels were made using sugar cane straw particles as raw material which were bonded together with urea-formaldehyde (UF, tannin-formaldehyde (TANI and PVC plastic (PVC resins. Decay tests were performed following procedures outlined in the ASTM D2017-81/1994 standard, whereby sample specimens were subjected to attack by white rot fungus Trametes versicolor and brown rot fungus Gloeophyllum trabeum using pine (Pinus sp. and embaúba (Cecropia sp. as reference timber. Panels bonded with PVC resin were rated ‘resistant’ to attack by both fungi while those bonded with UF and TANI resins were rated ‘slightly resistant’ to their attack.

  13. Characterization of fiberglass-filled diallyl phthalate plastic molding resins and molded parts

    Energy Technology Data Exchange (ETDEWEB)

    Whitaker, R.B.; Glaub, J.E.; Bonekowski, N.R.; Gillham, P.D.

    1980-12-01

    Characterization of diallyl phthalate (DAP) molding resins was undertaken by differential scanning calorimetry (DSC) and by combined size exclusion chromatography (SEC)/low angle laser light scattering (LALLS) in order to better predict moldability and storage life limits. Completeness of cure of molded parts, before and after any post-curing, was also determined by thermal analysis. Molecular weights and molecular weight distributions of the DAP molding resins by SEC/LALLS indicated that the better molding resins have lower M/sub w//M/sub n/ ratios. Association effects were observed, which could not be overcome by solvent modification alone. Determination of DAP molding resin heats of reaction by DSC indicated a linear relation between ..delta..H/sub R/ and weight percent filler for the good molding resins. DSC analyses of molded DAP parts showed that 95% cure was achieved in some as-molded parts, with a post-cure temperature of 165/sup 0/C being required to complete the cure to 100%. Thickness of the parts was a factor, with the thicker parts being 100% cured as molded. The glass transition temperature (T/sub g/) of the molded parts increased as cure was completed, to approx. 160 to 165/sup 0/C maximum. These results are consistent with a model of thermoset resin curing behavior which states that 100% cure can be achieved only if a post-curing operation is conducted above the T/sub g infinity/ (T/sub g/ at complete cure) of the polymer.

  14. Dimensional accuracy of acrylic resin maxillary denture base polymerized by a new injection pressing method.

    Science.gov (United States)

    Ono, Takahiro; Kita, Seiichi; Nokubi, Takashi

    2004-09-01

    The purpose of this study was to confirm the dimensional accuracy of a newly developed injection pressing method for resin polymerization by making use of the internal electric resistance of resin to determine the optimal timing for resin injection. A new injection pressing polymerization pot with a built-in system to measure the internal electric resistance of resin was used for resin polymerization. Fluid-type resin was injected into the mold of a maxillary complete denture base under nine different conditions: three different timings for resin injection according to the electric resistance of resin dough (early stage: 11 Mohms; intermediate stage: 16 Mohms; final stage: 21 Mohms) and three different motor powers for resin injection (2000 N, 4000 N, and 6000 N). In the best polymerization condition (injected during the early stage of resin dough under a motor power of 6000 N), the adaptation of the denture base showed a statistically significant improvement compared with the conventional pouring method.

  15. Environmental and health hazard ranking and assessment of plastic polymers based on chemical composition.

    Science.gov (United States)

    Lithner, Delilah; Larsson, Ake; Dave, Göran

    2011-08-15

    Plastics constitute a large material group with a global annual production that has doubled in 15 years (245 million tonnes in 2008). Plastics are present everywhere in society and the environment, especially the marine environment, where large amounts of plastic waste accumulate. The knowledge of human and environmental hazards and risks from chemicals associated with the diversity of plastic products is very limited. Most chemicals used for producing plastic polymers are derived from non-renewable crude oil, and several are hazardous. These may be released during the production, use and disposal of the plastic product. In this study the environmental and health hazards of chemicals used in 55 thermoplastic and thermosetting polymers were identified and compiled. A hazard ranking model was developed for the hazard classes and categories in the EU classification and labelling (CLP) regulation which is based on the UN Globally Harmonized System. The polymers were ranked based on monomer hazard classifications, and initial assessments were made. The polymers that ranked as most hazardous are made of monomers classified as mutagenic and/or carcinogenic (category 1A or 1B). These belong to the polymer families of polyurethanes, polyacrylonitriles, polyvinyl chloride, epoxy resins, and styrenic copolymers. All have a large global annual production (1-37 million tonnes). A considerable number of polymers (31 out of 55) are made of monomers that belong to the two worst of the ranking model's five hazard levels, i.e. levels IV-V. The polymers that are made of level IV monomers and have a large global annual production (1-5 million tonnes) are phenol formaldehyde resins, unsaturated polyesters, polycarbonate, polymethyl methacrylate, and urea-formaldehyde resins. This study has identified hazardous substances used in polymer production for which the risks should be evaluated for decisions on the need for risk reduction measures, substitution, or even phase out.

  16. LPG based all plastic pressure sensor

    DEFF Research Database (Denmark)

    Bundalo, Ivan-Lazar; Lwin, R.; Leon-Saval, S.

    2015-01-01

    A prototype all-plastic pressure sensor is presented and characterized for potential use as an endoscope. The sensor is based on Long Period Gratings (LPG) inscribed with a CO2 laser in 6-ring microstructured PMMA fiber. Through a latex coated, plastic 3D-printed transducer pod, external pressure...... is converted to longitudinal elongation of the pod and therefore of the fiber containing the LPG. The sensor has been characterised for pressures of up to 160 mBar in an in-house built pressure chamber. Furthermore, the influence of the fiber prestrain, fiber thickness and the effect of different glues...

  17. Optical Sensors Based on Plastic Fibers

    Science.gov (United States)

    Bilro, Lúcia; Alberto, Nélia; Pinto, João L.; Nogueira, Rogério

    2012-01-01

    The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented. PMID:23112707

  18. Optical Sensors Based on Plastic Fibers

    Directory of Open Access Journals (Sweden)

    Rogério Nogueira

    2012-09-01

    Full Text Available The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented.

  19. Evidence-Based Education in Plastic Surgery.

    Science.gov (United States)

    Johnson, Shepard P; Chung, Kevin C; Waljee, Jennifer F

    2015-08-01

    Educational reforms in resident training have historically been driven by reports from medical societies and organizations. Although educational initiatives are well intended, they are rarely supported by robust evidence. The Accreditation Council for Graduate Medical Education recently introduced competency-based training, a form of outcomes-based education that has been used successfully in nonmedical professional vocations. This initiative has promise to advance the quality of resident education, but questions remain regarding implementation within plastic surgery. In particular, how will competency-based training impact patient outcomes, and will the methodologies used to assess competencies (i.e., milestones) be accurate and validated by literature? This report investigates resident educational reform and the need for more evidence-based educational initiatives in plastic surgery training.

  20. Optical techniques for determination of the state of cure of epoxy resin based systems

    Science.gov (United States)

    Michie, W. C.; Thursby, G.; Johnstone, W.; Culshaw, B.

    1993-03-01

    Determination of the state of cure of epoxy resin based systems is of considerable interest to manufacturers of large carbon fiber reinforced plastic and glass reinforced plastic structures. Optical methods designed to indicate the cure state have been developed using a loss mechanism which is a function of the refractive index of the curing system. Such techniques are however subject to corruption from losses arising from other influences and consequently are limited in their measurement resolution. In this paper, two techniques which are able to provide a high degree of accuracy of measurement of refractive index are investigated as a means of performing cure measurements. The methods investigated involve the interaction of the evanescent field of a side polished optical fiber with an overlay waveguide or a surface plasmon. Coupling between the fiber and the overlay waveguide (or plasmon) is strongly influenced by the refractive index of the bulk superstrate above the overlay (in this case the curing resin system). Both sensing schemes are self referencing and are not influenced by loss.

  1. Optimization of the rheological properties of epoxy resins for glass and carbon reinforced plastics

    Science.gov (United States)

    Phyo Maung, Pyi; Malysheva, G.; Romanova, I.

    2016-10-01

    Vacuum assisted resin transfer moulding (VARTM) offers advantages such as simplicity, low cost of consumables, and the ability to carry out the impregnation process and curing without using expensive equipment and tooling. In the VARTM process, rheological properties of resin have a critical impact on the impregnation and curing process. In this article, the experimental results of viscosity are presented, including the glass transition temperature, and the tensile and bending strength of the epoxy binders with the amine hardener, which depend on the quantity of its active solvent composition. The active solvent used is diethylene glycol. It shows that for an increase in the content of the active solvent, a reduction in the viscosity and a reduction of the glass transition temperature and strength occurs. The optimum composition of the binder is selected by using the Pareto optimization criteria and the Cayley - Smorodinskaya method. By using the epoxy binder, the active solvent should not exceed 10-15% by weight. This approach helps to optimize the amount of active solvent added to the epoxy resins for the criterion of viscosity, strength, and heat resistance.

  2. Biodegradable foam plastics based on castor oil.

    Science.gov (United States)

    Wang, Hong Juan; Rong, Min Zhi; Zhang, Ming Qiu; Hu, Jing; Chen, Hui Wen; Czigány, Tibor

    2008-02-01

    In this work, a simple but effective approach was proposed for preparing biodegradable plastic foams with a high content of castor oil. First of all, castor oil reacted with maleic anhydride to produce maleated castor oil (MACO) without the aid of any catalyst. Then plastic foams were synthesized through free radical initiated copolymerization between MACO and diluent monomer styrene. With changes in MACO/St ratio and species of curing initiator, mechanical properties of MACO foams can be easily adjusted. In this way, biofoams with comparable compressive stress at 25% strain as commercial polyurethane (PU) foams were prepared, while the content of castor oil can be as high as 61 wt %. The soil burial tests further proved that the castor oil based foams kept the biodegradability of renewable resources despite the fact that some petrol-based components were introduced.

  3. Resin-based composite as a direct esthetic restorative material.

    Science.gov (United States)

    Malhotra, Neeraj; Mala, Kundabala; Acharya, Shashirashmi

    2011-06-01

    The search for an ideal esthetic material for tooth restoration has resulted in significant improvements in both materials and the techniques for using them. Various resin-based composite (RBC) materials have recently been introduced into the market that offer improved esthetic and physical properties. This article reviews RBCs, including their compositions, advantages, and disadvantages, that are contemporary to today's clinical practice as well as those that are under research consideration and/ or in clinical trial phase.

  4. SYNTHESIS AND CHARACTERIZATION OF KRAFT LIGNIN-BASED EPOXY RESINS

    Directory of Open Access Journals (Sweden)

    Nour Eddine El Mansouri

    2011-05-01

    Full Text Available Epoxidization is an interesting way to develop a new application of lignin and therefore to improve its application potential. In this work, kraft lignin-based epoxy resins were obtained by the epoxidization reaction, using the kraft lignin recovered directly from pulping liquor and modified by a methylolation reaction. The methylolated lignins were obtained by the reaction of original kraft lignin with formaldehyde and glyoxal, which is a less volatile and less toxic aldehyde. 1H-NMR spectroscopy showed that methylolated kraft lignin has more hydroxymethyl groups than glyoxalated kraft lignin. For the epoxidization reaction we studied the influence of the lignin:NaOH (w/w ratio, temperature, and time of the reaction on the properties of the prepared epoxidized lignins. The structures of lignin-based epoxy resins were followed by epoxy index test and FTIR spectroscopy. Optimal conditions were obtained for lignin-based epoxy resin produced at lignin/NaOH = 1/3 at 70 ºC for 3h. Thermogravimetry analysis (TGA revealed that the epoxidization enhances the thermal stability of lignins and may allow a wider temperature range for applications with lignin epoxy-PF blends.

  5. Preparation of liquefied wood-based resins and their application in molding material

    Institute of Scientific and Technical Information of China (English)

    Zhang Qiu-hui; Zhao Guang-jie; Yu Li-li; Jie Shu-jun

    2007-01-01

    To investigate value in use of liquefied wood-based resin applications in molding material, Chinese fir (Cunninghamia lanceolata) and poplar (Populus tomentosa) wood meal were liquefied in phenol. The reactant was co-condensed with formaldehyde to obtain liquefied wood-based resin. For this paper, we investigated the characterization of the resin and its application in molding material. The result shows that the basic properties of liquefied wood-based resin were satisfactory; the bonding strength of plywood prepared with liquefied Chinese fir and liquefied poplar resin can reach 1.54 and 1.00 MPa, respectively. The compression strengths of the molding material prepared with two kinds of liquefied wood resin were 73.01 and 73.58 MPa, almost the same as that of PF resin molding material. The limiting volume swelling of molding material made with liquefied Chinese resin and liquefied poplar resin were 8.5% and 8.3%, thickness swelling rates of water absorption were 3.3% and 4.2%, and the maximum weight ratios of water absorption were 25.9% and 26.2%, respectively. The soil burial test result shows that the weight loss rate of the molding materials made with liquefied Chinese resin and liquefied poplar resin were 8.3% and 9.1% and that of the PF resin molding material was 7.9%. After the soil internment test, the reduction ratio of compression strength of the two kinds of molding material achieved 16.9%and 17.7%, while that of the PF resin molding material was 15.4%. The test results of wood fungi inoculation on the three surfaces of the molding material indicate the breeding rate of molding material prepared with liquefied Chinese resin and liquefied poplar resin were at level 4 and that of PF resin molding material was at level 1 of the ISO standard.

  6. Analysis of tissue reactions to methacrylate resin-based, epoxy resin-based, and zinc oxide-eugenol endodontic sealers.

    Science.gov (United States)

    Scarparo, Roberta Kochenborger; Grecca, Fabiana Soares; Fachin, Elaine Vianna Freitas

    2009-02-01

    The purpose of this study was to investigate the reaction of the subcutaneous connective tissue of rats to methacrylate resin-based sealer (EndoREZ), epoxy resin-based sealer (AH Plus), and zinc oxide-eugenol sealer (EndoFill). Polyethylene tubes containing the test materials were implanted in 18 rats. After 7, 30, and 60 days, tissues were collected for biopsy and fixed and processed for histologic evaluation. Observations were made of the cellular inflammatory component, the fibrous condensation, and the abscess formation. Comparisons between groups and times were made with the Friedman and Kruskall-Wallis tests. EndoREZ and EndoFill sealers showed a more intense and longer-lasting inflammation. With AH Plus, the inflammatory reaction showed a tendency to diminish over time. The only group to show a statistically significant reduction in inflammation during the 60-day period was the control group. None of the materials tested proved to have ideal characteristics for biocompatibility.

  7. Replacing fossil based plastic performance products by bio-based plastic products-Technical feasibility.

    Science.gov (United States)

    van den Oever, Martien; Molenveld, Karin

    2017-07-25

    Larger scale market introduction of new bio-based products requires a clear advantage regarding sustainability, as well as an adequate techno-economic positioning relative to fossil based products. In a previous paper [Broeren et al., 2016], LCA results per kg and per functionality equivalent of bio-based plastics were presented, together with economic considerations. The present paper discusses the mechanical and thermal properties of a range of commercially available bio-based plastics based on polylactic acid (PLA), cellulose esters, starch and polyamides, and the feasibility of replacing fossil-based counterparts based on performance. The evaluation is approached from an end user perspective. First, potentially suitable bio-based plastics are selected based on manufacturers' specifications in technical data sheets, then a first experimental evaluation is performed on injection moulded ISO specimens, and finally a further selection of plastics is tested on large 50×70cm panels. This technical feasibility study indicates that so far bio-based plastics do not completely match the properties of high performance materials like flame retardant V-0 PC/ABS blends used in electronic devices. The performance gap is being decreased by the development of stereocomplex PLA and hybrid PLA blends with polycarbonate, which offer clearly improved properties with respect to maximum usage temperature and toughness. In addition, several materials meet the V-0 flammability requirements needed in specific durable applications. On the other hand, improving these properties so far has negative consequences for the bio-based content. This study also shows that replacement of bulk polymers like PS is feasible using PLA compounds with a bio-based content as high as 85%.

  8. MODIFICATION OF RESIN EDT-69N FOR THE PURPOSE OF MECHANICAL PROPERTIES OF PLASTICS

    Directory of Open Access Journals (Sweden)

    В. Краля

    2012-04-01

    Full Text Available The epoxy matrix EDT-69N it is one of license matrix which applies by aviation industry in theCommonwealth of Independent States. This matrix created according to the standards NLGS-3 with a glanceto requirements of a self-damping. A self-damping achieved by a mixing of resin UP-631 in a recipe of amatrix EDT-69N. It led to a increasing of matrix cost and a decreasing of the physical-mechanical properties.According to current standards AP-25 the matrix EDT-69N does not ensure the compliances by requirementsof combustibility, fume evolution and toxicity of combustion products. That is why a pressing problem ofmodification of matrix EDT-69N appears for the purpose of increasing of the physical-mechanical andtechnologic properties in the prejudice of requirement of combustibility.

  9. Environmental and health hazard ranking and assessment of plastic polymers based on chemical composition

    Energy Technology Data Exchange (ETDEWEB)

    Lithner, Delilah, E-mail: delilah.lithner@gmail.com; Larsson, Ake; Dave, Goeran

    2011-08-15

    Plastics constitute a large material group with a global annual production that has doubled in 15 years (245 million tonnes in 2008). Plastics are present everywhere in society and the environment, especially the marine environment, where large amounts of plastic waste accumulate. The knowledge of human and environmental hazards and risks from chemicals associated with the diversity of plastic products is very limited. Most chemicals used for producing plastic polymers are derived from non-renewable crude oil, and several are hazardous. These may be released during the production, use and disposal of the plastic product. In this study the environmental and health hazards of chemicals used in 55 thermoplastic and thermosetting polymers were identified and compiled. A hazard ranking model was developed for the hazard classes and categories in the EU classification and labelling (CLP) regulation which is based on the UN Globally Harmonized System. The polymers were ranked based on monomer hazard classifications, and initial assessments were made. The polymers that ranked as most hazardous are made of monomers classified as mutagenic and/or carcinogenic (category 1A or 1B). These belong to the polymer families of polyurethanes, polyacrylonitriles, polyvinyl chloride, epoxy resins, and styrenic copolymers. All have a large global annual production (1-37 million tonnes). A considerable number of polymers (31 out of 55) are made of monomers that belong to the two worst of the ranking model's five hazard levels, i.e. levels IV-V. The polymers that are made of level IV monomers and have a large global annual production (1-5 million tonnes) are phenol formaldehyde resins, unsaturated polyesters, polycarbonate, polymethyl methacrylate, and urea-formaldehyde resins. This study has identified hazardous substances used in polymer production for which the risks should be evaluated for decisions on the need for risk reduction measures, substitution, or even phase out

  10. Bulk-filled posterior resin restorations based on stress-decreasing resin technology

    DEFF Research Database (Denmark)

    van Dijken, Jan W.V.; Pallesen, Ulla

    2017-01-01

    This randomized study evaluated a flowable resin composite bulk-fill technique in posterior restorations and compared it intraindividually with a conventional 2-mm resin composite layering technique over a 6-yr follow-up period. Thirty-eight pairs of Class II restorations and 15 pairs of Class I...... restorations were placed in 38 adults. In all cavities a single-step self-etch adhesive (Xeno V) was applied. In the first cavity of each pair, the flowable resin composite (SDR) was placed, in bulk increments of up to 4 mm. The occlusal part was completed with a layer of nanohybrid resin composite (Ceram X...... mono). In the second cavity of each pair, the hybrid resin composite was placed in 2-mm increments. The restorations were evaluated using slightly modified US Public Health Service (USPHS) criteria at baseline and then annually for a time period of 6 yr. After 6 yr, 72 Class II restorations and 26...

  11. Selecting the Best Materials Compositions of Resin Based Bioasphalt

    Science.gov (United States)

    Setyawan, Ary; Widiharjo, Budi; Djumari

    2017-07-01

    Damar asphalt is one type of bioaspal which is a mixture with the main ingredient is a resin as a binder and cooking oil as a solvent. One major drawback of this damar asphalt is the low ductility. To improve the ductility values, then use the added material Filler. Filler serves as a divider between the impurities with damar asphalt, increases ductility and increase the ability of cohesion or bonding between the particles of material damar asphalt. The purpose of this study was to determine damar asphalt modifications to the properties in accordance with the properties of damar asphalt test specifications based on the value of penetration. This method uses some variant on material such as powder bricks and fly ash as a binder. Solvent in constituent used oil and used cooking oil. It also added the polymer latex up to 10% at intervals of 2%. The best composition of damar asphalt materials were obtained with gum rosin, Fly Ash, Oil and Latex. Damar asphalt modification damar asphalt optimum mix of resin (100g pure resin or resin chunk + 350g powder), Fly Ash powder (150g), cooking oil (205g), and latex 4%, ductility increased from 63.5 cm to 119.5 cm, the value of the flash point was originally at temperature of 240 °C to 260 °C, damar asphalt penetration of 68.2 dmm to 43 dmm, and the value of density decreases from 1.01 g / cm3 to 0.99 g / cm3. Damar asphalt at these modifications meet the specifications in terms of solubility in trichlore ethylene is equal to 99.5%, and also meet the affinity of damar asphalt at 99%. With the optimum value, damar asphalt could be categorized as bitumen 40/60 penetration.

  12. Immediate and delayed allergy from epoxy resins based on diglycidyl ether of bisphenol A.

    Science.gov (United States)

    Kanerva, L; Jolanki, R; Tupasela, O; Halmepuro, L; Keskinen, H; Estlander, T; Sysilampi, M L

    1991-06-01

    This case report presents two patients with immediate and delayed allergy to epoxy resins based on diglycidyl ether of bisphenol A (DGEBA). In patch testing, the epoxy resin (DGEBA-based) of the standard series gave allergic reactions. Both patients had a prick test reaction of histamine size or larger to the human serum albumin (HSA) conjugate of DGEBA-based epoxy resins. One had been occupationally exposed to methyl tetrahydrophthalic anhydride (MTHPA) and had a histamine-size prick test reaction to the HSA conjugate of MTHPA; the other did not react to the conjugate. Determinations of specific immunoglobulin E were carried out with HSA-DGEBA conjugates, two DGEBA-based epoxy resins, and phthalic anhydrides. The first patient had positive tests to DGEBA, the DGEBA-based epoxy resins, and two phthalic anhydrides, and the second to DGEBA and the DGEBA-based epoxy resins, but not to the phthalic anhydrides.

  13. Dimensional accuracy and stability of acrylic resin denture bases.

    Science.gov (United States)

    Huggett, R; Zissis, A; Harrison, A; Dennis, A

    1992-10-01

    Proponents of injection molding systems have claimed a number of benefits over conventional press-pack dough molding systems. The aim of this study was to evaluate a recently developed injection (dry heat) procedure of processing compared with press-pack dough molding utilizing three curing cycles. The dimensional accuracy and stability of acrylic resin bases produced by the two molding procedures were compared. Dimensional changes were assessed over a period of 4 months using an optical comparator. The results demonstrate that baseplates produced by the injection molding procedure exhibit less shrinkage than those produced by the conventional press-pack procedures.

  14. Effects of Chairside Polishing and Brushing on Surface Roughness of Acrylic Denture Base Resins

    Institute of Scientific and Technical Information of China (English)

    Seung-Kyun Kim; Ju-Mi Park; Min-Ho Lee; Jae-Youn Jung; Shipu Li; Xinyu Wang

    2009-01-01

    The effects of 3 chairside polishing kits and mechanical brushing on the surface roughness of 3 different acrylic denture base resins were compared. Acrylic denture base resins (auto-polymerizing, heat-polymerizing, injected heat-polymerizing resins) were examined after a tungsten carbide bur, and after chairside polishing using 3 polishing kits and pumice. The specimens were subjected to mechanical brushing using a wear tester to simulate 30 000 strokes of brushing. The surface roughness of the acrylic denture base resin specimens was measured using a contact pro-filometer. After the test, the random polished acrylic resins were evaluated by scanning electron mi-croscopy (SEM) and atomic force microscopy (AFM). Acrylic denture base resins polished using the 3 types of polishing kits had a smoother surface than those finished with the tungsten carbide bur (p <0.05). The surface of the resin polished by a TC cutter exceeded the Ra of 0.2 μm (p<0.05). The auto-polymerizing resin showed a significantly higher surface roughness than the heat-polymerizing resin and injected heat-polymerizing resin (p>0.05). In the case of polishing step wise, there was almost no change in surface roughness after brushing (p>0.05).

  15. D301 resin as a solid base for phosphine-free Heck reactions with heteroaryl halides

    Institute of Scientific and Technical Information of China (English)

    Wen Pei; Xiang Mei Wu

    2008-01-01

    A new and practical method of the D301 resin,a weak basic anion exchange resin with secondary amine functionality (Grade Matrix Structure:Styrene-DVB D301R),used as base to Heck reactions catalyzed by palladium reagent without phosphine compound as ligand is described.It was found that the D301 resin used as base is an efficient and reusable base and can be regenerated and recycled in the reaction.The olefination of heteroaryl halides prepared the corresponding products in good yields using D301 resin as base.

  16. Shear bond strength evaluation of resin composite to resin-modified glass-ionomer cement using three different resin adhesives vs. glass-ionomer based adhesive

    Directory of Open Access Journals (Sweden)

    Mostafa Sadeghi

    2015-12-01

    Full Text Available Background: The clinical success of sandwich technique depends on the strength of resin-modified glass ionomer cement (RMGIC bonding to both dentin and resin composite. Therefore, the shear bond strength (SBS of resin composite bonded to RMGIC utilizing different resin adhesives versus a GIC-based adhesive was compared. Materials and methods: In this in vitro study, 84 holes (5×2 mm were prepared in acrylic blocks, randomly divided into seven groups (n=12 and filled with RMGIC (Light-Cured Universal Restorative, GC. In the Group I; no adhesive was applied on the RMGIC. In the Group II, non-etched and Group III was etched with phosphoric acid. In groups II and III, after rinsing, etch-and-rinse adhesive (OptiBond Solo Plus; in the Group IV; a two-step self-etch adhesive (OptiBond XTR and in Group V; a one-step self-etch (OptiBond All-in-One were applied on the cement surfaces. Group VI; a GIC-based adhesive (Fuji Bond LC was painted over the cement surface and cured. Group VII; the GIC-based adhesive was brushed over RMGIC followed by the placement of resin composite and co-cured. Afterward; resin composite (Point 4 cylinders were placed on the treated cement surfaces. The specimens were placed in 100% humidity at 37 ± 1°C and thermo cycled. The shear bond test was performed at a cross-head speed of 1 mm/min and calculated in MPa; the specimens were examined to determine mode of failure. The results were analyzed using one-way ANOVA and Tukey test. Results: The maximum (24.62±3.70 MPa and minimum (18.15±3.38 MPa SBS mean values were recorded for OptiBond XTR adhesive and the control group, respectively. The pairwise comparisons showed no significant differences between the groups that bonded with different adhesives. The adhesive failure was the most common failure mode observed. Conclusion: This study suggests that GIC-based adhesive could be applied over RMGIC as co-cure technique for sandwich restorations in lieu of employing the resin

  17. The influence of urea formaldehyde resins on pyrolysis characteristics and products of wood-based panels

    Directory of Open Access Journals (Sweden)

    Yongshun Feng

    2012-11-01

    Full Text Available In China each year, large amounts of wood-based panels are consumed and abandoned. These are huge resources for energy recovery and materials reuse. In order to study the influence of urea formaldehyde resin (UF resin on waste wood-based panels during pyrolysis, thermobalance experiments together with the evolution of main gaseous products of wood, wood-based panels, and UF resins were carried out and analyzed by TG-FTIR. Elementary and GC-MS analyses were also done to study the characteristics of solid and liquid products. Results from TG and DTG analyses indicated that UF resin used in wood-based panels accelerated the degradation rate of wood-based panels at lower temperature; however the resin inhibited the degradation of wood-based panels over the later stage at higher temperatures. Compared with solid wood, the higher intensity and earlier releasing time of HNCO and NH3 in wood board revealed that the release of nitric gases is mainly due to the presence of UF resin, especially between 180 °C and 320 °C. Mass loss of hydrogen is significantly inhibited by UF resin, and nitrogen is quite stable in the char. The influence of UF resin on pyrolysis liquids of wood-based panels is mainly on nitrogen compounds and ketones rather than aldehydes and esters, which is probably due to the chemical reactions of UF resin with lignin constituent in wood.

  18. Color difference threshold determination for acrylic denture base resins.

    Science.gov (United States)

    Ren, Jiabao; Lin, Hong; Huang, Qingmei; Liang, Qifan; Zheng, Gang

    2015-01-01

    This study aimed to set evaluation indicators, i.e., perceptibility and acceptability color difference thresholds, of color stability for acrylic denture base resins for a spectrophotometric assessing method, which offered an alternative to the visual method described in ISO 20795-1:2013. A total of 291 disk specimens 50±1 mm in diameter and 0.5±0.1 mm thick were prepared (ISO 20795-1:2013) and processed through radiation tests in an accelerated aging chamber (ISO 7491:2000) for increasing times of 0 to 42 hours. Color alterations were measured with a spectrophotometer and evaluated using the CIE L*a*b* colorimetric system. Color differences were calculated through the CIEDE2000 color difference formula. Thirty-two dental professionals without color vision deficiencies completed perceptibility and acceptability assessments under controlled conditions in vitro. An S-curve fitting procedure was used to analyze the 50:50% perceptibility and acceptability thresholds. Furthermore, perceptibility and acceptability against the differences of the three color attributes, lightness, chroma, and hue, were also investigated. According to the S-curve fitting procedure, the 50:50% perceptibility threshold was 1.71ΔE00 (r(2)=0.88) and the 50:50% acceptability threshold was 4.00 ΔE00 (r(2)=0.89). Within the limitations of this study, 1.71/4.00 ΔE00 could be used as perceptibility/acceptability thresholds for acrylic denture base resins.

  19. Surface and line-edge roughness in acid-breakable resin-based positive resist

    Science.gov (United States)

    Sakamizu, Toshio; Shiraishi, Hiroshi

    2003-06-01

    A positive chemical amplification resist based on acid-catalyzed fragmentation of acetal groups in its main-chain has been developed as a means for reducing line-edge roughness. The resist consists of an acid-generator, an acid-diffusion controller and an acid-breakable (AB) resin that is synthesized through a co-condensation reaction between polyphenol and aromatic multi-functional vinylether compound. The effects of the fractionation of AB resins on resin properties and line-edge roughness (LER) are evaluated. Although AB resins have wide molecular-weight distributions, the density of acetal groups in this AB resin is found to be almost constant except in the lower molecular-weight components. The resist with a fractionated resin from which such components removed provides the high resolution of 60-nm line-and-space (L/S) patterns with fairly low LER. AFM analysis shows the surface roughness (SR) for the resist with the fractionated resin is smaller than that for a resist using non-fractionated AB resin, and that the SR value is not altered throughout the range of exposure doses up to just below the beginning of dissolution. By using the fractionated AB resin, the AB resin-based resist (ABR) is capable of forming sub-100 nm L/S patterns with less than 5 nm of LER (3σ).

  20. Incorporation of antimicrobial macromolecules in acrylic denture base resins: a research composition and update.

    Science.gov (United States)

    Sivakumar, Indumathi; Arunachalam, Kuthalingam Subbiah; Sajjan, Suresh; Ramaraju, Alluri Venkata; Rao, Bheemalingeshwara; Kamaraj, Bindu

    2014-06-01

    Contemporary research in acrylic denture base materials focuses on the development of a novel poly(methyl methacrylate) (PMMA) resin with antimicrobial properties. Although PMMA resin has fulfilled all the requirements of an ideal denture base material, its susceptibility to microbial colonization in the oral environment is a formidable concern to clinicians. Many mechanisms including the absence of ionic charge in the methyl methacrylate resins, hydrophobic interactions, electrostatic interactions, and mechanical attachment have been found to contribute to the formation of biofilm. The present article outlines the basic categories of potential antimicrobial polymer (polymeric biocides) formulations (modified PMMA resins) and considers their applicability, biological status, and usage potential over the coming years.

  1. Anion-exchange resin-based desulfurization process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sheth, A C; Dharmapurikar, R; Strevel, S D

    1994-01-01

    The following investigations were performed: (1) batch mode screening of eleven(11) commercially available resins and selection of three candidate resins for further evaluation in a fixed-bed setup. (2) Process variables study using three candidate resins in the fixed-bed setup and selection of the ``best`` resin for process economics development. (3) Exhaustion efficiency and solution concentration were found to be inversely related necessitating a trade-off between the resin cost versus the cost of evaporation/concentration of ensuing effluents. (4) Higher concentration of the HCO{sub 3}{sup {minus}} form of active sites over less active CO{sub 3}{sup 2{minus}} form of sites in the resin was believed to be the main reason for the observed increase in the equilibrium capacity of the resin at an elevated static CO{sub 2}-pressure. This Increase in capacity was found to level off around 80--120 psig range. The increase in CO{sub 2}-pressure, however, did not appear to affect the overall ion-exchange kinetics. (5) In the fixed-bed mode, the solution concentration was found to affect the equilibrium capacity of candidate resins. Their relationship was well satisfied by the Langmuir type non-linear equilibrium isotherm. Alternatively, the effect of solution concentration on overall ion-exchange kinetics varied from resin to resin. (6) Product inhibition effect on the resin was observed as an initial increase followed by a significant decrease in the resin`s equilibrium capacity for SO{sub 4}{sup 2{minus}} as the HCO{sub 3}{sup {minus}}/SO{sub 4}{sup 2{minus}} molar ratio in the solution was increased from 0 to 1.0. This ratio, however, did not affect the overall ion-exchange kinetics.

  2. Anion-exchange resin-based desulfurization process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sheth, A C; Dharmapurikar, R; Strevel, S D

    1994-01-01

    The following investigations were performed: (1) batch mode screening of eleven(11) commercially available resins and selection of three candidate resins for further evaluation in a fixed-bed setup. (2) Process variables study using three candidate resins in the fixed-bed setup and selection of the ``best`` resin for process economics development. (3) Exhaustion efficiency and solution concentration were found to be inversely related necessitating a trade-off between the resin cost versus the cost of evaporation/concentration of ensuing effluents. (4) Higher concentration of the HCO{sub 3}{sup {minus}} form of active sites over less active CO{sub 3}{sup 2{minus}} form of sites in the resin was believed to be the main reason for the observed increase in the equilibrium capacity of the resin at an elevated static CO{sub 2}-pressure. This Increase in capacity was found to level off around 80--120 psig range. The increase in CO{sub 2}-pressure, however, did not appear to affect the overall ion-exchange kinetics. (5) In the fixed-bed mode, the solution concentration was found to affect the equilibrium capacity of candidate resins. Their relationship was well satisfied by the Langmuir type non-linear equilibrium isotherm. Alternatively, the effect of solution concentration on overall ion-exchange kinetics varied from resin to resin. (6) Product inhibition effect on the resin was observed as an initial increase followed by a significant decrease in the resin`s equilibrium capacity for SO{sub 4}{sup 2{minus}} as the HCO{sub 3}{sup {minus}}/SO{sub 4}{sup 2{minus}} molar ratio in the solution was increased from 0 to 1.0. This ratio, however, did not affect the overall ion-exchange kinetics.

  3. Transparent plastic scintillators for neutron detection based on lithium salicylate

    Energy Technology Data Exchange (ETDEWEB)

    Mabe, Andrew N.; Glenn, Andrew M.; Carman, M. Leslie; Zaitseva, Natalia P.; Payne, Stephen A.

    2016-01-01

    Transparent plastic scintillators with pulse shape discrimination containing 6Li salicylate have been synthesized by bulk polymerization with a maximum 6Li loading of 0.40 wt%. Photoluminescence and scintillation responses to gamma-rays and neutrons are reported herein. Plastics containing 6Li salicylate exhibit higher light yields and permit a higher loading of 6Li as compared to previously reported plastics based on lithium 3-phenylsalicylate. However, pulse shape discrimination performance is reduced in lithium salicylate plastics due to the requirement of adding more nonaromatic monomers to the polymer matrix as compared to those based on lithium 3-phenylsalicylate. Reduction in light yield and pulse shape discrimination performance in lithium-loaded plastics as compared to pulse shape discrimination plastics without lithium is interpreted in terms of energy transfer interference by the aromatic lithium salts.

  4. Fracture strength and fatigue resistance of dental resin-based composites

    NARCIS (Netherlands)

    F. Keulemans; P. Palav; M.M.N. Aboushelib; A. van Dalen; C.J. Kleverlaan; A.J. Feilzer

    2009-01-01

    Objectives: The aim of this study was to evaluate in vitro the influence of fiber-reinforcement on the fracture strength and fatigue resistance of resin-based composites. Methods: One hundred rectangular bar-shaped specimens (2 mm × 2 mm × 25 mm) made of resin-based composite were prepared in a stai

  5. APPLICATION OF DIRECT CONTACT TEST IN EVALUATION OF CYTOTOXICITY OF ACRYLIC DENTURE BASE RESINS

    Directory of Open Access Journals (Sweden)

    Milena Kostić

    2012-03-01

    Full Text Available The use of acrylic denture base resins is widely spread in dental practice. They belong to the group of biomaterials due to their role of morphological and functional substituent in the mouth. However, clinical practice has shown that some toxic ingredients of these materials may lead to adverse local and even systemic changes. The aim of the study was to evaluate cytotoxic effect of various denture base resins on cell culture using direct contact test. The effect of four different acrylic materials on HeLa cell structure was evaluated. Upon light microscopy analysis, MTT test was performed without previous removal of material samples. The obtained values of MTT indicate that cell proliferation is dependant on the type of acrylic denture base resins. Cold polymerization denture base resins showed mild inhibitory effect on the cell culture growth. The signs of toxicity were not observed in heat polymerization denture base resins.

  6. Simulation of the Resin Film Infusion Process Based on the Finite Element Method

    Institute of Scientific and Technical Information of China (English)

    YANG Mei; YAN Shilin; TAN Hua

    2006-01-01

    A physically accurate and computationally effective pure finite element method (FEM) was developed to simulate the isothermal resin infusing process. The FEM was based on conservation of resin mass at any instant of time and was objective of resin film infusion (RFI) fiber impregnation and mold filling. The developed computer code was able to simulate the resin infusing visually. A numerical example presented here demonstrated that compared with traditional finite element/ control-volume (FE/CV), and FEM was physically accurate and computationally efficient.

  7. Effect of an Extra Hydrophobic Resin Layer on Repair Shear Bond Strength of a Silorane-Based Composite Resin.

    Science.gov (United States)

    Mohammadi, Narmin; Bahari, Mahmoud; Kimyai, Soodabeh; Rahbani Nobar, Behnam

    2015-12-01

    Composite repair is a minimally invasive and conservative approach. This study aimed to evaluate the effect of an additional hydrophobic resin layer on the repair shear bond strength of a silorane-based composite repaired with silorane or methacrylate-based composite. Sixty bar-shaped composite blocks were fabricated and stored in saline for 72 hours. The surface of the samples were roughened by diamond burs and etched with phosphoric acid; then, they were randomly divided into three groups according to the repairing process: Group 1: Silorane composite-silorane bonding agent-silorane composite; group 2: Silorane composite-silorane bonding agent-hydrophobic resin-silorane composite, and group 3: Silorane composite-silorane bonding agent-hydrophobic resin methacrylate-based composite. Repairing composite blocks measured 2.5×2.5×5mm. After repairing, the samples were stored in saline for 24 hours and thermocycled for 1500 cycles. The repair bond strength was measured at a strain rate of 1mm/min. Twenty additional cylindrical composite blocks (diameter: 2.5mm, height: 6mm) were also fabricated for measuring the cohesive strength of silorane-based composite. The data were analyzed using One-way ANOVA and the post hoc Tukey's test (α=0.05). Cohesive bond strength of silorane composite was significantly higher than the repair bond strengths in other groups (Presin layer for repair of silorane-based composite with a methacrylate-based composite enhanced the repair shear bond strength.

  8. Neutron shielding material based on colemanite and epoxy resin.

    Science.gov (United States)

    Okuno, Koichi

    2005-01-01

    In recent years, there has been a need for compact shielding design such as self-shielding of a PET cyclotron or upgradation of radiation machinery in existing facilities. In these cases, high performance shielding materials are needed. Concrete or polyethylene have been used for a neutron shield. However, for compact shielding, they fall short in terms of performance or durability. Therefore, a new type of neutron shielding material based on epoxy resin and colemanite has been developed. Slab attenuation experiments up to 40 cm for the new shielding material were carried out using a 252Cf neutron source. Measurement was carried out using a REM-counter, and compared with calculation. The results show that the shielding performance is better than concrete and polyethylene mixed with 10 wt% boron oxide. From the result, we confirmed that the performance of the new material is suitable for practical use.

  9. Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials.

    Science.gov (United States)

    Cui, Yong; Hou, Xiaopeng; Wang, Wenliang; Chang, Jianmin

    2017-06-18

    In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF) resin-a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

  10. Effect of denture base-resin with prereacted glass-ionomer filler on dentin demineralization

    NARCIS (Netherlands)

    Y. Mukai; K. Kamijo; F. Fujino; T. Teranaka; J.M. ten Cate

    2009-01-01

    The demineralization of dentin was studied when placed adjacent to one of four experimental denture base-resins. These experimental resins contained polymethylmethacrylate (PMMA) and 0, 5, 10, 20 or 30 wt% surface reaction-type prereacted glass-ionomer (S-PRG) filler, respectively. A dentin thin-sec

  11. Influence of aging solutions on wear resistance and hardness of selected resin-based dental composites.

    Science.gov (United States)

    Chladek, Grzegorz; Basa, Katarzyna; Żmudzki, Jarosław; Malara, Piotr; Nowak, Agnieszka J; Kasperski, Jacek

    2016-01-01

    The purpose of this study was to investigate the effect of different plasticizing aging solutions on wear resistance and hardness of selected universal resin-based dental composites. Three light cured (one nanofilled, two microhybride) and one hybride chemical cured composites were aged at 37 °C for 48 h in distillated water, ethyl alcohol solution or Listerine mouthwash. After aging the microhardness tests were carried out and then tribological tests were performed in the presence of aging solution at 37 °C. During wear testing coefficients of friction were determined. The maximal vertical loss in micrometers was determined with profilometer. Aging in all liquids resulted in a significant decrease in hardness of the test materials, with the largest values obtained successively in ethanol solution, mouthwash and water. The effect of the liquid was dependent on the particular material, but not the type of material (interpreted as the size of filler used). Introduction of mouthwash instead of water or ethanol solution resulted in a significant reduction in the coefficient of friction. The lowest wear resistance was registered after aging in ethanol and for the chemical cured hybrid composite, but the vertical loss was strongly material dependent. The effect of different aging solution, including commercial mouthrinse, on hardness and wear was material dependent, and cannot be deduced from their category or filler loading. There is no simple correlation between hardness of resin-based dental composites and their wear resistance, but softening of particular composites materials during aging leads to the reduction of its wear resistance.

  12. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Science.gov (United States)

    2010-07-01

    ... AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS... (HDPE) Polyethylene Resin (LPDE) Polyethylene Resin, Scrap Polyethylene Resin, Wax (Low M.W...

  13. Persistent organic pollutants monitoring in marine coastal environment using beached plastic resin pellets and effective risk communication via International Pellet Watch (IPW) as a tool.

    Science.gov (United States)

    Yeo, B. G. M.; Takada, H.; Hosoda, J.

    2014-12-01

    International Pellet Watch (IPW) is an ongoing global monitoring of persistent organic pollutants (POPs) using preproduction plastic resin pellets. These pellets are easily collected and transported allowing the general public worldwide to get involved. Thus, risk communication toward the pellet collectors is a significant part of IPW to ensure continuous effort and interest. The pellet samples were analyzed for polychlorinated biphenyl (PCBs), dichlorodiphenyltrichloroethane and degradation products (DDTs), and hexachlorocyclohexanes (HCHs). Additional pollutants such as polycyclic aromatic hydrocarbons (PAHs) and Hopanes were also analyzed for some samples. Analytical results showed distinct patterns with high concentrations (pollution where PCBs were used extensively before the ban in the late 1980's. Pesticide DDTs instead were found to be higher in developing countries such as Brazil and Vietnam (> 500ng/g-pellet). These countries may still be using DDTs as a vector control mostly to combat malaria. High concentrations of DDTs were also found in Greece, China and Australia (> 100ng/g-pellet) suggesting the possibility of illegal usage as pesticide or anti fouling paint. HCHs concentrations were mostly low due to its low retention in the environment. However, high HCHs concentrations were mostly found in the southern hemisphere. Very high concentration of PAHs in pellet samples can be utilized for early identification of recent oil pollution. High PAHs concentration in Tauranga, New Zealand was found to be caused by local oil spill. Hopanes in pellets can be used for source identification of oil pollution. Global mapping and comparison among IPW data can be used to provide better explanations to IPW volunteers by sorting concentrations into pollution categories. Communication reports are tailor written based on the volunteers familiarity to IPW's issues, educational background, occupation and their potential to further spread awareness. Based on feedbacks, the

  14. Solidification of ion exchange resins saturated with Na+ ions: Comparison of matrices based on Portland and blast furnace slag cement

    Science.gov (United States)

    Lafond, E.; Cau dit Coumes, C.; Gauffinet, S.; Chartier, D.; Stefan, L.; Le Bescop, P.

    2017-01-01

    This work is devoted to the conditioning of ion exchange resins used to decontaminate radioactive effluents. Calcium silicate cements may have a good potential to encapsulate spent resins. However, certain combinations of cement and resins produce a strong expansion of the final product, possibly leading to its full disintegration. The focus is placed on the understanding of the behaviour of cationic resins in the Na+ form in Portland or blast furnace slag (CEM III/C) cement pastes. During hydration of the Portland cement paste, the pore solution exhibits a decrease in its osmotic pressure, which causes a transient expansion of small magnitude of the resins. At 20 °C, this expansion takes place just after setting in a poorly consolidated material and is sufficient to induce cracks. In the CEM III/C paste, swelling of the resins also occurs, but before the end of setting, and induces limited stress in the matrix which is still plastic.

  15. Measurement of persistent organic pollutants (POPs) in plastic resin pellets from remote islands: toward establishment of background concentrations for International Pellet Watch.

    Science.gov (United States)

    Heskett, Marvin; Takada, Hideshige; Yamashita, Rei; Yuyama, Masaki; Ito, Maki; Geok, Yeo Bee; Ogata, Yuko; Kwan, Charita; Heckhausen, Angelika; Taylor, Heidi; Powell, Taj; Morishige, Carey; Young, Doug; Patterson, Hugh; Robertson, Bryson; Bailey, Elizabeth; Mermoz, Jorge

    2012-02-01

    Plastic resin pellets collected from remote islands in the Pacific, Atlantic, and Indian Oceans and the Caribbean Sea were analyzed for polychlorinated biphenyls (PCBs), dichloro-diphenyltrichloroethane and its degradation products (DDTs), and hexachlorocyclohexanes (HCHs). Concentrations of PCBs (sum of 13 congeners) in the pellets were 0.1-9.9 ng/g-pellet. These were 1-3 orders of magnitude smaller than those observed in pellets from industrialized coastal shores. Concentrations of DDTs in the pellets were 0.8-4.1 ng/g-pellet. HCH concentrations were 0.6-1.7 ng/g-pellet, except for 19.3 ng/g-pellet on St. Helena, where current use of lindane is likely influence. This study provides background levels of POPs (PCBspollutants on plastic debris.

  16. Attribute Based Selection of Thermoplastic Resin for Vacuum Infusion Process: A Decision Making Methodology

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran; Lystrup, Aage; Løgstrup Andersen, Tom

    2012-01-01

    The composite industry looks toward a new material system (resins) based on thermoplastic polymers for the vacuum infusion process, similar to the infusion process using thermosetting polymers. A large number of thermoplastics are available in the market with a variety of properties suitable...... for different engineering applications, and few of those are available in a not yet polymerised form suitable for resin infusion. The proper selection of a new resin system among these thermoplastic polymers is a concern for manufactures in the current scenario and a special mathematical tool would...... be beneficial. In this paper, the authors introduce a new decision making tool for resin selection based on significant attributes. This article provides a broad overview of suitable thermoplastic material systems for vacuum infusion process available in today’s market. An illustrative example—resin selection...

  17. [Current status and further prospects of dental resin-based materials with antibacterial properties].

    Science.gov (United States)

    Shi, X; Lu, H B; Mao, J; Gong, S Q

    2016-09-01

    The mode of dental antibacterial resin-based materials can be divided into two types, namely, single and combined antibacterial mode. With regard to single antibacterial mode, only one kind of antibacterial agent is added into the resin, which can be released or act as contacting antibacterial agent. The single mode resin has limitation in sterilization methods and effect. As for combined antibacterial mode, it is a combination of different types of biocides and thus maximizes the sterilizing effect, including the releasing antibacterial agent incorporated with the contacting antibacterial agent or antibacterial agents combined with calcium compound possessing biological mineralization function. In this paper, current status and further prospects of dental resin-based materials with antibacterial properties are reviewed from the perspectives of single and combined antibacterial modes to provide guidance for dental antibacterial resin material research.

  18. Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

    Directory of Open Access Journals (Sweden)

    Naomi Tanoue

    2013-07-01

    Full Text Available OBJECTIVE: The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated. MATERIAL AND METHODS: Disk specimens (diameter 10 mm and thickness 2.5 mm were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1 air-abraded with 50-70-µm grain alumina (CON; 2 1 + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA; 3 1 + conditioned with a primer including a diphosphate monomer (MDP; 4 treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles. RESULTS: The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05 greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy. CONCLUSION: Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used.

  19. Evaluation of Cellular Toxicity of Three Denture Base Acrylic Resins

    OpenAIRE

    Ebrahimi Saravi, M.; M. Vojdani; Bahrani, F

    2012-01-01

    Objective This study aimed to evaluate the cellular toxicity of two newly-released acrylic resins (Futura Gen and GC Reline Hard) in comparison with the conventional heat-cure resin (Meliodent). Materials and Methods: Sample discs from each acrylic resin were placed in 24-well culture plates along with L929 mouse fibroblast cell line. A mixture of the RPMI 1640 medium, antibiotics and 10% FBS was added to the plates and the specimens were incubated in a CO2 incubator. The amount of light abso...

  20. Plastic casting resin poisoning

    Science.gov (United States)

    ... the stool Heart and blood vessels Low blood pressure (develops rapidly) Collapse Skin Irritation Burns Holes in the skin or ... signs, including temperature, pulse, breathing rate, and blood pressure. ... oxygen, a tube through the mouth into the throat, and a ...

  1. Development of melamine modified urea formaldehyde resins based o nstrong acidic pH catalyzed urea formaldehyde polymer

    Science.gov (United States)

    Chung-Yun Hse

    2009-01-01

    To upgrade the performance of urea-formaldehyde (UF) resin bonded particleboards, melamine modified urea-formaldehyde (MUF) resins based on strong acidic pH catalyzed UF polymers were investigated. The study was conducted in a series of two experiments: 1) formulation of MUF resins based on a UF polymer catalyzed with strong acidic pH and 2) determination of the...

  2. Evaluation of Shear Bond Strength of Methacrylate- and Silorane-based Composite Resin Bonded to Resin-Modified Glass-ionomer Containing Micro- and Nano-hydroxyapatite.

    Science.gov (United States)

    Sharafeddin, Farahnaz; Moradian, Marzie; Motamedi, Mehran

    2016-06-01

    The adhesion of resin-modified glass-ionomer (RMGI) to composite resin has a very important role in the durability of sandwich restorations. Hydroxyapatite is an excellent candidate as a filler material for improving the mechanical properties of glass ionomer cement. The aim of this study was to assess the effect of adding micro- and nano-hydroxyapatite (HA) powder to RMGI on the shear bond strength (SBS) of nanofilled and silorane-based composite resins bonded to RMGI containing micro- and nano-HA. Sixty cylindrical acrylic blocks containing a hole of 5.5×2.5 mm (diameter × height) were prepared and randomly divided into 6 groups as Group 1 with RMGI (Fuji II LC) plus Adper Single Bond/Z350 composite resin (5.5×3.5 mm diameter × height); Group 2 with RMGI containing 25 wt% of micro-HA plus Adper Single Bond/Z350 composite resin; Group3 with RMGI containing 25 wt% of nano-HA plus Adper Single Bond/Z350 composite resin; Group 4 with RMGI plus P90 System Adhesive/P90 Filtek composite resin (5.5×3.5 mm diameter × height); Group 5 with RMGI containing 25 wt% of micro-HA plus P90 System Adhesive/P90Filtek composite resin; and Group 6 with RMGI containing 25 wt% of nano-HA plus P90 System Adhesive/P90 Filtek composite resin. The specimens were stored in water (37° C, 1 week) and subjected to 1000 thermal cycles (5°C/55°C). SBS test was performed by using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed by two-way ANOVA and Tukey test (pcomposite resins. Meanwhile, RMGI without HA has the best bond strength to silorane-based composite resins.

  3. Is the bond between acrylic resin denture teeth and denture base resin stronger if they are both made by the same manufacturer?

    Science.gov (United States)

    Patil, Reshma; Juszczyk, Andrzej S; Radford, David R; Clark, Robert K F

    2010-03-01

    A previous study suggested that a stronger bond may be achieved between acrylic resin denture base material and acrylic denture teeth when both are made by the same manufacturer. Three denture base acrylic resins from three different manufacturers were bonded to three different acrylic resin denture teeth, one of which was manufactured by each of the manufacturers of the base material. In each group there was a trend that the bond strength achieved between the teeth and base material from the same manufacturer was higher than the unmatched pairs but statistical significance was not achieved.

  4. Characterisation of Rapeseed Oil Based Resins Using Infrared and ...

    African Journals Online (AJOL)

    Rapeseed oil which is a triglyceride had undergone chemical modification ... methylene-pphenyl diisocyanate to produce a thermoset rapeseed oil resin. ... The applications of more than one analytical method offer a complement of the results.

  5. Modification Bituminous Binders Petroleum Resin (Based on C9 Fraction

    Directory of Open Access Journals (Sweden)

    Elena A. Chigorina

    2015-12-01

    Full Text Available The goal of the present study is to measure the basic parameters of a bituminous binder obtained by modification of the BND 60/90 binder with petroleum resin, for both dynamic and static modification modes.

  6. Furfural resin-based bio-nanocomposites reinforced by reactive nanocrystalline cellulose

    Science.gov (United States)

    Wang, C.; Sun, S.; Zhao, G.; He, B.; Xiao, H.

    2009-07-01

    The work presented herein has been focused on reinforcing the furfural resins (FA) by reactive-modified nanocrystalline cellulose (NCC) in an attempt to create a bio-nanocomposite completely based on natural resources. FA prepolymers were synthesized with an acid catalyst, and NCC was rendered reactive via the grafting of maleic anhydride (MAH). The resulting NCC and nanocomposites were characterized using TEM, SEM and FT-IR. It was found that NCC appeared to be spherical in shape with diameters under 100 nm. FT-IR confirmed that there were hydrogen and esterification bonding between MAH and NCC or FA prepolymer. After solidified with paratoluenesulfonic acid, NCC-reinforced FA resin composites showed granular cross-section while FA resin with layered structures. Mechanical property tests indicated that NCC-reinforced FA resin composites possessed the improved tensile and flexural strengths, in comparison with FA resin.

  7. Novel Epoxy Resin/SiO2 Nanocomposites Preparation Method Based on Diminutive Bubbles Explosion

    Institute of Scientific and Technical Information of China (English)

    NIE Peng; ZHAO Xue-zeng; CHEN Fang; WANG Wei-jie; BAI Yong-ping

    2006-01-01

    To obtain suspended dispersion of nano-particles in liquid without any dispersant, a novel epoxy resin/SiO2 nanocomposites preparation method based on diminutive bubbles explosion is presented. And, corresponding nanocomposites preparation system was designed. The preparation system applies compressed gas as transmission medium to carry nanomaterials into epoxy resin solution. The compressed gas with nanomaterials turns into diminutive bubbles distributing in epoxy resin/SiO2. The great pressure difference between inner and outer-bubbles led to bubbles inflation and explosion. During the bubble inflation, bubble oscillation may generate. The stretching rate may reach 106 s-1, which favors more homogeneous dispersion of nanoparticles. During the bubbles explosion the released energy and the explosion shock waves disperse the nanoparticles into epoxy resin solution. By using the preparation system, epoxy resin/SiO2 nanocomposites were prepared. The SiO2 dispersed into epoxy as the configuration of 15 nm - 30 nm particles.

  8. Phenol resin-based supports of inclined workings

    Energy Technology Data Exchange (ETDEWEB)

    Boldin, V.M.; Krivoshchekova, N.P.; Fedorova, G.G.

    1980-10-01

    This article evaluates experimental tubing supports produced in the Kuzbass. The tubings are formed from coal and phenol-formaldehyde resins. Benzene sulfonic acid is used as hardening agent. Coal with grains up to 10 mm is used as filling agent. Five phenol-formaldehyde resins (SFZh-3032U, SF-142, SF-40K0, SFZh-3032NV, SFZh-3032) are evaluated as the basis for support production. The results are given in a table. Experiments show that SFZh-3032 resin is superior to other resins as a means of improving strength and mechanical parameters of the coal body in which workings are driven. It is noted that until now 10 km of resin reinforced coal tubing support have been constructed. Capacity of equipment producing the supports is 2.5 km/year. Resin reinforced tubing is economical: it need not be removed, can be mined together with coal seam, it reduces hazard of wall or floor swelling, increases haulage capacity of workings used for underground haulage 3 to 4 times, and improves safety of work for miners. (In Russian)

  9. Transparent plastic scintillators for neutron detection based on lithium salicylate

    Energy Technology Data Exchange (ETDEWEB)

    Mabe, Andrew N., E-mail: mabe2@llnl.gov; Glenn, Andrew M.; Carman, M. Leslie; Zaitseva, Natalia P.; Payne, Stephen A.

    2016-01-11

    Transparent plastic scintillators with pulse shape discrimination containing {sup 6}Li salicylate have been synthesized by bulk polymerization with a maximum {sup 6}Li loading of 0.40 wt%. Photoluminescence and scintillation responses to gamma-rays and neutrons are reported herein. Plastics containing {sup 6}Li salicylate exhibit higher light yields and permit a higher loading of {sup 6}Li as compared to previously reported plastics based on lithium 3-phenylsalicylate. However, pulse shape discrimination performance is reduced in lithium salicylate plastics due to the requirement of adding more nonaromatic monomers to the polymer matrix as compared to those based on lithium 3-phenylsalicylate. Reduction in light yield and pulse shape discrimination performance in lithium-loaded plastics as compared to pulse shape discrimination plastics without lithium is interpreted in terms of energy transfer interference by the aromatic lithium salts. - Highlights: • Plastic scintillator with 0.4% {sup 6}Li loading is reported using lithium salicylate. • Influence of lithium salts on the scintillation mechanism is explored. • New lithium-loaded scintillator provides improved light yield and reduced cost.

  10. Determination of oil reservoir radiotracer (S{sup 14}CN{sup -}) in a single step using a plastic scintillator extractive resin

    Energy Technology Data Exchange (ETDEWEB)

    Bagan, H.; Tarancon, A. [Departament de Quimica Analitica, Universitat de Barcelona, Diagonal 645, E-08028 Barcelona (Spain); Stavsetra, L. [Department for Reservoir and Exploration Technology, Institute for Energy Technology (IFE), Instituttveien 18, N-2027 Kjeller (Norway); Rauret, G. [Departament de Quimica Analitica, Universitat de Barcelona, Diagonal 645, E-08028 Barcelona (Spain); Garcia, J.F., E-mail: jfgarcia@ub.edu [Departament de Quimica Analitica, Universitat de Barcelona, Diagonal 645, E-08028 Barcelona (Spain)

    2012-07-29

    Highlights: Black-Right-Pointing-Pointer A new procedure for S{sup 14}CN{sup -} radiotracer determination using PS resin was established. Black-Right-Pointing-Pointer The minimum detectable activity for a 100 mL sample is 0.08 Bq L{sup -1}. Black-Right-Pointing-Pointer The minimum quantifiable activity for a 100 mL sample is 0.31 Bq L{sup -1}. Black-Right-Pointing-Pointer PS resin is capable to quantify S{sup 14}CN{sup -} radiotracer samples with errors lower than 5%. Black-Right-Pointing-Pointer PS resin is also capable to quantify complex matrices obtained from oil reservoirs. - Abstract: The analysis of radiotracers is important in the study of oil reservoir dynamics. One of the most widely used radiotracer is S{sup 14}CN{sup -}. Prior to activity measurements by Liquid Scintillation (LS), routine determinations require the pretreatment steps of purification and concentration of the samples using anion exchange columns. The final elution media produces samples with high salt concentration that may lead to problems with phase separation during the LS measurement. Plastic Scintillation (PS) is an alternative technique that provides a solid surface that can be used as a platform for the immobilisation of selective extractants to obtain a PS resin. The proposed procedure unifies chemical separation and sample measurement preparation in a single step, serving to reduce the number of reagents needed and manpower required for the analysis while also avoiding mixed waste production by LS. The objective of this study is to develop a PS resin for the determination of {sup 14}C-labelled thiocyanate radiotracer in water samples. For this purpose, the immobilisation procedure was optimised, including optimisation of the proportion of PS microspheres:extractant and the use of a control blank to monitor the PS resin immobilisation process. The breakthrough volume was studied and the detection and quantification limits for 100 mL of sample were determined to be 0.08 Bq L{sup -1

  11. Laser based metal and plastics joining for lightweight design

    Science.gov (United States)

    Kahmann, Max; Quentin, Ulf; Kirchhoff, Marc; Brockmann, Rüdiger; Löffler, Klaus

    2015-03-01

    One of the most important issues in automotive industry is lightweight design, especially since the CO2 emission of new cars has to be reduced by 2020. Plastic and fiber reinforced plastics (e.g. CFRP and GFRP) receive besides new manufacturing methods and the employment of high-strength steels or non-ferrous metals increasing interest. Especially the combination of different materials such as metals and plastics to single components exhausts the entire potential on weight reduction. This article presents an approach based on short laser pulses to join such dissimilar materials in industrial applications.

  12. Elastic modulus and flexural strength comparisons of high-impact and traditional denture base acrylic resins

    Directory of Open Access Journals (Sweden)

    Nour M. Ajaj-ALKordy

    2014-01-01

    Conclusion: Within the limitations of this study, it can be concluded that the high-impact acrylic resin is a suitable denture base material for patients with clinical fracture of the acrylic denture.

  13. Alkyd-amino resins based on waste PET for coating applications.

    Science.gov (United States)

    Torlakoğlu, A; Güçlü, G

    2009-01-01

    Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 degrees C. The physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins.

  14. Effect of post-polymerization heat treatments on the cytotoxicity of two denture base acrylic resins

    OpenAIRE

    Janaina Habib Jorge; Eunice Teresinha Giampaolo; Carlos Eduardo Vergani; Ana Lúcia Machado; Ana Cláudia Pavarina; Iracilda Zeppone Carlos

    2006-01-01

    INTRODUCTION: Most denture base acrylic resins have polymethylmethacrylate in their composition. Several authors have discussed the polymerization process involved in converting monomer into polymer because adequate polymerization is a crucial factor in optimizing the physical properties and biocompatibility of denture base acrylic resins. To ensure the safety of these materials, in vitro cytotoxicity assays have been developed as preliminary screening tests to evaluate material biocompatibil...

  15. Synthesis, Characterization and Thermal Analysis of Resins from Different Cardanol Based Dyes

    Directory of Open Access Journals (Sweden)

    Tapan K. Das

    2014-06-01

    Full Text Available Cardanol(Cashew phenol is subjected to diazotisation with Aniline and m-Toluidine to get monomers like Cardanol based dye from Aniline (CBDFA and Cardanol based dye from m-Toludine (CBDFT. Such monomers have been condensed with formaldehyde in presence of acid catalyst to form resins. The resins have been characterized by FTIR spectra and their thermal behaviour have been studied.

  16. APPLICATION OF DIRECT CONTACT TEST IN EVALUATION OF CYTOTOXICITY OF ACRYLIC DENTURE BASE RESINS

    OpenAIRE

    Milena Kostić; Stevo Najman; Jelena Najdanović; Nebojša Krunić; Ivan Kostić

    2012-01-01

    The use of acrylic denture base resins is widely spread in dental practice. They belong to the group of biomaterials due to their role of morphological and functional substituent in the mouth. However, clinical practice has shown that some toxic ingredients of these materials may lead to adverse local and even systemic changes. The aim of the study was to evaluate cytotoxic effect of various denture base resins on cell culture using direct contact test. The effect of four different acrylic...

  17. Effect of different housing retaining materials on the flexural strength of an acrylic resin overdenture base.

    Science.gov (United States)

    Ozkir, Serhat Emre; Yilmaz, Burak

    2017-04-03

    An attachment housing inside an overdenture may weaken the acrylic resin base. The type of housing retaining material may affect the strength of the housing retaining material-acrylic resin base assembly. The effect of different housing retaining materials on the strength of acrylic resin base is unknown. The purpose of this in vitro study was to evaluate the effects of different materials used to retain the housing on the flexural strength of a poly(methyl methacrylate) (PMMA) resin base. Sixty PMMA specimens (64×10×4 mm) were prepared with a clearance inside to allow the insertion of overdenture housings. Five different materials were used for housing orientation: an autopolymerizing composite resin, an acrylic resin reline material, a heat-polymerized PMMA, an autopolymerizing PMMA (n=10), and a control group (n=10) were prepared without any preparation or housing. The specimens were thermocycled 5000 times between 5°C and 55°C. The flexural strength data were analyzed by an analysis of variance using the maximum likelihood estimation method to eliminate the needs for normality within the groups and for equality of variances between the groups. If statistically significant, resolution of the significance factor was obtained by pairwise comparisons using the Tukey adjustment (α=.05). The fracture values were statistically significantly higher (Pmaterial (26.78 ±6.72 MPa), the acrylic resin reline material (16.94 ±4.38 MPa), the Ufigel (16.07 ±3.40 MPa), and the autopolymerizing composite resin (19.37 ±3.13 MPa). Heat- and autopolymerizing PMMA groups were significantly different from acrylic resin-based hard reline materials (Pmaterial except for one of the hard reline groups, which separated from the PMMA. The tested retaining materials significantly reduced the flexural strength of PMMA denture base. The flexural strength of the resin base with housing was significantly higher when PMMA-based retaining materials were used than when acrylic resin-based

  18. Synthesis and characterization of a novel bio-based resin from maleated soybean oil polyols

    Science.gov (United States)

    Li, Y. T.; Yang, L. T.; Zhang, H.

    2017-02-01

    In this paper, a novel bio-based resin was prepared by the radical copolymerization of maleated soybean oil polyols (MSBOP) and styrene (ST). Structure of the product was studied by Fourier transformation infrared spectrometer (FT-IR), and the result was found to be consistent with that of theoretical structure. Swelling experiments indicated that the crosslinking degree increased with the increase of hydroxyl value. Thermal analysis by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TG) revealed that glass transition temperature (Tg) of the polymer increased with increasing hydroxyl values, and that its thermal stability showed a good correlation with the hydroxyl value. The tensile strength and impact strength were significantly affected by the hydroxyl value of soybean oil polyols. With increasing hydroxyl value, the tensile strength presented an increasing trend, while the impact strength showed a decreasing one. Moreover, the property of the polymer from elastomer to plastic character also depended on the functionality of the hydroxyl value of soybean oil polyols.

  19. Boron removal from water and wastewater using new polystyrene-based resin grafted with glycidol

    OpenAIRE

    2015-01-01

    A divinylbenzene cross-linked polystyrene resin with amine functional groups (Purolite A170) was grafted with glycidol and characterized as a novel sorbent, GLY-resin, for the oxoborate removal from model solutions and post-crystallization lye. The sorption behavior of GLY-resin was investigated using a batch system. The results showed that the sorption was maximal at pH=9.5. The equilibrium was achieved after 24 h. Calculations based on Langmuir model show the monolayer sorption capacity qm=...

  20. The Electrical Properties for Phenolic Isocyanate-Modified Bisphenol-Based Epoxy Resins Comprising Benzoate Group.

    Science.gov (United States)

    Lee, Eun Yong; Chae, Il Seok; Park, Dongkyung; Suh, Hongsuk; Kang, Sang Wook

    2016-03-01

    Epoxy resin has been required to have a low dielectric constant (D(k)), low dissipation factor (Df), low coefficient of thermal expansion (CTE), low water absorption, high mechanical, and high adhesion properties for various applications. A series of novel phenolic isocyanate-modified bisphenol-based epoxy resins comprising benzoate group were prepared for practical electronic packaging applications. The developed epoxy resins showed highly reduced dielectric constants (D(k)-3.00 at 1 GHz) and low dissipation values (Df-0.014 at 1 GHz) as well as enhanced thermal properties.

  1. 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.

  2. Development of Refined Natural Resin based Cashew Nut Shell Oil Liquid (CNSL) for Brake Pads Composite

    Science.gov (United States)

    Wahyuningsih, S.; Ramelan, A. H.; Rahmawati, P.; Tamtama, B. P. N.; Sari, P. P.; Sari, P. L.; Ichsan, S.; Kristiawan, Y. R.; Aini, F. N.

    2017-02-01

    Brake is one of the most important components in the vehicle. One type of brake that widely used is brake-based composites. One of the manufacture of composite material is resin. Cashew Nut Shell Liquid (CNSL) is a natural material which has chemical structure similar to synthetic phenol so it can be an alternative as a resin. Brake pads manufacture using CNSL as resin composites made to obtain the brake which is strong, wear-resistant, and environmentally friendly. The composite made using powder metallurgy techniques by mixing ingredients such as rubber, fibre glass, carbon, mineral sands and phenolic resin. Two formulas were composed by varying the resin and iron mineral sands in 5 grams. Composites were tested using Universal Testing Machine (UTM). The tensile strength result of those formulas are 600 N and 900 N and the elongations are 1.98 mm and 2.59 mm respectively. Formula 2 has a better tensile strength due to the addition of more resin is 15%. Since the better properties, formula 2 was derivated to 4 extended formulas and showed excellent pressure strength reached 20.000 N. It indicates that the addition of the resin can improve the mechanical properties of a composite.

  3. Fabrication of Glass Fiber Reinforced Composites Based on Bio-Oil Phenol Formaldehyde Resin

    Directory of Open Access Journals (Sweden)

    Yong Cui

    2016-11-01

    Full Text Available In this study, bio-oil from fast pyrolysis of renewable biomass was added by the mass of phenol to synthesize bio-oil phenol formaldehyde (BPF resins, which were used to fabricate glass fiber (GF reinforced BPF resin (GF/BPF composites. The properties of the BPF resin and the GF/BPF composites prepared were tested. The functional groups and thermal property of BPF resin were thoroughly investigated by Fourier transform infrared (FTIR spectra and dynamic thermomechanical analysis (DMA. Results indicated that the addition of 20% bio-oil exhibited favorable adaptability for enhancing the stiffness and heat resistance of phenol formaldehyde (PF resin. Besides, high-performance GF/BPF composites could be successfully prepared with the BPF resin based on hand lay-up process. The interface characteristics of GF/BPF composites were determined by the analysis of dynamic wettability (DW and scanning electron microscopy (SEM. It exhibited that GF could be well wetted and embedded in the BPF resin with the bio-oil addition of 20%.

  4. Novel high glass temperature sugar-based epoxy resins: Characterization and comparison to mineral oil-based aliphatic and aromatic resins

    Directory of Open Access Journals (Sweden)

    P. Niedermann

    2015-02-01

    Full Text Available Curing and rheological behaviour, glass transition temperature, mechanical and thermal properties of two newly synthesized glucopyranoside- (GPTE and glucofuranoside- (GFTE based renewable epoxy resin (EP components were investigated and compared to aromatic and aliphatic EPs. The glucose-based EPs can be successfully cured with amine and anhydride type curing agents, their gel times are suitable for processing and can be well-adopted to the needs of the common composite preparation methods. GPTE showed the highest glass transition temperature (Tg among all investigated resins, followed by GFTE and DGEBA. Below the Tg there was no significant difference between the storage modulus values of the EP systems. The glucose-based EPs had lower tensile and bending strength, but their tensile modulus values are not significantly different from the mineral oil based EPs. The thermal stability of the synthesized GPTE and GFTE is between DGEBA and the aliphatic resins. In applications where bending stresses are dominant over the tensile ones, and outstanding Tg is required, these glucose-based resins offer a feasible renewable option.

  5. Hyperbranched Polymers for Resin Transfer Molding

    Science.gov (United States)

    2005-03-01

    refereed journals and referencing AFOSR support: 6 H. Qin, P.T. Mather, J.-B. Baek, and L.-S. Tan, "Modification of bisphenol-A based bismaleimide resin...Burstone, "Shape Memory Polymer Orthodontics ," SPE ANTEC Medical Plastics Division, May 9, 2006. b. Consultation and Advisory Functions with other

  6. Retention of a Flowable Composite Resin in Comparison to a Conventional Resin-Based Sealant: One-year Follow-up

    OpenAIRE

    N. Tadayon; B. Malekafzali; M.Jafarzadeh; Fallahi, S.

    2010-01-01

    Objective: Long-term retention of pit and fissure sealants is crucial for their success. This clinical study evaluated the retention rate of a flowable composite resin (Filtek Supreme XT Flowable Restorative) compared to a conventional resin-based sealant (Concise Light Cure White Sealant) over 12 months. Materials and Methods: Forty subjects aged 6 to 9 years were included in the study. Using a half-mouth design, a total of 80 first permanent molars were sealed with conventional fissure seal...

  7. Nanoparticles-based phenol-formaldehyde hybrid resins.

    Science.gov (United States)

    Hernández-Padrón, Genoveva; García-Garduño, Margarita; Canseco, Miguel A; Castaño, Victor M

    2008-06-01

    The synthesis, characterization and corrosion properties of a novel material, produced by the reaction of silica nanoparticles with a functionalized Phenol-Formaldehyde Resin (PFR), are presented. Carboxylic groups were attached in situ to the PFR skeleton to produce a functionalized resin (PFR-SA), which is then reacted with sol-gel-prepared silica nanoparticles, yielding a novel hybrid (organic/inorganic) material (PFR-SA-nanoSiO2). This hybrid material was characterized by FT-IR, FT-Raman, TGA, DSC, SEM and corrosion tests, whose results showed significant improvement of the thermal properties in comparison with the PFR coating. In addition, the new material was efficient and durable against corrosion of metals, with the anticorrosive performance of PFR-SA and PFR-SA/nanoSiO2 coating films being superior to those of the original PFR coating.

  8. A nonlocal, ordinary, state-based plasticity model for peridynamics.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, John Anthony

    2011-05-01

    An implicit time integration algorithm for a non-local, state-based, peridynamics plasticity model is developed. The flow rule was proposed in [3] without an integration strategy or yield criterion. This report addresses both of these issues and thus establishes the first ordinary, state-based peridynamics plasticity model. Integration of the flow rule follows along the lines of the classical theories of rate independent J{sub 2} plasticity. It uses elastic force state relations, an additive decomposition of the deformation state, an elastic force state domain, a flow rule, loading/un-loading conditions, and a consistency condition. Just as in local theories of plasticity (LTP), state variables are required. It is shown that the resulting constitutive model does not violate the 2nd law of thermodynamics. The report also develops a useful non-local yield criterion that depends upon the yield stress and horizon for the material. The modulus state for both the ordinary elastic material and aforementioned plasticity model is also developed and presented.

  9. Chemical analysis of monomers in epoxy resins based on bisphenols F and A.

    Science.gov (United States)

    Pontén, A; Zimerson, E; Sörensen, O; Bruze, M

    2004-05-01

    Diglycidyl ether of bisphenol A (DGEBA) is the monomer and most important contact allergen in epoxy resin(s) based on bisphenol A (DGEBA-R). Both thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC) methods are available for the analysis of products containing DGEBA-R. With respect to detection and quantification, epoxy resins of the bisphenol F-type, i.e. epoxy resins containing the isomers of diglycidyl ethers of bisphenol F (DGEBF), are not as well investigated as DGEBA-R. The isomers of DGEBF are p,p'-DGEBF, o,p'-DGEBF and o,o'-DGEBF. Both p,p'-DGEBF and o,p'-DGEBF have been shown to be contact allergens in humans, and all 3 isomers are sensitizers in the guinea pig maximization test. We aimed (i). to develop HPLC methods for separation and purification of the individual DGEBF isomers, (ii). to detect and quantify the DGEBF isomers in epoxy resins of the bisphenol F-type and (iii). to evaluate and develop the TLC as a method for the detection of the DGEBF monomers. We found the total content of the DGEBF isomers in the investigated epoxy resins of the bisphenol F-type to vary from 17.0 to 81.7% w/w. Some of them also contained 0.1-2.4% w/w DGEBA. The HPLC method showed a sensitivity that was 2000-20 000x higher than that obtained with the TLC method for the DGEBF monomers. We concluded that the range of the DGEBF isomer content in epoxy resins of the bisphenol F-type is approximately the same as the monomer content in liquid compared to solid DGEBA-R. The relevance of contact allergy to DGEBA-R can remain unrecognized if the suspected product is an epoxy resin of the bisphenol F-type, which is analysed with the TLC method.

  10. Resin Catalyst Hybrids

    Institute of Scientific and Technical Information of China (English)

    S. Asaoka

    2005-01-01

    @@ 1Introduction: What are resin catalyst hybrids? There are typically two types of resin catalyst. One is acidic resin which representative is polystyrene sulfonic acid. The other is basic resin which is availed as metal complex support. The objective items of this study on resin catalyst are consisting of pellet hybrid, equilibrium hybrid and function hybrid of acid and base,as shown in Fig. 1[1-5].

  11. Variations in survival time for amalgam and resin composite restorations: a population based cohort analysis.

    Science.gov (United States)

    Birch, S; Price, R; Andreou, P; Jones, G; Portolesi, A

    2016-09-01

    To estimate the association between the restorative material used and time to further treatment across population cohorts with universal coverage for dental treatment. Cohort study of variation in survival time for tooth restorations over time and by restoration material used based on an Accelerated Failure Time model. Primary dental care clinics. Members of Canada's First Nations and Inuit population covered by the Non-Insured Health Benefits program of Health Canada for the period April 1, 1999 to March 31, 2012. Tooth restorations using resin composite or amalgam material. Survival time of restoration to further treatment. Median survival time for resin composite was 51 days longer than amalgam, for restorations placed in 1999-2000. This difference was not statistically significant (p⟩0.05). Median survival times were lower for females, older subjects. Those visiting the dentist annually, and decreased monotonically over time from 11.2 and 11.3 years for resin composite and amalgam restorations respectively placed in 1999-2000 to 6.9 and 7.0 years for those placed in 2009-10. Resin composite restorations performed no better than amalgams over the study period, but cost considerably more. With the combination of the overall decrease in survival times for both resin composite and amalgam restorations and the increase in use of resin composite, the costs of serving Health Canada's Non-Insured Health Benefits population will rise considerably, even without any increase in the incidence of caries.

  12. Safety assessment for hair-spray resins: risk assessment based on rodent inhalation studies.

    Science.gov (United States)

    Carthew, Philip; Griffiths, Heather; Keech, Stephen; Hartop, Peter

    2002-04-01

    The methods involved in the safety assessment of resins used in hair-spray products have received little peer review, or debate in the published literature, despite their widespread use, in both hairdressing salons and the home. The safety assessment for these resins currently involves determining the type of lung pathology that can be caused in animal inhalation exposure studies, and establishing the no-observable-effect level (NOEL) for these pathologies. The likely human consumer exposure is determined by techniques that model the simulated exposure under "in use" conditions. From these values it is then possible to derive the likely safety factors for human exposure. An important part of this process would be to recognize the intrinsic differences between rodents and humans in terms of the respiratory doses that each species experiences during inhalation exposures, for the purpose of the safety assessment. Interspecies scaling factors become necessary when comparing the exposure doses experienced by rats, compared to humans, because of basic differences between species in lung clearance rates and the alveolar area in the lungs. The rodent inhalation data and modeled human exposure to Resin 6965, a resin polymer that is based on vinyl acetate, has been used to calculate the safety factor for human consumer exposure to this resin, under a range of "in use" exposure conditions. The use of this safety assessment process clearly demonstrates that Resin 6965 is acceptable for human consumer exposure under the conditions considered in this risk assessment.

  13. Bond of acrylic teeth to different denture base resins after various surface-conditioning methods.

    Science.gov (United States)

    Lang, Reinhold; Kolbeck, Carola; Bergmann, Rainer; Handel, Gerhard; Rosentritt, Martin

    2012-02-01

    The study examined the bond between different denture base resins and highly cross-linked acrylic denture teeth with different base surface-conditioning methods. One hundred fifty highly cross-linked resin denture teeth (SR-Antaris, No. 11, Ivoclar-Vivadent, FL) were divided into five groups with different surface-conditioning methods of the base surfaces of the teeth (C = control, no surface conditioning, MM = application of methyl methacrylate monomer, SB = sand blasting, SBB = sand blasting + bonding agent, TSS = tribochemical silica coating + silanization). Teeth were bonded to either a cold-cured denture base resin (ProBase Cold, Ivoclar-Vivadent, FL) or heat-cured denture base resins (SR Ivocap Plus, Ivoclar-Vivadent, FL and Lucitone 199, Dentsply, USA). After 24 h of storage in distilled water, compressive load was applied at 90° on the palatal surface of each tooth until fracture. Median failure load ranged between 103 and 257 N for Probase Cold groups, 91 to 261 N for Lucitone 199, and 149 to 320 N for SR Ivocap Plus. For Probase Cold, significant highest failure loads resulted when teeth were treated with SB, SBB, or TSS. For Lucitone 199, significant highest failure loads has been found with MM and TSS treatment. For SR Ivocap Plus, highest failure loads resulted using SBB and TSS. Conditioning of the base surfaces of the teeth prior to denture base processing is highly recommended. Tooth bond is significantly affected by the surface-conditioning method and applied denture base resin. Tribochemical silica coating + silanization method can be recommended for pre-treatment of teeth applying either heat-cured or cold-cured denture base resin.

  14. Novel high glass temperature sugar-based epoxy resins: Characterization and comparison to mineral oil-based aliphatic and aromatic resins

    OpenAIRE

    Niedermann, P.; G. Szebenyi; A. Toldy

    2015-01-01

    Curing and rheological behaviour, glass transition temperature, mechanical and thermal properties of two newly synthesized glucopyranoside- (GPTE) and glucofuranoside- (GFTE) based renewable epoxy resin (EP) components were investigated and compared to aromatic and aliphatic EPs. The glucose-based EPs can be successfully cured with amine and anhydride type curing agents, their gel times are suitable for processing and can be well-adopted to the needs of the common composite preparation method...

  15. Effects of different cavity disinfectants on shear bond strength of a silorane-based resin composite.

    Science.gov (United States)

    Arslan, Soley; Yazici, A Ruya; Gorucu, Jale; Ertan, Atilla; Pala, Kansad; Ustun, Yakup; Antonson, Sibel A; Antonson, Donald E

    2011-07-01

    This in vitro study evaluated the effect of different cavity disinfection agents on bond strength of a silorane-based resin composite. Thirty-six caries-free human third mandibular molars sectioned in mesio-distal direction were mounted in acrylic resin with their flat dentin surfaces exposed. After the dentin surfaces were wet ground with # 600 silicon carbide paper, the teeth were randomly divided into 6 groups of 12 each according to the cavity disinfection agents; chlorhexidine (CHX); sodium hypochlorite (NaOCl), propolis, ozone, Er,Cr:YSGG laser and no treatment (control). After treatment of dentin surfaces with one of these cavity disinfection agents, Filtek Silorane adhesive system was applied. The silorane-based resin composite, Filtek Silorane was condensed into a mold and polymerized. After storage at 37°C for 24 hours, the specimens were tested in shear mode at a crosshead speed of 1.0 mm/minute. The results were analyzed by one-way ANOVA. No statistically significant difference was observed between the groups (p>0.05). The use of the tested cavity disinfection agents, chlorhexidine, sodium hypochlorite, propolis, ozone and Er,Cr:YSGG laser did not significantly affect the dentin bond strength of a silorane-based resin composite, filtek supreme. Cavity disinfectant applications did not affect the dentin bond strength of a silorane-based resin composite.

  16. Plastic variational principle based on the least work consumption principle

    Institute of Scientific and Technical Information of China (English)

    唐松花; 罗迎社; 周筑宝; 王智超

    2008-01-01

    Plastic variational principles are foundation to solve the boundary-value problems of plastic mechanics with the variational method(or energy method) and finite element method.The most convenient way of establishing different kinds of variational principles is to set up the extreme principle related to the studied problem.Based on a general new extreme principle-the Least work consumption principle,the variational principles of the rigid-plastic and rigid-viscoplastic material were derived.In comparison with existing methods,the method in this paper is more clear and direct,and the physical meaning is clear-cut.This method can offer a new way for establishing other kinds of variational principles.

  17. Scintillation properties of acrylate based plastic scintillator by photoploymerization method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Hwan [Dept. of Radiological Science, Cheongju University, Cheongju (Korea, Republic of); Lee, Joo Il [Dept. of of Radiology, Daegu Health College, Daegu (Korea, Republic of)

    2016-12-15

    In this study, we prepared and characterized a acrylate based UV-curable plastic scintillator. It was used co-polymers TMPTA, DHPA and Ultima GoldTM LLT organic scintillator. The emission spectrum of the plastic scintillator was located in the range of 380⁓520 nm, peaking at 423 nm. And the scintillator is more than 50% transparent in the range of 400⁓ 800 nm. The emission spectrum is well match to the quantum efficiency of photo-multiplier tube and the fast decay time of the scintillation is 12 ns, approximately. This scintillation material provides the possibility of combining 3D printing technology, and then the applications of the plastic scintillator may be expected in human dosimetry etc.

  18. Acid-Breakable Resin-Based Chemical Amplification Positive Resist for Electron-Beam Mastering: Design and Lithographic Performance

    Science.gov (United States)

    Sakamizu, Toshio; Shiraishi, Hiroshi

    2004-07-01

    A positive chemical amplification resist based on acid-catalyzed fragmentation of acetal groups in its main chain has been developed as a means of reducing line-edge roughness. The resist consists of an acid generator, an acid-diffusion controller and an acid-breakable (AB) resin that is synthesized through a co-condensation reaction between polyphenol and aromatic multifunctional vinylether compound. The effects of the fractionation of AB resins on resin properties and line-edge roughness (LER) are evaluated. Although AB resins have wide molecular weight distributions, the density of acetal groups in this AB resin is found to be almost constant except in the lower molecular weight components. The resist with a fractionated resin from which such components are removed provides high-resolution patterns (70-nm-wide pit) with fairly low LER. AFM analysis shows that the surface roughness (SR) of the resist with the fractionated resin is smaller than that of a resist using nonfractionated AB resin, and that the SR value is not altered throughout the range of exposure doses up to just below the start of dissolution. By using the fractionated AB resin, the AB resin-based resist (ABR) is capable of forming sub-100 nm L/S patterns with less than 5 nm of LER (3σ).

  19. Effect of different plasticizers on the properties of bio-based thermoplastic elastomer containing poly(lactic acid and natural rubber

    Directory of Open Access Journals (Sweden)

    V. Tanrattanakul

    2014-06-01

    Full Text Available Bio-based thermoplastic elastomers (TPE containing natural rubber and poly(lactic acid were prepared by melt blending in an internal mixer. The blend ratio was 60% of natural rubber and 40% of poly(lactic acid. Dynamic vulcanization of natural rubber was performed with the sulfur system. The 2 mm – thick sheet samples were prepared by compression molding. The objective of this study was to investigate the effect of plasticization of PLA on the mechanical and physical properties of the derived TPE. Four plasticizers were selected: tributyl acetyl citrate (TBAC, tributyl citrate (TBC, glycerol triacetate (GTA, and triethyl-2-acetyl citrate (TEAC. The investigated properties were the tensile properties, tear strength, thermal ageing and ozone resistance, hardness, resilience, tension set and compression set. All plasticizers increased the strain at break. TBAC and TBC increased the stress at break. All plasticizers decreased the tear strength, hardness and resilience, and slightly changed the tension and compression set. TBAC seemed to be the best plasticizer for the TPE. The presence of 4 pph (parts per hundred resin of plasticizer provided the highest strength and tensile toughness and the strain at break increased with the increasing plasticizer content. The plasticizers decreased the Tg and Tcc of the PLA and did not affect the degree of crystallinity of PLA in the TPE.

  20. Chitosan whiskers from shrimp shells incorporated into dimethacrylate-based dental resin sealant.

    Science.gov (United States)

    Mahapoka, Ekamon; Arirachakaran, Pratanporn; Watthanaphanit, Anyarat; Rujiravanit, Ratana; Poolthong, Suchit

    2012-01-01

    A resin-based sealant containing chitosan whiskers was developed for use as a pit and fissure sealer. Chitosan whiskers were synthesized and then characterized using Fourier transform infrared spectrometry and transmission electron microscopy. The whiskers were next incorporated into dimethacrylate monomer at various ratios by weight and subsequently analyzed for their antimicrobial and physical properties. The dimethacrylate-based sealant containing chitosan whiskers had a greater antimicrobial activity than control sealant and they were comparable with antimicrobial commercial resin sealants. The inclusion of the whiskers did not reduce the curing depth or degree of double bond conversion and the reduction in hardness was minimal. In conclusion, a resin-based sealant containing chitosan whiskers can be considered an effective antimicrobial pit and fissure sealant.

  1. Extraction of Carbon Dioxide From Seawater by Ion Exchange Resin. Part 2. Using Strong Base Anion Exchange Resin

    Science.gov (United States)

    2009-09-29

    Figure 1. Table 2 - Resin Properties of Static Experiments Using Amberjet 4400 in OH Form (150 minute contact time). Sample Concentration (Molar...0.271 1 36 17.9 0.0075 150 0.267 134 19.0 Table 4 - Resin Properties of Static Experiments Using Amberjet 4400 in Cl Form (150 minute contact time

  2. Reducing composite restoration polymerization shrinkage stress through resin modified glass-ionomer based adhesives.

    Science.gov (United States)

    Naoum, S J; Mutzelburg, P R; Shumack, T G; Thode, Djg; Martin, F E; Ellakwa, A E

    2015-12-01

    The aim of this study was to determine whether employing resin modified glass-ionomer based adhesives can reduce polymerization contraction stress generated at the interface of restorative composite adhesive systems. Five resin based adhesives (G Bond, Optibond-All-in-One, Optibond-Solo, Optibond-XTR and Scotchbond-Universal) and two resin modified glass-ionomer based adhesives (Riva Bond-LC, Fuji Bond-LC) were analysed. Each adhesive was applied to bond restorative composite Filtek-Z250 to opposing acrylic rods secured within a universal testing machine. Stress developed at the interface of each adhesive-restorative composite system (n = 5) was calculated at 5-minute intervals over 6 hours. The resin based adhesive-restorative composite systems (RBA-RCS) demonstrated similar interface stress profiles over 6 hours; initial rapid contraction stress development (0-300 seconds) followed by continued contraction stress development ≤0.02MPa/s (300 seconds - 6 hours). The interface stress profile of the resin modified glass-ionomer based adhesive-restorative composite systems (RMGIBA-RCS) differed substantially to the RBA-RCS in several ways. Firstly, during 0-300 seconds the rate of contraction stress development at the interface of the RMGIBA-RCS was significantly (p resin modified glass-ionomer based adhesives can significantly reduce the magnitude and rate of polymerization contraction stress developed at the interface of adhesive-restorative composite systems. © 2015 Australian Dental Association.

  3. Epoxy Resin Based Composites, Mechanical and Tribological Properties: A Review

    Directory of Open Access Journals (Sweden)

    S.A. Bello

    2015-12-01

    Full Text Available High fuel consumption by automobile and aerospace vehicles built from legacy alloys has been a great challenge to global design and material engineers. This has called for researches into material development for the production of lighter materials of the same or even superior mechanical properties to the existing materials in this area of applications. This forms a part of efforts to achieve the global vision 2025 i.e to reduce the fuel consumption by automobile and aerospace vehicles by at least 75 %. Many researchers have identified advanced composites as suitable materials in this regard. Among the common matrices used for the development of advanced composites, epoxy resin has attained a dominance among its counterparts because of its excellent properties including chemical, thermal and electrical resistance properties, mechanical properties and dimensional stability. This review is a reflection of the extensive study on the currently ongoing research aimed at development of epoxy resin hybrid nanocomposites for engineering applications. In this paper, brief explanation has been given to different terms related to the research work and also, some previous works (in accordance with materials within authors’ reach in the area of the ongoing research have been reported.

  4. Bonding of acrylic denture teeth to resin denture bases.

    Science.gov (United States)

    Geerts, G A V M; Stuhlinger, M E

    2012-07-01

    Anterior teeth debonding from dentures is a common problem. This study tested the bond strength of denture teeth to two types of denture resin, with and without grooving the ridge-lap surface. Bond strength and fracture type of three different groups were compared: 1. Teeth bonded to heat-cured polymethyl methacrylate (PMMA); 2. Teeth bonded to pour-type PMMA; 3. Grooved teeth bonded to pour-type PMMA. Specimens were manufactured following ISO standard 22112. Force values at failure were analysed using one-way analysis of variance, using the mixed procedure with confidence interval of 95%. Types of failure were identified as adhesive, cohesive or combination. In descending order, mean failure forces were 418.55N (Group One), 367.55N (Group Two) and 290.05N (Group Three). There was no significant difference between the means of groups 1 and 2 (p = 0.0627). Group Three differed from both other groups (p denture teeth (83% and 72% respectively); group Three showed predominantly cohesive fractures within the denture PMMA (75%). Without ridge-lap modification, the bond strengths of denture teeth to pour-type and heat-cured denture resin were similar. Failures were predominantly of cohesive nature within the teeth themselves. Grooving the ridge-lap reduced fracture resistance and led to breakages predominantly in denture PMMA.

  5. A 24-month evaluation of amalgam and resin-based composite restorations

    DEFF Research Database (Denmark)

    McCracken, Michael S; Gordan, Valeria V; Litaker, Mark S

    2013-01-01

    Knowing which factors influence restoration longevity can help clinicians make sound treatment decisions. The authors analyzed data from The National Dental Practice-Based Research Network to identify predictors of early failures of amalgam and resin-based composite (RBC) restorations....

  6. DETERMINATION OF ION EXCHANGE EQUILIBRIUM CONSTANTS FOR THE WEAK ACID CATION AND THE WEAK BASE ANION EXCHANGE RESINS

    Institute of Scientific and Technical Information of China (English)

    TAOZuyi; WANGChangshou

    1992-01-01

    The general procedure based on the potentiometric titration has developed.According to the procedure,the rational equilibrium constants of the ion exchange reactions RH/Na,RH/Ca,RH/Sr,RH/Ba for the weak acid cation exchange resin D725 and ROH/Cl for the weak base anion exchange resin D705 have been determined.

  7. Boron removal from water and wastewater using new polystyrene-based resin grafted with glycidol

    Directory of Open Access Journals (Sweden)

    Joanna Kluczka

    2015-09-01

    Full Text Available A divinylbenzene cross-linked polystyrene resin with amine functional groups (Purolite A170 was grafted with glycidol and characterized as a novel sorbent, GLY-resin, for the oxoborate removal from model solutions and post-crystallization lye. The sorption behavior of GLY-resin was investigated using a batch system. The results showed that the sorption was maximal at pH=9.5. The equilibrium was achieved after 24 h. Calculations based on Langmuir model show the monolayer sorption capacity qm=1.3 mg/g and the fitted experimental data chemisorption as a dominating mechanism of boron sorption on GLY-resin. Boron removal from the solution containing 5 mg B/L and post-crystallization lye having a 9.1 mg B/L was 99% and 80% respectively. The thermodynamic calculations indicated the spontaneous and endothermic nature of the sorption process. The pseudo-second-order model adequately described the boron sorption on GLY-resin. Sorption−desorption efficiency was 100%, which means the boron sorption at next cycle did not decrease.

  8. Gurson-type elastic-plastic damage model based on strain-rate plastic potential

    Science.gov (United States)

    Balan, Tudor; Cazacu, Oana

    2013-12-01

    Ductile damage is generally described by stress-space analytical potentials. In this contribution, it is shown that strain rate potentials, which are exact conjugate of the stress-based potentials, can be equally used to describe the dilatational response of porous metals. This framework is particularly appropriate for porous materials with matrix described by complex yield criteria for which a closed-form expression of the stress-based potential is not available. Illustration of the new approach is done for porous metals containing randomly distributed spherical voids in a von Mises elasto-plastic matrix. Furthermore, a general time integration algorithm for simulation of the mechanical response using this new formulation is developed and implemented in Abaqus/Standard. The proposed model and algorithm are validated with respect to the Abaqus built-in GTN model, which is based on a stress potential, through the simulation of a tensile test on a round bar.

  9. Epoxy Resin Composite Based on Functional Hybrid Fillers

    Directory of Open Access Journals (Sweden)

    Mariusz Oleksy

    2014-08-01

    Full Text Available A study was carried out involving the filling of epoxy resin (EP with bentonites and silica modified with polyhedral oligomeric silsesquioxane (POSS. The method of homogenization and the type of filler affect the functional and canceling properties of the composites was determined. The filler content ranged from 1.5% to 4.5% by mass. The basic mechanical properties of the hybrid composites were found to improve, and, in particular, there was an increase in tensile strength by 44%, and in Charpy impact strength by 93%. The developed hybrid composites had characteristics typical of polymer nanocomposites modified by clays, with a fine plate morphology of brittle fractures observed by SEM, absence of a plate separation peak in Wide Angles X-ray Scattering (WAXS curves, and an exfoliated structure observed by TEM.

  10. Epoxy Resin Composite Based on Functional Hybrid Fillers

    Science.gov (United States)

    Oleksy, Mariusz; Szwarc-Rzepka, Karolina; Heneczkowski, Maciej; Oliwa, Rafał; Jesionowski, Teofil

    2014-01-01

    A study was carried out involving the filling of epoxy resin (EP) with bentonites and silica modified with polyhedral oligomeric silsesquioxane (POSS). The method of homogenization and the type of filler affect the functional and canceling properties of the composites was determined. The filler content ranged from 1.5% to 4.5% by mass. The basic mechanical properties of the hybrid composites were found to improve, and, in particular, there was an increase in tensile strength by 44%, and in Charpy impact strength by 93%. The developed hybrid composites had characteristics typical of polymer nanocomposites modified by clays, with a fine plate morphology of brittle fractures observed by SEM, absence of a plate separation peak in Wide Angles X-ray Scattering (WAXS) curves, and an exfoliated structure observed by TEM. PMID:28788177

  11. Effect of dentinal tubules and resin-based endodontic sealers on fracture properties of root dentin.

    Science.gov (United States)

    Jainaen, Angsana; Palamara, Joseph E A; Messer, Harold H

    2009-10-01

    To investigate the role of dentinal tubules in the fracture properties of human root dentin and whether resin-filled dentinal tubules can enhance fracture resistance. Crack propagation in human root dentin was investigated in 200 microm thick longitudinal samples and examined by light and scanning electron microscopy. 30 maxillary premolar teeth were prepared for work of fracture (Wf) test at different tubule orientations, one perpendicular and two parallel to dentinal tubules. Another 40 single canal premolars were randomly divided into four groups of 10 each: intact dentin, prepared but unobturated canal, canal obturated with epoxy rein (AH Plus/gutta percha), or with UDMA resin sealer (Resilon/RealSeal. The samples were prepared for Wf test parallel to dentinal tubules. Wf was compared under ANOVA with statistical significance set at pcanal preparation nor obturation using epoxy- or UDMA-based resins as sealer cements substantially influenced fracture properties of root dentin, despite extensive infiltration of dentinal tubules by both sealer cements.

  12. Influence of a peracetic acid-based immersion on indirect composite resin.

    Science.gov (United States)

    Samuel, Susana Maria Werner; Fracaro, Gisele Baggio; Collares, Fabrício Mezzomo; Leitune, Vicente Castelo Branco; Campregher, Ulisses Bastos

    2011-06-01

    The aim of this study was to evaluate the influence of immersion in a 0.2% peracetic acid-based disinfectant on the three-point flexural strength, water sorption and water solubility of an indirect composite resin. Specimens were produced according to ISO 4049:2000 specifications and were divided in two groups: Control group, with no disinfection and Disinfected group, with three 10 min immersions in the peracetic acid intercalated with 10 min immersions in sterile distilled water. All evaluations were conducted in compliance with ISO specifications. Three-point flexural strength, water sorption and solubility of indirect composite resin before and after immersion showed no statistical significant differences (p > 0.05) and met ISO standard requirements. Immersion in peracetic acid solution showed no influence in indirect composite resin tested properties.

  13. Adsorption characteristics of thorium on silica-based anion exchange resins

    Institute of Scientific and Technical Information of China (English)

    陈彦良; 赵龙; 韦悦周; 何林锋; 唐方东

    2015-01-01

    To isolate and separate thorium from nitric acid solutions, three silica-based anion exchange resins were synthesized. Batch experiments were carried out to investigate adsorption behavior of thorium in nitric acid solutions. Adsorption at different concentrations of nitric acid and thorium, influence of contact time and coex-isting metal ions, and effect of NO–3 were investigated in detail. It was found that at high HNO3 concentrations, the resins exhibited higher adsorption capacity and better affinity towards thorium. The adsorption kinetics could be described by the pseudo-second order model equation, while the adsorption isotherms were well cor-related by the Langmuir model. The maximum capacity towards thorium species on SiPyR-N4 was evaluated at 27–28 mg/g-resin. The thermodynamic parameters indicated the adsorption was an exothermic reaction. The presence of NO–3 was found to promote the retention of the thorium species.

  14. Synthesis of Antistatic Composite Based on Reaction Flame Retarding Unsaturated Polyester Resin

    Institute of Scientific and Technical Information of China (English)

    WANG Shui-ping; GONG Wen-hua; ZENG Jia

    2002-01-01

    The synthesis of reaction flame retarding unsaturated polyester resin and the flame retarding mechanism are investigated. By taking the synthesis flame retarding unsaturated polyester resin as a base material,glass fibers as reinforced material, under the condition of adding graphite or carbon black respectively, the composites were manufactured. The flame retarding and antistatic properties are also studied. In the experiment, bromidebearing flame retarding resin decomposed under a high temperature. Compound HBr was set out and retarded or stopped the flame. High concentration of HBr gas wall was formed between gas and solid phrases, which decreased flame. The results show that antistatic property of carbon black is higher than that of graphite. Adding a threshed value of 1% carbon black into composite, the antistatic property is at its highest value.

  15. Laminated composite based on polyester geotextile fibers and polyurethane resin for coating wood structures

    Directory of Open Access Journals (Sweden)

    Yuri Andrey Olivato Assagra

    2013-01-01

    Full Text Available New environmental laws have restricted the use of hardwood trees in overhead power lines structures, such as, poles and cross-arms, leading companies to seek alternative materials. Reforested wood coated with polymeric resin has been proposed as an environmental friendly solution, with improved electrical properties and protection against external agents, e.g. moisture, ultraviolet radiation and fungi. However, the single thin layer of resin, normally applied on such structures reveal to be inefficient, due to be easily damage during handling. In this paper, we present a composite coating, based on geotextile fibers and polyurethane resin that is suitable for wooden structures. Results obtained from two different tree species (from managed and reforested areas coated with the composite reveal that the additional layer not only provided a stronger adhesion between wood and ccoating layer but also a further improvement in the electrical properties and better protection against abrasion and moisture.

  16. Nanostructured composites based on carbon nanotubes and epoxy resin for use as radar absorbing materials

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Valdirene Aparecida [Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil); Folgueras, Luiza de Castro; Candido, Geraldo Mauricio; Paula, Adriano Luiz de; Rezende, Mirabel Cerqueira, E-mail: mirabelmcr@iae.cta.br [Instituto de Aeronautica e Espaco (IAE), Sao Jose dos Campos, SP (Brazil). Div. de Materiais; Costa, Michelle Leali [Universidade Estadual Paulista Julio de Mesquita Filho (DMT/UNESP), Guaratingueta, SP (Brazil). Dept. de Materiais e Tecnologia

    2013-07-01

    Nanostructured polymer composites have opened up new perspectives for multifunctional materials. In particular, carbon nanotubes (CNTs) present potential applications in order to improve mechanical and electrical performance in composites with aerospace application. The combination of epoxy resin with multi walled carbon nanotubes results in a new functional material with enhanced electromagnetic properties. The objective of this work was the processing of radar absorbing materials based on formulations containing different quantities of carbon nanotubes in an epoxy resin matrix. To reach this objective the adequate concentration of CNTs in the resin matrix was determined. The processed structures were characterized by scanning electron microscopy, rheology, thermal and reflectivity in the frequency range of 8.2 to 12.4 GHz analyses. The microwave attenuation was up to 99.7%, using only 0.5% (w/w) of CNT, showing that these materials present advantages in performance associated with low additive concentrations (author)

  17. Removal of dissolved oxygen from water using a Pd-resin based catalytic reactor

    Institute of Scientific and Technical Information of China (English)

    Wenxin SHI; Chongwei CUI; Liye ZHAO; Shuili YU; Xia YUN

    2009-01-01

    The removal of dissolved oxygen (DO) from water was studied experimentally in a Pd-resin base catalyst reactor using purified hydrogen gas as a reducing agent. The effects of various operating conditions, such as hydrogen and water flow rates, height of the catalytic resin bed, temperature, pH value and nan time, on the removal of DO, had been studied extensively. The results shows that DO could be removed by the reactor from ppm to ppb levels at ambient temperature. Increases of temperature, H2gas rate and the height of the catalytic resin were helpful to improve the DO removal rate. The change of pH value fom 4 to 12 resulted in no effect on DO removal. Reaction time was the key factor to control the DO removal efficiency. Only when the reaction time was longer than 2.3 minutes under the experimental conditions, could a very low DO level be achieved.

  18. 18-year survival of posterior composite resin restorations with and without glass ionomer cement as base.

    NARCIS (Netherlands)

    Sande, F.H. van de; Rosa Rodolpho, P.A. Da; Basso, G.R.; Patias, R.; Rosa, Q.F. da; Demarco, F.F.; Opdam, N.J.M.; Cenci, M.S.

    2015-01-01

    OBJECTIVE: Advantages and disadvantages of using intermediate layers underneath resin-composite restorations have been presented under different perspectives. Yet, few long-term clinical studies evaluated the effect of glass-ionomer bases on restoration survival. The present study investigated the i

  19. Long-term performance of resin based fissure sealants placed in a general dental practice.

    NARCIS (Netherlands)

    Hevinga, M.; Opdam, N.J.M.; Bronkhorst, E.M.; Truin, G.J.; Huysmans, M.C.D.N.J.M.

    2010-01-01

    OBJECTIVES: The aim of the present retrospective study was to evaluate the long-term performance of resin based fissure sealants applied in a general dental practice. METHODS: Regularly attending patients visiting the practice between July 2006 until November 2007 and who had received sealants befor

  20. Assessment of the impact strength of the denture base resin polymerized by various processing techniques

    Directory of Open Access Journals (Sweden)

    Rajashree Jadhav

    2013-01-01

    Full Text Available Aim : To measure the impact strength of denture base resins polymerized using short and long curing cycles by water bath, pressure cooker and microwave techniques. Materials and Methods: For impact strength testing, 60 samples were made. The sample dimensions were 60 mm × 12 mm × 3 mm, as standardized by the American Standards for Testing and Materials (ASTM. A digital caliper was used to locate the midpoint of sample. The impact strength was measured in IZOD type of impact tester using CEAST Impact tester. The pendulum struck the sample and it broke. The energy required to break the sample was measured in Joules. Data were analyzed using Student′s " t" test. Results: There was statistically significant difference in the impact strength of denture base resins polymerized by long curing cycle and short curing cycle in each technique, with the long curing processing being the best. Conclusion: The polymerization technique plays an important role in the influence of impact strength in the denture base resin. This research demonstrates that the denture base resin polymerized by microwave processing technique possessed the highest impact strength.

  1. Fracture strength of root filled premolar teeth restored with silorane and methacrylate-based resin composite.

    Science.gov (United States)

    Taha, N A; Maghaireh, G A; Bagheri, R; Abu Holy, A

    2015-06-01

    To compare fracture characteristics of root-filled teeth with variable cavity design restored with a low shrinkage silorane and methacrylate-based resin composite. 77 extracted maxillary premolars were divided randomly into seven groups: (Group 1) intact teeth; (Groups 2-4) MOD plus endodontic access with the buccopalatal width of the occlusal isthmus equals one third of the intercuspal width; (Groups 5-7) MOD plus endodontic access with the buccopalatal width of the occlusal isthmus equals one half of the intercuspal width. Groups 2 and 5 were left unrestored, Groups 3 and 6 were restored with a silorane-based resin composite (Filtek P90) and Groups 4 and 7 with a methacrylate-based resin composite (Z250). Teeth were loaded in a universal testing machine; load and fracture patterns were recorded and compared statistically using 2-way ANOVA and t-test for pairwise comparisons and 1-way ANOVA with Dunnett test for multiple comparisons. Unrestored teeth became progressively weaker with more extensive preparations, Group 5 (unfilled ½) showed the lowest fracture load among the groups (71±22N, Presin composite have no superior strengthening effect over the conventional methacrylate-based resin composite in restoration of root filled teeth. Both materials showed similar fracture patterns. Root filled teeth are considerably weakened via restorative and endodontic procedures. A direct adhesive restoration will aid in preserving tooth structure as far as it provides enough strength. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Azido--meconine-`high ortho’ Novolak resin-based negative photoresists for deep UV lithography

    Indian Academy of Sciences (India)

    Maneesh Sharma; Anant A Naik; Manoj Gaur; P Raghunathan; S V Eswaran

    2009-07-01

    Photoactive chemicals blended with polymers, solvents and certain other additives serve as photoresists. A new photoactive compound (PAC), azido--meconine absorbing in the deep UV region has been blended with `alternating’ and `semi-alternating’ and `high ortho’ alternating novolak resins, based on /-cresol. The new photoresists have been evaluated as a negative tone deep UV photoresist for mircolithography.

  3. Performance of chromium nitride based coatings under plastic processing conditions

    OpenAIRE

    Cunha, l.; Andritschky, M.; Pischow, K.; Wang, Z.(Institute of High Energy Physics, Beijing, China); Zarychta, A.; Miranda, A. S.; A.M. Cunha

    2000-01-01

    Chromium nitride based coatings were produced in the form of monolithic and multilayer coatings, by DC and RF reactive magnetron sputtering. These coatings were deposited onto stainless steel and tool steel substrates. Chromium nitride coatings have;proved to be wear and corrosion resistant. The combination of these characteristics was necessary to protect surfaces during plastic processing. In order to select the best coatings, some mechanical and tribological tests were performed. Har...

  4. Physicochemical Properties of Epoxy Resin-Based and Bioceramic-Based Root Canal Sealers

    Science.gov (United States)

    Lee, Ju Kyung; Kwak, Sang Won; Ha, Jung-Hong; Lee, WooCheol

    2017-01-01

    Three bioceramic sealers (EndoSequence BC sealer, EndoSeal MTA, and MTA Fillapex) and three epoxy resin-based sealers (AH-Plus, AD Seal, and Radic-Sealer) were tested to evaluate the physicochemical properties: flow, final setting time, radiopacity, dimensional stability, and pH change. The one-way ANOVA and Tukey's post hoc test were used to analyze the data (P = 0.05). The MTA Fillapex sealer had a highest flow and the BC Sealer presented a flow significantly lower than the others (P MTA Fillapex samples were not set in humid incubator condition even after one month. EndoSeal MTA had the longest setting time among the measurable materials and Radic-Sealer and AD Seal showed shorter setting time than the AH-Plus (P MTA showed statistically higher values and MTA Fillapex showed statistically lower radiopacity (P MTA presented a significant increase of pH over experimental time for 4 weeks. In conclusion, the bioceramic sealer and epoxy resin-based sealers showed clinical acceptable physicochemical properties, but BC Sealer and MTA Fillapex were not set completely. PMID:28210204

  5. Effect of high-pressure polymerization on mechanical properties of PMMA denture base resin.

    Science.gov (United States)

    Murakami, Natsuko; Wakabayashi, Noriyuki; Matsushima, Rie; Kishida, Akio; Igarashi, Yoshimasa

    2013-04-01

    The aim of this study was to assess the effect of high-pressure polymerization on mechanical properties of denture base resin. A heat-curing denture base resin and an experimental PMMA were polymerized under 500MPa of pressure by means of an isostatic pressurization machine at 70°C for 24h to make rectangular specimens whose dimensions were 30mm×2mm×2mm. Each specimen was deflected on a three-point flexural test until either fracture occurred or the sample was loaded up to 8mm in deflection. The molecular weight of the PMMA without filler was analyzed using the high-speed liquid chromatography system. Increased ductility without fracture was shown in the specimens subjected to high pressure, while most of the control specimens (ambient pressure) fractured. The mean toughness of the PMMA specimens polymerized under the high pressure was significantly higher than the same material polymerized under ambient pressure (ppressure groups of the denture resin and the PMMA revealed a significantly lower mean 0.2% yield stress, flexural strength, and elastic modulus than control groups (ppressure specimens than were present in the controls. The increased toughness shown in the PMMA polymerized under the high pressure was presumably attributed to the higher molecular weight produced by the pressure. The result suggests a potential application of the high-pressure polymerization to the development of PMMA-based denture resin with improved fracture resistance.

  6. Multicenter Patch Testing With a Resol Resin Based on Phenol and Formaldehyde Within the International Contact Dermatitis Research Group

    DEFF Research Database (Denmark)

    Isaksson, M.; Ale, I.; Andersen, Klaus Ejner

    2015-01-01

    Background Contact allergy to phenol-formaldehyde resins (PFRs) based on phenol and formaldehyde is not detected by a p-tertiary-butylphenol-formaldehyde resin included in most baseline patch test series. Objective The aims of this study were to investigate the contact allergy rate to PFR-2...

  7. The teaching of posterior resin composites: planning for the future based on 25 years of research.

    Science.gov (United States)

    Wilson, Nairn H F; Lynch, Christopher D

    2014-05-01

    The restoration of posterior teeth affected by caries, trauma or wear remains one of the commonest procedures in the practice of dentistry. Over the past 20 years the first author and latterly the second author have led a series of surveys around the world to capture information on the teaching of posterior resin composites. The aim of this paper is to identify trends, reflect on the findings and make recommendations for the further development of this important aspect of the curriculum for primary dental qualifications. Surveys on the teaching of posterior resin composites were completed in 1986, 1997-99, 2004-05 and 2007-2009. The findings from these surveys were reviewed and drawn together to allow historical and contemporary international trends to be identified. Recommendations for further developments in the teaching of posterior resin composites were formulated from the cumulated data and trends identified. Information was available from a total of 679 survey returns. Increased teaching of posterior resin composites has been observed over the period of the surveys: while 90% of dental school curricula did not include any didactic teaching of posterior resin composites in the mid-1980s, this dropped to 4% or less in the late 1990s, and to 0% in the early 2000s. In the late 2000s, however, 21% of dental schools still did not teach the placement of resin composites in three-surface cavities in permanent molar teeth. Areas of confusion were reported in the teaching of certain aspects of cavity design, notably the use of bevels, and in the protection of operatively exposed dentine. While there has been steady growth in, and trends towards evidence-based teaching of posterior resin composites in dental schools around the world over the last 20-25 years, there is a need for further developments and harmonisation in this important aspect of curricula for primary dental qualifications. This need is now pressing, subsequent to the signing of the Minamata Convention

  8. Measurement of Persistent Organic Pollutants (POPs) in plastic resin pellets from remote islands : Toward establishment of baseline level for International Pellet Watch

    Science.gov (United States)

    Takada, H.; Heskett, M.; Yamashita, R.; Yuyama, M.; Itoh, M.; Geok, Y. B.; Ogata, Y.

    2011-12-01

    Plastic resin pellets collected from remote islands in open oceans (Canary, St. Helena, Cocos, Hawaii, Maui Islands and Barbados) were sorted and yellowing polyethylene (PE) pellets were measured for polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and the degradation products (DDTs), and hexachlorocyclohexanes (HCHs) by gas chromatograph equipped with mass spectrometer (GC-MS) and with electron capture detector (GC-ECD). PCBs were detected from all the pellet samples, confirming the global dispersion of PCBs. Median concentrations of PCBs (sum of 13 congeners : CB-66, CB-101, CB-110, CB-118, CB-105, CB-149, CB-153, CB-138, CB-128, CB-187, CB-180, CB-170, CB-206) in the remote island pellets ranged from 0.1 to 10 ng/g-pellet. These were one to three orders of magnitude lower than those observed for pellets from industrialized coastal zones (hundreds ng/g in Los Angeles, Boston, Tokyo; Ogata et al., 2009). Because these remote islands are far (>100 km) from industrialized zones, these concentrations (i.e., 0.1 to 10 ng/g-pellet) can be regarded as global "baseline" level of PCB pollution. Concentrations of DDTs in the remote island pellets ranged from 0.2 to 5.5 ng/g-pellet. At some locations, DDT was dominant over the degradation products (DDE and DDD), suggesting current usage of the pesticides in the islands. HCHs concentrations were 0.4 - 1.8 ng/g-pellet and lower than PCBs and DDTs, except for St. Helena Island at 18.8 ng/g-pellet where the current usage of the pesticides are of concern. The analyses of pellets from the remote islands provided "baseline" level of POPs (PCBs plastic debris which were contaminated in industrialized coastal zones may have rapidly transported to the remote islands before they would reach equilibrium (i.e., desorption completed). Because POPs concentrations in the other media are at trace levels in these remote environments, the sporadic high concentrations of POPs in the plastic debris may pose threat to the

  9. Mechanical properties of four methylmethacrylate-based resins for provisional fixed restorations.

    Science.gov (United States)

    Hernandez, E P; Oshida, Y; Platt, J A; Andres, C J; Barco, M T; Brown, D T

    2004-01-01

    The use of a provisional restoration is an important phase in the treatment of the dental prosthetic patient. A good provisional restoration should satisfy the following requirements: pulpal protection, positional stability, ease in cleaning, accurate margins, wear resistance, dimensional stability, and serve as a diagnostic aid in treatment assessment and esthetics. There is a tendency for discoloration, occlusal wear, and fracture that eventually leads to unnecessary repair. Heat-processed and reinforced methacrylate-based resins have been used to improve the mechanical and physical properties of provisional restorations. Among various improvements, the interpenetrating network crosslinked PMMA (IPN) has been shown to have superior mechanical properties if manufactured through a dough compression molding process at 130 degrees C. However, there have been no published data that relate with the use of this material for fixed provisional restorations. The objective of this study was to compare four methyl methacrylate-based resins for provisional crowns and bridges with varying processing cycles, including JET [self-cure], ACRALON [heat-cured], titanium dioxide filled PMMA [heat-cured], and IPN [heat-cured denture tooth resin]. Properties studied included transverse strength, toughness, rigidity, and hardness. From the results of this study the following conclusions can be made: the IPN group may have had a lower degree of conversion as demonstrated by decreased strength, toughness, and hardness data as compared with Acralon. Increasing the polymerization cycle of unmodified Acralon resin causes a significant increase in strength.

  10. The Influence of Chicken Egg Shell as Fillers on Biocomposite Acrylic Resin for Denture Based

    Science.gov (United States)

    Lubis, M.; Ginting, M. H. S.; Dalimunthe, N. F.; Hasibuan, D. M. T.; Sastrodihardjo, S.

    2017-03-01

    This research was conducted to discover the influence of the addition of chicken egg shells microparticle as filler on the mechanical properties such as modulus of elasticity, modulus of rapture and particle size analysis on biocomposite acrylic resin for denture based. The raw materials used in this research were acrylic resin, egg shell, cold mold seals, gypsum, Vaseline and wax. The process of making biocomposite acrylic resin for denture based with mix the acrylic resin in ratio 2:1 (w/w). Then added the microparticle filler 0,10,20,30 (%w) to mold and boil in 75°C for 90 minutes and increase the temperature to 90 °C for 30 minutes. Took the sample and let it dried. The results of research showed the increase of modulus elasticity and modulus of rapture. The modulus of elasticity showed a very significant increase by adding fillers 10% of 2.123 GPa, which was only 1.932 GPa without adding the filler of chicken egg shells. For modulus of rapture showed the increase by adding fillers 20% of 48,311MPa, which was only 46,865 GPa without adding the filler of chicken egg shells

  11. Hardness of resin cement cured under different thickness of lithium disilicate-based ceramic

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuan; WANG Fu

    2011-01-01

    Background The lithium disilicate-based ceramic is a newly developed all-ceramic material,which is lithium disilicate-based and could be used for fabricating almost all kinds of restorations.The extent of light attenuation by ceramic material was material-dependent.Ceramic materials with different crystal composition or crystalline content would exhibit distinct light-absorbing characteristics.The aim of this study was to analyze the influence of ceramic thickness and light-curing time on the polymerization of a dual-curing resin luting material with a lithium disilicate-based ceramic.Methods A lithium disilicate-based ceramic was used in this study.The light attenuation caused by ceramic with different thickness was determined using a spectral radiometer.The commercial dual-cured resin cement was light-cured directly or through ceramic discs with different thickness (1,2 and 3 mm,respectively) for different times (10,20,30,40,50 and 60 seconds,respectively).The polymerization efficiency of resin cement was expressed in terms as Vickers hardness (VHN) measured after 24 hours storage.Two-way analysis of variance (ANOVA) and Tukey's HSD tests were used to determine differences.Results Intensity of polymerizing light transmitted through ceramic discs was reduced from 584 mW/cm2 to about 216 mW/cm2,80 mW/cm2 and 52 mW/cm2 at thicknesses of 1 mm,2 mm and 3 mm,respectively.Resin cement specimens self-cured alone showed significantly lower hardness values.When resin cement was light-cured through ceramic discs with a thickness of 1 mm,2 mm and 3 mm,no further increasing in hardness values was observed when light-curing time was more than 30 seconds,40 seconds and 60 seconds,respectively.Conclusions Within the limitation of the present study,ceramic thickness and light-curing time had remarkable influence on the polymerization of dual-cured resin cement.When resin cement is light-cured beneath a lithium disilicate ceramic with different thickness,prolonging light

  12. Molecular dynamics simulations of RDX and RDX-based plastic-bonded explosives.

    Science.gov (United States)

    Zhu, Wei; Xiao, Jijun; Zhu, Weihua; Xiao, Heming

    2009-05-30

    Molecular dynamics simulations have been performed to investigate well-known energetic material cyclotrimethylene trinitramine (RDX) crystal and RDX-based plastic-bonded explosives (PBXs) with four typical fluorine-polymers, polyvinylidenedifluoride (PVDF), polychlorotri-fluoroethylene (PCTFE), fluorine rubber (F(2311)), and fluorine resin (F(2314)). The elastic coefficients, mechanical properties, binding energies, and detonation performances are obtained for the RDX crystal and RDX-based PBXs. The results indicate that the mechanical properties of RDX can be effectively improved by blending with a small amount of fluorine polymers and the overall effect of fluorine polymers on the mechanical properties of the PBXs along three crystalline surfaces is (001)>(010) approximately (100) and PVDF is regarded to best improve the mechanical properties of the PBXs on three surfaces. The order of the improvement in the ductibility made by the fluorine polymers on different surfaces is (001) approximately (010)>(100). The average binding energies between different RDX crystalline surfaces and different polymer binders are obtained, and the sequence of the binding energies of the PBXs with the four fluorine polymers on the three different surfaces is varied. Among the polymer binders, PVDF is considered as best one for RDX-based PBXs. The detonation performances of the PBXs decrease in comparison with the pure crystal but are superior to those of TNT.

  13. Properties of silorane-based dental resins and composites containing a stress-reducing monomer.

    Science.gov (United States)

    Eick, J David; Kotha, Shiva P; Chappelow, Cecil C; Kilway, Kathleen V; Giese, Gregory J; Glaros, Alan G; Pinzino, Charles S

    2007-08-01

    To evaluate properties of silorane-based resins and composites containing a stress reducing monomer. Resin mixtures and composites were formulated containing (a) a developmental stress reducing monomer [TOSU; Midwest Research Institute]; (b) Sil-Mix (3M-ESPE); (c) photo cationic initiator system. Standard BISGMA/TEGDMA resin (B/T) and composite (Filtek Z250) were used as controls. Polymerization volume change was measured using a NIST mercury dilatometer and polymerization stress using an Enduratec mechanical testing machine. Three point bend tests determined flexural elastic modulus, work of fracture, and ultimate strength (ADA 27; ISO 4049). Fracture toughness was measured using ASTM E399-90. Four groups of resins and composites were tested: Sil-Mix, methacrylate standard, and Sil-Mix with two addition levels of TOSU. An ANOVA was used and significant differences ranked using Student-Newman-Keuls test (alpha=0.05). Polymerization stress values for resins containing TOSU were significantly less than the other materials. Polymerization shrinkage values for Sil-Mix formulations were significantly less than for B/T, but were not different from each other. TOSU-containing formulations generally had somewhat lower mechanical properties values than Sil-Mix or B/T. Polymerization stress values for Sil-Mix-based composites were significantly less as compared to Z250. The 1wt.% TOSU composite had the lowest stress. No difference between composite groups was noted for fracture toughness or work of fracture. For ultimate strength, the 5wt.% TOSU formulation differed significantly from Z250. All Sil-Mix formulations had elastic modulus values significantly different from Z250. The ability of TOSU to reduce polymerization stress without a proportional reduction in mechanical properties provides a basis for improvement of silorane-based composites.

  14. Stohastic Properties of Plasticity Based Constitutive Law for Concrete

    DEFF Research Database (Denmark)

    Frier, Christian; Sørensen, John Dalsgaard

    1998-01-01

    The purpose of this paper is to obtain a stochastic model for the parameters in a constitutive model for concrete based on associated plasticity theory and with emphasis placed on the pre-failure range. The constitutive model is based on a Drucker Prager yield surface augmented by a Rankine cut......-off criterion. The statistics of the material parameters are obtained by applying biaxial test results for plane concrete slabs to the constitutive model using the maximum likelihood method. Response surfaces are used to obtain the statistics for a parameter depending on other previously obtained parameters...

  15. Stochastic Properties of Plasticity Based Constitutive Law for Concrete

    DEFF Research Database (Denmark)

    Frier, Christian; Sørensen, John Dalsgaard

    The purpose of this paper is to obtain a stochastic model for the parameters in a constitutive model for concrete based on associated plasticity theory and with emphasis placed on the pre-failure range. The constitutive model is based on a Drucker Prager yield surface augmented by a Rankine cut......-off criterion. The statistics of the material parameters are obtained by applying biaxial test results for plane concrete slabs to the constitutive model using the maximum likelihood method. Response surfaces are used to obtain the statistics for a parameter depending on other previously obtained parameters...

  16. All-plastic fiber-based pressure sensor.

    Science.gov (United States)

    Bundalo, Ivan-Lazar; Lwin, Richard; Leon-Saval, Sergio; Argyros, Alexander

    2016-02-01

    We present a feasibility study and a prototype of an all-plastic fiber-based pressure sensor. The sensor is based on long period gratings inscribed for the first time to the best of our knowledge by a CO2 laser in polymethyl methacrylate (PMMA) microstructured fibers and coupled to a pod-like transducer that converts pressure to strain. The sensor prototype was characterized for pressures up to 150 mbars, and various parameters related to its construction were also characterized in order to enhance sensitivity. We consider this sensor in the context of future applications in endoscopic pressure sensors.

  17. All-plastic fiber-based pressure sensor

    DEFF Research Database (Denmark)

    Bundalo, Ivan-Lazar; Lwin, Richard; Leon-Saval, Sergio

    2016-01-01

    We present a feasibility study and a prototype of an all-plastic fiber-based pressure sensor. The sensor is based on long period gratings inscribed for the first time to the best of our knowledge by a CO2 laser in polymethyl methacrylate (PMMA) microstructured fibers and coupled to a pod......-like transducer that converts pressure to strain. The sensor prototype was characterized for pressures up to 150 mbars, and various parameters related to its construction were also characterized in order to enhance sensitivity. We consider this sensor in the context of future applications in endoscopic pressure...... sensors....

  18. Plasticizing Effects of Polyamines in Protein-Based Films

    Directory of Open Access Journals (Sweden)

    Mohammed Sabbah

    2017-05-01

    Full Text Available Zeta potential and nanoparticle size were determined on film forming solutions of native and heat-denatured proteins of bitter vetch as a function of pH and of different concentrations of the polyamines spermidine and spermine, both in the absence and presence of the plasticizer glycerol. Our results showed that both polyamines decreased the negative zeta potential of all samples under pH 8.0 as a consequence of their ionic interaction with proteins. At the same time, they enhanced the dimension of nanoparticles under pH 8.0 as a result of macromolecular aggregations. By using native protein solutions, handleable films were obtained only from samples containing either a minimum of 33 mM glycerol or 4 mM spermidine, or both compounds together at lower glycerol concentrations. However, 2 mM spermidine was sufficient to obtain handleable film by using heat-treated samples without glycerol. Conversely, brittle materials were obtained by spermine alone, thus indicating that only spermidine was able to act as an ionic plasticizer. Lastly, both polyamines, mainly spermine, were found able to act as “glycerol-like” plasticizers at concentrations higher than 5 mM under experimental conditions at which their amino groups are undissociated. Our findings open new perspectives in obtaining protein-based films by using aliphatic polycations as components.

  19. Cytotoxicity and cytokine expression induced by silorane and methacrylate-based composite resins

    Science.gov (United States)

    LONGO, Daniele Lucca; PAULA-SILVA, Francisco Wanderley Garcia; FACCIOLI, Lucia Helena; GATÓN-HERNÁNDEZ, Patrícia Maria; de QUEIROZ, Alexandra Mussolino; da SILVA, Léa Assed Bezerra

    2016-01-01

    ABSTRACT The successful use of composite resins in Dentistry depends on physicochemical properties, but also on the biological compatibility of resins, because of the close association between pulp and dentin. Objective The aim of this study was to evaluate cytotoxicity and cytokine production induced by light-cured or non-light-cured methacrylate-based and silorane composite resins in RAW 264.7 macrophages. Material and Methods Cells were stimulated with the extracts from light-cured or non-light-cured composite resins. After incubation for 24 h, cytotoxicity was assessed with the lactate dehydrogenase (LDH) and methyl thiazolyl tetrazolium (MTT) assays, and total protein was quantified using the Lowry method. TNF-α detection was examined with an enzyme-linked immunosorbent assay (ELISA) conducted with cell supernatants after cell stimulation for 6, 12, and 24 h. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s post hoc test (α=0.05). Results KaloreTM and FiltekTM Silorane were cytotoxic with or without light curing (p0.05). However, after 24 h FiltekTM Silorane inhibited the production of TNF-α (p<0.05). Conclusions KaloreTM and FiltekTM Silorane were cytotoxic regardless of light curing. The extract obtained from KaloreTM after 15 days of incubation stimulated the production of TNF-α, unlike that obtained from FiltekTM Silorane. PMID:27556204

  20. Work of adhesion of resin on treated lithia disilicate-based ceramic.

    Science.gov (United States)

    Della Bona, Alvaro; Shen, Chiayi; Anusavice, Kenneth J

    2004-05-01

    This study is to test the hypothesis that chemical etching and silane coating of a ceramic surface will influence the work of adhesion (WA) of adhesive resin to dental ceramic. A hot-pressed lithia disilicate-based ceramic was used as a model material to investigate the influence of probing media and surface treatments on WA using a dynamic contact angle analyzer. Eighty ceramic specimens were randomly divided into eight experimental groups and treated as follows: (1 and 3) as polished; (2 and 4) etched with 9.5% hydrofluoric acid (HF) for 1 min; (5) etched with 4% acidulated phosphate fluoride (APF) for 2 min; (6) silane coated; (7) etched with HF for 1 min and silane coated; (8) etched with APF for 2 min and silane coated. Advancing and receding contact angles (theta(a) and theta(r)) were measured using high purity water (gamma = 72.6 mN/m) for groups 1 and 2, and a liquid resin (gamma = 39.7) for groups 3-8 as probing liquids. The liquid resin medium yielded a lower WA than water. Silanization produced a significantly lower WA (p < 0.001) than non-silanated surfaces. Etching alone consistently yielded a greater WA for all surface treatments (p < 0.001). The silanated ceramic surface exhibited a lower surface energy and did not enhance bonding to the liquid resin by work of adhesion.

  1. Staining susceptibility of methacrylate and silorane-based materials: influence of resin type and storage time

    Directory of Open Access Journals (Sweden)

    Leonardo Fernandes da Cunha

    2013-06-01

    Full Text Available Introduction: The color stability of composite resins is a fundamental factor in their clinical behavior. Objective: To evaluate the color stability of composite resins of different colors exposed to a cola-based soft drink after different storage periods. Additionally, three methacrylate-based materials and one silorane-based material were evaluated. Material and methods: Specimens of three methacrylate-based materials (Opallis EA3, DA3 and T-Neutral; Filtek Supreme XT A3E, A3D and CT; 4 Seasons A3 Enamel, A3 Dentin and High Value and one silorane-based material (Filtek P90 A3 were prepared, light-cured for 40 s, and manually polished with Sof-Lex discs. Samples were stored for 1 h, 24 h or 7 days. The color was evaluated by CIE-Lab system before and after immersion for 10 min in a cola-based soft drink. Color variation (∆E was calculated from individual values of L*, a* and b*, being considered imperceptible when < 1, clinically acceptable when ≤ 3.3, and clinically inacceptable when higher than 3.3. Data were evaluated by two-way Anova and Dunnett’s T3 tests (α = 0.05. Results: There were differences among the resins (p < 0.001, with an interaction effect being also observed (p < 0.001. Storage time was not significant (p = 0.246. P90 showed a ∆E smaller than one unit at all studied times. Supreme XT CT and 4 Seasons High Value showed higher ∆E, but not above the critical value of 3.3. The only material that showed ∆E higher than 3.3 was Opallis DA3 after 1 h of storage. Conclusion: The silorane-based composite resin showed smaller ∆E at the times studied.

  2. Characterisation of plastic packaging waste for recycling: problems related to current approaches

    DEFF Research Database (Denmark)

    Götze, Ramona; Astrup, Thomas Fruergaard

    2013-01-01

    were addressed by a resin type-based sorting analysis and a washing test for plastic packaging material from Danish household waste. Preliminary results show that, for a quarter of the hand sorted material, no resin type could be identified and that Polypropylene and Polyethylene terephthalate were...... criteria of recycling processes. A lack of information in current waste characterisation practise on polymer resin composition, black coloured material content and the influence of surface adherent material on physico-chemical characteristics of plastic packaging waste were identified. These shortcomings...... the dominating resin types in plastic packaging. The suggested washing procedure caused a decrease of 70% of the ash content of the plastic material. The analysed metals and nutrients were reduced by up to 24%...

  3. Allergic effects of the residual monomer used in denture base acrylic resins

    Science.gov (United States)

    Rashid, Haroon; Sheikh, Zeeshan; Vohra, Fahim

    2015-01-01

    Denture base resins are extensively used in dentistry for a variety of purposes. These materials can be classified as chemical, heat, light, and microwave polymerization materials depending upon the factor which starts the polymerization reaction. Their applications include use during denture base construction, relining existing dentures, and for fabrication of orthodontic removable appliances. There have been increased concerns regarding the safe clinical application of these materials as their biodegradation in the oral environment leads to harmful effects. Along with local side effects, the materials have certain occupational hazards, and numerous studies can be found in the literature mentioning those. The purpose of this article is to outline the cytotoxic consequences of denture base acrylic resins and clinical recommendations for their use. PMID:26929705

  4. Polycyclic Aromatic Hydrocarbons (PAHs) and Hopanes in Plastic Resin Pellets as Markers of Oil Pollution via International Pellet Watch Monitoring.

    Science.gov (United States)

    Yeo, Bee Geok; Takada, Hideshige; Hosoda, Junki; Kondo, Atsuko; Yamashita, Rei; Saha, Mahua; Maes, Thomas

    2017-08-01

    Oil pollution in the marine environment is an unavoidable problem due to chronic input from local sources, particularly in urban areas and oil spills. Oil pollution not only causes immediate physical damages to surrounding wildlife but also some components, including higher molecular weight PAHs, can persist in the environment for many years and pose insidious threats to the ecosystem. Long-term and nontargeted monitoring of oil pollution is important. This paper examines the ability of International Pellet Watch (IPW) for initial identification and monitoring of oil pollution by analysing PAHs and hopanes in plastic pellet samples collected globally by volunteers. PAH concentrations with the sum of 28 parent and methyl PAHs vary geographically, ranging from 0.035 to 24.4 µg/g-pellet, in line with the presence or absence of local oil pollution sources, such as oil refineries or oil spill sites. This suggests that PAHs can be used to monitor petroleum pollution in IPW. A colour-coded categorization for PAH concentrations within IPW monitoring also is established to facilitate data presentation and understanding. PAH concentrations are generally higher in Western Europe, especially around the North Sea shorelines, moderate in East Asia and North America, and lower in South East Asia, Oceania, South America, and Africa. Hopane concentrations, with a smaller spatial variation (1.7-101 µg/g-pellet), showed no spatial pattern. This result and the poor correlation between hopanes and PAHs suggest that hopane concentrations alone are unsuited to identify petroleum pollution. However, hopane compositions can be used for fingerprinting sources of oil pollution. Thus, both PAHs and hopanes in IPW allow for low cost, remote monitoring of global oil pollution.

  5. Effect of different solutions on color stability of acrylic resin-based dentures

    Directory of Open Access Journals (Sweden)

    Marcelo Coelho Goiato

    2014-01-01

    Full Text Available The aim of this study was to evaluate the effect of thermocycling and immersion in mouthwash or beverage solutions on the color stability of four different acrylic resin-based dentures (Onda Cryl, OC; QC20, QC; Classico, CL; and Lucitone, LU. The factors evaluated were type of acrylic resin, immersion time, and solution (mouthwash or beverage. A total of 224 denture samples were fabricated. For each type of resin, eight samples were immersed in mouthwashes (Plax-Colgate, PC; Listerine, LI; and Oral-B, OB, beverages (coffee, CP; cola, C; and wine, W, and artificial saliva (AS; control. The color change (DE was evaluated before (baseline and after thermocycling (T1, and after immersion in solution for 1 h (T2, 3 h (T3, 24 h (T4, 48 h (T5, and 96 h (T6. The CIE Lab system was used to determine the color changes. The thermocycling test was performed for 5000 cycles. Data were submitted to three-way repeated-measures analysis of variance and Tukey's test (p < 0.05. When the samples were immersed in each mouthwash, all assessed factors, associated or not, significantly influenced the color change values, except there was no association between the mouthwash and acrylic resin. Similarly, when the samples were immersed in each beverage, all studied factors influenced the color change values. In general, regardless of the solution, LU exhibited the greatest DE values in the period from T1 to T5; and QC presented the greatest DE values at T6. Thus, thermocycling and immersion in the various solutions influenced the color stability of acrylic resins and QC showed the greatest color alteration.

  6. Analysis of a plastic optical fiber-based displacement sensor.

    Science.gov (United States)

    Jiménez, Felipe; Arrue, Jon; Aldabaldetreku, Gotzon; Durana, Gaizka; Zubia, Joseba; Ziemann, Olaf; Bunge, Christian-Alexander

    2007-09-01

    An easy-to-manufacture setup for a displacement sensor based on plastic optical fiber (POF) is analyzed, showing computational and experimental results. If the displacement is the consequence of force or pressure applied to the device, this can be used as a force or pressure transducer. Its principle of operation consists of bending a POF section around a flexible cylinder and measuring light attenuation when the whole set is subjected to side pressure. Attenuations are obtained computationally as a function of side deformation for different design parameters. Experimental results with an actually built prototype are also provided.

  7. Concomitant contact allergy to the resins, reactive diluents and hardener of a bisphenol A/F-based epoxy resin in subway construction workers.

    Science.gov (United States)

    Chu, Chia-Yu; Pontén, Ann; Sun, Chee-Ching; Jee, Shiou-Hwa

    2006-03-01

    An outbreak of suspected contact dermatitis among subway construction workers was suspected to be due to a new bisphenol A/F-based epoxy resin system (ERS). The construction workers used ERSs during the insertion of iron bars into concrete walls. The objective of the study was to determine the components (if any) of the ERS responsible for the contact allergy. Patch testing was performed on 20 of the 22 construction workers who had had contact with the ERS, and to the various subcomponents of component A on 5 of the 7 who reacted to this component. 9 patients (9/22, 40.9%) had clinical symptoms and signs of suspected contact dermatitis at presentation. 7 of these 9, but none of the 11 asymptomatic individuals, were positive to component A, while all were negative to component B. Of the 5 cases receiving further patch testing, all reacted to m-xylylene diamine, 4 to 1,6-hexanediol diglycidyl ether, 3 to epoxy resins of the bisphenol F-type and trimethylolpropane triglycidyl ether 0.25% petrolatum, and only 1 to epoxy resins of the bisphenol A-type. Contact allergy to ERSs may involve hardeners and diluents as well as resins, and patch testing for reaction to all components should be performed.

  8. Improving water resistance of wheat straw-based medium density fiberboards bonded with aminoplastic and phenolic resins

    Directory of Open Access Journals (Sweden)

    Laborie, M.-P. G.

    2007-05-01

    Full Text Available A long standing problem in the manufacture of wheat-straw based composites with cost-effective formaldehyde-based resins is their poor water resistance as demonstrated by their large water thickness swell. In this study, wheat straw based medium density fiberboards were manufactured using 3 resin/wax systems: a melamine-urea-formalde-hyde resin with either low or high wax content, and a phenol-formal-dehyde resin with low wax content. The flexural properties, internal bond strength, and thickness swell of the resulting composites were evaluated and compared according to ASTM methods. The three MDF compos-ites passed the requirements for MDF in interior application, except for the MDF manufactured with the aminoplastic resin and low wax content that failed to provide acceptable thickness swell. Using the phenolic resin in combination with low wax content resulted in a higher grade MDF composite, grade 120, than with the aminoplastic and high wax content. This study demonstrates that wheat straw based MDF manu-factured with cost-effective aminoplastic and phenolic resins can have flexural properties, internal bond strength and thickness swell perfor-mance above the requirements from the American National Standards Institute.

  9. Reinforcement of Aluminum Oxide Filler on the Flexural Strength of Different Types of Denture Base Resins: An In vitro Study.

    Science.gov (United States)

    Dhole, Rohit I; Srivatsa, G; Shetty, Rohit; Huddar, Dayanand; Sankeshwari, Banashree; Chopade, Swapnil

    2017-04-01

    Acrylic resins have been used extensively for the fabrication of denture bases because of their aesthetic qualities, ease of manipulation and repairability. Flexural fatigue of the denture base has been shown to be a factor in the clinical failure of polymethyl methacrylate resin dentures. Also, the fracture can result from impact, fatigue or degradation of the base material. Hence, there is a need to increase the strength of denture base resins. To evaluate the effect of reinforcing alumina oxide filler on the flexural strength of different acrylic resins. A total of 180 acrylic specimens were fabricated, which were divided into three groups self cure acrylic resin (SC), conventional heat cure resin (HC) and high strength heat cure resin (HI). Each group was divided into four subgroups i.e., control group and the specimens of the remaining three groups were reinforced with aluminum oxide (Al2O3) powder by 5%, 10% and 15% by weight. Specimens were stored in distilled water for one week; flexural strength was tested by universal testing machine. Results were analysed by one-way analysis of variance and post-hoc Tukey paired group comparison tests. Flexural strength of SC increased by 9%, 13% and 19%, Flexural strength of HC increased by 8%, 15% and 19% and that of HI increased by 21%, 26% and 29% compared to control group by adding 5%,10% and 15% of alumina filler (p-value lead to more clinical success.

  10. Effects of ethanol on the surface and bulk properties of a microwave-processed PMMA denture base resin.

    Science.gov (United States)

    Regis, Rômulo Rocha; Soriani, Natércia Carreira; Azevedo, Alessandra Miranda; Silva-Lovato, Cláudia Helena; Paranhos, Helena Freitas Oliveira; de Souza, Raphael Freitas

    2009-08-01

    This study evaluated the effect of different concentrations of ethanol on hardness, roughness, flexural strength, and color stability of a denture base material using a microwave-processed acrylic resin as a model system. Sixty circular (14 x 4 mm) and 60 rectangular microwave-polymerized acrylic resin specimens (65 x 10 x 3 mm(3)) were employed in this study. The sample was divided into six groups according to the ethanol concentrations used in the immersion solution, as follows: 0% (water), 4.5%, 10%, 19%, 42%, and 100%. The specimens remained immersed for 30 days at 37 degrees C. The hardness test was performed by a hardness tester equipped with a Vickers diamond penetrator, and a surface roughness tester was used to measure the surface roughness of the specimens. Flexural strength testing was carried out on a universal testing machine. Color alterations (DeltaE) were measured by a portable spectrophotometer after 12 and 30 days. Variables were analyzed by ANOVA/Tukey's test (alpha= 0.05). For the range of ethanol-water solutions for immersion (water only, 4.5%, 10%, 19.5%, 42%, and 100%), the following results were obtained for hardness (13.9 +/- 2.0, 12.1 +/- 0.7, 12.9 +/- 0.9, 11.2 +/- 1.5, 5.7 +/- 0.3, 2.7 +/- 0.5 VHN), roughness (0.13 +/- 0.01, 0.15 +/- 0.07, 0.13 +/- 0.05, 0.13 +/- 0.02, 0.23 +/- 0.05, 0.41 +/- 0.19 mum), flexural strength (90 +/- 12, 103 +/- 18, 107 +/- 16, 90 +/- 25, 86 +/- 22, 8 +/- 2 MPa), and color (0.8 +/- 0.6, 0.8 +/- 0.3, 0.7 +/- 0.4, 0.9 +/- 0.3, 1.3 +/- 0.3, 3.9 +/- 1.5 DeltaE) after 30 days. The findings of this study showed that the ethanol concentrations of tested drinks affect the physical properties of the investigated acrylic resin. An obvious plasticizing effect was found, which could lead to a lower in vivo durability associated with alcohol consumption.

  11. Study on Transferring for PF_6 Plasticized PVC Paste Resin Film%[bmim]PF_6增塑PVC糊树脂膜迁移规律研究

    Institute of Scientific and Technical Information of China (English)

    江炜; 刘江涛

    2012-01-01

    文章应用固相萃取、液相色谱联用技术,研究了[bmim]PF6增塑PVC糊树脂膜中的[bmim]PF6在水环境及低酒精含量模拟溶剂(15%乙醇-水溶液)中的迁移规律,同时研究了[bmim]PF6迁移对薄膜力学性能的影响。结果表明:时间和温度对[bmim]PF6向水环境中迁移均有加速效应,在中性条件下迁移量较小,在酸性和碱性条件下迁移量较大。[bmim]PF6在低酒精含量模拟溶剂中与浸泡在去离子水中的薄膜迁移量相比,迁移量明显降低。增塑剂迁出后PVC糊树脂膜的断裂伸长率降低,弹性模量、拉伸强度均升高,可望用于医疗制品的开。%Transfer of plasticizers in water and simulated solvent of low-alcohol were studied by using solid-phase-extraction and high-performance-liquid-chromatography.Effect of plasticizer transfer on mechanical properties of the film was studied.The result showed that the operating conditions such as temperature and macerating time had a great accelerated effect on it.There was smaller migration in the neutral conditions,however,the migrations were volume in acidic and alkaline conditions.Compared with in the water environment,the migration was reduced evidenced in the simulated solvent of low-alcohol.The tensile strength and elastic moduli hoisted;and their elongation at break were dropped obviously.After transferring,the tensile strength and elastic moduli of PVC paste resin films' were hoisted,and their elongation at break dropped obviously.

  12. Biodegradable and bio-based polymers: future prospects of eco-friendly plastics.

    Science.gov (United States)

    Iwata, Tadahisa

    2015-03-09

    Currently used plastics are mostly produced from petrochemical products, but there is a growing demand for eco-friendly plastics. The use of bio-based plastics, which are produced from renewable resources, and biodegradable plastics, which are degraded in the environment, will lead to a more sustainable society and help us solve global environmental and waste management problems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Effect of aggressive beverage on the color stability of different nano-hybrid resin based composite

    Directory of Open Access Journals (Sweden)

    Hicham Oday Nuaimi

    2014-01-01

    Full Text Available Background: The purpose of this study was to evaluate the color stability of different types of nano-hybrid resin based composite restorative materials upon exposure to aggressive staining solutions (coffee and tea over time. The color of all specimens before and after storage in the solutions were measured by a spectrophotometer based on CIE Lab system that is recommended by the American Dental Association and the color differences thereby is calculated. Materials and Methods: The color differences of three nano-hybrid composites after immersion for 30 days in tea and coffee as aggressive beverage solutions. Results: Within the limitations of the study, Venus Diamond was found the most color stable in tea, while Ceram X was shown the most color stable in coffee. There were statistically significant differences between Filtek 350 XT in tea and coffee storage (P 0.005. Conclusion: Staining solutions are significant factors that affect color stability of composite resins.

  14. Staining of resin-based veneering materials with coffee and tea.

    Science.gov (United States)

    Um, C M; Ruyter, I E

    1991-05-01

    Two light-activated, and three heat-polymerized, resin-based veneering materials were exposed to boiled coffee, filtered coffee, or tea at 50 degrees C and evaluated for color stability. Specimens immersed in distilled water in the dark at 37 degrees C for 4 months were also assessed. One of the light-activated, resin-based veneering materials underwent intrinsic discoloration during the long-term immersion both in distilled water and in the staining solutions. The discoloration of the other materials by tea was mainly due to surface adsorption of the colorants. Discoloration by coffee was due to adsorption, and also to absorption of colorants by two of the materials investigated. This absorption and penetration of colorants into the organic phase of the veneering materials were probably due to compatibility of the polymer phase with the yellow colorants of coffee.

  15. Production and characterization of MDF using eucalyptus fibers and castor oil-based polyurethane resin

    Directory of Open Access Journals (Sweden)

    Campos Cristiane Inácio de

    2004-01-01

    Full Text Available The growing popularity of wooden panels renders this market segment increasingly competitive. MDF (Medium Density Fiberboard, in particular, is widely employed for a variety of applications, including civil construction, furniture, and packaging. This paper discusses a study of MDF produced from alternative raw materials, i.e., Eucalyptus fibers and castor-oil-based polyurethane resin. Physical and mechanical tests were performed to determine the MDF's modulus of elasticity and modulus of rupture in static bending tests, its swelling, water absorption, moisture and density. The results of the physical and mechanical characterization of this laboratory-produced MDF are discussed and compared with the Euro MDF Board standard. MDF produced with eucalyptus fiber and castor-oil-based polyurethane resin presents results very satisfactory.

  16. The biocompatibility evaluation of epoxy resin-based root canal sealers in vitro.

    Science.gov (United States)

    Huang, Tsui-Hsien; Yang, Jaw-Ji; Li, Huei; Kao, Chia-Tze

    2002-01-01

    The cytotoxic and mutagenic effects of epoxy resin-based root canal sealer AH26 and AH-Plus were determined in vitro. Root canal sealers were eluted for 24 h in dimethyl sulfoxide (DMSO) and diluted in culture medium. Cytotoxic effects were assessed using the MTT [tetrazolium dye, 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide, C18H16N5SBr] assay for mitochondrial enzyme activity and also the cell viability. Genotoxicity assays were assessed using the alkaline single cell gel electrophoresis assay (comet assay) for DNA damage measurement. Result indicated that both the AH26 and AH-Plus sealers exhibited a dose-dependent increase in astrocyte toxic effects. Additionally, dose-dependent astrocyte DNA damage was also noted for both sealers. Therefore, these epoxy resin-based sealers, AH26 and AH-Plus demonstrated both cytotoxicity and genotoxicity in vitro.

  17. Evaluation of chitosan quaternary ammonium salt-modified resin denture base material.

    Science.gov (United States)

    Song, Rong; Zhong, Zhaohua; Lin, Lexun

    2016-04-01

    Chitosan quaternary ammonium salt displays good antioxidant and antibacterial characteristics and it shows appreciable solubility in water. When added to the traditional denture material to form a resin base, it could promote good oral health by improving the oral environment. In this study, chitosan quaternary ammonium salt was added to the denture material following two different methods. After three months of immersion in artificial saliva, the specimens were tested for tensile strength and were scanned by electron microscope. The murine fibroblast cytotoxicity and antibacterial properties were also tested. The result showed no significant differences in the tensile strength and in the proliferation of murine L929 fibroblast cells. The two structures of chitosan quaternary ammonium salt-modified denture material had different degrees of corrosion resistance and antimicrobial properties. These results indicate that chitosan quaternary ammonium salt-modified resin denture base material has the potential to become a new generation oral denture composite material.

  18. Polymerization and Structure of Bio-Based Plastics: A Computer Simulation

    Science.gov (United States)

    Khot, Shrikant N.; Wool, Richard P.

    2001-03-01

    We recently examined several hundred chemical pathways to convert chemically functionalized plant oil triglycerides, monoglycerides and reactive diluents into high performance plastics with a broad range of properties (US Patent No. 6,121,398). The resulting polymers had linear, branched, light- and highly-crosslinked chain architectures and could be used as pressure sensitive adhesives, elastomers and high performance rigid thermoset composite resins. To optimize the molecular design and minimize the number of chemical trials in this system with excess degrees of freedom, we developed a computer simulation of the free radical polymerization process. The triglyceride structure, degree of chemical substitution, mole fractions, fatty acid distribution function, and reaction kinetic parameters were used as initial inputs on a 3d lattice simulation. The evolution of the network fractal structure was computed and used to measure crosslink density, dangling ends, degree of reaction and defects in the lattice. The molecular connectivity was used to determine strength via a vector percolation model of fracture. The simulation permitted the optimal design of new bio-based materials with respect to monomer selection, cure reaction conditions and desired properties. Supported by the National Science Foundation

  19. Isothermal curing of polymer layered silicate nanocomposites based upon epoxy resin by means of anionic homopolymerisation

    OpenAIRE

    Román Concha, Frida Rosario; Calventus Solé, Yolanda; Colomer Vilanova, Pere; Hutchinson, John M.

    2013-01-01

    The use of an initiator, 4-(dimethylamino) pyridine (DMAP), to promote an anionic homopolymerisation reaction for the isothermal cure of polymer layered silicate (PLS) nanocomposites based on an epoxy resin, as well as the effect of the nanoclay content, have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dielectric relaxation spectroscopy (DRS) and transmission electron microscopy (TEM). The vitrification phenomenon was observed during the isotherm...

  20. Phenol-Formaldehyde Resin-Based Carbons for CO2 Separation at Sub-Atmospheric Pressures

    OpenAIRE

    2016-01-01

    The challenge of developing effective separation and purification technologies that leave much smaller energy footprints is greater for carbon dioxide (CO2) than for other gases. In addition to its involvement in climate change, CO2 is present as an impurity in biogas and bio-hydrogen (biological production by dark fermentation), in post-combustion processes (flue gas, CO2-N2) and many other gas streams. Selected phenol-formaldehyde resin-based activated carbons prepared in our laboratory hav...

  1. The mechanical properties of nanofilled resin-based composites: characterizing discrete filler particles and agglomerates using a micromanipulation technique.

    LENUS (Irish Health Repository)

    Curtis, Andrew R

    2009-02-01

    To assess the mechanical properties of discrete filler particles representative of several inorganic fillers in modern dental resin-based composites (RBCs) and to assess the validity of a novel micromanipulation technique.

  2. Comparison of Shear Bond Strengths of three resin systems for a Base Metal Alloy bonded to

    Directory of Open Access Journals (Sweden)

    Jlali H

    1999-12-01

    Full Text Available Resin-bonded fixed partial dentures (F.P.D can be used for conservative treatment of partially edentulous"npatients. There are numerous studies regarding the strength of resin composite bond to base meta! alloys. Shear bond"nstrength of three resin systems were invistigated. In this study these systems consisted of: Panavia Ex, Mirage FLC and"nMarathon V. Thirty base metal specimens were prepared from rexillium III alloy and divided into three groups. Then each"ngroup was bonded to enamel of human extracted molar teeth with these systems. All of specimens were stored in water at"n37ac for 48 hours. A shear force was applied to each specimen by the instron universal testing machine. A statistical"nevaluation of the data using one-way analysis of variance showed that there was highly significant difference (P<0.01"nbetween the bond strengths of these three groups."nThe base metal specimens bonded with panavia Ex luting agent, exhibited the highest mean bond strength. Shear bond"nstrength of the specimens bonded to enamel with Mirage F1C showed lower bond strenght than panavia EX. However, the"nlowest bond strength was obtained by the specimens bonded with Marathon V.

  3. Effect of different bleaching strategies on microhardness of a silorane-based composite resin

    Science.gov (United States)

    Bahari, Mahmoud; Savadi Oskoee, Siavash; Mohammadi, Narmin; Ebrahimi Chaharom, Mohammad Esmaeel; Godrati, Mostafa; Savadi Oskoee, Ayda

    2016-01-01

    Background. Dentists’ awareness of the effects of bleaching agents on the surface and mechanical properties of restorative materials is of utmost importance. Therefore, this in vitro study was undertaken to investigate the effects of different bleaching strategies on the microhardness of a silorane-based composite resin. Methods. Eighty samples of a silorane-based composite resin (measuring 4 mm in diameter and 2 mm in thickness) were prepared within acrylic molds. The samples were polished and randomly assigned to 4 groups (n=20). Group 1 (controls) were stored in distilled water for 2 weeks. The samples in group 2 underwent a bleaching procedure with 15% carbamide peroxide for two weeks two hours daily. The samples in group 3 were bleached with 35% hydrogen peroxide twice 5 days apart for 30 minutes each time. The samples in group 4 underwent a bleaching procedure with light-activated 35% hydrogen peroxide under LED light once for 40 minutes. Then the microhardness of the samples was determined using Vickers method. Data were analyzed with one-way ANOVA and post hoc Tukey tests (P 0.05). Conclusion. Bleaching agents decreased microhardness of silorane-based composite resin restorations, the magnitude of which depending on the bleaching strategy used. PMID:28096946

  4. Replacing fossil based plastic performance products by bio-based plastic products-Technical feasibility

    NARCIS (Netherlands)

    Oever, van den Martien; Molenveld, Karin

    2016-01-01

    Larger scale market introduction of new bio-based products requires a clear advantage regarding sustainability, as well as an adequate techno-economic positioning relative to fossil based products. In a previous paper [Broeren et al., 2016], LCA results per kg and per functionality equivalent of

  5. Replacing fossil based plastic performance products by bio-based plastic products-Technical feasibility

    NARCIS (Netherlands)

    Oever, van den Martien; Molenveld, Karin

    2017-01-01

    Larger scale market introduction of new bio-based products requires a clear advantage regarding sustainability, as well as an adequate techno-economic positioning relative to fossil based products. In a previous paper [Broeren et al., 2016], LCA results per kg and per functionality equivalent of bio

  6. Properties evaluation of silorane, low-shrinkage, non-flowable and flowable resin-based composites in dentistry

    OpenAIRE

    Maia, Rodrigo R.; Reis, Rodrigo S.; Moro, André F.V.; Perez, Cesar R.; Bárbara M. Pessôa; Dias, Katia R.H.C.

    2015-01-01

    Purpose. This study tested the null hypothesis that different classes of direct restorative dental materials: silorane-based resin, low-shrinkage and conventional (non-flowable and flowable) resin-based composite (RBC) do not differ from each other with regard to polymerization shrinkage, depth of cure or microhardness. Methods. 140 RBC samples were fabricated and tested by one calibrated operator. Polymerization shrinkage was measured using a gas pycnometer both before and immediately after ...

  7. Properties of unidirectional GFRPs based on an epoxy resin modified with polysulphone or an epoxyurethane oligomer

    Science.gov (United States)

    Solodilov, V. I.; Gorbatkina, Yu. A.

    2006-11-01

    The mechanical properties of unidirectional GFRPs based on an ED-22 epoxy resin were investigated. The resin was modified with a PSK-1 polysulphone or a PEF-3a epoxyurethane oligomer. Triethanolaminotitanate or diaminodiphenilsulphone was used as a hardener. The modification did not improve the mechanical properties of GFRPs in quasi-static loading; but in a low-speed impact loading, the shear strength of epoxypolysulphone GFRPs with 20 wt.% PSK-1 increased by 20-25%. For all the GFRPs investigated, the shear strength grew linearly with the logarithm of loading rate. The introduction of the modifiers increased the fracture toughness considerably: by 100 and 70% for GFRPs modified with 20 wt.% PSK-1 and 50 wt.% PEF-3a, respectively.

  8. A Statistics-Based Cracking Criterion of Resin-Bonded Silica Sand for Casting Process Simulation

    Science.gov (United States)

    Wang, Huimin; Lu, Yan; Ripplinger, Keith; Detwiler, Duane; Luo, Alan A.

    2017-02-01

    Cracking of sand molds/cores can result in many casting defects such as veining. A robust cracking criterion is needed in casting process simulation for predicting/controlling such defects. A cracking probability map, relating to fracture stress and effective volume, was proposed for resin-bonded silica sand based on Weibull statistics. Three-point bending test results of sand samples were used to generate the cracking map and set up a safety line for cracking criterion. Tensile test results confirmed the accuracy of the safety line for cracking prediction. A laboratory casting experiment was designed and carried out to predict cracking of a cup mold during aluminum casting. The stress-strain behavior and the effective volume of the cup molds were calculated using a finite element analysis code ProCAST®. Furthermore, an energy dispersive spectroscopy fractographic examination of the sand samples confirmed the binder cracking in resin-bonded silica sand.

  9. Genotoxicity and cytotoxicity of the epoxy resin-based root canal sealer AH plus.

    Science.gov (United States)

    Leyhausen, G; Heil, J; Reifferscheid, G; Waldmann, P; Geurtsen, W

    1999-02-01

    Previous studies with four rapid in vitro and in vivo test systems have shown that the epoxy resin-based root canal sealer AH26 may be genotoxic and cytotoxic (9). The purpose of this study was to determine the cytotoxic and genotoxic effects of the new resinous root canal sealer AH Plus by means of the growth inhibition test with primary human periodontal ligament fibroblasts and permanent 3T3 monolayers, the procaryotic umu test, the eucaryotic DNA synthesis inhibition test, and the in vivo alkaline filter elution test. In addition, Ames tests were performed with extracts from AH Plus. AH Plus caused only slight or no cellular injuries. Furthermore, no genotoxicity and mutagenicity were revealed by AH Plus. These data should be taken into consideration when deciding about a root canal sealer.

  10. Time-related surface modification of denture base acrylic resin treated by atmospheric pressure cold plasma.

    Science.gov (United States)

    Qian, Kun; Pan, Hong; Li, Yinglong; Wang, Guomin; Zhang, Jue; Pan, Jie

    2016-01-01

    The changes of denture base acrylic resin surface properties under cold plasma and the relationships with time were investigated. Cold plasma treated the specimens for 30 s, 60 s, 90 s, and 120 s, respectively. Water contact angles were measured immediately after the treatment, 48 h, 15 days and 30 days later. Surface roughness was measured with 3-D laser scanning microscope. Candida albicans adherence was evaluated by CFU counting. Chemical composition was monitored by X-ray photoelectron spectroscopy analysis. Water contact angle reduced after treated for 30 s. No changes were observed with time prolonged, except the durability. There were no differences in roughness among all groups. However, treatment groups showed significantly lower C. albicans adherence. XPS demonstrated a decrease in C/O, and this reduction was affected by treatment time. Cold plasma was an effective means of increasing hydrophilicity of acrylic resin and reducing C. albicans adherence without affecting physical properties.

  11. Water sorption of CH3- and CF3-Bis-GMA based resins with additives

    Directory of Open Access Journals (Sweden)

    Anuradha Prakki

    2012-08-01

    Full Text Available OBJECTIVES: To evaluate the effect of additives on the water sorption characteristics of Bis-GMA based copolymers and composites containing TEGDMA, CH3Bis-GMA or CF3Bis-GMA. MATERIAL AND METHODS: Fifteen experimental copolymers and corresponding composites were prepared combining Bis-GMA and TEGDMA, CH3Bis-GMA or CF3Bis-GMA, with aldehyde or diketone (24 and 32 mol% totaling 30 groups. For composites, barium aluminosilicate glass and pyrogenic silica was added to comonomer mixtures. Photopolymerization was effected by 0.2 wt% each of camphorquinone and N,N-dimethyl-p-toluidine. Specimen densities in dry and water saturated conditions were obtained by Archimedes' method. Water sorption and desorption were evaluated in a desorption-sorption-desorption cycle. Water uptake (%WU, water desorption (%WD, equilibrium solubility (ES; µg/mm³, swelling (f and volume increase (%V were calculated using appropriate equations. RESULTS: All resins with additives had increased %WU and ES. TEGDMA-containing systems presented higher %WU, %WD, ES, f and %V values, followed by resins based on CH3Bis-GMA and CF3Bis-GMA. CONCLUSIONS: Aldehyde and diketone led to increases in the water sorption characteristics of experimental resins.

  12. Dimensional changes of acrylic resin denture bases: conventional versus injection-molding technique.

    Directory of Open Access Journals (Sweden)

    Jafar Gharechahi

    2014-08-01

    Full Text Available Acrylic resin denture bases undergo dimensional changes during polymerization. Injection molding techniques are reported to reduce these changes and thereby improve physical properties of denture bases. The aim of this study was to compare dimensional changes of specimens processed by conventional and injection-molding techniques.SR-Ivocap Triplex Hot resin was used for conventional pressure-packed and SR-Ivocap High Impact was used for injection-molding techniques. After processing, all the specimens were stored in distilled water at room temperature until measured. For dimensional accuracy evaluation, measurements were recorded at 24-hour, 48-hour and 12-day intervals using a digital caliper with an accuracy of 0.01 mm. Statistical analysis was carried out by SPSS (SPSS Inc., Chicago, IL, USA using t-test and repeated-measures ANOVA. Statistical significance was defined at P<0.05.After each water storage period, the acrylic specimens produced by injection exhibited less dimensional changes compared to those produced by the conventional technique. Curing shrinkage was compensated by water sorption with an increase in water storage time decreasing dimensional changes.Within the limitations of this study, dimensional changes of acrylic resin specimens were influenced by the molding technique used and SR-Ivocap injection procedure exhibited higher dimensional accuracy compared to conventional molding.

  13. SORPTION AND SOLUBILITY OF LOW-SHRINKAGE RESIN-BASED DENTAL COMPOSITES

    Directory of Open Access Journals (Sweden)

    Sevda Yantcheva

    2016-04-01

    Full Text Available Background: Resin-based composites are well-established restorative materials. However, these materials may absorb significant amounts of water when exposed to aqueous environments. Sorption and solubility are affecting composite restorations by two different mechanisms; the first is the up taking of water producing an increased weight and the second is the dissolution of materials in water, leading to a weight reduction of the final conditioned samples. Objective: To measure the water sorption and solubility of different low-shrinkage resin-based composites. Six materials were selected: Filtek P60, Filtek Ultimate, SonicFill, Filtek Silorane, Kalore and Venus Diamond. Materials and methods: Five disc specimens were prepared of each material and polymerized with diode light-curing unit. Water sorption and solubility of the different materials were were calculated by means of weighting the samples before and after water immersion and desiccation. Data were statistically analyzed using Shapiro-Wilk One Way Analysis of Variance followed by the Holm-Sidak comparison test . Results: There were significant differences (p<=0.001 between materials regarding sorption and solubility. Regarding sorption F. Silorane showed lowest values, followed by SonicFill, without significant difference between them. Statistical significant differences exist between F. Silorane and F.P60, F. Ultimate, Kalore. Significant differences exist between SonicFill and F. Ultimate. F.Silorane (-0.018 and Kalore (-0.010 showed lowest values of solubility but there were marginal difference among all composites investigated. Conclusions: 1.The material with lowest values of sorption and solubility was F.Silorane. 2. The attained sorption and solubility values for composites are influenced by the differences in resin matrix composition and filler contend. 3. Modifications of dimethacrylate matrix did not minimize significantly sorption and solubility of composites. 4. Besides water

  14. Silorane- and high filled-based"low-shrinkage" resin composites: shrinkage, flexural strength and modulus

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Galvão Arrais

    2013-04-01

    Full Text Available This study compared the volumetric shrinkage (VS, flexural strength (FS and flexural modulus (FM properties of the low-shrinkage resin composite Aelite LS (Bisco to those of Filtek LS (3M ESPE and two regular dimethacrylate-based resin composites, the microfilled Heliomolar (Ivoclar Vivadent and the microhybrid Aelite Universal (Bisco. The composites (n = 5 were placed on the Teflon pedestal of a video-imaging device, and VS was recorded every minute for 5 min after 40 s of light exposure. For the FS and FM tests, resin discs (0.6 mm in thickness and 6.0 mm in diameter were obtained (n = 12 and submitted to a piston-ring biaxial test in a universal testing machine. VS, FS, and FM data were submitted to two-way repeated measures and one-way ANOVA, respectively, followed by Tukey's post-hoc test (a = 5%. Filtek LS showed lower VS than did Aelite LS, which in turn showed lower shrinkage than did the other composites. Aelite Universal and Filtek LS exhibited higher FS than did Heliomolar and Aelite LS, both of which exhibited the highest FM. No significant difference in FM was noted between Filtek LS and Aelite Universal, while Heliomolar exhibited the lowest values. Aelite LS was not as effective as Filtek LS regarding shrinkage, although both low-shrinkage composites showed lower VS than did the other composites. Only Filtek LS exhibited FS and FM comparable to those of the regular microhybrid dimethacrylate-based resin composite.

  15. Effect of Energy Drinks on Discoloration of Silorane- and Dimethacrylate-Based Composite Resins

    Directory of Open Access Journals (Sweden)

    Ghazaleh Ahmadizenouz

    2016-11-01

    Full Text Available Objectives: This study aimed to assess the effects of two energy drinks on color change (∆E of two methacrylate-based and a silorane-based composite resin after one week and one month.Materials and Methods: Thirty cubic samples were fabricated from Filtek P90, Filtek Z250 and Filtek Z350XT composite resins. All the specimens were stored in distilled water at 37°C for 24 hours. Baseline color values (L*a*b* of each specimen were measured using a spectrophotometer according to the CIEL*a*b* color system. Ten randomly selected specimens from each composite were then immersed in the two energy drinks (Hype, Red Bull and artificial saliva (control for one week and one month. Color was re-assessed after each storage period and ∆E values were calculated. The data were analyzed using the Kruskal Wallis and Mann–Whitney U tests.Results: Filtek Z250 composite showed the highest ∆E irrespective of the solutions at both time points. After seven days and one month, the lowest ∆E values were observed in Filtek Z350XT and Filtek P90 composites immersed in artificial saliva, respectively. The ∆E values of Filtek Z250 and Z350XT composites induced by Red Bull and Hype energy drinks were not significantly different. Discoloration of Filtek P90 was higher in Red Bull energy drink at both time points.Conclusions: Prolonged immersion time in all three solutions increased ∆E values of all composites. However, the ∆E values were within the clinically acceptable range (<3.3 at both time points.Keywords: Color; Composite Resins; Energy Drinks; Silorane Composite Resin; Spectrophotometry

  16. Sensitivity of catalyst/base ratio on curing of resin luting agents: polymerization exotherm analysis.

    Science.gov (United States)

    Griggs, J A; Shen, C; Anusavice, K J

    1994-09-01

    Currently, the proposed test of the International Standardization Organization (ISO) for measuring working and setting times of resin luting agents is based on measurement of times to reach specified stages on the polymerization exotherm. The objective of this study was to use this test to investigate the influence of variations in the mass ratios of catalyst paste to base paste on the working and setting times of three dual-cured dental resin luting agents. The materials used were Dicor Light Activated Cement (Dentsply International Inc.), Palfique Inlay Resin Cement (Tokuyama Soda Co.), and Vivadent Dual Cement (Vivadent). Fifteen specimens of each material were tested for working time by spatulating mass ratios from 0.7 to 1.3 for 30s at 23 degrees C and recording the time from beginning of spatulation to the time at which a temperature increase occurs. Ten specimens of each material were tested for setting time by spatulating in a similar manner at 37 degrees C and recording the time at which the temperature reaches a maximum value. The data were fitted to the relation, In t = In A + Bm, where t is the time in seconds, m is the mass ratio, and A and B are regression coefficients. The results suggest that working and setting times of the specimens were independent of variations in mass ratio. A comparison among the materials was made by using a multiple linear regression with the relation, In t = In C + Dm + E gamma + Fm gamma, where gamma is a dummy variable to help distinguish between materials, and C, D, E, and F are regression coefficients. The results suggest that differences in materials influence the working time but not the setting time. These results infer that variations in mass ratio (+/- 20%) often observed in the clinical setting should not have a significant influence on the working and setting times of resin luting agents.

  17. L(+-Lactic acid recovery from cassava bagasse based fermented medium using anion exchange resins

    Directory of Open Access Journals (Sweden)

    Rojan P. John

    2008-12-01

    Full Text Available The properties of the ion exchange resins, Amberlite IRA 402, a strong anion exchange resin and IRA 67, a weak anion exchange resin were determined to evaluate their comparative suitability for lactic acid recovery from fermented cassava bagasse. Data on binding capacities and recovery proved that weak base resin in chloride form was the most favourable ones for lactic acid recovery from aqueous solutions and fermentation media. Fermented media obtained through simultaneous saccharification and fermentation of cassava bagasse starch hydrolysate based medium were used for lactic acid recovery study using weak base resin column. Amberlite IRA 67 had much more efficiency than Amberlite IRA 402 to recover lactic acid. Like in other reports, due to the presence of nutrients and ions other than lactate, the binding capacity was slightly lesser while using fermented media (~93% instead of aqueous lactic acid solutions (~98%.As propriedades das resinas de troca iônica, da Amberlite IRA 402, uma resina de troca aniônica forte, e da IRA 67, uma resina de troca aniônica fraca, foram determinadas para se avaliar a adequabilidade comparativa delas à obtenção de ácido lático de bagaço de mandioca fermentado. Dados sobre a capacidade de ligação e sobre a obtenção provaram que a resina de base fraca na forma de cloreto era a mais adequada para a obtenção de ácido lático em soluções aquosas e meios de fermentação. Os meios de fermentação obtidos da sacarificação e da fermentação simultâneas de meios baseados hidrolisados de fécula de bagaço de mandioca foram usados para o estudo da obtenção de ácido lático usando uma coluna de resina de base fraca. A Amberlite IRA 67 mostrou-se muito mais eficaz do que a Amberlite IRA 402 para a obtenção de ácido lático. Como em outros relatórios, devido à presença de nutrientes e íons que não lactatos, a capacidade de ligação foi ligeiramente inferior enquanto se utilizavam meios

  18. Analytical methods for the measurement of polymerization kinetics and stresses of dental resin-based composites: A review

    Science.gov (United States)

    Ghavami-Lahiji, Mehrsima; Hooshmand, Tabassom

    2017-01-01

    Resin-based composites are commonly used restorative materials in dentistry. Such tooth-colored restorations can adhere to the dental tissues. One drawback is that the polymerization shrinkage and induced stresses during the curing procedure is an inherent property of resin composite materials that might impair their performance. This review focuses on the significant developments of laboratory tools in the measurement of polymerization shrinkage and stresses of dental resin-based materials during polymerization. An electronic search of publications from January 1977 to July 2016 was made using ScienceDirect, PubMed, Medline, and Google Scholar databases. The search included only English-language articles. Only studies that performed laboratory methods to evaluate the amount of the polymerization shrinkage and/or stresses of dental resin-based materials during polymerization were selected. The results indicated that various techniques have been introduced with different mechanical/physical bases. Besides, there are factors that may contribute the differences between the various methods in measuring the amount of shrinkages and stresses of resin composites. The search for an ideal and standard apparatus for measuring shrinkage stress and volumetric polymerization shrinkage of resin-based materials in dentistry is still required. Researchers and clinicians must be aware of differences between analytical methods to make proper interpretation and indications of each technique relevant to a clinical situation. PMID:28928776

  19. EFFECT OF FLUORIDE-CONTAINING DESENSITIZING AGENTS ON THE BOND STRENGTH OF RESIN-BASED CEMENTS TO DENTIN

    Science.gov (United States)

    Saraç, Duygu; Külünk, Safak; Saraç, Y. Sinasi; Karakas, Özlem

    2009-01-01

    Objective: The objective of this study was to evaluate the effect of desensitizing agents containing different amounts of fluoride on the shear bond strength of a dual polymerized resin cement and a resin-modified glass ionomer cement (RMGIC) to dentin. Material and Methods: One hundred human molars were mounted in acrylic resin blocks and prepared until the dentin surface was exposed. The specimens were treated with one of four desensitizing agents: Bifluorid 12, Fluoridin, Thermoline and PrepEze. The remaining 20 specimens served as untreated controls. All groups were further divided into 2 subgroups in which a dual polymerized resin cement (Bifix QM) or a resin-modified glass ionomer cement (AVANTO) was used. The shear bond strength (MPa) was measured using a universal testing machine at a 0.5 mm/min crosshead speed. The data were analyzed statistically with a 2-way ANOVA, Tukey HSD test and regression analysis (α=0.05). The effect of the desensitizing agents on the dentin surface was examined by scanning electron microscopy. Results: The fluoride-containing desensitizing agents affected the bond strength of the resin-based cements to dentin (p<0.001). PrepEze showed the highest bond strength values in all groups (p<0.001). Conclusion: Regression analysis showed a reverse relation between bond strength values of resin cements to dentin and the amount of fluoride in the desensitizing agent (p<0.05). PMID:19936532

  20. Effect of resin infiltration on the thermal and mechanical properties of nano-sized silica-based thermal insulation.

    Science.gov (United States)

    Lee, Jae Chun; Kim, Yun-Il; Lee, Dong-Hun; Kim, Won-Jun; Park, Sung; Lee, Dong Bok

    2011-08-01

    Several kinds of nano-sized silica-based thermal insulation were prepared by dry processing of mixtures consisting of fumed silica, ceramic fiber, and a SiC opacifier. Infiltration of phenolic resin solution into the insulation, followed by hot-pressing, was attempted to improve the mechanical strength of the insulation. More than 22% resin content was necessary to increase the strength of the insulation by a factor of two or more. The structural integrity of the resin-infiltrated samples could be maintained, even after resin burn-out, presumably due to reinforcement from ceramic fibers. For all temperature ranges and similar sample bulk density values, the thermal conductivities of the samples after resin burn-out were consistently higher than those of the samples obtained from the dry process. Mercury intrusion curves indicated that the median size of the nanopores formed by primary silica aggregates in the samples after resin burn-out is consistently larger than that of the sample without resin infiltration.

  1. Environmentally Friendly Bio-Based Vinyl Ester Resins for Military Composite Structures

    Science.gov (United States)

    2008-12-01

    Protection Agency, 2003: National Emission Standards for Hazardous Air Pollutants: Reinforced Plastic Composites Production, Federal Register, 68...G.R., 2007: Fatty acid-based vinyl ester composites with low hazardous air pollutant contents, J. of BioBased Matl. and BioEnergy, 1, 409-416

  2. Effect of surface treatments on shear bond strength of denture teeth to denture base resins

    Directory of Open Access Journals (Sweden)

    Farideh Bahrani

    2014-01-01

    Full Text Available Background: Debonding of denture teeth from denture bases is the most common failure in removable dentures. The purpose of this study was to evaluate the effect of surface treatments on shear bond strength of denture teeth to heat-polymerized and autopolymerized denture base resins. Materials and Methods: In this experimental in vitro study, 60 maxillary central incisor acrylic teeth were divided into two groups. Group M was polymerized with heat-polymerized acrylic resin (Meliodent by compression molding technique and group F was processed by autopolymerized acrylic resin (Futura Gen by injection molding technique. Within each group, specimens were divided into three subgroups according to the teeth surface treatments (n = 10: (1 ground surface as the control group (M 1 and F 1 , (2 ground surface combined with monomer application (M 2 and F 2 , and (3 airborne particle abrasion by 50 μm Al 2 O 3 (M 3 and F 3 . The shear bond strengths of the specimens were tested by universal testing machine with crosshead speed of 5 mm/min. Data were analyzed by two-way analysis of variance (ANOVA and Tukey′s honestly significant difference (HSD tests (P < 0.05. Results: The mean shear bond strengths of the studied groups were 96.40 ± 14.01, 124.70 ± 15.64, and 118 ± 16.38 N for M 1 , M 2 , and M 3 and 87.90 ± 13.48, 117 ± 13.88, and 109.70 ± 13.78 N for F 1 , F 2 , and F 3 , respectively. The surface treatment of the denture teeth significantly affected their shear bond strengths to the both the denture base resins (P < 0.001. However, there were no significant differences between the groups treated by monomer or airborne particle abrasion (P = 0.29. The highest percentage of failure mode was mixed in Meliodent and adhesive in Futura Gen. Conclusion: Monomer application and airborne particle abrasion of the ridge lap area of the denture teeth improved their shear bond strengths to the denture base resins regardless of the type of polymerization.

  3. Effect of base monomer's refractive index on curing depth and polymerization conversion of photo-cured resin composites.

    Science.gov (United States)

    Fujita, Kou; Nishiyama, Norihiro; Nemoto, Kimiya; Okada, Tamami; Ikemi, Takuji

    2005-09-01

    In this study, we examined the effect of the transmitted amount of visible light through a resin composite on the curing depth and polymerization conversion. Transmitted amount of visible light was strongly dependent on the magnitude of refractive index difference that existed between the resin and silica filler. More specifically, the differences arose from the type of base monomer used. The transmitted amount of visible light exhibited a good correlation with the curing depth and Knoop hardness ratio of the bottom surface against the top surface of the resin composite. To improve the polymerization conversion of the cavity floor, it is important to reduce the refractive index difference that exists between the base resin and silica filler.

  4. Synthesis, properties and applications of interacting blends of acrylated novalac epoxy resin based poly(ester-amides and vinyl ester

    Directory of Open Access Journals (Sweden)

    Pragnesh N. Dave

    2016-09-01

    Full Text Available Epoxy resin based unsaturated poly(ester-amide resins (UPEAs were prepared by the reported method. These UPEAs were then treated with acryloyl chloride to afford acrylated UPEAs resin (i.e. AUPEAs. Interacting blends of equal proportional AUPEAs and vinyl ester epoxy (VE resin were prepared. APEAs and AUPEAs were characterized by elemental analysis, molecular weight determined by vapor pressure osmometer and by IR spectral study and by thermogravimetry. The curing of interacting blends was monitored on differential scanning calorimeter (DSC. Based on DSC data in situ glass reinforced composites of the resultant blends have been prepared and characterized for mechanical, electrical and chemical properties. Unreinforced blends were characterized by thermogravimetry (TGA.

  5. Selective concentration of aromatic bases from water with a resin adsorbent

    Science.gov (United States)

    Stuber, H.A.; Leenheer, J.A.

    1983-01-01

    Aromatic bases are concentrated from water on columns of a resin adsorbent and recovered by aqueous-acid elution. The degree of concentration attainable depends on the ratio of the capacity factor (k) of the neutral form of the amine to that of the ionized form. Capacity factors of ionic forms of amines on XAD-8 resin (a methylacrylic ester polymer) are greater than zero, ranging from 20 to 250 times lower than those of their neutral forms; they increase with increasing hydrophobicity of the amine. Thus, desorption by acid is an edition (k during desorption >0) rather than a displacement (k during desorption = 0) process. The degree of concentration attainable on XAD-8 resin varies with the hydrophobicity of the amine, being limited for hydrophilic solutes (for example, pyridine) by small neutral-form k's, reaching a maximum for amines of intermediate hydrophobicity (for example, quinoline), and decreasing for more hydrophobc solutes (for example, acridine) because of their large ionic-form k's.

  6. Pilot scale production, characterization, and optimization of epoxidized vegetable oil-based resins

    Science.gov (United States)

    Monono, Ewumbua Menyoli

    Novel epoxidized sucrose soyate (ESS) resins perform much better than other vegetable oil-based resins; thus, they are of current interest for commercial scale production and for a wide range of applications in coatings and polymeric materials. However, no work has been published that successfully scaled-up the reaction above a 1 kg batch size. To achieve this goal, canola oil was first epoxidized at a 300 g scale to study the epoxidation rate and thermal profile at different hydrogen peroxide (H2O2) addition rates, bath temperatures, and reaction times. At least 83% conversion of double bonds to oxirane was achieved by 2.5 h, and the reaction temperature was 8-15 °C higher than the water bath temperature within the first 30-40 min of epoxidation. A 38 L stainless steel kettle was modified as a reactor to produce 10 kg of ESS. Twenty 7-10 kg batches of ESS were produced with an overall 87.5% resin yield and > 98% conversion after batch three. The conversion and resin quality were consistent across the batches due to the modifications on the reaction that improved mixing and reaction temperature control within 55-65 oC. The total production time was reduced from 8 to 4 days due to the fabrication of a 40 L separatory funnel for both washing and filtration. A math model was developed to optimize the epoxidation process. This was done by using the Box-Behnken design to model the conversion at various acetic acid, H2O2, and Amberlite ratios and at various reaction temperatures and times. The model had an adjusted R2 of 97.6% and predicted R2 of 96.8%. The model showed that reagent amounts and time can be reduced by 18% without compromising the desired conversion value and quality.

  7. Highly active, recyclable catalyst for the manufacture of viscous, low molecular weight, CO–ethene–propene-based polyketone, base component for a new class of resins

    NARCIS (Netherlands)

    Broekhuis, Antonius A.; Dirkzwager, Hendrik; Mul, Wilhelmus P.; Heeres, Hero J.; Linden, Adrianus J. van der; Orpen, A. Guy

    2002-01-01

    A highly active, recyclable homogeneous palladium(II) catalyst is described for the manufacture of viscous, low molecular weight CO–ethene–propene-based polyketone (Carilite Oligomer), used for the manufacture of a new class of resins (Carilite Resins). The catalyst is composed of palladium acetate,

  8. Novel bio-based thermoset resins based on epoxidized vegetable oils for structural adhesives

    Science.gov (United States)

    Sivasubramanian, Shivshankar

    Conventional engineered wood composites are bonded for the most part through formaldehyde-based structural adhesives such as urea formaldehyde (UF), melamine formaldehyde (MF), phenol formaldehyde (PF) and resorcinol formaldehyde (RF). Formaldehyde is a known human carcinogen; the occupational exposure and emission after manufacturing of these binders is raising more and more concern. With increasing emphasis on environmental issues, there is clear incentive to replace these hazardous conventional formaldehyde-based binders with cco-friendly resins having similar properties but derived from renewable sources, bearing in mind the economics of the structural wood composite industry. In this thesis, the curing reaction of bio-derived epoxy thermosets with inexpensive, low-toxicity precursors, including polyimines and amino acids was investigated. Epoxidized linseed oil (ELO) and epoxidized soybean oil (ESO) were successfully crosslinked with both branched polyethyleneimine (PEI) and triethylenetetramine (fETA). Epoxidized castor oil (ECO) was crosslinked with polyethyleneimine (PEI), having different molecular weights. Curing conditions were optimized through solvent uptake and soluble fraction analysis. Finally, the mechanical properties of the optimized compositions of rigid bioepoxies were evaluated using dynamic mechanical rheological testing (DMRT). While not as stiff as conventional materials, optimized materials have sufficient room temperature moduli to show promise for coatings and as binders in engineered wood products.

  9. The Use of Commercial Non-Hazardous Air Pollutant Monomers to Optimize the Properties of Fatty Acid-Based Resins

    Science.gov (United States)

    2009-05-01

    Reviewing all of the data, it was found that the di-functional monomers produced resins with lower viscosities, higher modulus, and higher Tg than the...to storage modulus Tg Glass transition temperature of polymer TGA Thermogravimetric analysis UPE Unsaturated polyester VE Vinyl ester...The Use of Commercial Non-Hazardous Air Pollutant Monomers to Optimize the Properties of Fatty Acid-Based Resins by John J. La Scala, Priya

  10. The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations

    Directory of Open Access Journals (Sweden)

    Parnian Alizadeh Oskoee

    2017-03-01

    Full Text Available Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90] and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C. Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P < 0.05. Results. The maximum and minimum gaps were detected in groups 1-A and 2-B, respectively. The effects of composite resin type, preheating and interactive effect of these variables on gap formation were significant (P<0.001. Post-hoc Tukey tests showed greater gap in dimethacrylate compared to silorane composite resins (P< 0.001. In each group, gap values were greater in composite resins at room temperature compared to composite resins after 40 preheating cycles (P<0.001. Conclusion. Gap formation at the gingival margins of Class V cavities decreased due to preheating of both composite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation.

  11. Through Lignin Biodegradation to Lignin-based Plastics

    Science.gov (United States)

    Wang, Yun-Yan

    The consequences of strong noncovalent intermolecular interactions between oligomeric and/or polymeric lignin components are encountered during enzyme-catalyzed lignin degradation and in the properties of lignin-based plastics. A new chapter in the 30-year quest for functional lignin-depolymerizing enzymes has been opened. The lignin-degrading capacity of the flavin-dependent monooxygenase, salicylate hydroxylase acting as a putative lignin depolymerase, has been characterized using a water-soluble native softwood lignin substrate under mildly acidic aqueous conditions. When macromolecular lignins undergo lignin-depolymerase catalyzed degradation, the cleaved components tend to associate with one another, or with nearby associated lignin complexes, through processes mediated by the enzyme acting in a non-catalytic capacity. As a result, the radius of gyration (Rg) falls rapidly to approximately constant values, while the weight-average molecular weight (Mw) of the substrate rises more slowly to an extent dependent on enzyme concentration. Xylanase, when employed in an auxiliary capacity, is able to facilitate dissociation of the foregoing complexes through its interactions with the lignin depolymerase. The flavin-dependent lignin depolymerase must be reduced before reaction with oxygen can occur to form the hydroperoxy intermediate that hydroxylates the lignin substrate prior to cleavage. In the absence of the cofactor, NADH, the necessary reducing power can be provided (albeit more slowly) by the lignin substrate itself. Under such conditions, a simultaneous decrease in R g and Mw is initially observed during the enzymatic process through which the lignin is cleaved. The partially degraded product-lignins arising from lignin depolymerase activity can be readily converted into polymeric materials with mechanical properties that supersede those of polystyrene. Methylation and blending of ball-milled softwood lignins with miscible low-Tg polymers, or simple low

  12. B-Loaded Plastic Scintillator on the Base of Polystyrene

    CERN Document Server

    Brudanin, V B; Nemchenok, I B; Smolnikov, A A

    2000-01-01

    A method to produce polystyrene-based plastic scintillators with boron concentration from 0.38 to 5.0% of boron have been developed. o-Carborane was used as B-containing additive. The results of investigations of the optical, spectral and scintillation characteristics are presented and discussed. It is shown that 5% B-loaded scintillator has a light output as much as 70% relative to the unloaded one. High efficiency for thermal neutron registration achieved for produced samples makes it possible to use such scintillators in complex neutron high sensitive spectrometers. Measured level of radioactive contamination in this scintillation materials is good enough for using the B-loaded scintillators in the proposed large scale neutrino experiments.

  13. Protein-based green resins and nanocomposites from waste residues

    Science.gov (United States)

    Rahman, Muhammad Maksudur

    The main goal of the present research is to design and fabricate 'green' nanocomposites using eco-friendly and biodegradable polymers, an effort driven towards an alternative of conventional petroleum-derived polymers in structural applications considering environmental and economic concerns. The behavior of structure, composition and property relationships between the novel combinations of these materials has been analyzed and discussed. The materials used in this study, many of them from non-edible sources, are obtained, derived and/or synthesized using various wastes from agricultural and food industries, as much as possible, so as to utilize wastes that are discarded at present. At the same time, the use of waste sources reduces the dependency of edible source-based biopolymers in various structural applications and thus, reduces the cost of materials significantly. Overall, this study opens up new avenues in the fabrication of low-cost 'green' nanocomposite with facile and 'green' methodology using various agricultural and food wastes.

  14. Separation of thorium and uranium in nitric acid solution using silica based anion exchange resin.

    Science.gov (United States)

    Chen, Yanliang; Wei, Yuezhou; He, Linfeng; Tang, Fangdong

    2016-09-30

    To separate thorium and uranium in nitric acid solution using anion exchange process, a strong base silica-based anion exchange resin (SiPyR-N4) was synthesized. Batch experiments were conducted and the separation factor of thorium and uranium in 9M nitric acid was about 10. Ion exchange chromatography was applied to separate thorium and uranium in different ratios. Uranium could be eluted by 9M nitric acid and thorium was eluted by 0.1M nitric acid. It was proved that thorium and uranium can be separated and recovered successfully by this method.

  15. Selective separation of mercury(II) using magnetic chitosan resin modified with Schiff's base derived from thiourea and glutaraldehyde.

    Science.gov (United States)

    Donia, Ahmed M; Atia, Asem A; Elwakeel, Khalid Z

    2008-03-01

    Magnetic chitosan resin was chemically modified by a Schiff's base cross-linker. The interaction of the resin obtained with Hg(II) was studied and uptake value of 2.8 mmol/g was reported. The kinetic and thermodynamic parameters of the adsorption process were estimated. These data indicated that the adsorption process is exothermic and follow the pseudo-second-order kinetics. The selectivity of Hg(II) from other different metal ions in solutions using the studied resin was also reported. Breakthrough curves for the recovery of Hg(II) were studied. The critical bed height was found to be 2.05 cm. The adsorbed Hg(II) was eluted from the resin effectively using 0.1 M potassium iodide.

  16. Effect of surface treatment methods on the shear bond strength of auto-polymerized resin to thermoplastic denture base polymer.

    Science.gov (United States)

    Koodaryan, Roodabeh; Hafezeqoran, Ali

    2016-12-01

    Polyamide polymers do not provide sufficient bond strength to auto-polymerized resins for repairing fractured denture or replacing dislodged denture teeth. Limited treatment methods have been developed to improve the bond strength between auto-polymerized reline resins and polyamide denture base materials. The objective of the present study was to evaluate the effect of surface modification by acetic acid on surface characteristics and bond strength of reline resin to polyamide denture base. 84 polyamide specimens were divided into three surface treatment groups (n=28): control (N), silica-coated (S), and acid-treated (A). Two different auto-polymerized reline resins GC and Triplex resins were bonded to the samples (subgroups T and G, respectively, n=14). The specimens were subjected to shear bond strength test after they were stored in distilled water for 1 week and thermo-cycled for 5000 cycles. Data were analyzed with independent t-test, two-way analysis of variance (ANOVA), and Tukey's post hoc multiple comparison test (α=.05). The bond strength values of A and S were significantly higher than those of N (Pauto-polymerized reline resin.

  17. Effect of Antimicrobial Denture Base Resin on Multi-Species Biofilm Formation.

    Science.gov (United States)

    Zhang, Keke; Ren, Biao; Zhou, Xuedong; Xu, Hockin H K; Chen, Yu; Han, Qi; Li, Bolei; Weir, Michael D; Li, Mingyun; Feng, Mingye; Cheng, Lei

    2016-06-29

    Our aims of the research were to study the antimicrobial effect of dimethylaminododecyl methacrylate (DMADDM) modified denture base resin on multi-species biofilms and the biocompatibility of this modified dental material. Candida albicans (C. albicans), Streptococcus mutans (S. mutans), Streptococcus sanguinis (S. sanguinis), as well as Actinomyces naeslundii (A. naeslundii) were used for biofilm formation on denture base resin. Colony forming unit (CFU) counts, microbial viability staining, and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) array were used to evaluate the antimicrobial effect of DMADDM. C. albicans staining and Real-time PCR were used to analyze the morphology and expression of virulence genes of C. albicans in biofilm. Lactate dehydrogenase (LDH) array and Real-time PCR were conducted to examine the results after biofilm co-cultured with epithelial cell. Hematoxylin and eosin (HE) staining followed by histological evaluation were used to study the biocompatibility of this modified material. We found that DMADDM containing groups reduced both biomass and metabolic activity of the biofilm significantly. DMADDM can also inhibit the virulence of C. albicans by means of inhibiting the hyphal development and downregulation of two virulence related genes. DMADDM significantly reduced the cell damage caused by multi-species biofilm according to the LDH activity and reduced the expression of IL-18 gene of the cells simultaneously. The in vivo histological evaluation proved that the addition of DMADDM less than 6.6% in denture material did not increase the inflammatory response (p > 0.05). Therefore, we proposed that the novel denture base resin containing DMADDM may be considered as a new promising therapeutic system against problems caused by microbes on denture base such as denture stomatitis.

  18. Effect of Antimicrobial Denture Base Resin on Multi-Species Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Keke Zhang

    2016-06-01

    Full Text Available Our aims of the research were to study the antimicrobial effect of dimethylaminododecyl methacrylate (DMADDM modified denture base resin on multi-species biofilms and the biocompatibility of this modified dental material. Candida albicans (C. albicans, Streptococcus mutans (S. mutans, Streptococcus sanguinis (S. sanguinis, as well as Actinomyces naeslundii (A. naeslundii were used for biofilm formation on denture base resin. Colony forming unit (CFU counts, microbial viability staining, and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl-2H-tetrazolium-5-carboxanilide (XTT array were used to evaluate the antimicrobial effect of DMADDM. C. albicans staining and Real-time PCR were used to analyze the morphology and expression of virulence genes of C. albicans in biofilm. Lactate dehydrogenase (LDH array and Real-time PCR were conducted to examine the results after biofilm co-cultured with epithelial cell. Hematoxylin and eosin (HE staining followed by histological evaluation were used to study the biocompatibility of this modified material. We found that DMADDM containing groups reduced both biomass and metabolic activity of the biofilm significantly. DMADDM can also inhibit the virulence of C. albicans by means of inhibiting the hyphal development and downregulation of two virulence related genes. DMADDM significantly reduced the cell damage caused by multi-species biofilm according to the LDH activity and reduced the expression of IL-18 gene of the cells simultaneously. The in vivo histological evaluation proved that the addition of DMADDM less than 6.6% in denture material did not increase the inflammatory response (p > 0.05. Therefore, we proposed that the novel denture base resin containing DMADDM may be considered as a new promising therapeutic system against problems caused by microbes on denture base such as denture stomatitis.

  19. Polishing of denture base acrylic resin with chairside polishing kits: an SEM and surface roughness study.

    Science.gov (United States)

    Chatzivasileiou, Konstantinos; Emmanouil, Ioannis; Kotsiomiti, Eleni; Pissiotis, Argirios

    2013-01-01

    Heat-cured acrylic resin specimens were polished using either conventional laboratory polishing, sandpaper, or three commercial chairside kits. The surface roughness of the polished specimens was measured with a contact profilometer. Scanning electron microscopy was used to obtain microphotographs of the polished surfaces. Laboratory polishing produced the smoothest surfaces in all cases, while sandpaper application produced the roughest. Use of the chairside polishing kits resulted in significantly rougher surfaces compared to those produced by laboratory polishing. Nonetheless, polishing of trimmed denture bases using chairside polishing kits is an effective alternative procedure for cases in which the laboratory procedure is not applicable.

  20. Dynamic measurement of local displacements within curing resin-based dental composite using optical coherence elastography

    Science.gov (United States)

    Tomlins, Peter H.; Rahman, Mohammed Wahidur; Donnan, Robert S.

    2016-04-01

    This study aimed to determine the feasibility of using optical coherence elastography to measure internal displacements during the curing phase of a light-activated, resin-based composite material. Displacement vectors were spatially mapped over time within a commercial dental composite. Measurements revealed that the orientation of cure-induced displacement vectors varied spatially in a complex manner; however, each vector showed a systematic evolution with time. Precision of individual displacements was estimated to be ˜1 to 2 μm, enabling submicrometer time-varying displacements to be detected.

  1. Polymerization contraction and conversion of light-curing BisGMA-based methacrylate resins.

    Science.gov (United States)

    Venhoven, B A; de Gee, A J; Davidson, C L

    1993-09-01

    The aim of this study was to investigate the polymerization contraction and the conversion of light-curing methacrylate resins based on bisphenol-A bis(2-hydroxypropyl)methacrylate (BisGMA) diluted with triethylene glycol dimethyacrylate (TEGDMA), methyl methacrylate (MMA), hydroxypropyl methacrylate (HPMA) or (+/-)-2-ethylhexyl methacrylate (EHMA). The contraction measurements were carried out with a linometer, a simple device to determine true linear polymerization contraction of liquid monomers at ambient temperature. The contraction increased with the amount of diluting monomer. The estimated conversion of the BisGMA-TEGDMA, calculated using the contraction, is consistent with literature values. The BisGMA-HPMA mixtures showed high conversions at moderate contraction.

  2. Clinical Study of ENA HRI Plastic Resin Veneers Fix Anterior Tooth Gap%美塑树脂贴面修复前牙间隙的临床研究

    Institute of Scientific and Technical Information of China (English)

    毛晓东; 战策; 袁芳

    2013-01-01

    Objective:To explore Italy and the ENA HRI plastic resin veneers are not prepared in case of restoration of anterior teeth tooth gap. Methods:Come to my hospital dental visits 26 patients, no front teeth missing, normal occlusion, periodontal health, anterior≤3mm gap exists in the case asked to close the gap. By cleaning the tooth surface, gingival, modulus, color, resin chip production, bonding, grinding, polishing and other steps 78 units mesotherapy resin veneer, followed up for 6 months to 2 years.Results:26 patients were followed for 6 months to 2 years showed that 25 patients resin veneers were normal, color, shape did not change significantly;1 case of loss, no allergies.Conclusions:ENA HRI plastic resin veneers can without tooth preparation close the gap front teeth, veneers and natural tooth color in excessive strength, wear, stability and biological characteristics and other aspects have very good results.%目的:探讨意大利美塑树脂贴面在不备牙情况下修复前牙间隙。方法:来我院口腔科就诊26位患者,前牙无缺失,咬合关系正常,牙周健康,前牙存在≤3mm间隙的情况下要求关闭间隙。通过牙面清洁,排龈,取模,比色,树脂贴片制作,粘结,打磨,抛光等步骤进行78单位美塑树脂贴面修复,随访6个月~2年。结果:26位患者随访6个月~2年显示,25位患者树脂贴面均正常,色泽、形态均无明显变化;1例发生脱落,无过敏现象。结论:美塑树脂贴面可以在不进行牙体预备情况下关闭前牙间隙,贴面在与天然牙颜色过度、强度、耐磨、稳定性及生物学特性等方面都有很理想的效果。

  3. A bio-based fibre-reinforced plastic pedestrian bridge for Schiphol

    NARCIS (Netherlands)

    Smits, J.E.P.; Gkaidatzis, R.

    2015-01-01

    The present paper investigates Bio-based fibre-reinforced plastics, used as a load-bearing element of a bridge. We aim to increase the renewable content and decreasing the embodied energy of FRP. To achieve that, the consisting raw materials of these plastics which are based on non-renewable resourc

  4. A bio-based fibre-reinforced plastic pedestrian bridge for Schiphol

    NARCIS (Netherlands)

    Smits, J.E.P.; Gkaidatzis, R.

    2015-01-01

    The present paper investigates Bio-based fibre-reinforced plastics, used as a load-bearing element of a bridge. We aim to increase the renewable content and decreasing the embodied energy of FRP. To achieve that, the consisting raw materials of these plastics which are based on non-renewable resourc

  5. A bio-based fibre-reinforced plastic pedestrian bridge for Schiphol

    NARCIS (Netherlands)

    Smits, J.E.P.; Gkaidatzis, R.

    2015-01-01

    The present paper investigates Bio-based fibre-reinforced plastics, used as a load-bearing element of a bridge. We aim to increase the renewable content and decreasing the embodied energy of FRP. To achieve that, the consisting raw materials of these plastics which are based on non-renewable

  6. Effect of 4-MET- and 10-MDP-based primers on resin bonding to titanium.

    Science.gov (United States)

    Tsuchimoto, Youhei; Yoshida, Yasuhiro; Mine, Atsushi; Nakamura, Mariko; Nishiyama, Norihiro; Van Meerbeek, Bart; Suzuki, Kazuomi; Kuboki, Takuo

    2006-03-01

    The purpose of this study was to investigate the effect of a 4-MET- and 10-MDP-based primer on the bond strength of two resin cements (SuperBond C&B, Sun Medical; Panavia Fluoro Cement, Kuraray) to titanium (Ti). Ti plates were treated with six experimental primers consisting of, respectively, 10-MDP and 4-MET in concentrations of 0.1, 1 and 10wt%, or were kept untreated (control). The highest tensile bond strength of Panavia Fluoro Cement to Ti was obtained when the Ti surface was pre-treated with 10wt% 10-MDP and was significantly higher than that when a lower concentrated 10-MDP-based primer or any 4-MET-based primer was used. On the contrary, no significant difference in tensile bond strength of SuperBond C&B was found for the untreated and six pre-treated Ti surfaces, although pre-treatment with each 10-MDP-based primer resulted in a higher tensile bond strength as compared to any 4-MET pre-treatment. Altogether, the data obtained strongly suggest that 10-MDP is effective to improve the adhesive performance of resin to titanium.

  7. Treatment of Perchlorate-Contaminated Groundwater Using Highly-Selective, Regenerable Anion-Exchange Resins at Edwards Air Force Base

    Energy Technology Data Exchange (ETDEWEB)

    Gu, B.

    2003-05-30

    Selective ion exchange is one of the most effective treatment technologies for removing low levels of perchlorate (ClO{sub 4}{sup -}) from contaminated water because of its high efficiency without adverse impacts on the water quality caused by adding or removing any chemicals or nutrients. This report summarizes both the laboratory and a field pilot-scale studies to determine the ability and efficiency of the bifunctional synthetic resins to remove ClO{sub 4}{sup -} from the contaminated groundwater at the Edwards Air Force Base in California. Regeneration of the resins after groundwater treatment was also evaluated using the FeCl{sub 3}-HCl regeneration technique recently developed at Oak Ridge National Laboratory. On the basis of this study, the bifunctional resin, D-3696 was found to be highly selective toward ClO{sub 4}{sup -} and performed much better than one of the best commercial nitrate-selective resins (Purolite A-520E) and more than an order of magnitude better than the Purolite A-500 resin (with a relatively low selectivity). At an influent concentration of {approx} 450 {micro}g/L ClO{sub 4}{sup -} in groundwater, the bifunctional resin bed treated {approx} 40,000 empty bed volumes of groundwater before a significant breakthrough of ClO{sub 4}{sup -} occurred. The presence of relatively high concentrations of chloride and sulfate in site groundwater did not appear to affect the ability of the bifunctional resin to remove ClO{sub 4}{sup -}. However, the presence of high iron or iron oxyhydroxides and/or biomass in groundwater caused a significant fouling of the resin beds and greatly influenced the effectiveness in regenerating the resins sorbed with ClO{sub 4}{sup -}. Under such circumstances, a prefilter ({approx} 0.5-1 {micro}m) was found to be necessary to remove these particulates and to reduce the risk of fouling of the resin beds. Without significant fouling, the resin bed could be effectively regenerated by the FeCl{sub 3} displacement technique

  8. Biocompatibility of composite resins

    OpenAIRE

    Sayed Mostafa Mousavinasab

    2011-01-01

    Dental materials that are used in dentistry should be harmless to oral tissues, so they should not contain any leachable toxic and diffusible substances that can cause some side effects. Reports about probable biologic hazards, in relation to dental resins, have increased interest to this topic in dentists. The present paper reviews the articles published about biocompatibility of resin-restorative materials specially resin composites and monomers which are mainly based on Bis-GMA and concern...

  9. Thermal expansion characteristics of light-cured dental resins and resin composites.

    Science.gov (United States)

    Sideridou, Irini; Achilias, Dimitris S; Kyrikou, Eleni

    2004-07-01

    The thermal expansion characteristics of dental resins prepared by light-curing of Bis-GMA, TEGDMA, UDMA, Bis-EMA(4) or PCDMA dimethacrylate monomers and of commercial light-cured resin composites (Z-100 MP, Filtek Z-250, Sculpt-It and Alert), the organic matrix resin of which is based on different combinations of the above monomers, were studied by thermomechanical analysis (TMA). This study showed the existence of a glass transition temperature at around 35-47 degrees C for the resins and 40-45 degrees C for the composites; then the coefficient of linear thermal expansion (CLTE) was calculated at the temperature intervals 0-60 degrees C, 0-T(g) and T(g)-60 degrees C. The CLTE values of Bis-GMA, TEGDMA and UDMA resins are similar and lower than those of Bis-EMA (4) and PCDMA resins. The CLTE values of the composites indicated that the major factor that affects the CLTE of a composite is the filler content, but it also seems to be affected by the chemical structure of the matrix resin. TMA on water-saturated samples showed that water desorption takes place during the measurement and that the residual water acts as a plasticizer decreasing the T(g) and increasing the CLTE values. Furthermore, TMA on post-heated samples for 1, 3 or 6h showed, only for the resins, an initial decrease of CLTE and increase of the T(g) after 1h that was not significantly changed after 6h of heating.

  10. Innovative Design of Plastic Bottle Recycling Box Based on ARM

    Directory of Open Access Journals (Sweden)

    Yuedong Xiong

    2014-04-01

    Full Text Available Aiming at the problems of on-site plastic bottles recycling and the reuse of waste, the automatic recycling system was developed on the basis of ARM. As the main controller, ARM not only controls the mechanical system of the collector to recover and break plastic bottles, but also communicates with and rewards the user by the automatic reward system through the wireless network. The experimental prototype test results show: post treated fragments of plastic bottles are small, which are convenient to transport and take advantage of; the operation of recovery is easy, and the interface of man-machine interaction is friendly which is easy to expand functions.

  11. Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base.

    Science.gov (United States)

    Shinawi, Lana Ahmed

    2017-05-01

    The application of computer-aided design computer-aided manufacturing (CAD CAM) technology in the fabrication of complete dentures, offers numerous advantages as it provides optimum fit and eliminates polymerization shrinkage of the acrylic base. Additionally, the porosity and surface roughness of CAD CAM resins is less compared to conventionally processed resins which leads to a decrease in the adhesion of bacteria on the denture base, which is associated with many conditions including halitosis and aspiration pneumonia in elderly denture wearers. To evaluate the influence of tooth brushing with dentifrices on CAD CAM resin blocks in terms of abrasion resistance, surface roughness and scanning electron photomicrography. This experimental study was carried out at the Faculty of Dentistry of King Abdulaziz University during 2016. A total of 40 rectangular shaped polymerized CAD CAM resin samples were subjected to 40.000 and 60.000 brushing strokes under a 200-gram vertical load simulating three years of tooth brushing strokes using commercially available denture cleaning dentifrice. Data were analyzed by SPSS version 20, using descriptive statistics and ANOVA. ANOVA test revealed a statistical significant weight loss of CAD CAM acrylic resin denture base specimens following 40.000 and 60.000 brushing strokes as well as a statistical significant change (p=0.0.5) in the surface roughness following brushing. The CAD CAM resin samples SEM baseline imaging revealed a relatively smooth homogenous surface, but following 40,000 and 60,000 brushing strokes, imaging displayed the presence of small scratches on the surface. CAD CAM resin displayed a homogenous surface initially with low surface roughness that was significantly affected following simulating three years of manual brushing, but despite the significant weight loss, the findings are within the clinically acceptable limits.

  12. Bond strength of acrylic teeth to denture base resin after various surface conditioning methods before and after thermocycling

    NARCIS (Netherlands)

    Saavedra, Guilherme; Valandro, Luz Felipe; Leite, Fabiola Pessoa; Amaral, Regina; Oezcan, Mutlu; Bottino, Marco A.; Kimpara, Estevao T.

    2007-01-01

    This study aimed to evaluate the durability of adhesion between acrylic teeth and denture base acrylic resin. The base surfaces of 24 acrylic teeth were flatted and submitted to 4 surface treatment methods: SM1 (control): No SM; SM2: application of a methyl methacrylate-based bonding agent (Vitacol)

  13. Removal of dyes from water using crosslinked aminomethane sulfonic acid based resin.

    Science.gov (United States)

    Kaner, Damla; Saraç, Ayfer; Senkal, Bahire Filiz

    2010-08-01

    A new polymeric resin with amino sulfonic acid pendant functions has been prepared for the extraction of acidic and basic dyes from water. Beaded polymer supports were prepared by suspension polymerization of vinyl benzyl chloride (0.9 mol) and ethylene glycol dimethacrylate (0.1 mol). The resulting copolymer beads were modified with amino methane sulfonic acid. The dye adsorption capacity of the resin was found as 0.16 g dye/g resin for ramazol black and 0.15 g dye/g resin for crystal violet. The pH depending measurements and dye sorption kinetics of the resin were also investigated.

  14. Simplified theory of plastic zones based on Zarka's method

    CERN Document Server

    Hübel, Hartwig

    2017-01-01

    The present book provides a new method to estimate elastic-plastic strains via a series of linear elastic analyses. For a life prediction of structures subjected to variable loads, frequently encountered in mechanical and civil engineering, the cyclically accumulated deformation and the elastic plastic strain ranges are required. The Simplified Theory of Plastic Zones (STPZ) is a direct method which provides the estimates of these and all other mechanical quantities in the state of elastic and plastic shakedown. The STPZ is described in detail, with emphasis on the fact that not only scientists but engineers working in applied fields and advanced students are able to get an idea of the possibilities and limitations of the STPZ. Numerous illustrations and examples are provided to support the reader's understanding.

  15. Development of a composite resin disclosing agent based on the understanding of tooth staining mechanisms.

    Science.gov (United States)

    Abdallah, Mohamed-Nur; Light, Nathan; Amin, Wala M; Retrouvey, Jean-Marc; Cerruti, Marta; Tamimi, Faleh

    2014-06-01

    To characterize the surface composition of dental enamel and composite resin, assess the ability of dyes with different affinities to stain these surfaces, and use this information to develop a disclosing agent that stains composite resin more than dental enamel. One hundred and ten sound extracted teeth were collected and 60 discs of composite resin, 9 mm diameter and 3 mm thick, were prepared. X-ray photoelectron spectroscopy (XPS) was employed to determine the elemental composition on the different surfaces. A tooth shade spectrophotometer was used to assess the change in shade after staining the surfaces with different dyes. XPS analysis revealed that surfaces of both outer dental enamel and composite resin contained relatively high amounts of carbon, specifically hydrocarbons. Both dental enamel and composite surfaces were stainable with the hydrophobic dye (pcomposite resin was stained more than the dental enamel (pcomposite resin might explain their high affinity to be stained by food and beverages containing hydrophobic molecules. The composite resin is more stainable by hydrophobic dyes than dental enamel. We used this information to develop an agent for disclosing composite resins that could be used to visualize composite resins that need to be removed. Removal of composite resin can be problematic, time consuming and stressful to the dental practitioner. A composite disclosing agent would help the dental practitioner identify the composite resin and facilitate its removal without damaging the adjacent healthy tooth tissues. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Advantages and drawbacks of Thiol-ene based resins for 3D-printing

    Science.gov (United States)

    Leonards, Holger; Engelhardt, Sascha; Hoffmann, Andreas; Pongratz, Ludwig; Schriever, Sascha; Bläsius, Jana; Wehner, Martin; Gillner, Arnold

    2015-03-01

    The technology of 3D printing is conquering the world and awakens the interest of many users in the most varying of applications. New formulation approaches for photo-sensitive thiol-ene resins in combination with various printing technologies, like stereolithography (SLA), projection based printing/digital light processing (DLP) or two-photon polymerization (TPP) are presented. Thiol-ene polymerizations are known for its fast and quantitative reaction and to form highly homogeneous polymer networks. As the resins are locally and temporally photo-curable the polymerization type is very promising for 3D-printing. By using suitable wavelengths, photoinitiator-free fabrication is feasible for single- and two photon induced polymerization. In this paper divinyl ethers of polyethylene glycols in combination with star-shaped tetrathiols were used to design a simple test-system for photo-curable thiol-ene resins. In order to control and improve curing depth and lateral resolution in 3D-polymerization processes, either additives in chemical formulation or process parameters can be changed. The achieved curing depth and resolution limits depend on the applied fabrication method. While two-/multiphoton induced lithography offers the possibility of micron- to sub-micron resolution it lacks in built-up speed. Hence single-photon polymerization is a fast alternative with optimization potential in sub-10-micron resolution. Absorber- and initiator free compositions were developed in order to avoid aging, yellowing and toxicity of resulting products. They can be cured with UV-laser radiation below 300 nm. The development at Fraunhofer ILT is focusing on new applications in the field of medical products and implants, technical products with respect to mechanical properties or optical properties of 3D-printed objects. Recent process results with model system (polyethylene glycol divinylether/ Pentaerithrytol tetrakis (3-mercaptopropionat), Raman measurements of polymer conversion

  17. Phenol-Formaldehyde Resin-Based Carbons for CO2 Separation at Sub-Atmospheric Pressures

    Directory of Open Access Journals (Sweden)

    Noelia Álvarez-Gutiérrez

    2016-03-01

    Full Text Available The challenge of developing effective separation and purification technologies that leave much smaller energy footprints is greater for carbon dioxide (CO2 than for other gases. In addition to its involvement in climate change, CO2 is present as an impurity in biogas and bio-hydrogen (biological production by dark fermentation, in post-combustion processes (flue gas, CO2-N2 and many other gas streams. Selected phenol-formaldehyde resin-based activated carbons prepared in our laboratory have been evaluated under static conditions (adsorption isotherms as potential adsorbents for CO2 separation at sub-atmospheric pressures, i.e., in post-combustion processes or from biogas and bio-hydrogen streams. CO2, H2, N2, and CH4 adsorption isotherms at 25 °C and up to 100 kPa were obtained using a volumetric equipment and were correlated by applying the Sips model. Adsorption equilibrium was then predicted for multicomponent gas mixtures by extending the multicomponent Sips model and the Ideal Adsorbed Solution Theory (IAST in conjunction with the Sips model. The CO2 uptakes of the resin-derived carbons from CO2-CH4, CO2-H2, and CO2-N2 at atmospheric pressure were greater than those of the reference commercial carbon (Calgon BPL. The performance of the resin-derived carbons in terms of equilibrium of adsorption seems therefore relevant to CO2 separation in post-combustion (flue gas, CO2-N2 and in hydrogen fermentation (CO2-H2, CO2-CH4.

  18. Robustness of learning that is based on covariance-driven synaptic plasticity.

    Directory of Open Access Journals (Sweden)

    Yonatan Loewenstein

    2008-03-01

    Full Text Available It is widely believed that learning is due, at least in part, to long-lasting modifications of the strengths of synapses in the brain. Theoretical studies have shown that a family of synaptic plasticity rules, in which synaptic changes are driven by covariance, is particularly useful for many forms of learning, including associative memory, gradient estimation, and operant conditioning. Covariance-based plasticity is inherently sensitive. Even a slight mistuning of the parameters of a covariance-based plasticity rule is likely to result in substantial changes in synaptic efficacies. Therefore, the biological relevance of covariance-based plasticity models is questionable. Here, we study the effects of mistuning parameters of the plasticity rule in a decision making model in which synaptic plasticity is driven by the covariance of reward and neural activity. An exact covariance plasticity rule yields Herrnstein's matching law. We show that although the effect of slight mistuning of the plasticity rule on the synaptic efficacies is large, the behavioral effect is small. Thus, matching behavior is robust to mistuning of the parameters of the covariance-based plasticity rule. Furthermore, the mistuned covariance rule results in undermatching, which is consistent with experimentally observed behavior. These results substantiate the hypothesis that approximate covariance-based synaptic plasticity underlies operant conditioning. However, we show that the mistuning of the mean subtraction makes behavior sensitive to the mistuning of the properties of the decision making network. Thus, there is a tradeoff between the robustness of matching behavior to changes in the plasticity rule and its robustness to changes in the properties of the decision making network.

  19. Cloud-Based Applications for Organizing and Reviewing Plastic Surgery Content.

    Science.gov (United States)

    Luan, Anna; Momeni, Arash; Lee, Gordon K; Galvez, Michael G

    2015-01-01

    Cloud-based applications including Box, Dropbox, Google Drive, Evernote, Notability, and Zotero are available for smartphones, tablets, and laptops and have revolutionized the manner in which medical students and surgeons read and utilize plastic surgery literature. Here we provide an overview of the use of Cloud computing in practice and propose an algorithm for organizing the vast amount of plastic surgery literature. Given the incredible amount of data being produced in plastic surgery and other surgical subspecialties, it is prudent for plastic surgeons to lead the process of providing solutions for the efficient organization and effective integration of the ever-increasing data into clinical practice.

  20. Bulk Density Adjustment of Resin-Based Equivalent Material for Geomechanical Model Test

    Directory of Open Access Journals (Sweden)

    Pengxian Fan

    2015-01-01

    Full Text Available An equivalent material is of significance to the simulation of prototype rock in geomechanical model test. Researchers attempt to ensure that the bulk density of equivalent material is equal to that of prototype rock. In this work, barite sand was used to increase the bulk density of a resin-based equivalent material. The variation law of the bulk density was revealed in the simulation of a prototype rock of a different bulk density. Over 300 specimens were made for uniaxial compression test. Test results indicated that the substitution of quartz sand by barite sand had no apparent influence on the uniaxial compressive strength and elastic modulus of the specimens but can increase the bulk density, according to the proportional coarse aggregate content. An ideal linearity was found in the relationship between the barite sand substitution ratio and the bulk density. The relationship between the bulk density and the usage of coarse aggregate and barite sand was also presented. The test results provided an insight into the bulk density adjustment of resin-based equivalent materials.

  1. Water sorption and solubility of methacrylate resin-based root canal sealers.

    Science.gov (United States)

    Donnelly, Adam; Sword, Jeremy; Nishitani, Yoshihiro; Yoshiyama, Masahiro; Agee, Kelli; Tay, Franklin R; Pashley, David H

    2007-08-01

    The water sorption and solubility characteristics of three contemporary methacrylate resin-based endodontic sealers, EndoREZ, Epiphany, and InnoEndo, were compared with those obtained from Kerr EWT, Ketac-Endo (positive control), GuttaFlow, and AH Plus (both negative controls). Ten disks of each material were dehydrated in Drierite for 24 h and weighed to constant dry mass. They were placed in water and weighed periodically until maximum water sorption was obtained. The disks were dehydrated again to determine their mass loss (solubility) at equilibrium. Epiphany exhibited the highest apparent water sorption (8%) followed by Ketac-Endo (6.2%), InnoEndo (3.4%), EndoREZ (3.0%), AH Plus (1.1%), GuttaFlow (0.4%), and Kerr EWT (0.3%). Significantly higher solubility (3.5-4%) were observed for all three methacrylate resin-based sealers and Kerr EWT (3.95%), compared with Ketac-Endo (1.6%), AH Plus (0.16%), and GuttaFlow (0.13%). American Dental Association specifications require<3% solubility for endodontic sealers. Only Ketac-Endo, AH Plus, and GuttaFlow met that criterion.

  2. Evaluation of sealing ability of two temporary resin-based cements used in Endodontics

    Directory of Open Access Journals (Sweden)

    Paloma Mariana Ramos Bitencourt

    2010-07-01

    Full Text Available Introduction: The outcome of endodontic treatment is related to the sealing ability of temporary dental restoration, which aims to prevent bacterial infiltration and recontamination of the root canal system.Objective: The purpose of this study was to evaluate the sealing ability of two temporary resin-based cements: Fill Magic Tempo and Bioplic.Material and methods: Twenty-four third molars were used, and twenty-two of them were opened to the pulp chamber (resulting in a class I cavity and randomly divided: group 1 was restored using Fill Magic Tempo (n = 10 and group 2 was restored using Bioplic (n = 10.The negative control group was not opened (n = 2, and the positive control group was opened but not restored (n = 2. Then the root and apex of the teeth were varnished to become impermeable. All samples were immersed in 2% methylene blue and kept at 37°C for 72h.After longitudinal sectioning, the linear leakage was measured in mm.In sequence, the statistical analysis was performed using Mann-Whitney test with a level of significance of 5%. Results: Most part of the samples showed leakage of 1 mm, and only the negative control group showed total leakage. There was no significant difference between the tested materials. Conclusion: It is possible to conclude that both resin-based cements showed satisfactory results on sealing ability during endodontic treatment.

  3. Penetration of resin-based materials into initial erosion lesion: A confocal microscopic study.

    Science.gov (United States)

    Ionta, Franciny Querobim; Boteon, Ana Paula; Moretto, Marcelo Juliano; Júnior, Odair Bim; Honório, Heitor Marques; Silva, Thiago Cruvinel; Wang, Linda; Rios, Daniela

    2016-02-01

    The application of resin-based materials is an alternative of treatment for eroded lesions. Nevertheless, there are no studies about the penetration of these materials into eroded lesion, which might affect its adhesion. Therefore, this study evaluated the penetration of four resin-based materials, with and without enamel etching. By using an in vitro protocol, types of treatment were studied at five levels (AdheSE(®) , Tetric N-Bond(®) , Single Bond 2(®) , Helioseal Clear(®) , Icon(®) ) and types of enamel etching in two levels (with and without). Materials were stained with 0.02 mg/mL ethanolic solution of tetramethylrhodamine isothiocyanate. Bovine enamel samples (4 × 4 mm) were immersed in 0.01 M HCl, pH 2.3, for 30 seconds to produce initial eroded lesions. Afterward, the materials were applied on half of sample enamel surface following the manufacturer's instructions. On the other half of sample, the materials were applied without etching the enamel. Materials penetration into the enamel was assessed by Confocal Laser Scanning Microscopy on reflection and fluorescence modes. The penetration depth (PD) was measured using ImageJ software. Data were analyzed by two-way ANOVA and Tukey test (P material, etched enamel resulted in higher PD than non-etched (P  0.05). It can be concluded that prior enamel etching increased the materials penetration into eroded enamel and the Icon(®) -infiltrant presented highest penetration.

  4. Effect of silanization of hydroxyapatite fillers on physical and mechanical properties of a bis-GMA based resin composite.

    Science.gov (United States)

    Lung, Christie Ying Kei; Sarfraz, Zenab; Habib, Amir; Khan, Abdul Samad; Matinlinna, Jukka Pekka

    2016-02-01

    To evaluate the physical and mechanical properties of an experimental bis-GMA-based resin composite incorporated with non-silanized and silanized nano-hydroxyapatite (nHAP) fillers. Experimental bis-GMA based resin composites samples which were reinforced with nHAP fillers were prepared. Filler particles were surface treated with a silane coupling agent. Five test groups were prepared: 1. Unfilled, 2. Reinforced with 10wt% and 30wt% non-silanized nHAP fillers, and 3. Reinforced with 10wt% and 30wt% silanized nHAP fillers. The samples were subjected to tests in dry condition and in deionized water, aged at 37°C for 30 days. Prepared silanized and non-silanized nHAP were analyzed with Fourier Transform Infrared (FTIR) Spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The micro-hardness and water sorption were evaluated. Data were analyzed by one-way ANOVA (psilane treated fillers was superior to unfilled and untreated fillers resins. The resin matrix loaded with 30wt% silanized-nHAP fillers would improve the physical and mechanical properties of a bis-GMA based resin.

  5. 18-year survival of posterior composite resin restorations with and without glass ionomer cement as base.

    Science.gov (United States)

    van de Sande, Françoise H; Rodolpho, Paulo A Da Rosa; Basso, Gabriela R; Patias, Rômulo; da Rosa, Quéren F; Demarco, Flávio F; Opdam, Niek J; Cenci, Maximiliano S

    2015-06-01

    Advantages and disadvantages of using intermediate layers underneath resin-composite restorations have been presented under different perspectives. Yet, few long-term clinical studies evaluated the effect of glass-ionomer bases on restoration survival. The present study investigated the influence of glass-ionomer-cement base in survival of posterior composite restorations, compared to restorations without base. Original datasets of one dental practice were used to retrieve data retrospectively. The presence or absence of an intermediate layer of glass-ionomer-cement was the main factor under analysis, considering survival, annual failure rate and types of failure as outcomes. Other investigated factors were: patient gender, jaw, tooth, number of restored surfaces and composite. Statistical analysis was performed using Fisher's exact test, Kaplan-Meier method and multivariate Cox-regression. In total 632 restorations in 97 patients were investigated. Annual failure rates percentages up to 18-years were 1.9% and 2.1% for restorations with and without base, respectively. In restorations with glass-ionomer-cement base, fracture was the predominant reason for failure, corresponding to 57.8% of total failures. Failure type distribution was different (p=0.007) comparing restorations with and without base, but no effect in the overall survival of restorations was found (p=0.313). The presence of a glass-ionomer-cement base did not affect the survival of resin-composite restorations in the investigated sample. Acceptable annual failure rates after 18-years can be achieved with both techniques, leading to the perspective that an intermediate layer, placed during an interim treatment, may be maintained without clinical detriment, but no improvement in survival should be expected based on such measure. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Investigate the Possibility of Tekcast Methods Used for Casting Polymeric Resin Materials

    Directory of Open Access Journals (Sweden)

    Mäsiar H.

    2014-06-01

    Full Text Available Contribution gives an overview of knowledge about the method of centrifugal casting with orientate on Tekcast system. Company Tekcast Industries has developed a device for centrifugal casting, extending the area of production of castings or prototyping of metal or plastic. Materials suitable for the centrifugal casting with flexible operating parameters may include non-ferrous metal alloy based on zinc or aluminum or non-metallic materials such as polyester resins, polyurethane resins, epoxy resins, waxes and the like. The casting process is particularly suitable for a wide range of commercial castings and decorative objects.

  7. Dental cavity liners for Class I and Class II resin-based composite restorations.

    Science.gov (United States)

    Schenkel, Andrew B; Peltz, Ivy; Veitz-Keenan, Analia

    2016-10-25

    Resin-based composite (RBC) is currently accepted as a viable material for the restoration of caries for posterior permanent teeth requiring surgical treatment. Despite the fact that the thermal conductivity of the RBC restorative material closely approximates that of natural tooth structure, postoperative hypersensitivity is sometimes still an issue. Dental cavity liners have historically been used to protect the pulp from the toxic effects of some dental restorative materials and to prevent the pain of thermal conductivity by placing an insulating layer between restorative material and the remaining tooth structure. The objective of this review was to assess the effects of using dental cavity liners in the placement of Class I and Class II resin-based composite posterior restorations in permanent teeth in children and adults. Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 25 May 2016), the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 4) in the Cochrane Library (searched 25 May 2016), MEDLINE Ovid (1946 to 25 May 2016), Embase Ovid (1980 to 25 May 2016) and LILACS BIREME Virtual Health Library (Latin American and Caribbean Health Science Information database; 1982 to 25 May 2016). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. We included randomized controlled trials assessing the effects of the use of liners under Class I and Class II posterior resin-based composite restorations in permanent teeth (in both adults and children). We included both parallel and split-mouth designs. We utilized standard methodological procedures prescribed by Cochrane for data collection and analysis. Two review authors screened the search results and assessed the eligibility of studies for

  8. The Bond Strength of Composite Resin to Dental Casting Alloys Using an Electro-Chemical Tin Plating System.

    Science.gov (United States)

    1985-06-01

    limit and modulus of elasticity of acrylic resins may lead to excessive plastic deformation when placed under the stresses encounted in prosthetic...etching process has been recently introduced which is reported to be effective in bonding composite resin to both base metal and gold based alloys. (Veen et... dentures , porcelain inlays, metal ceramic restorations, and porcelain laminate veneers. (Tylman, 1970; Craig, 1980; Horn, 1983) The complete porcelain

  9. THE POLYMERIZATION OF ROOM TEMPERATURE CURING EPOXY RESINS

    Science.gov (United States)

    EPOXY RESINS , *PLASTICS, *POLYMERIZATION, AGING (PHYSIOLOGY), CHEMICAL BONDS, ELECTRICAL PROPERTIES, EMBEDDING SUBSTANCES, MONITORS, POLYMERS, RESISTANCE (ELECTRICAL), STORAGE, STRUCTURES, TEMPERATURE, TEST METHODS, VOLUME

  10. Marine fungi: Degraders of poly-3-hydroxyalkanoate based plastic materials

    Directory of Open Access Journals (Sweden)

    Matavulj Milan

    2009-01-01

    Full Text Available The search for new biosynthetic and biodegradable materials to save nonrenewable resources and reduce global pollution problems is an urgent task. Recently, materials like thermoplastic poly-3-hydroxyalkanoates (PHA, have been found synthesized by bacteria as storage materials. The major PHAs synthesized are poly-b-hydroxybutyrate (PHB, poly-b-hydroxyvalerate (PHV and their copolymers. They are already commercially produced and used as BIOPOLTM (ICI, England. Their complete degradability by bacteria has already been shown. Today, oceans and estuaries serve as major landfills, and since fungi are an important part of the degrading microbiota, in order to prove their participation in the degradation process, a simple degradation test suitable for fungi and marine conditions had to be developed. Several solid media based on artificial sea water, differing in the content of non-alkanoate organics and supplemented with 0.1% PHA (or BIOPOLTM as a main source of carbon have been tested. The testing principle consists of clearing the turbid medium in test tube or plates caused by suspended granules of PHA. All media tested supported the growth of fungi. For the discrete and transparent clearing of zones, a mineral medium with 0.01% peptone, 0.01% yeast extract, and 0.1% PHB or BIOPOLTM was finally chosen where the fine and evenly distributed turbidity is accomplished by a specific procedure. This method allows the investigation of degradability of PHA-based plastic materials as well as screening for fungal ability to depolymerise pure PHA homopolymers. Using this medium, 32 strains of marine yeasts and 102 strains of marine mycelial fungi belonging to different systematic and ecological groups were tested for their ability to degrade PHAs. Only about 4% of the strains were able to degrade BIOPOLTM and about 6% depolymerised pure PHB homopolymer. This is in sharp contrast to the results of our previous experiments with 143 strains of terrestrial fungi

  11. Effect of Mechanical Surface Treatment on the Repair Bond Strength of the Silorane-based Composite Resin

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    Parnian Alizadeh Oskoee

    2014-06-01

    Full Text Available Background and aims. A proper bond must be created between the existing composite resin and the new one for successful repair. The aim of this study was to compare the effect of three mechanical surface treatments, using diamond bur, air abrasion, and Er,Cr:YSGG laser, on the repair bond strength of the silorane-based composite resin. Materials and methods. Sixty cylindrical composite resin specimens (Filtek Silorane were fabricated and randomly divided into four groups according to surface treatment: group 1 (control group without any mechanical surface treatment, groups 24 were treated with air abrasion, Er,Cr:YSGG laser, and diamond bur, respectively. In addition, a positive control group was assigned in order to measure the cohesive strength. Silorane bonding agent was used in groups 14 before adding the new composite resin. Then, the specimens were subjected to a shear bond strength test and data was analyzed using one-way ANOVA and post hoc Tukey tests at a significance level of P < 0.05. The topographical effects of surface treatments were characterized under a scanning electron microscope. Results. There were statistically significant differences in the repair bond strength values between groups 1 and 2 and groups 3 and 4 (P < 0.001. There were no significant differences between groups 1 and 2 (P = 0.98 and groups 3 and 4 (P = 0.97. Conclusion. Surface treatment using Er,Cr:YSGG laser and diamond bur were effective in silorane-based composite resin repair.

  12. Properties of experimental resins based on synthesized propoxylated bis-GMA with different propionaldehyde ratios

    Directory of Open Access Journals (Sweden)

    Aline Bassi Denis

    2012-06-01

    Full Text Available The effect of different propionaldehyde ratios on the properties of bis-GMA-based comonomers and copolymers diluted with propoxylated bis-GMA (CH3bis-GMA was evaluated. Five experimental comonomers were prepared combining bis-GMA with CH3bis-GMA and propionaldehyde at 0, 2, 8, 16, 24 mol%. Light polymerization was effected with the use of 0.2 wt. (% each of camphorquinone and N,N-dimethyl-p-toluidine. Resin degrees of conversion (%DC were evaluated by FT-IR spectrophotometry and Tg by Differential Scanning Calorimeter. Complex viscosity (η*, the effect of temperature on η*, and Microhardness (H for dry and wet samples were also determined. Data were analyzed by Student's t-test, one-way ANOVA and Tukey-Kramer test (α = 0.05. The group with 24 mol% additive had a significant increase in %DC and H, and the lowest comonomer Tg and η*. No remarkable variation was noted in copolymers Tg s. All resins presented Newtonian behavior of viscosity, which linearly decreased with increased temperature. The η* decreased sigmoidally as the additive ratio increased.

  13. Isothermal curing of polymer layered silicate nanocomposites based upon epoxy resin by means of anionic homopolymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Román, Frida, E-mail: roman@mmt.upc.edu; Calventus, Yolanda, E-mail: calventus@mmt.upc.edu; Colomer, Pere, E-mail: colomer@mmt.upc.edu; Hutchinson, John M., E-mail: hutchinson@mmt.upc.edu

    2013-12-20

    Highlights: • The nanocomposite with low content of clay displayed improved thermal properties. • The vitrification was observed in the isothermal curing. • Dielectric relaxations outside and inside of the clay galleries were detected. - Abstract: The use of an initiator, 4-(dimethylamino) pyridine (DMAP), to promote an anionic homopolymerisation reaction for the isothermal cure of polymer layered silicate (PLS) nanocomposites based on an epoxy resin, as well as the effect of the nanoclay content, have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dielectric relaxation spectroscopy (DRS) and transmission electron microscopy (TEM). The vitrification phenomenon was observed during the isothermal cure process, and it was found that the nanocomposite with a low clay content (2 wt%), denoted EDM2, shows improved thermal properties with respect to the unreinforced resin (denoted ED), while the nanocomposite with a higher clay content (5 wt%), denoted EDM5, displayed inferior properties. The cure kinetics were analysed by different methods, and it was observed that the activation energy and kinetic parameters of EDM2 were lower compared to the other two systems. Examination of the nanostructure of the cured EDM2 nanocomposite showed partial exfoliation, while the EDM5 system retains an intercalated nanostructure. In the DRS studies of the curing process of the EDM2 system, two dielectric relaxations were detected, which are associated with the molecular mobility in the curing reaction which takes place both outside and inside the clay galleries.

  14. Cation exchange resin nanocomposites based on multi-walled carbon nanotubes

    Science.gov (United States)

    Fathy, Mahmoud; Abdel Moghny, Th.; Awad Allah, Ahmed Elsayed; Alblehy, AbdElhamid

    2014-01-01

    Carbon nanotubes (CNTs) are of great interest due to their potential applications in different fields such as water treatment and desalination. The increasing exploitation of multi-walled carbon nanotubes (MWCNTs) into many industrial processes has raised considerable concerns for environmental applications. The interactions of soluble salt with MWNCTs influence in the total salt content in saline water. In this work, we synthesized two cation exchange resins nano composites from polystyrene divinylbenzene copolymer (PSDVB) and pristine MWNCTs. The prepared compounds were characterized using infra red spectroscopy, thermal stability, X-ray diffraction, and electro scan microscope. Also, the ion capacities of prepared cation exchange resins were determined by titration. Based on the experimental results, it was found that the thermal stability of prepared nanocomposites in the presence of MWNCTs increased up to 617 °C. The X-ray of PSDVB and its sulfonated form exhibits amorphous pattern texture structure, whereas the nano composite exhibits amorphous structure with indication peak at 20° and 26° for the PSDVB and MWCNTs, respectively. The ion-exchange capacity increased from 225.6 meq/100 g to 466 mg/100 g for sulfonated PSDVB and sulfonated PSDVB MWNCTs-pristine, respectively.

  15. Development of dental resin luting agents based on Bis-EMA4: bond strength evaluation

    Directory of Open Access Journals (Sweden)

    2008-02-01

    Full Text Available The aim of this study was to investigate the influence of incorporating Bis-EMA4 monomer into experimental Bis-GMA/TEGDMA-based resin luting agents on the bond strength to dentin. Seven mixtures were prepared with the following ratios (wt% of Bis-GMA/TEGDMA/Bis-EMA4: 50/50/0, 50/30/20, 50/10/40, 50/0/50, 30/10/60, 10/10/80 and 0/0/100. Camphorquinone (0.4 wt%, N,N-dimethyl-p-toluidine (0.8 wt% and hydroquinone (0.2 wt% were dissolved in each mixture, which was loaded with silanated strontium glass fillers to a constant content of 60 wt%. Bond strength was evaluated by microshear testing (n = 10 on bovine dentin. Data were submitted to Analysis of Variance (p<0.05. Modes of failure were classified under magnification (200×. Bond strength means (MPa, respective to each agent, were: 19.4, 19.8, 20.0, 19.1, 16.8, 18.7 and 17.8. No significant differences were detected among groups. Mixed failures were generally predominant for all materials. In conclusion, the addition of Bis-EMA4 presented no significant influence on the bond strength of the experimental resin luting agents to dentin.

  16. Correlation between the degree of conversion and the elution of leachable components from dental resin-based cements

    Directory of Open Access Journals (Sweden)

    KOSOVKA OBRADOVIĆ-DJURIČIĆ

    2011-09-01

    Full Text Available This study examined the possible correlation between the degree of conversion (DC and the amount of substances eluted from three commercial cured resin-based cements. The DC of the various resin-based cements was measured by Raman spectroscopy, while the quantity of unreacted monomers released from the cement matrix (triethylene glycol dimethacrylate, TEGDMA, urethane dimethacrylate, UDMA, 2-hydroxyethyl methacrylate, HEMA and bisphenol A was determined by high pressure liquid chromatography (HPLC. The obtained results, after multiple statistical evaluation (one way ANOVA, LSD post hoc test, showed no significant differences in the DC values between the resin cements. On the contrary, the results of the HPLC analysis depicted statistically significant differences between the three materials with respect to the amount of leached monomers. In addition, no correlation between the DC and the amount of eluted substances from the tested cured composite cements was found.

  17. Restored viability and function of dental pulp cells on poly-methylmethacrylate (PMMA)-based dental resin supplemented with N-acetyl cysteine (NAC).

    Science.gov (United States)

    Kojima, N; Yamada, M; Paranjpe, A; Tsukimura, N; Kubo, K; Jewett, A; Ogawa, T

    2008-12-01

    This study examines cytotoxicity of poly-methylmethacrylate (PMMA)-based dental temporary filling resin to dental pulp cells, and the potential amelioration of the toxicity with an anti-oxidant amino-acid, N-acetyl cysteine (NAC). Dental pulp cells extracted from rat maxillary incisors were cultured on the resin material with or without NAC incorporation, or on the polystyrene. The cultures were supplied with osteoblastic media, containing dexamethasone. Forty five percent of cells on the PMMA dental resin were necrotic at 24h after seeding. However, this percentage was reduced to 27% by incorporating NAC in the resin, which was the level equivalent to that in the culture on polystyrene. The culture on the untreated resin was found to be negative for alkaline phosphate (ALP) activity at days 5 and 10 or von Kossa mineralized nodule formation at day 20. In contrast, some areas of the cultures on NAC-incorporated resin substrates were ALP and von Kossa positive. Collagen I and dentin sialoprotein genes were barely expressed in day 7 culture on the untreated resin. However, those genes were expressed in the culture on the resin with NAC. These results suggest that the decreased cell viability and the nearly completely suppressed odontoblast-like cell phenotype of dental pulp cells cultured on PMMA dental resin can be salvaged to a biologically significant degree by the incorporation of NAC in the resin.

  18. Pilot-scale base hydrolysis processing of HMX-based plastic-bonded explosives

    Energy Technology Data Exchange (ETDEWEB)

    Flesner, R.L.; Dell`Orco, P.C.; Spontarelli, T.; Bishop, R.L.; Skidmore, C.B.; Uher, K.; Kramer, J.F.

    1997-10-01

    Los Alamos National Laboratory has demonstrated that many energetic materials can be rendered non-energetic via reaction with sodium hydroxide or ammonia. This process is known as base hydrolysis. A pilot scale reactor has been developed to process up to 20 kg of plastic bonded explosive in a single batch operation. In this report, we discuss the design and operation of the pilot scale reactor for the processing of PBX 9404, a standard Department of Energy plastic bonded explosive containing HMX and nitrocellulose. Products from base hydrolysis, although non-energetic, still require additional processing before release to the environment. Decomposition products, destruction efficiencies, and rates of reaction for base hydrolysis will be presented. Hydrothermal processing, previously known as supercritical water oxidation, has been proposed for converting organic products from hydrolysis to carbon dioxide, nitrogen, and nitrous oxide. Base hydrolysis in combination with hydrothermal processing may yield a viable alternative to open burning/open detonation for destruction of many energetic materials.

  19. Pilot-scale base hydrolysis processing of HMX-based plastic-bonded explosives

    Energy Technology Data Exchange (ETDEWEB)

    Flesner, R.L.; Dell`orco, P.C.; Spontarelli, T.; Bishop, R.L.; Skidmore, C.; Uher, K.J.; Kramer, J.F.

    1996-07-01

    Los Alamos National Laboratory has demonstrated that many energetic materials can be rendered non-energetic via reaction with sodium hydroxide or ammonia. This process is known as base hydrolysis. A pilot scale reactor has been developed to process up to 20 kg of plastic bonded explosive in a single batch operation. In this report, we discuss the design and operation of the pilot scale reactor for the processing of PBX 9404, a standard Department of Energy plastic bonded explosive containing HMX and nitrocellulose. Products from base hydrolysis, although non-energetic, still require additional processing before release to the environment Decomposition products, destruction efficiencies, and rates of reaction for base hydrolysis will be presented. Hydrothermal processing, previously known as supercritical water oxidation, has been proposed for converting organic products from hydrolysis to carbon dioxide, nitrogen, and nitrous oxide. Base hydrolysis in combination with hydrothermal processing may yield a viable alternative to open burning/open detonation for destruction of many energetic materials.

  20. Optimization of the wavelength shifter ratio in a polystyrene based plastic scintillator through energy spectrum analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ye Won; Kim, Myung Soo; Yoo, Hyun Jun; Lee, Dae Hee; Cho, Gyu Seong [Dept. of Nuclear and Quantum Engineering, KAIST, Daejeon (Korea, Republic of); Moon, Myung Kook [Neutron Instrumentation Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-02-15

    The scintillation efficiency of the polystyrene based plastic scintillator depends on the ratio of the wavelength shifters, organic fluors (PPO and POPOP). Thus, 24 samples of the plastic scintillator were fabricated in order to find out the optimum ratio of the wavelength shifters in the plastic scintillator. The fabricated plastic scintillators were trimmed through a cutting and polishing process. They were used in gamma energy spectrum measurement with the {sup 137}Cs emitting monoenergy photon with 662 keV for the comparison of the scintillation efficiency. As a result, it was found out that the scintillator sample with 1.00 g of PPO (2,5-Diphenyloxazole) and 0.50 g of POPOP (1,4-Bis(5-phnyl-2oxidazolyl)benzene) dissolved in 100 g of styrene solution has the optimum ratio in terms of the light yield of the polystyrene based plastic scintillator.

  1. Toughening of wood plastic composite based on X-PP

    Science.gov (United States)

    Meekum, U.; Khongrit, A.

    2016-03-01

    Wood plastic composite(WPC) based on crosslinked polypropylene(X-PP)/wood flour was explored. The peroxide/silane was used as crosslinking system. The sauna incubation under moisture saturated oven was applied to accelerate the competition of the siloxy/moisture networking reaction. There were three parts of the research work; design of experiment, toughening of WPC and the effect of peroxide, silane and PP copolymer on properties of the WPC, respectively. In this published work, the toughness improvement of the composite was focused. Ultra-high molecular weight polyethylene (UHMWPE) and Ethylene propylene diene terpolymer(EPDM) were employed to improve impact strength via blending with x-PP matrix. Composites were compounded into pellets by co-rotational twin screw extruder and test specimens were prepared by injection molding. Sauna incubation at 105°C for 12 hrs in oven chamber was performed to accelerate the final silane condensation crosslink reaction. MFI, impact strength, flexural properties and heat deflection temperature measurement were conducted. Impact strength, HDT and flexural modulus were improved with increasing UHMWPE content, and the optimal values around 5-10 phr of UHMWPE were achieved. Addition of EPDM elastomer to the matrix blends, reduced flexural strength and modulus but increased impact strength. While incorporation of EPDM into the PP/UHMWPE blends was exhibited much higher impact strength than that of the PP/UHMWPE binary blends. Silane crosslinked through sauna treatment improved the impact strength. HDT were also much risen for the crosslinked composite comparing with the non-crosslinked one.

  2. In vitro comparison of autoclave polymerization on the transverse strength of denture base resins.

    Science.gov (United States)

    Durkan, Rukiye; Ozel, Mehmet Birol; Bağiş, Bora; Usanmaz, Ali

    2008-07-01

    The aim of this study was to determine the effect of autoclave polymerization on the transverse strength of denture base polymers. To this end, 30 rectangular test specimens were fabricated of two heat-polymerized denture base polymers. The test groups were: (I) control, i.e., conventional water bath to polymerize resins by heat at 100 degrees C for 30 minutes; (II) autoclave polymerization at 60 degrees C for 30 minutes followed by 130 degrees C for 10 minutes; and (III) autoclave polymerization at 60 degrees C for 30 minutes followed by 130 degrees C for 20 minutes. The specimens were tested with three-point bending test at a crosshead speed of 5 mm/min. It was revealed that the transverse strength of specimens increased with statistical significance when the autoclave was used for polymerization.

  3. Resin-assisted enrichment of thiols as a general strategy for proteomic profiling of cysteine-based reversible modifications

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jia [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gaffrey, Matthew J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Su, Dian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Genentech Inc., South San Francisco, CA (United States); Liu, Tao [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Camp, David G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, Richard D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Qian, Weijun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-12-12

    Reversible modifications on cysteine thiols play a significant role in redox signaling and regulation. A number of reversible redox modifications, including disulfide formation, S-nitrosylation, and S-glutathionylation, have been recognized for their significance in various physiological and pathological processes. Here we describe in detail a resin-assisted thiol-affinity enrichment protocol for both biochemical and proteomics applications. This protocol serves as a general approach for specific isolation of thiol-containing proteins or peptides derived from reversible redox-modified proteins. This approach utilizes thiol-affinity resins to directly capture thiol-containing proteins or peptides through a disulfide exchange reaction followed by on-resin protein digestion and on-resin multiplexed isobaric labeling to facilitate LC-MS/MS based quantitative site-specific analysis of redox modifications. The overall approach requires a much simpler workflow with increased specificity compared to the commonly used biotin switch technique. By coupling different selective reduction strategies, the resin-assisted approach provides the researcher with a useful tool capable of enriching different types of reversible modifications on protein thiols. Procedures for selective enrichment and analyses of S-nitrosylation and total reversible cysteine oxidation are presented to demonstrate the utility of this general strategy.

  4. Mechanical properties of composites based on unsaturated polyester resins obtained by chemical recycling of poly(ethylene terephthalate

    Directory of Open Access Journals (Sweden)

    Marinković Aleksandar D.

    2013-01-01

    Full Text Available Composites based on unsaturated polyester (UPe resins and fumed silica AEROSIL® RY 50, NY 50, RX 50 and NAX 50, as well as graphite, TiO2 or organically modified clay CLOISITE 30B were prepared in order to investigate the influence of reinforcing agents on the mechanical properties of composites. Unsaturated polyester resins were synthesized from maleic anhydride and products of glycolysis, obtained by depolymerization of poly(ethylene terephthalate with dipropylene glycol (UPe1 resin and triethylene glycol (UPe2 resin in the presence of tetrabutyl titanate catalyst. The obtained unsaturated polyesters were characterized by FTIR spectroscopy, acid and hydroxyl values, and their mechanical properties were also examined. Significant increase of the tensile modulus, tensile strength and decrease of the elongation at break was observed for composites prepared after addition of 10 wt.% of graphite or 10 wt.% of TiO2 to the UPe resins, indicating strong interaction between matrix and filler particles. On the other hand, nanocomposites prepared using UPe2 and hydrophobically modified silica nanoparticles showed lower tensile strength and tensile modulus than polymer matrix. The presence of CLOISITE 30B had no significant influence on the mechanical properties of UPe1, while tensile strength and tensile modulus of UPe2 increased after adding 10 wt.% of clay. [Projekat Ministarstva nauke Republike Srbije, br. 172013

  5. Influence of acrylamide monomer addition to the acrylic denture-base resins on mechanical and physical properties.

    Science.gov (United States)

    Aydogan Ayaz, Elif; Durkan, Rukiye

    2013-12-01

    The aim of the study was to evaluate the effect of adding acrylamide monomer (AAm) on the characterization, flexural strength, flexural modulus and thermal degradation temperature of poly(methyl methacrylate) (PMMA) denture-base resins. Specimens (n=10) were fabricated from a conventional heat-activated QC-20 (Qc-) and a microwave heat-activated Acron MC (Ac-) PMMA resins. Powder/liquid ratio followed the manufacturer's instructions for the control groups (Qc-c and Ac-c) and for the copolymer groups, the resins were prepared with 5% (-5), 10% (-10), 15% (-15) and 20% (-20) acrylamide contents, according to the molecular weight ratio, respectively. The flexural strength and flexural modulus were measured by a three-point bending test. The data obtained were statistically analyzed by Kruskal-Wallis test (α=0.05) to determine significant differences between the groups. The chemical structures of the resins were characterized by the nuclear magnetic resonance spectroscopy. Thermal stabilities were determined by thermogravimetric analysis (TGA) with a heating rate of 10 °C⋅min(-1) from 35 °C to 600 °C. Control groups from both acrylic resins showed the lowest flexural strength values. Qc-15 showed significant increase in the flexural strength when compared to Qc-c (PPMMA is increased by the insertion of AAm.

  6. Effect of surface treatment methods on the shear bond strength of auto-polymerized resin to thermoplastic denture base polymer

    Science.gov (United States)

    Koodaryan, Roodabeh

    2016-01-01

    PURPOSE Polyamide polymers do not provide sufficient bond strength to auto-polymerized resins for repairing fractured denture or replacing dislodged denture teeth. Limited treatment methods have been developed to improve the bond strength between auto-polymerized reline resins and polyamide denture base materials. The objective of the present study was to evaluate the effect of surface modification by acetic acid on surface characteristics and bond strength of reline resin to polyamide denture base. MATERIALS AND METHODS 84 polyamide specimens were divided into three surface treatment groups (n=28): control (N), silica-coated (S), and acid-treated (A). Two different auto-polymerized reline resins GC and Triplex resins were bonded to the samples (subgroups T and G, respectively, n=14). The specimens were subjected to shear bond strength test after they were stored in distilled water for 1 week and thermo-cycled for 5000 cycles. Data were analyzed with independent t-test, two-way analysis of variance (ANOVA), and Tukey's post hoc multiple comparison test (α=.05). RESULTS The bond strength values of A and S were significantly higher than those of N (P<.001 for both). However, statistically significant difference was not observed between group A and group S. According to the independent Student's t-test, the shear bond strength values of AT were significantly higher than those of AG (P<.001). CONCLUSION The surface treatment of polyamide denture base materials with acetic acid may be an efficient and cost-effective method for increasing the shear bond strength to auto-polymerized reline resin. PMID:28018569

  7. Distortion behavior of heat-activated acrylic denture-base resin in conventional and long, low-temperature processing methods.

    Science.gov (United States)

    Kawara, M; Komiyama, O; Kimoto, S; Kobayashi, N; Kobayashi, K; Nemoto, K

    1998-06-01

    There have been many reports on fatal distortion of heat-activated acrylic denture-base resin which is still widely used in the field of removable prosthodontics. However, these reports have failed to report quantitatively on polymerization and thermal shrinkage factors. In the present study, we attempted to verify that the shrinkage of heat-activated acrylic denture-base resin was caused mainly by thermal contraction after processing. Furthermore, we examined the degree of distortion resulting from long, low-temperature processing, and compared the results with that of the conventional method. The strain gauge and thermo-couple were embedded in a specimen at the time of resin packing. The measurement started from the beginning of processing and continued until the specimen was bench-cooled and immediately before and after it was de-flasked, as well as during seven-day immersion in water at 37 degrees C. The resin expanded when processed by the conventional method. Meanwhile, mild shrinkage, possibly polymerization shrinkage, was observed when the resin was processed by the low-temperature method. This suggested that polymerization shrinkage was compensated for by thermal expansion during processing by the conventional method. Moreover, the shrinkage strains in the period from the completion of processing to immediately after de-flasking, in both the conventional and low-temperature methods, were identical to the theoretical value of thermal shrinkage which we obtained by multiplying the linear coefficients of thermal expansion by temperature differences. The shrinkage strain in the specimen processed by the low-temperature method, measured from the end of processing to immediately after de-flasking, averaged 64% of that in the specimen processed by the conventional method. The results revealed quantitatively that the shrinkage of heat-activated acrylic denture-base resin was mainly thermal shrinkage, and demonstrated the advantage of the low-temperature method in

  8. Retention of a Flowable Composite Resin in Comparison to a Conventional Resin-Based Sealant: One-year Follow-up

    Directory of Open Access Journals (Sweden)

    N. Tadayon

    2010-03-01

    Full Text Available Objective: Long-term retention of pit and fissure sealants is crucial for their success. This clinical study evaluated the retention rate of a flowable composite resin (Filtek SupremeXT Flowable Restorative compared to a conventional resin-based sealant (Concise Light Cure White Sealant over 12 months.Materials and Methods: Forty subjects aged 6 to 9 years were included in the study. Using a half-mouth design, a total of 80 first permanent molars were sealed with conventional fissure sealant on one side of the mouth and flowable composite on the contralateralside. Clinical evaluation was performed at 3, 6, and 12 months by a single blind examiner and the retention was classified as complete retention, partial loss, or total loss.Results: For both materials, there was no total loss of sealants over 12 months. Partial loss of both materials was observed in one sealant after 3 months. After 6 months, 36 teeth sealed with conventional fissure sealant were intact compared with 37 sealed with a flowable composite, and after 12 months, 33 teeth sealed with conventional fissure sealant were intact compared with 35 that were sealed with a flowable composite. There were no statistically significant difference (P>0.05 between the two materials regarding the retention rate at each follow-up period.Conclusion: As flowable composite resulted in comparable sealant retention rates, this material could be a good choice for fissure sealant.

  9. Effect of surface roughness and adhesive system on repair potential of silorane-based resin composite

    Directory of Open Access Journals (Sweden)

    Enas H. Mobarak

    2012-07-01

    Full Text Available This study was performed to evaluate the influence of surface roughness and adhesive system on the repair strength of silorane-based resin composite. Twenty-four substrate discs from silorane-based FiltekP90 were made and stored for 24 h. Half of the discs were roughened against 320 grit SiC paper while the other half was polished against 4000 grit SiC paper. All discs were etched with phosphoric acid. Repair resin composite, FiltekP90 or FiltekZ250, was bonded to the treated surfaces using their corresponding adhesive; P90 System Adhesive (SA or Adper Scotchbond Multipurpose (SBMP ending up with four repair groups. The groups were as follows: G1: Smooth + SA + FiltekP90; G2: Roughened + SA + FiltekP90; G3: Smooth + SBMP + FiltekZ250; G4: Roughened + SBMP + FiltekZ250. Additional six unrepaired discs from each resin composite (G5 and G6 were prepared to test the cohesive strength. After 24 h, discs (n = 6/group were serially sectioned to obtain sticks (n = 30/group for microtensile bond strength (μTBS testing. Scanning electron microscopic (SEM evaluation of substrates that received different treatments as well as representative substrate-repair sticks from each group were performed. Modes of failure were also determined. Two-way ANOVA with Repeated-Measures revealed that surface treatment and repair material had no significant effect on repair bond strength of silorane-based composite material. Paired t-test showed that all repair strength values were significantly lower than the cohesive strength of FiltekP90. Adhesive failure was the predominant mode of failure which was confirmed by SEM. Surface treated FiltekP90 composite showed different textures under SEM whereas phosphoric acid did not produce clear changes. An interaction layer between SBMP adhesive and FiltekZ250 repairing composite was detected. Repair of the silorane composite was successful irrespective of the surface roughness and chemistry of the repair

  10. Evaluation of the responses of MHC class II molecule-expressing cells and macrophages to epoxy resin-based and 4-META-containing, methacrylate resin-based root canal sealers in rat subcutaneous tissue.

    Science.gov (United States)

    Yamanaka, Yusuke; Shigetani, Yoshimi; Yoshiba, Kunihiko; Kaneko, Tomoatsu; Yoshiba, Nagako; Okiji, Takashi

    2013-01-01

    Major histocompatibility complex (MHC) class II molecule-expressing cells and macrophages play a pivotal role in mediating the host tissue response to biomaterials. This study investigated the responses of these cells to epoxy resin-based and 4-META-containing, methacrylate resin-based endodontic sealers (AH Plus and MetaSEAL respectively) in rat connective tissue. Silicone tubes loaded with one of the sealers or solid silicone rods (control) were subcutaneously implanted in male Wistar rats for three time periods of 7, 14, or 28 days. Tissue specimens were immunoperoxidase-stained for MHC class II molecules and CD68 (a general macrophage marker). Results showed that AH Plus-implanted tissue displayed significantly more MHC class II-positive cells than the control at 14 and 28 days, whereas MetaSEAL-implanted tissue showed significantly more CD68-positive cells than both AH Plus-implanted tissue and the control at all time periods. It was concluded that the epoxy resin-based sealer induced the infiltration of MHC class II molecule-expressing cells, whereas 4-META-containing, methacrylate resin-based sealer elicited macrophage infiltration.

  11. A novel sustained release drug-resin complex-based microbeads of ciprofloxacin HCl.

    Science.gov (United States)

    Jain, Sunil K; Prajapati, Neeraj; Rajpoot, Kuldeep; Kumar, Amrish

    2016-12-01

    Objective A novel multiparticulate system for the gastro-mucoadhesive delivery of ciprofloxacin HCl (CFN) was developed with the help of ion-exchange resin to deal with urinary tract (UT) infections effectively. Materials and methods An optimized complex (resinate) of CFN with sodium polystyrene sulfonate USP resin was prepared and entrapped within microbeads of sodium alginate and pectin. The developed systems were evaluated for drug entrapment efficiency, percentage of mucoadhesion and in vitro release patterns in simulated gastric fluid (pH 1.2). Results and discussion The interaction of the resin complex and polycation via alginate was consequently supported the formation of polyelectrolyte complex membrane. The in vitro drug release studies demonstrate that formulation without drug-resin complex (NRB) released the drug more swiftly than formulation containing drug-resin complex (DRC). This controlled release pattern of drug, resin complex containing microbeads was owed to complexation between drug and resin. Conclusion Preliminary results from the study suggested that this drug-resin complex-entrapped microbeads can be used to incorporate other antibiotic drugs and could be effective against UT infection. Such developed formulation could be subjected to in vivo studies in future in order to prove their efficacy for such type of infections.

  12. Shielding properties of composite materials based on epoxy resin with graphene nanoplates in the microwave frequency range

    Science.gov (United States)

    Volynets, N. I.; Bychenok, D. S.; Lyubimov, A. G.; Kuzhir, P. P.; Maksimenko, S. A.; Baturkin, S. A.; Klochkov, A. Ya.; Mastrucci, M.; Micciulla, F.; Bellucci, S.

    2016-12-01

    Analysis of the electromagnetic properties of composite materials based on epoxy resin with the addition of 0.5 wt % graphene nanoplates in the frequency range of 26-37 GHz is performed. The influence of types of epoxy resin with different viscosities and the type of solvent used (ethanol, acetone) on the electromagnetic response in this frequency range are determined. It is established that the least viscous epoxy resin, Epikote 828, and solvent ethanol are most effective for creation of a shielding covering in the microwave range. Composite materials with optimal composition provide attenuation of the electromagnetic signal at a level at least 10 dB in power for a film thickness of 1.1 mm.

  13. Development of Plastic Scintillator Detector Array Based on SPMT

    Institute of Scientific and Technical Information of China (English)

    SU; Dan; ZHANG; Guo-guang; ZHAO; Xiao; FENG; Shu-qiang; ZHANG; Shuai

    2015-01-01

    Silicon photoelectric multiplier tuber(SPMT)is made of silicon chip,which can collect weak optical signal(Fig.1).When visible light irradiates SPMT,SPMT can change optical signal to electrical signal.The electrical signal size can be obtained through detecting optical signal size.When putting plastic scintillator before

  14. Cellular and molecular bases of memory: synaptic and neuronal plasticity.

    Science.gov (United States)

    Wang, J H; Ko, G Y; Kelly, P T

    1997-07-01

    Discoveries made during the past decade have greatly improved our understanding of how the nervous system functions. This review article examines the relation between memory and the cellular mechanisms of neuronal and synaptic plasticity in the central nervous system. Evidence indicating that activity-dependent short- and long-term changes in strength of synaptic transmission are important for memory processes is examined. Focus is placed on one model of synaptic plasticity called long-term potentiation, and its similarities with memory processes are illustrated. Recent studies show that the regulation of synaptic strength is bidirectional (e.g., synaptic potentiation or depression). Mechanisms involving intracellular signaling pathways that regulate synaptic strength are described, and the specific roles of calcium, protein kinases, protein phosphatases, and retrograde messengers are emphasized. Evidence suggests that changes in synaptic ultrastructure, dendritic ultrastructure, and neuronal gene expression may also contribute to mechanisms of synaptic plasticity. Also discussed are recent findings about postsynaptic mechanisms that regulate short-term synaptic facilitation and neuronal burst-pattern activity, as well as evidence about the subcellular location (presynaptic or postsynaptic) of mechanisms involved in long-term synaptic plasticity.

  15. Tutorial on state variable based plasticity: an Abaqus UHARD subroutine

    CSIR Research Space (South Africa)

    Jansen van Rensburg, GJ

    2012-12-01

    Full Text Available of the yield stress, the incremental (differential) update from a previous converged time step is required instead of a closed form expression that relates flow stress to plastic strain. Elastoviscoplastic models that make use of state variables better capture...

  16. Cumulative effect of disinfection procedures on microhardness and tridimensional stability of a poly(methyl methacrylate) denture base resin.

    Science.gov (United States)

    Sartori, Evandro Afonso; Schmidt, Caroline Bom; Mota, Eduardo Gonçalves; Hirakata, Luciana Mayumi; Shinkai, Rosemary Sadami Arai

    2008-08-01

    Microwave irradiation has been used for disinfection of dentures instead of chemical solutions; yet, its effect on resin properties after repeated procedures still is unclear. This study evaluated the cumulative effect of two disinfection methods on Knoop microhardness and tridimensional stability of a poly(methyl methacrylate) denture base resin. For the microhardness measurement, 24-resin discs received mechanical polishing and were submitted to the following treatments: (1) control (no disinfection), (2) chemical disinfection (immersion in 100ppm chloride solution for 24h), or (3) microwave disinfection (irradiation at 690 W for 6 min). Disinfection procedures were performed twice (T1, T2) with a 7-day interval. Knoop microhardness was recorded after polishing (T0) and after T1 and T2. For the dimensional stability test (measured by the adaptation of the denture bases), 36-maxillary denture bases were obtained from type III dental stone casts duplicated from a metallic master model and submitted to the disinfection treatment. Adaptation of denture bases was measured at baseline (T0) and after T1 and T2 by weighing a vinyl polysiloxane film reproducing the gap between resin base and master model. Data were analyzed by ANOVA GLM for repeated measures and Bonferroni's test, alpha = 0.05. Knoop microhardness was not modified by any disinfection procedure but decreased over time. Denture resin bases submitted to microwave disinfection had gradual increase of distortion over time, while bases immersed in chloride solution did not differ from the control group and remained dimensionally stable from T1 to T2.

  17. Thermal and Mechanical Characteristics of Polymer Composites Based on Epoxy Resin, Aluminium Nanopowders and Boric Acid

    Science.gov (United States)

    Nazarenko, O. B.; Melnikova, T. V.; Visakh, P. M.

    2016-01-01

    The epoxy polymers are characterized by low thermal stability and high flammability. Nanoparticles are considered to be effective fillers of polymer composites for improving their thermal and functional properties. In this work, the epoxy composites were prepared using epoxy resin ED-20, polyethylene polyamine as a hardener, aluminum nanopowder and boric acid fine powder as flame-retardant filler. The thermal characteristics of the obtained samples were studied using thermogravimetric analysis and differential scanning calorimetry. The mechanical characteristics of epoxy composites were also studied. It was found that an addition of all fillers enhances the thermal stability and mechanical characteristics of the epoxy composites. The best thermal stability showed the epoxy composite filled with boric acid. The highest flexural properties showed the epoxy composite based on the combination of boric acid and aluminum nanopowder.

  18. Chaos Analysis of Discharge Current Based on Tracking Test of Phenolic Resin

    Institute of Scientific and Technical Information of China (English)

    DU Boxue; ZHENG Xiaolei; DONG Dianshuai

    2009-01-01

    In tracking test,discharge is a complicated process and comparative tracking index(CTI)has wide variation.To evaluate tracking resistance,the chaos analysis of discharge current is presented based on the tracking test ofphenolic resin in accordance with IEC601 12.According to the characteristics of statistical self-similarity and complexity of discharge current,the largest Lyapunov exponent is calculated,and the 2-dimensional attractor ofdischarge current is reconstructed.Moreover,the attractors of discharge current and recurrence plots of different discharge states are reconstructed.The results indicate that the chaos attractors have different characteristics in evolutionary tracks,the topological structure and grain direction of recurrence plots show significant differences.The chaos attractor can describe the tracking process,the recurrence plot can identify the tracking state clearly,while its arithmetic is simple.

  19. New Flexible Flame Retardant Coatings Based on Siloxane Resin and Ethylene-Vinyl Chloride Copolymer

    Directory of Open Access Journals (Sweden)

    Dorota Wesolek

    2016-12-01

    Full Text Available This work presents the effectiveness of a phosphorus-containing flame retardant based on siloxane resin and ethylene-vinyl chloride copolymer as a back-coating of fabrics. The possibility of improving flame retardant efficiency of this composition by introducing fumed silica, montmorillonite, carbon nanotubes, and graphite was evaluated. The effect of each additive on the efficiency of the composition was examined separately. Flammability tests of flame retardant-coated fabrics (natural and synthetic were carried out using pyrolysis combustion flow calorimetry (PCFC, cone calorimetry, and limiting oxygen index determination. An assessment of the ignitability of upholstered furniture containing flame retardant fabric, resistance to washing, antifungal activity, and some of the utility properties of the final newly-developed flame-retardant coating was conducted.

  20. Influence of halogen irradiance on short- and long-term wear resistance of resin-based composite materials.

    LENUS (Irish Health Repository)

    Bhamra, Gurcharn S

    2009-02-01

    The Oregon Health Science University (OHSU) four-chamber oral wear simulator was used to examine the impact of halogen irradiance on the short- and long-term wear behavior of four-methacrylate resin-based composites (RBCs). The hypothesis proposed was that exacerbated wear would occur following the long-term wear of RBCs irradiated under non-optimized irradiance conditions.

  1. Designed biodegradable hydrogel structures prepared by stereolithography using poly(ethylene glycol)/poly(D,L-lactide)-based resins

    NARCIS (Netherlands)

    Seck, Tetsu M.; Melchels, Ferry P. W.; Feijen, Jan; Grijpma, Dirk W.

    2010-01-01

    Designed three-dimensional biodegradable poly(ethylene glycol)/poly(D,L-lactide) hydrogel structures were prepared for the first time by stereolithography at high resolutions. A photo-polymerisable aqueous resin comprising PDLLA-PEG-PDLLA-based macromer, visible light photo-initiator, dye and inhibi

  2. Bio-based and biodegradable plastics for use in crop production.

    Science.gov (United States)

    Riggi, Ezio; Santagata, Gabriella; Malinconico, Mario

    2011-01-01

    The production and management of crops uses plastics for many applications (e.g., low tunnels, high tunnels, greenhouses, mulching, silage bags, hay bales, pheromone traps, coatings of fertilizers or pesticides or hormones or seeds, and nursery pots and containers for growing transplants). All these applications have led some authors to adopt the term "plasticulture" when discussing the use of plastic materials in agriculture and related industries. Unfortunately, the sustainability of this use of plastics is low, and renewability and degradability have become key words in the debate over sustainable production and utilization of plastic. Recently, researchers and the plastics industry have made strong efforts (i) to identify new biopolymers and natural additives from renewable sources that can be used in plastics production and (ii) to enhance the degradability (biological or physical) of the new ecologically sustainable materials. In the present review, we describe the main research results, current applications, patents that have been applied for in the last two decades, and future perspectives on sustainable use of plastics to support crop production. The article presents some promising patents on bio-based and biodegradable plastics for use in crop production.

  3. Calculation of temperature distribution in adiabatic shear band based on gradient-dependent plasticity

    Institute of Scientific and Technical Information of China (English)

    王学滨

    2004-01-01

    A method for calculation of temperature distribution in adiabatic shear band is proposed in terms of gradient-dependent plasticity where the characteristic length describes the interactions and interplaying among microstructures. First, the increment of the plastic shear strain distribution in adiabatic shear band is obtained based on gradient-dependent plasticity. Then, the plastic work distribution is derived according to the current flow shear stress and the obtained increment of plastic shear strain distribution. In the light of the well-known assumption that 90% of plastic work is converted into the heat resulting in increase in temperature in adiabatic shear band, the increment of the temperature distribution is presented. Next, the average temperature increment in the shear band is calculated to compute the change in flow shear stress due to the thermal softening effect. After the actual flow shear stress considering the thermal softening effect is obtained according to the Johnson-Cook constitutive relation, the increment of the plastic shear strain distribution, the plastic work and the temperature in the next time step are recalculated until the total time is consumed. Summing the temperature distribution leads to rise in the total temperature distribution. The present calculated maximum temperature in adiabatic shear band in titanium agrees with the experimental observations. Moreover, the temperature profiles for different flow shear stresses are qualitatively consistent with experimental and numerical results. Effects of some related parameters on the temperature distribution are also predicted.

  4. Differential hardening in IF steel - Experimental results and a crystal plasticity based model

    NARCIS (Netherlands)

    Mulder, J.; Eyckens, P.; van den Boogaard, Antonius H.; Hora, P.

    2015-01-01

    Work hardening in metals is commonly described by isotropic hardening, especially for monotonically increasing proportional loading. The relation between different stress states in this case is determined by equivalent stress and strain definitions, based on equal plastic dissipation. However,

  5. Effects of constitutive parameters on adiabatic shear localization for ductile metal based on JOHNSON-COOK and gradient plasticity models

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-bin

    2006-01-01

    By using the widely used JOHNSON-COOK model and the gradient-dependent plasticity to consider microstmctural effect beyond the occurrence of shear strain localization, the distributions of local plastic shear strain and deformation in adiabatic shear band(ASB) were analyzed. The peak local plastic shear strain is proportional to the average plastic shear strain, while it is inversely proportional to the critical plastic shear strain corresponding to the peak flow shear stress. The relative plastic shear deformation between the top and base of ASB depends on the thickness of ASB and the average plastic shear strain. A parametric study was carried out to study the influence of constitutive parameters on shear strain localization. Higher values of static shear strength and work to heat conversion factor lead to lower critical plastic shear strain so that the shear localization is more apparent at the same average plastic shear strain. Higher values of strain-hardening exponent, strain rate sensitive coefficient, melting point,thermal capacity and mass density result in higher critical plastic shear strain, leading to less apparent shear localization at the same average plastic shear strain. The strain rate sensitive coefficient has a minor influence on the critical plastic shear strain, the distributions of local plastic shear strain and deformation in ASB. The effect of strain-hardening modulus on the critical plastic shear strain is not monotonous. When the maximum critical plastic shear strain is reached, the least apparent shear localization occurs.

  6. Effect of Energy Drinks on Discoloration of Silorane and Dimethacrylate-Based Composite Resins.

    Science.gov (United States)

    Ahmadizenouz, Ghazaleh; Esmaeili, Behnaz; Ahangari, Zohreh; Khafri, Soraya; Rahmani, Aghil

    2016-08-01

    This study aimed to assess the effects of two energy drinks on color change (ΔE) of two methacrylate-based and a silorane-based composite resin after one week and one month. Thirty cubic samples were fabricated from Filtek P90, Filtek Z250 and Filtek Z350XT composite resins. All the specimens were stored in distilled water at 37°C for 24 hours. Baseline color values (L*a*b*) of each specimen were measured using a spectrophotometer according to the CIEL*a*b* color system. Ten randomly selected specimens from each composite were then immersed in the two energy drinks (Hype, Red Bull) and artificial saliva (control) for one week and one month. Color was re-assessed after each storage period and ΔE values were calculated. The data were analyzed using the Kruskal Wallis and Mann-Whitney U tests. Filtek Z250 composite showed the highest ΔE irrespective of the solutions at both time points. After seven days and one month, the lowest ΔE values were observed in Filtek Z350XT and Filtek P90 composites immersed in artificial saliva, respectively. The ΔE values of Filtek Z250 and Z350XT composites induced by Red Bull and Hype energy drinks were not significantly different. Discoloration of Filtek P90 was higher in Red Bull energy drink at both time points. Prolonged immersion time in all three solutions increased ΔE values of all composites. However, the ΔE values were within the clinically acceptable range (<3.3) at both time points.

  7. Bio-Based Resin Reinforced with Flax Fiber as Thermorheologically Complex Materials

    Directory of Open Access Journals (Sweden)

    Ali Amiri

    2016-04-01

    Full Text Available With the increase in structural applications of bio-based composites, the study of long-term creep behavior of these materials turns into a significant issue. Because of their bond type and structure, natural fibers and thermoset resins exhibit nonlinear viscoelastic behavior. Time-temperature superposition (TTS provides a useful tool to overcome the challenge of the long time required to perform the tests. The TTS principle assumes that the effect of temperature and time are equivalent when considering the creep behavior, therefore creep tests performed at elevated temperatures may be converted to tests performed at longer times. In this study, flax fiber composites were processed with a novel liquid molding methacrylated epoxidized sucrose soyate (MESS resin. Frequency scans of flax/MESS composites were obtained at different temperatures and storage modulus and loss modulus were recorded and the application of horizontal and vertical shift factors to these viscoelastic functions were studied. In addition, short-term strain creep at different temperatures was measured and curves were shifted with solely horizontal, and with both horizontal and vertical shift factors. The resulting master curves were compared with a 24-h creep test and two extrapolated creep models. The findings revealed that use of both horizontal and vertical shift factors will result in a smoother master curves for loss modulus and storage modulus, while use of only horizontal shift factors for creep data provides acceptable creep strain master curves. Based on the findings of this study, flax/MESS composites can be considered as thermorheologically complex materials.

  8. Determination of surface roughness and topography of dental resin-based nanocomposites using AFM analysis.

    Science.gov (United States)

    Lainović, Tijana; Vilotić, Marko; Blažić, Larisa; Kakaš, Damir; Marković, Dubravka; Ivanišević, Aljoša

    2013-02-01

    The aim of this study was to determine surface roughness and topography of polished dental resin-based nanocomposites. Four representative dental resin-based nanocomposites were tested in the study: two nanohybrids (Filtek Z550 and Tetric EvoCeram) and two nanofilled (Filtek Ultimate Body and Filtek Ultimate Translucent); and two reference materials: one microfilled (Gradia Direct) and one microhybrid (Filtek Z250). Polymerized cylindrical specimens (4 mm x 2 mm) were polished with multi-step polishing system- Super Snap. Immediately after the polishing, topography of each specimen was examined by Veeco di CP-II Atomic Force Microscope. Specimen's surface has been scanned in 6 points in contact mode with CONT20A-CP tips. 1 Hz scan rate and 256 × 256 resolution were used to obtain topography on a 90 µm × 90 µm scanning area. Measured topography data were processed by Image Processing and Data Analysis v2.1.15 software. Following parameters were compared among specimens: average roughness and maximum peak-to-valley distance. All of the tested materials had similar average surface roughness after finishing and polishing procedure. The lowest values occurred in the material Filtek Ultimate Body, and the highest in the Filtek Z550. When interpreting maximum peak-to-valley distance the larger differences in values (up to 100%) occurred in Filtek Z550, Filtek Z250 and Filtek Ultimate Body, which is a result of the deep polishing channels and tracks. Type, size, distribution of fillers and filler loading in tested materials, didn't influence average roughness values, but had an impact on maximum peak-to-valley distance values.

  9. The influence of monomeric resin and filler characteristics on the performance of experimental resin-based composites (RBCs) derived from a commercial formulation.

    LENUS (Irish Health Repository)

    Hahnel, Sebastian

    2012-04-01

    To explore experimental RBCs derived from a successful commercially available RBC (Grandio) to investigate resin monomer blend and filler parameters (volume fraction, density and diameter) on RBC performance.

  10. Si-based thin film coating on Y-TZP: Influence of deposition parameters on adhesion of resin cement

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, José Renato Cavalcanti, E-mail: joserenatocq@hotmail.com [Potiguar University, Department of Biotechnology, Natal (Brazil); Nogueira Junior, Lafayette [São Paulo State University, Department of Prosthodontics and Dental Materials, São José dos Campos (Brazil); Massi, Marcos [Federal University of São Paulo, Institute of Science and Technology, São José dos Campos (Brazil); Silva, Alecssandro de Moura; Bottino, Marco Antonio [São Paulo State University, Department of Prosthodontics and Dental Materials, São José dos Campos (Brazil); Sobrinho, Argemiro Soares da Silva [Technological Institute of Aeronautics, Department of Physics, São José dos Campos (Brazil); Özcan, Mutlu [University of Zurich, Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Zurich (Switzerland)

    2013-10-01

    This study evaluated the influence of deposition parameters for Si-based thin films using magnetron sputtering for coating zirconia and subsequent adhesion of resin cement. Zirconia ceramic blocks were randomly divided into 8 groups and specimens were either ground finished and polished or conditioned using air-abrasion with alumina particles coated with silica. In the remaining groups, the polished specimens were coated with Si-based film coating with argon/oxygen magnetron discharge at 8:1 or 20:1 flux. In one group, Si-based film coating was performed on air-abraded surfaces. After application of bonding agent, resin cement was bonded. Profilometry, goniometry, Energy Dispersive X-ray Spectroscopy and Rutherford Backscattering Spectroscopy analysis were performed on the conditioned zirconia surfaces. Adhesion of resin cement to zirconia was tested using shear bond test and debonded surfaces were examined using Scanning Electron Microscopy. Si-based film coating applied on air-abraded rough zirconia surfaces increased the adhesion of the resin cement (22.78 ± 5.2 MPa) compared to those of other methods (0–14.62 MPa) (p = 0.05). Mixed type of failures were more frequent in Si film coated groups on either polished or air-abraded groups. Si-based thin films increased wettability compared to the control group but did not change the roughness, considering the parameters evaluated. Deposition parameters of Si-based thin film and after application of air-abrasion influenced the initial adhesion of resin cement to zirconia.

  11. Do Red-cockaded Woodpeckers Select Cavity Trees Based on Chemical Composition of Pine Resin?

    Science.gov (United States)

    Richard N. Conner; Robert H. Johnson; D. Craig Rudolph; Daniel Saenz

    2003-01-01

    We examined resin chemistry of loblolly (Pinus taeda) and shortleaf (P. echinata) pines selected as cavity trees by Red-cockaded Woodpeckers (Picoides borealis) in eastern Texas. We sampled resin from (1) pines selected by Red-cockaded Woodpeckers that contained naturally excavated active cavities, (2) pines...

  12. Influence of matrix and filler fraction on biofilm formation on the surface of experimental resin-based composites.

    Science.gov (United States)

    Ionescu, Andrei; Brambilla, Eugenio; Wastl, Daniel S; Giessibl, Franz J; Cazzaniga, Gloria; Schneider-Feyrer, Sibylle; Hahnel, Sebastian

    2015-01-01

    The aim of this study was to investigate the impact of resin matrix chemistry and filler fraction on biofilm formation on the surface of experimental resin-based composites (RBCs). Specimens were prepared from eight experimental RBC formulations differing in resin matrix blend (BisGMA/TEGDMA in a 7:3 wt% ratio or UDMA/aliphatic dimethacrylate in a 1:1 wt% ratio) and filler fraction (no fillers; 65 wt% dental glass with an average diameter of 7 or 0.7 µm or 65 wt% SiO2 with an average diameter of 20 nm). Surface roughness, surface free energy, and chemical surface composition were determined; surface topography was visualized using atomic force microscopy. Biofilm formation was simulated under continuous flow conditions for a 48 h period using a monospecies Streptococcus mutans and a multispecies biofilm model. In the monospecies biofilm model, the impact of the filler fraction overruled the influence of the resin matrix, indicating lowest biofilm formation on RBCs with nano-scaled filler particles and those manufactured from the neat resin blends. The multispecies model suggested a more pronounced effect of the resin matrix blend, as significantly higher biofilm formation was identified on RBCs with a UDMA/dimethacrylate matrix blend than on those including a BisGMA/TEGDMA matrix blend but analogous filler fractions. Although significant differences in surface properties between the various materials were identified, correlations between the surface properties and biofilm formation were poor, which highlights the relevance of surface topography and chemistry. These results may help to tailor novel RBC formulations which feature reduced biofilm formation on their surface.

  13. Water sorption characteristics of light-cured dental resins and composites based on Bis-EMA/PCDMA.

    Science.gov (United States)

    Sideridou, Irini; Achilias, Dimitris S; Spyroudi, Chrysa; Karabela, Maria

    2004-01-01

    The water uptake characteristics of resins and composites based on an ethoxylated bisphenol A glycol dimethacrylate (Bis-EMA) and a polycarbonate dimethacrylate (PCDMA) were studied in detail. Polydimethacrylate resins were prepared by photopolymerization of the neat monomers and mixtures of them with various weight ratios, using the camphoroquinone/N,N-dimethylaminoethyl methacrylate system as initiator, while the composites were prepared from the light-curing of commercial samples (Sculpt-It and Alert). Water sorption/desorption was examined both in equilibrium and dynamic conditions in two adjacent sorption-desorption cycles. The equilibrium water uptake from all resins was very small with a trend to increase as the amount of PCDMA was increased. The inverse effect was observed in the solubility values. The composites studied exhibited also very low water uptake values in comparison to other composite materials reported in the literature. It was also observed that the equilibrium uptake decreased with increasing filler loading. Slightly larger equilibrium water uptake and much smaller solubility values were obtained during the second sorption-desorption cycle in comparison to the first one. Concerning the sorption rate data, it was observed that the resin materials followed Fickian diffusion during almost the whole sorption or desorption curve, while the composites showed this behavior until only M(t)/M( infinity ) congruent with 0.5. The diffusion coefficients calculated for the resins were larger than those of the composites and always higher during desorption compared to sorption. The values of the diffusion coefficients for both resins and composites were in the same order of magnitude with the values of the corresponding materials reported in the literature.

  14. Phenolic Resin Sector Enters New Stage

    Institute of Scientific and Technical Information of China (English)

    Pu Zeshuang

    2007-01-01

    @@ Rapid output increase With the importation of new production technologies and the boom of large timber processing, insulation refractory material, composite material and foam plastics sectors in recent years, the phenolic resin production in China has developed rapidly.

  15. Fracture resistance of computer-aided design/computer-aided manufacturing-generated composite resin-based molar crowns.

    Science.gov (United States)

    Harada, Akio; Nakamura, Keisuke; Kanno, Taro; Inagaki, Ryoichi; Örtengren, Ulf; Niwano, Yoshimi; Sasaki, Keiichi; Egusa, Hiroshi

    2015-04-01

    The aim of this study was to investigate whether different fabrication processes, such as the computer-aided design/computer-aided manufacturing (CAD/CAM) system or the manual build-up technique, affect the fracture resistance of composite resin-based crowns. Lava Ultimate (LU), Estenia C&B (EC&B), and lithium disilicate glass-ceramic IPS e.max press (EMP) were used. Four types of molar crowns were fabricated: CAD/CAM-generated composite resin-based crowns (LU crowns); manually built-up monolayer composite resin-based crowns (EC&B-monolayer crowns); manually built-up layered composite resin-based crowns (EC&B-layered crowns); and EMP crowns. Each type of crown was cemented to dies and the fracture resistance was tested. EC&B-layered crowns showed significantly lower fracture resistance compared with LU and EMP crowns, although there was no significant difference in flexural strength or fracture toughness between LU and EC&B materials. Micro-computed tomography and fractographic analysis showed that decreased strength probably resulted from internal voids in the EC&B-layered crowns introduced by the layering process. There was no significant difference in fracture resistance among LU, EC&B-monolayer, and EMP crowns. Both types of composite resin-based crowns showed fracture loads of >2000 N, which is higher than the molar bite force. Therefore, CAD/CAM-generated crowns, without internal defects, may be applied to molar regions with sufficient fracture resistance. © 2015 Eur J Oral Sci.

  16. Degree of conversion and leached monomers of urethane dimethacrylate-hydroxypropyl methacrylate-based dental resin systems.

    Science.gov (United States)

    Zhang, Meng; Puska, Mervi A; Botelho, Michael G; Säilynoja, Eija S; Matinlinna, Jukka P

    2016-01-01

    The degree of conversion (DC) and monomer leaching of three experimental urethane dimethacrylate (UEDMA)-hydroxypropyl methacrylate (HPMA)-based resin systems were studied. Three experimental resins (E1: 70.6 wt% UEDMA + 27.4 wt% HPMA, E2: 80.6 wt% UEDMA + 17.4 wt% HPMA, E3: 90.6 wt% UEDMA + 7.4 wt% HPMA) and one control resin [C: 70.6 wt% bis-phenol A glycidyl methacrylate (bis-GMA) + 27.4 wt% methyl methacrylate (MMA)] were prepared. For the DC test, cylindrical specimens [1.5 mm (h) × 6 mm (d)] were scanned with an ATR-FTIR instrument before and after light-curing (n = 5). For the monomer leaching test, block-shaped specimens [5.67 mm (l) × 2.00 mm (w) × 2.00 mm (h)] were light-cured (n = 6), stored in a 75% ethanol:water solution for 3 days, and then analyzed with HPLC. The UEDMA-HPMA-based experimental groups showed higher DC (62-78%) than the bis-GMA-MMA-based control group (58-66%), and the DC decreased as the UEDMA content increased (P < 0.05). Amongst the four groups, E3 exhibited the lowest leaching of both mono methacrylate (0.1% HPMA) and dimethacrylate (<0.043% UEDMA) monomers after 30 or 40 s of curing. The UEDMA-HPMA-based resins, therefore, exhibited higher DC and less monomer leaching compared to the bis-GMA-MMA-based resin. (J Oral Sci 58, 15-22, 2016).

  17. Study on the Characteristics of a Scintillator for Beta-ray Detection using Epoxy Resin

    Science.gov (United States)

    Nam, Jong Soo; Choi, Yong Seok; Hong, Sang Bum; Seo, Bum Kyung; Moon, Jei Kwon; Choi, Jong Won

    2017-09-01

    A thin plate of a plastic scintillator for detecting a beta-ray was developed. The plastic scintillator was made using epoxy resin and organic scintillators such as 2.5-diphenyloxazole (PPO) and 1,4-bis [5-phenyl-2-oxazole] benzene (POPOP). The mixture ratio of epoxy resin and the organic scintillators was determined using their absorbance, transmittance, emission spectra, and transparency. Their optimal weight percentage of PPO and POPOP in the organic scintillators was adjusted to 0.2 wt%:0.01 wt%. The prepared plastic scintillator was used to measure the standard source of Sr-90. The pulse height spectra and total counts of the prepared plastic scintillator were similar to a commercial plastic scintillator. Based on the above results, a large-area plastic scintillator was prepared for rapid investigation of a site contaminated with Sr-90. The prepared large-area plastic scintillator was evaluated for the characteristics in the laboratory. The evaluation results are expected to be usefully utilized in the development of a large-area plastic scintillation detector. The large-area plastic scintillation detector developed on the basis of the evaluation results is expected to be utilized to quickly measure the contamination of Sr-90 in the grounds used as a nuclear power facility.

  18. Influence of ionizing radiation on the mechanical properties of BisGMA/TEGDMA based experimental resin

    Science.gov (United States)

    LMP, Campos; Boaro, LC; LKG, Santos; Parra, DF; Lugão, AB

    2015-10-01

    Dental restorative composites are activated by visible light and the polymerization process, known as direct technique, is initiated by absorbing light in a specific wavelength range (450-500 nm). However this technique presented some disadvantages. If light is not inserted correctly, layers uncured can cause countless damage to restoration, especially with regard to mechanical properties. A clinical alternative used to reduce the shortcomings of direct application is the use of composite resins for indirect application. These composites are adaptations of resins prepared for direct use, with differences mainly in the healing process. Besides the traditional photoactivation, indirect application composites may be submitted to particular curing conditions, such as a slow curing rate, heating, vacuum, and inert-gas pressure leading to an oxygen-free environment. However few studies have been conducted on the process of post-curing by ionizing radiation at low doses. On this sense the purpose of this study was to evaluate possible interactions of ionizing radiation in the post-curing process of the experimental composites based on BisGMA/TEGDMA filled with silica Aerosil OX-50 silanized. Characterization of the experimental composites was performed by thermogravimetry analysis, infrared spectroscopy, elastic modulus and flexural strength. Statistical analysis of results was calculated by one-way ANOVA/Tukey's test. Cross-linking of the polymeric matrix caused by ionizing radiation, influenced the thermal stability of irradiated specimens. FTIR analysis showed that the ionizing radiation induced a post-cure reaction in the specimens. The irradiation dose influenced directly the mechanical properties that showed a strong positive correlation between flexural strength and irradiation and between modulus strength and irradiation.

  19. Novel bioactive polyester scaffolds prepared from unsaturated resins based on isosorbide and succinic acid

    Energy Technology Data Exchange (ETDEWEB)

    Śmiga-Matuszowicz, Monika, E-mail: monika.smiga-matuszowicz@polsl.pl [Silesian University of Technology, Department of Physical Chemistry and Technology of Polymers, M. Strzody Street 9, 44-100 Gliwice (Poland); Janicki, Bartosz; Jaszcz, Katarzyna; Łukaszczyk, Jan [Silesian University of Technology, Department of Physical Chemistry and Technology of Polymers, M. Strzody Street 9, 44-100 Gliwice (Poland); Kaczmarek, Marcin [Silesian University of Technology, Department of Biomaterials and Medical Devices Engineering, de Gaulle' a Street 66, 41-800 Zabrze (Poland); Lesiak, Marta; Sieroń, Aleksander L. [Medical University of Silesia, Department of General and Molecular Biology and Genetics, Medyków Street 18, 40-752 Katowice (Poland); Simka, Wojciech [Silesian University of Technology, Department of Chemistry, Inorganic Technology and Fuels, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Mierzwiński, Maciej; Kusz, Damian [Medical University of Silesia, Department of Orthopedics and Traumatology, Ziołowa Street 45, 40-635 Katowice (Poland)

    2014-12-01

    In this study new biodegradable materials obtained by crosslinking poly(3-allyloxy-1,2-propylene succinate) (PSAGE) with oligo(isosorbide maleate) (OMIS) and small amount of methyl methacrylate were investigated. The porous scaffolds were obtained in the presence of a foaming system consisted of calcium carbonate/carboxylic acid mixture, creating in situ porous structure during crosslinking of liquid formulations. The maximum crosslinking temperature and setting time, the cured porous materials morphology as well as the effect of their porosity on mechanical properties and hydrolytic degradation process were evaluated. It was found that the kind of carboxylic acid used in the foaming system influenced compressive strength and compressive modulus of porous scaffolds. The MTS cytotoxicity assay was carried out for OMIS using hFOB1.19 cell line. OMIS resin was found to be non-toxic in wide range of concentrations. On the ground of scanning electron microscopy (SEM) observations and energy X-ray dispersive analysis (EDX) it was found that hydroxyapatite (HA) formation at the scaffolds surfaces within short period of soaking in phosphate buffer solution occurs. After 3 h immersion a compact layer of HA was observed at the surface of the samples. The obtained results suggest potential applicability of resulted new porous crosslinked polymeric materials as temporary bone void fillers. - Highlights: • Isosorbide-based resin was used as a component of biodegradable scaffolds. • CAC/carboxylic acid system was proven as facile method to obtain porous scaffolds. • Porous scaffolds displayed the formation of hydroxyapatite at their surfaces.

  20. POPs monitoring in Australia and New Zealand using plastic resin pellets, and International Pellet Watch as a tool for education and raising public awareness on plastic debris and POPs.

    Science.gov (United States)

    Yeo, Bee Geok; Takada, Hideshige; Taylor, Heidi; Ito, Maki; Hosoda, Junki; Allinson, Mayumi; Connell, Sharnie; Greaves, Laura; McGrath, John

    2015-12-15

    Persistent organic pollutants (i.e. PCBs, DDTs, and HCHs) were analyzed along Australia and New Zealand North Island coastlines. PCB concentrations were high in urban areas (107-294 ng/g-pellet), with Sydney Harbour the most polluted. Hepta-chlorinated PCB was abundant, with ~30% in urban areas suggesting legacy pollution. DDT concentrations showed similar pattern except in rural agricultural sites, Taupo Bay and Ahipara, New Zealand (23 and 47 ng/g-pellet). p,p'-DDE predominance at these 2 sites suggested historical input; they also had high HCH concentrations (17 and 29 ng/g-pellet). The role of International Pellet Watch (IPW) in science communication was studied through feedbacks from IPW volunteers, case studies and examples. IPW data were categorized into understandable terms and tailored reports based on volunteers' backgrounds complemented with pollution maps. The effectiveness of IPW science communication has led to its use in awareness and education activities focusing on both POPs and plastic debris issues.

  1. Plastic Deformation of Copper-Based Alloy Reinforced with Incoherent Nanoparticles

    Science.gov (United States)

    Matvienko, O. V.; Daneiko, O. I.; Kovalevskaya, T. A.

    2017-06-01

    The paper deals with research carried out into plastic deformation of a heavy-wall pipe made of nanoparticle reinforced copper-based alloy. We present an original approach which combines methods of crystal plasticity and deformable solid mechanics, thereby allowing to study the stress-strain state of the heavy-wall pipe strengthened with incoherent nanoparticles using a homogeneous internal pressure. Dependences are constructed for the yielding area and the pressure, the limit of elasto-plastic resistance is obtained for the heavy-wall pipe and its deformation degree is described. It is shown that the particle size has an effect on strength properties of the material.

  2. Simplified non-linear time-history analysis based on the Theory of Plasticity

    DEFF Research Database (Denmark)

    Costa, Joao Domingues

    2005-01-01

    is based on the Theory of Plasticity. Firstly, the formulation and the computational procedure to perform time-history analysis of a rigid-plastic single degree of freedom (SDOF) system are presented. The necessary conditions for the method to incorporate pinching as well as strength degradation......This paper aims at giving a contribution to the problem of developing simplified non-linear time-history (NLTH) analysis of structures which dynamical response is mainly governed by plastic deformations, able to provide designers with sufficiently accurate results. The method to be presented...

  3. Simplified non-linear time-history analysis based on the Theory of Plasticity

    DEFF Research Database (Denmark)

    Costa, Joao Domingues

    2005-01-01

    is based on the Theory of Plasticity. Firstly, the formulation and the computational procedure to perform time-history analysis of a rigid-plastic single degree of freedom (SDOF) system are presented. The necessary conditions for the method to incorporate pinching as well as strength degradation......This paper aims at giving a contribution to the problem of developing simplified non-linear time-history (NLTH) analysis of structures which dynamical response is mainly governed by plastic deformations, able to provide designers with sufficiently accurate results. The method to be presented...

  4. Mechanical properties and fire retardancy of bidirectional reinforced composite based on biodegradable starch resin and basalt fibres

    Directory of Open Access Journals (Sweden)

    2008-11-01

    Full Text Available Environmental problems caused by extensive use of polymeric materials arise mainly due to lack of landfill space and depletion of finite natural resources of fossil raw materials, such as petroleum or natural gas. The substitution of synthetic petroleum-based resins with natural biodegradable resins appears to be one appropriate measure to remedy the above-mentioned situation. This study presents the development of a composite that uses environmentally degradable starch-based resin as matrix and basalt fibre plain fabric as reinforcement. Prepreg sheets were manufactured by means of a modified doctor blade system and a hot power press. The sheets were used to manufacture bidirectional-reinforced specimens with fibre volume contents ranging from 33 to 61%. Specimens were tested for tensile and flexural strength, and exhibited values of up to 373 and 122 MPa, respectively. Through application of silane coupling agents to the reinforcement fibres, the flexural composite properties were subsequently improved by as much as 38%. Finally, in order to enhance the fire retardancy and hence the applicability of the composite, fire retardants were applied to the resin, and their effectiveness was tested by means of flame rating (according to UL 94 and thermogravimetric analysis (TGA, respectively.

  5. Microscale characterisation of stochastically reconstructed carbon fiber-based Gas Diffusion Layers; effects of anisotropy and resin content

    Science.gov (United States)

    Yiotis, Andreas G.; Kainourgiakis, Michael E.; Charalambopoulou, Georgia C.; Stubos, Athanassios K.

    2016-07-01

    A novel process-based methodology is proposed for the stochastic reconstruction and accurate characterisation of Carbon fiber-based matrices, which are commonly used as Gas Diffusion Layers in Proton Exchange Membrane Fuel Cells. The modeling approach is efficiently complementing standard methods used for the description of the anisotropic deposition of carbon fibers, with a rigorous model simulating the spatial distribution of the graphitized resin that is typically used to enhance the structural properties and thermal/electrical conductivities of the composite Gas Diffusion Layer materials. The model uses as input typical pore and continuum scale properties (average porosity, fiber diameter, resin content and anisotropy) of such composites, which are obtained from X-ray computed microtomography measurements on commercially available carbon papers. This information is then used for the digital reconstruction of realistic composite fibrous matrices. By solving the corresponding conservation equations at the microscale in the obtained digital domains, their effective transport properties, such as Darcy permeabilities, effective diffusivities, thermal/electrical conductivities and void tortuosity, are determined focusing primarily on the effects of medium anisotropy and resin content. The calculated properties are matching very well with those of Toray carbon papers for reasonable values of the model parameters that control the anisotropy of the fibrous skeleton and the materials resin content.

  6. A new hyperspectral imaging based device for quality control in plastic recycling

    Science.gov (United States)

    Bonifazi, G.; D'Agostini, M.; Dall'Ava, A.; Serranti, S.; Turioni, F.

    2013-05-01

    The quality control of contamination level in the recycled plastics stream has been identified as an important key factor for increasing the value of the recycled material by both plastic recycling and compounder industries. Existing quality control methods for the detection of both plastics and non-plastics contaminants in the plastic waste streams at different stages of the industrial process (e.g. feed, intermediate and final products) are currently based on the manual collection from the stream of a sample and on the subsequent off-line laboratory analyses. The results of such analyses are usually available after some hours, or sometimes even some days, after the material has been processed. The laboratory analyses are time-consuming and expensive (both in terms of equipment cost and their maintenance and of labour cost).Therefore, a fast on-line assessment to monitor the plastic waste feed streams and to characterize the composition of the different plastic products, is fundamental to increase the value of secondary plastics. The paper is finalized to describe and evaluate the development of an HSI-based device and of the related software architectures and processing algorithms for quality assessment of plastics in recycling plants, with particular reference to polyolefins (PO). NIR-HSI sensing devices coupled with multivariate data analysis methods was demonstrated as an objective, rapid and non-destructive technique that can be used for on-line quality and process control in the recycling process of POs. In particular, the adoption of the previous mentioned HD&SW integrated architectures can provide a solution to one of the major problems of the recycling industry, which is the lack of an accurate quality certification of materials obtained by recycling processes. These results could therefore assist in developing strategies to certify the composition of recycled PO products.

  7. Retention and penetration of a conventional resin-based sealant and a photochromatic flowable composite resin placed on occlusal pits and fissures

    Directory of Open Access Journals (Sweden)

    Aguilar F

    2007-01-01

    Full Text Available This study compares the retention and penetration of a conventional resin-based sealant (Fluroshield and a photochromatic flowable composite resin (Tetric Flow Chroma placed on occlusal pits and fissures and submitted to thermal or chemical cycling regimens. Penetration assessment - ten premolars were sealed with each material, isolated (except for the sealed surface and immersed in 0.2% Rhodamine B. The teeth were serially sectioned in a mesiodistal direction. The images of the sections were digitized and analyzed (ImageLab. The distance between the most superficial and the deepest points on the occlusal central groove was calculated to determine the groove′s total depth. The length of the central groove filled with the sealant was divided by its total depth to obtain the percentage of sealing of the occlusal groove. Retention assessment - 30 premolars were sealed, their occlusal surfaces were photographed and the area occupied by the sealing materials was demarcated (ImageLab. The teeth were submitted to different treatments: thermocycled, stored in artificial saliva and immersed in acetic acid and saliva (10 cycles/day protocol for 30 days. New photographs were taken to assess the final area occupied by the materials. The difference between the final and initial area was calculated to obtain the material loss. The data was analyzed (two-way anova and Tukey′s test P < 0.05. Both materials presented similar penetration of the occlusal central groove. After thermal and chemical cycling, the materials did not differ with respect to retention, except for immersion in acetic acid. In this case, Tetric Flow Chroma presented greater retention than Fluoroshield.

  8. Bio-based and recycled polymers for cleaner production : an assessment of plastics and fibres

    OpenAIRE

    L. Shen

    2011-01-01

    Today, almost all man-made plastics and fibres are produced from synthetic polymers. Synthetic polymers, made from petroleum which took millions of years to form, have three sustainability challenges: (i) the limited fossil fuel resources, (ii) the environmental impacts caused by non-degradable plastics waste, and (iii) greenhouse gas emissions caused by combusting fossil fuels. To tackle these sustainability challenges, two strategies have been proposed. First, use bio-based polymers to repl...

  9. Bio-based and recycled polymers for cleaner production : an assessment of plastics and fibres

    OpenAIRE

    Shen, L.

    2011-01-01

    Today, almost all man-made plastics and fibres are produced from synthetic polymers. Synthetic polymers, made from petroleum which took millions of years to form, have three sustainability challenges: (i) the limited fossil fuel resources, (ii) the environmental impacts caused by non-degradable plastics waste, and (iii) greenhouse gas emissions caused by combusting fossil fuels. To tackle these sustainability challenges, two strategies have been proposed. First, use bio-based polymers to repl...

  10. Application of WLS strips for position determination in Strip PET tomograph based on plastic scintillators

    CERN Document Server

    Smyrski, J; Bednarski, T; Białas, P; Czerwiński, E; Kapłon, Ł; Kochanowski, A; Korcyl, G; Kowal, J; Kowalski, P; Kozik, T; Krzemień, W; Molenda, M; Niedźwiecki, Sz; Pałka, M; Pawlik, M; Raczyński, L; Rudy, Z; Salabura, P; Sharma, N G; Silarski, M; Słomski, A; Strzelecki, A; Wiślicki, W; Zieliński, M; Zoń, N

    2013-01-01

    A method of determination of a gamma quantum absorption point in a plastic scintillator block using a matrix of wavelength-shifting (WLS) strips is proposed. Application of this method for improvement of position resolution in newly proposed PET detectors based on plastic scintillators is presented. The method enables to reduce parallax errors in reconstruction of images which occurs in the presently used Positron Emission Tomography scanners.

  11. Mechanical characteristics of plastic base Ports and impact on flushing efficacy

    Science.gov (United States)

    Guiffant, Gérard; Flaud, Patrice; Royon, Laurent; Burnet, Espérie; Merckx, Jacques

    2017-01-01

    Background Three types of totally implantable venous access devices, Ports, are currently in use: titanium, plastic (polyoxymethylene, POM), and mixed (titanium base with a POM shell). Physics theory suggests that the interaction between a non-coring needle (NCN, made of stainless steel) and a plastic base would lead to the stronger material (steel) altering the more malleable material (plastic). Objectives To investigate whether needle impacts can alter a plastic base’s surface, thus potentially reducing flushing efficacy. Study design and methods A Port made of POM was punctured 200 times with a 19-gauge NCN. Following the existing guidelines, the needle tip pricked the base with each puncture. The Port’s base was then examined using a two-dimensional optical instrument, and a bi-dimensional numerical simulation using COMSOL® was performed to investigate potential surface irregularities and their impact on fluid flow. Results Each needle impact created a hole (mean depth, 0.12 mm) with a small bump beside it (mean height, 0.02 mm) the Reynolds number Rek≈10. A numerical simulation of the one hole/bump set showed that the flushing efficacy was 60% that of flushing along a flat surface. Discussion In clinical practice, the number of times a Port is punctured depends on patient and treatment characteristics, but each needle impact on the plastic base may increase the risk of decreased flushing effectiveness. Therefore, the more a plastic Port is accessed, the greater the risk of microorganisms, blood products, and medication accumulation. Conclusions Multiple needle impacts created an irregular surface on the Port’s base, which decreased flushing efficacy. Clinical investigation is needed to determine whether plastic base Ports are associated with an increased risk of Port infection and occlusion compared to titanium base Ports. PMID:28176897

  12. Syntheses of silsesquioxane (POSS)-based inorganic/organic hybrid and the application in reinforcement for an epoxy resin.

    Science.gov (United States)

    Ni, Caihua; Ni, Guifeng; Zhang, Liping; Mi, Jiaquan; Yao, Bolong; Zhu, Changping

    2011-10-01

    A new inorganic/organic hybrid material containing silsesquioxane was prepared by the reaction of caged octa (aminopropyl silsesquioxane) (POSS-NH(2)) with n-butyl glycidyl ether (nBGE) and 1,4-butanediol diglycidyl ether (BDGE). The copolymers of POSS, nBGE, and BDGE could be obtained with varied feed ratio of POSS-NH(2), nBGE, and BDGE in the preparation. The hybrid material was added into an epoxy resin (E51) for enhancing the toughening and thermal properties of the epoxy resin. The results showed that the toughening and the thermal properties of the cured epoxy resin were greatly improved by the addition of the hybrid. The enhancement was ascribed to nano-scale effect of the POSS structure and the formation of anchor structure in the cured network. The investigation of kinetics for the curing process of the hybrid-modified epoxy resin revealed that two kinds of curing reactions occurred in different temperature ranges. They were attributed to the reactions between amino groups of the curing agent with epoxy groups of E51 and with residue epoxy groups in the hybrid. The reacting activation energies were calculated based on Kissinger's and Flynn-Wall-Ozawa's methods, respectively.

  13. Modelling of the interaction between chemical and mechanical behaviour of ion exchange resins incorporated into a cement-based matrix

    Directory of Open Access Journals (Sweden)

    Le Bescop P.

    2013-07-01

    Full Text Available In this paper, we present a predictive model, based on experimental data, to determine the macroscopic mechanical behavior of a material made up of ion exchange resins solidified into a CEM III cement paste. Some observations have shown that in some cases, a significant macroscopic expansion of this composite material may be expected, due to internal pressures generated in the resin. To build the model, we made the choice to break down the problem in two scale’s studies. The first deals with the mechanical behavior of the different heterogeneities of the composite, i.e. the resin and the cement paste. The second upscales the information from the heterogeneities to the Representative Elementary Volume (REV of the composite. The heterogeneities effects are taken into account in the REV by applying a homogenization method derived from the Eshelby theory combined with an interaction coefficient drawn from the poroelasticity theory. At the first scale, from the second thermodynamic law, a formulation is developed to estimate the resin microscopic swelling. The model response is illustrated on a simple example showing the impact of the calculated internal pressure, on the macroscopic strain.

  14. From time-based to competency-based standards: core transitional competencies in plastic surgery.

    Science.gov (United States)

    Lutz, Kristina; Yazdani, Arjang; Ross, Douglas

    2015-01-01

    Competency-based medical education is becoming increasingly prevalent and is likely to be mandated by the Royal College in the near future. The objective of this study was to define the core technical competencies that should be possessed by plastic surgery residents as they transition into their senior (presently postgraduate year 3) years of training. A list of potential core competencies was generated using a modified Delphi method that included the investigators and 6 experienced, academic plastic surgeons from across Canada and the United States. Generated items were divided into 7 domains: basic surgical skills, anesthesia, hand surgery, cutaneous surgery, esthetic surgery, breast surgery, and craniofacial surgery. Members of the Delphi group were asked to rank particular skills on a 4-point scale with anchored descriptors. Item reduction resulted in a survey consisting of 48 skills grouped into the aforementioned domains. This self-administered survey was distributed to all Canadian program directors (n = 11) via e-mail for validation and further item reduction. The response rate was 100% (11/11). Using the average rankings of program directors, 26 "core" skills were identified. There was agreement of core skills across all domains except for breast surgery and esthetic surgery. Of them, 7 skills were determined to be above the level of a trainee at this stage; a further 15 skills were agreed to be important, but not core, competencies. Overall, 26 competencies have been identified as "core" for plastic surgery residents to possess as they begin their senior, on-service years. The nature of these skills makes them suitable for teaching in a formal, simulated environment, which would ensure that all plastic surgery trainees are competent in these tasks as they transition to their senior years of residency. Copyright © 2014 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  15. Effect of incorporation of 2-tert-butylaminoethyl methacrylate on flexural strength of a denture base acrylic resin

    Directory of Open Access Journals (Sweden)

    André Gustavo Paleari

    2011-06-01

    Full Text Available Polymethyl methacrylate (PMMA resins have commonly been used as a denture base material. However, denture bases may act as a reservoir for microorganisms and contribute to oral diseases in denture wearers. It is hypothesized that the 2-tert-butylaminoethyl methacrylate (TBAEMA incorporated to acrylic resins should have antimicrobial activity related to the presence of amino groups on acrylic resin surface. OBJECTIVES: The objectives of this study were to evaluate the presence of amino groups on acrylic resin surface and the influence on flexural strength after incorporation of TBAEMA. MATERIAL AND METHODS: Six groups were divided according to the concentration of TBAEMA incorporated to acrylic resin (Lucitone 550: 0, 0.5, 1.0, 1.5, 1.75 and 2%. Specimens surface were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA to detect the presence of amino groups, represented by nitrogen ratios. Flexural strength of the specimens was tested and results were analyzed by ANOVA and Tukey's test (α=0.05. RESULTS: Different nitrogen ratios were observed on specimen surfaces: 0, 0.13, 0.74, 0.66, 0.92 and 0.33% for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively. Significant differences were found for flexural strength (p<0.001. The mean flexural strength values were 98.3±3.9, 93.3±3.2, 83.9±2.1, 82.8±5.2, 71.2±5.1 and 17.3±3.2 MPa for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively. CONCLUSION: Within the limitations of this study, the incorporation of TBAEMA results in the presence of the potentially antimicrobial amino groups on specimen surfaces, but affect the flexural strength, depending on the concentration of TBAEMA.

  16. Phenolic resin-based porous carbons for adsorption and energy storage applications

    Science.gov (United States)

    Wickramaratne, Nilantha P.

    The main objective of this dissertation research is to develop phenolic resin based carbon materials for range of applications by soft-templating and Stober-like synthesis strategies. Applications Studied in this dissertation are adsorption of CO2, bio-molecular and heavy metal ions, and energy storage devices. Based on that, our goal is to design carbon materials with desired pore structure, high surface area, graphitic domains, incorporated metal nanoparticles, and specific organic groups and heteroatoms. In this dissertation the organic-organic self-assembly of phenolic resins and triblock copolymers under acidic conditions will be used to obtain mesoporous carbons/carbon composites and Stober-like synthesis involving phenolic resins under basic condition will be used to prepare polymer/carbon particles and their composites. The structure of this dissertation consists of an introductory chapter (Chapter 1) discussing the general synthesis of carbon materials, particularly the soft-templating strategy and Stober-like carbon synthesis. Also, Chapter 1 includes a brief outline of applications namely adsorption of CO2, biomolecule and heavy metal ions, and supercapacitors. Chapter 2 discusses the techniques used for characterization of the carbon materials studied. This chapter starts with nitrogen adsorption analysis, which is used to measure the specific surface area, pore volume, distribution of pore sizes, and pore width. In addition to nitrogen adsorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution thermogravimetric analysis (HR-TGA), cyclic voltammetry (CV) and CHNS elemental analysis (EA) are mentioned too. Chapter 3 is focused on carbon materials for CO2 adsorption. There are different types of porous solid materials such as silicate, MOFs, carbons, and zeolites studied for CO2 adsorption. However, the carbon based materials are considered to be the best candidates for CO 2 adsorption to the industrial point of

  17. Computational procedures for finite deformation rate-independent plasticity and viscoplasticity based on overstress

    Science.gov (United States)

    Gomaa, Said Taha Khalil

    2000-10-01

    This thesis is dedicated to developing the computational procedures required in implementing the finite element method for finite deformation, rate-independent plasticity and finite deformation viscoplasticity theory based on overstress. The classical rate-independent, von Mises plasticity is formulated using both hypoelastic-plastic model and hyperelastic-plastic model. In the hypoelastic-plastic model, a relationship between an objective rate of Kirchhoff stress, based on a new recently proposed logarithmic spin [13], and the elastic part of rate of deformation tensor is postulated. In the hyperelastic-plastic model, the deformation gradient is decomposed into elastic and plastic deformations, a relationship between Kirchhoff stress and the logarithm of the elastic left stretch tensor is used. Numerical procedures for the integration of both models are developed. The isotropic, viscoplasticity theory based on overstress consisting of a flow law and two tensor valued and one scalar valued stress-like state variables is extended to finite deformation. To this end the Cauchy stress rate and the rates of the two tensor-valued state variables are interpreted as Eulerian tensors. The rate of deformation is equal to the sum of the elastic (the rate form of Hooke's law) and the inelastic rate of deformation, which depends on the overstress. The model does not contain a strain like quantity. Two integration schemes are considered: (i) a one step time integration scheme based on the forward gradient approximation and (ii) unconditionally stable implicit integration scheme based on backward Euler. The finite deformation, anisotropic, viscoplasticity theory based on overstress is formulated. A hypoelastic relation between the Lagrangian, rotated, logarithmic Cauchy stress rate and the rotated rate of deformation is used. The deformation induced anisotropy is modeled using a compliance tensor that allowed to grow according to Armstrong-Frederick law for fourth order tensors

  18. Structural Engineering Properties of Fibre Reinforced Concrete Based On Recycled Glass Fibre Polymer (GFRP)

    OpenAIRE

    Adetiloye A; Ephraim M. E

    2015-01-01

    Glass fibre reinforced plastics (GFRP) based on resin recovered from recycling plastic waste has been shown to possess mechanical properties satisfying normative requirements. This paper investigates the flexural behavior of concrete beams reinforced with GFRP produced from resin recovered from recycled plastic wastes. A total of twelve of beams of sizes 150 ×150 ×900mm and 100 × 100 × 500mm reinforced with GFRP made from recycled glass fibre reinforced polymer was tested. The fle...

  19. Thermosetting epoxy resin/thermoplastic system with combined shape memory and self-healing properties

    Science.gov (United States)

    Yao, Yongtao; Wang, Jingjie; Lu, Haibao; Xu, Ben; Fu, Yongqing; Liu, Yanju; Leng, Jinsong

    2016-01-01

    A novel and facile strategy was proposed to construct a thermosetting/thermoplastic system with both shape memory and self-healing properties based on commercial epoxy resin and poly(ɛ-caprolactone)-PCL. Thermoplastic material is capable of re-structuring and changing the stiffness/modulus when the temperature is above melting temperature. PCL microfiber was used as a plasticizer in epoxy resin-based blends, and served as a ‘hard segment’ to fix a temporary shape of the composites during shape memory cycles. In this study, the electrospun PCL membrane with a porous network structure enabled a homogenous PCL fibrous distribution and optimized interaction between fiber and epoxy resin. The self-healing capability is achieved by phase transition during curing of the composites. The mechanism of the shape memory effect of the thermosetting (rubber)/thermoplastic composite is attributed to the structural design of the thermoplastic network inside the thermosetting resin/rubber matrix.

  20. Biocompatibility of composite resins

    Directory of Open Access Journals (Sweden)

    Sayed Mostafa Mousavinasab

    2011-01-01

    Full Text Available Dental materials that are used in dentistry should be harmless to oral tissues, so they should not contain any leachable toxic and diffusible substances that can cause some side effects. Reports about probable biologic hazards, in relation to dental resins, have increased interest to this topic in dentists. The present paper reviews the articles published about biocompatibility of resin-restorative materials specially resin composites and monomers which are mainly based on Bis-GMA and concerns about their degradation and substances which may be segregated into oral cavity.

  1. Properties of powdered ion-exchange resins based on petroleum asphaltites

    Energy Technology Data Exchange (ETDEWEB)

    Pokonova, Y.V.; Mitrofanova, L.M.; Proskuryakov, V.A.

    1977-02-01

    The following properties of the resins were studied: physical-mechanical properties, total effective exchange capacity, particle size distribution, dissociation constants, and dynamic and static exchange capacities. 6 tables. (DLC)

  2. Isolation and characterization of a bacterium that degrades various polyester-based biodegradable plastics.

    Science.gov (United States)

    Teeraphatpornchai, T; Nakajima-Kambe, T; Shigeno-Akutsu, Y; Nakayama, M; Nomura, N; Nakahara, T; Uchiyama, H

    2003-01-01

    Microorganisms isolated from soil samples were screened for their ability to degrade various biodegradable polyester-based plastics. The most active strain, designated as strain TB-13, was selected as the best strain for degrading these plastics. From its phenotypic and genetic characteristics, strain TB-13 was closely related to Paenibacillus amyloyticus. It could degrade poly(lactic acid), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone) and poly(ethylene succinate) but not poly(hydroxybutylate-co-valerate). However, it could not utilize these plastics as sole carbon sources. Both protease and esterase activities, which may be involved in the degradation of plastic, were constitutively detected in the culture broth.

  3. Revealing homogeneous plastic deformation in dendrite-reinforced Ti-based metallic glass composites under tension

    Science.gov (United States)

    Wu, F. F.; Wei, J. S.; Chan, K. C.; Chen, S. H.; Zhao, R. D.; Zhang, G. A.; Wu, X. F.

    2017-01-01

    The tensile plastic deformation of dendrite-reinforced Ti-based metallic glass composites (MGCs) was investigated. It was found that there is a critical normalized strain-hardening rate (NSHR) that determines the plastic stability of MGCs: if the NSHR is larger than the critical value, the plastic deformation of the MGCs will be stable, i.e. the necking and strain localization can be effectively suppressed, resulting in homogeneous plastic elongation. In addition, dendrite-reinforce MGCs are verified as being intrinsically ductile, and can be used as good coatings for improving the surface properties of pure titanium or titanium alloys. These findings are helpful in designing, producing, and using MGCs with improved performance properties. PMID:28195216

  4. Imidazole-based deep eutectic solvents for starch dissolution and plasticization.

    Science.gov (United States)

    Zdanowicz, Magdalena; Spychaj, Tadeusz; Mąka, Honorata

    2016-04-20

    Potato starch and high-amylose starch were treated with imidazole-based deep eutectic solvents (DESs) as dissolution and plasticization media. Beside imidazole (IM) for two-component DESs preparation choline chloride (CC), glycerol (G) or carboxylic acids (citric or malic) were used. An influence of water content in starch (as well as an extra water in the starch/DES system) on polymer dissolution and plasticization processes was investigated. Dissolution and gelatinization of starch in DESs were followed via DSC and laser scanning microscopy. A rheometric characteristics revealed an influence of starch/DES system storage time on the plasticization process. The tendency to recrystallization of compression-molded-starch films was evaluated using XRD technique. High dissolution and plasticization effectiveness of CC/IM and G/IM and a low tendency to film retrogradation of thermoplasticized starch were noted.

  5. Preparation of Bio-Based Polyamide Elastomer by Using Green Plasticizers

    Directory of Open Access Journals (Sweden)

    Miaomiao He

    2016-07-01

    Full Text Available The purpose of this work was to study the effects of three green plasticizers H2O, glycerol, and soybean oil, on the properties of bio-based BDIS polyamides. The BDIS polyamides synthesized from the following biomass monomers: 1,4-butanediamine (BD, 1,10-decanediamine (DD, itaconic acid (IA, and sebacic acid (SA. It is interesting to note that the amorphous BDIS (IA-80% polyamide was changed from the glassy state to the rubbery state after water soaking and induced crystallization at the same time. The H2O-plasticized non-crosslinked BDIS (IA-80% polyamides can be very useful for the preparation of physical water gel. The glycerol- and soybean oil-plasticized BDIS (IA-80% polyamides displayed excellent toughness. The plasticized BDIS (IA-80% polyamides were characterized by Fouriertransform infrared spectroscopy (FTIR, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, mechanical testing, and X-ray diffraction (XRD.

  6. Application of XAD-resin based passive air samplers to assess local (roadside) and regional patterns of persistent organic pollutants.

    Science.gov (United States)

    Barthel, Paul; Thuens, Sabine; Shunthirasingham, Chubashini; Westgate, John N; Wania, Frank; Radke, Michael

    2012-07-01

    We used XAD-resin based passive air samplers (PAS) to measure atmospheric levels of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) at five ombrotrophic bogs in Eastern Canada. The aims of our study were to investigate the influence of local roads on contaminant levels in the bogs, to derive the regional pattern of atmospheric concentrations, and to assess the uncertainties of the method. Expanded uncertainties based on the duplicate PAS deployed at 24 sites were good for the PAHs, while the deployment period of approx. 100 days was too short to yield acceptable uncertainties for PCBs. The regional PAH distribution was in good agreement with the calculated source proximity of the sampled bogs. We conclude that XAD-resin based PAS deployed for comparatively short periods are well suited for measuring atmospheric concentrations of volatile PAHs, while in remote regions longer deployment is necessary for less volatile PAHs and for PCBs.

  7. Modification of epoxy resins with thermoplastic segmented polycarbonate-based polyurethanes

    OpenAIRE

    Pavličević Jelena; Jovičić Mirjana; Simendić Vesna; Bera Oskar; Radičević Radmila; Špírková Milena

    2014-01-01

    In this work, epoxy hybrid materials were synthesized by addition of thermoplastic segmented aliphatic polyurethanes with good elastic properties. The modified epoxy samples were obtained by curing of previously homogenized mixture of prepared polyurethane melts, epoxy resin and crosslinking agent Jeffamine D-2000. The influence of different weight content of polyurethanes (5, 10 and 15 wt. % compared to pure epoxy resin) as well the influence of different ...

  8. Differences in physico-mechanical behaviors of resol(e) and novolac type phenolic resin based composite bipolar plate for proton exchange membrane (PEM) fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Kakati, Biraj Kumar [Department of Chemical Engineering, Indian Institute of Technology Guwahati, North Guwahati, PIN 781 039, Dist. Kamrup (Assam) (India); Deka, Dhanapati [Department of Energy, Tezpur University, Tezpur 784 028, Dist. Sonitpur (Assam) (India)

    2007-09-15

    Composite bipolar plates for Proton Exchange Membrane Fuel Cell (PEMFC) are prepared by compression molding technique using polymer as binder and graphite as electric filler material with some other reinforcements. Study on the effect of resole and novolac type phenolic resin on the properties of composite bipolar plate, such as bulk density, porosity, bulk conductivity, hardness, flexural strength, etc. shows that both of the resin shows different physico-mechanical properties. Moreover, single cell performance analysis also shows variation for resole and novolac based composites. A novel concept of triple continuous structure to provide graphite polymer blends with high electrical conductivity, high shore hardness, high flexural strength, less porosity and low density has been proposed and study on the effect of different types of phenolic resin on the properties and performance of bipolar plate reveals that novolac type powdered phenolic resin gives better mechanical properties than resole type phenolic resin. However, resole type phenolic resin compound has slightly higher electrical conductivity due to more number of polar -OH group presents on its cured form. But due to the less porosity and higher mechanical strength, bipolar plates with novolac type phenolic resin gives better performance in I-V analysis than bipolar plates with resole type phenolic resin. (author)

  9. A new classification scheme of plastic wastes based upon recycling labels

    Energy Technology Data Exchange (ETDEWEB)

    Özkan, Kemal, E-mail: kozkan@ogu.edu.tr [Computer Engineering Dept., Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Ergin, Semih, E-mail: sergin@ogu.edu.tr [Electrical Electronics Engineering Dept., Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Işık, Şahin, E-mail: sahini@ogu.edu.tr [Computer Engineering Dept., Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Işıklı, İdil, E-mail: idil.isikli@bilecik.edu.tr [Electrical Electronics Engineering Dept., Bilecik University, 11210 Bilecik (Turkey)

    2015-01-15

    Highlights: • PET, HPDE or PP types of plastics are considered. • An automated classification of plastic bottles based on the feature extraction and classification methods is performed. • The decision mechanism consists of PCA, Kernel PCA, FLDA, SVD and Laplacian Eigenmaps methods. • SVM is selected to achieve the classification task and majority voting technique is used. - Abstract: Since recycling of materials is widely assumed to be environmentally and economically beneficial, reliable sorting and processing of waste packaging materials such as plastics is very important for recycling with high efficiency. An automated system that can quickly categorize these materials is certainly needed for obtaining maximum classification while maintaining high throughput. In this paper, first of all, the photographs of the plastic bottles have been taken and several preprocessing steps were carried out. The first preprocessing step is to extract the plastic area of a bottle from the background. Then, the morphological image operations are implemented. These operations are edge detection, noise removal, hole removing, image enhancement, and image segmentation. These morphological operations can be generally defined in terms of the combinations of erosion and dilation. The effect of bottle color as well as label are eliminated using these operations. Secondly, the pixel-wise intensity values of the plastic bottle images have been used together with the most popular subspace and statistical feature extraction methods to construct the feature vectors in this study. Only three types of plastics are considered due to higher existence ratio of them than the other plastic types in the world. The decision mechanism consists of five different feature extraction methods including as Principal Component Analysis (PCA), Kernel PCA (KPCA), Fisher’s Linear Discriminant Analysis (FLDA), Singular Value Decomposition (SVD) and Laplacian Eigenmaps (LEMAP) and uses a simple

  10. Modification of epoxy resins with thermoplastic segmented polycarbonate-based polyurethanes

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2014-01-01

    Full Text Available In this work, epoxy hybrid materials were synthesized by addition of thermoplastic segmented aliphatic polyurethanes with good elastic properties. The modified epoxy samples were obtained by curing of previously homogenized mixture of prepared polyurethane melts, epoxy resin and crosslinking agent Jeffamine D-2000. The influence of different weight content of polyurethanes (5, 10 and 15 wt. % compared to pure epoxy resin as well the influence of different hard segments of elastomers (20, 25 and 30 wt. % on the curing of modified epoxy systems was studied. The curing was followed by differential scanning calorimetry (DSC, in dynamic regime from 30 to 300°C, at three heating rates (5, 10 and 20°C/min. With the increase of hard segments content of polyurethanes added in higher concentration (10 and 15 wt. % into epoxy matrix, the temperature of maximum ratio of curing was shifted to lower values (from 205 to 179°C. Obtained DSC data were analyzed using two integral methods (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose and one differential kinetic model (Friedman. The significant differences were observed in the second part of the epoxy curing (for the reaction degrees higher than 60 %, where the values of activation energies remarkably increase. The addition of polyurethane elastomers retarded the curing process due to decreased mobility of reactant molecules caused by higher viscosity of reaction mixture. By detailed analysis of determined kinetic parameters, it is concluded that the influence of slow diffusion is more pronounced in the presence of thermoplastic polycarbonate-based polyurethanes, which confirmed their effect on the mechanism of epoxy curing. The highest tensile strength and hardness showed the DGEBA modified with the polyurethane with highest hard segment content. Increasing the hard segment content of polyurethane and its concentration in matrix, the tensile strength of modified epoxy was increased. The elongation at break of

  11. Electron spectroscopy of rubber and resin-based composites containing 2D carbon

    Energy Technology Data Exchange (ETDEWEB)

    Kaciulis, S., E-mail: saulius.kaciulis@ismn.cnr.it [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Mezzi, A.; Balijepalli, S.K. [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Lavorgna, M. [Institute of Polymers, Composites and Biomaterials, IPCB-CNR, P.le Fermi, 80055 Napoli (Italy); Xia, H.S. [State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065 Sichuan (China)

    2015-04-30

    Composite materials with 2D carbon (graphene and/or single wall carbon nanotubes) are very promising due to their extraordinary electrical and mechanical properties. Graphene and natural rubber composites, which may be used for the gaskets or sealants, were prepared by ultrasonically assisted latex-mixing exfoliation and in-situ reduction process, with two vulcanization approaches: roll-mixing and hot-pressing. Also the resin-based composites, filled with micro-particles of Ag and graphene or carbon nanotubes, have been studied. The standards for the compositional characterization of these materials still are not established. In addition to the mostly used techniques, such as Raman spectroscopy and electron microscopy, also Auger electron spectroscopy can be employed for the identification of graphene. In this study, the shape of C KVV peak, excited by electron beam and X-ray photons, has been investigated in different composite materials containing graphene and carbon nanotubes. A spectroscopic method for 2D carbon recognition, based on the D{sub x} parameter which is determined from C KVV signal excited by X-ray photons, was proposed and verified. Even a small content of graphene in different types of composites was sufficient for this recognition due to the dominating presence of graphene on the surface of composites. - Highlights: • Chemical composition of the rubber composites was determined by XPS. • Auger spectrum of carbon was used for graphene identification in composites. • Small content of graphene was sufficient for its recognition from the D parameter.

  12. Simultaneous measurement of refractive index and temperature using an epoxy resin-based interferometer.

    Science.gov (United States)

    Wang, Jian; Wu, Shengli; Ren, Wenyi

    2014-11-20

    A fiber-optics reflection probe based on fiber Fabry-Perot interference (FFPI) is proposed and experimentally demonstrated. The sensing structure comprises an epoxy resin (ER)-based cap on the end-face of the single-mode fiber. A well-defined interference spectrum is obtained by the reflective beams of two surfaces of the ER cap. The simultaneous measurements, including fringe contrast-referenced for the surrounding refractive index (SRI) and wavelength-referenced for temperature, have been achieved via selective interference dips monitoring. Experimental results indicate that the proposed FFPI presents an SRI sensitivity of 57.69 dB/RIU in the measurement range of 1.33-1.40 RIU and a temperature sensitivity of 0.98  pm·μm-1·°C-1 with per unit cavity length in the range of 30°C-70°C. The proposed sensor has advantages of being compact and robust, making it an alternative candidate as a smart sensor in chemical and biological applications.

  13. Mechanical and electrical properties of a polyester resin reinforced with clay-based fillers

    Energy Technology Data Exchange (ETDEWEB)

    Buncianu, Dorel; Jadaneant, Mihai [UPT Timisoara, Timisoara (Romania); Tessier-Doyen, Nicolas; Absi, Joseph [Centre Européen de la Céramique, Limoges Cedex (France); Courreges, Fabien [Laboratoire XLIM, 123, Limoges Cedex (France)

    2017-03-15

    In this study, composite polymer-based materials were fabricated, in which a significant proportion of polyester resin was substituted by low-cost and environmentally-friendly clay-based raw materials. The main objective is to improve mechanical properties while maintaining a reasonable electrical insulating behavior. A homogenized distribution of fillers within the matrix compatible with the processing parameters was obtained up to a maximum added fraction of 20 vol%. Mechanical characterization using uniaxial traction tests and Charpy impact pendulum machine showed that stress-to-rupture can be enhanced of approximately 25 %. In addition, fracture energy was doubled for the best formulation. Dielectric constant was decreased and loss factor was slightly increased when electrical resistivity remained almost constant. In general, the composite materials with metakaolin fillers exhibited higher mechanical properties and greater electrical insulating behavior. Microstructural observation showed the presence of decohesive agglomerates of particles at the interface with the matrix. The mechanical properties were found to be more sensitive than electrical properties to the homogeneity of filler dispersion in the matrix.

  14. Life cycle impact assessment of bio-based plastics from sugarcane ethanol

    NARCIS (Netherlands)

    Tsiropoulos, I.; Faaij, A. P C; Lundquist, L.; Schenker, U.; Briois, J. F.; Patel, M. K.

    2015-01-01

    The increasing production of bio-based plastics calls for thorough environmental assessments. Using life cycle assessment, this study compares European supply of fully bio-based high-density polyethylene and partially bio-based polyethylene terephthalate from Brazilian and Indian sugarcane ethanol w

  15. Life cycle impact assessment of bio-based plastics from sugarcane ethanol

    NARCIS (Netherlands)

    Tsiropoulos, I.; Faaij, A. P C; Lundquist, L.; Schenker, U.; Briois, J. F.; Patel, M. K.

    2015-01-01

    The increasing production of bio-based plastics calls for thorough environmental assessments. Using life cycle assessment, this study compares European supply of fully bio-based high-density polyethylene and partially bio-based polyethylene terephthalate from Brazilian and Indian sugarcane ethanol

  16. Life cycle impact assessment of bio-based plastics from sugarcane ethanol

    NARCIS (Netherlands)

    Tsiropoulos, I.; Faaij, A. P C; Lundquist, L.; Schenker, U.; Briois, J. F.; Patel, M. K.

    2015-01-01

    The increasing production of bio-based plastics calls for thorough environmental assessments. Using life cycle assessment, this study compares European supply of fully bio-based high-density polyethylene and partially bio-based polyethylene terephthalate from Brazilian and Indian sugarcane ethanol w

  17. Influence of acrylamide monomer addition to the acrylic denture-base resins on mechanical and physical properties

    Institute of Scientific and Technical Information of China (English)

    Elif Aydogan Ayaz; Rukiye Durkan

    2013-01-01

    The aim of the study was to evaluate the effect of adding acrylamide monomer (AAm) on the characterization, flexural strength, flexural modulus and thermal degradation temperature of poly(methyl methacrylate) (PMMA) denture-base resins. Specimens (n510) were fabricated from a conventional heat-activated QC-20 (Qc-) and a microwave heat-activated Acron MC (Ac-) PMMA resins. Powder/liquid ratio followed the manufacturer’s instructions for the control groups (Qc-c and Ac-c) and for the copolymer groups, the resins were prepared with 5%(25), 10%(210), 15%(215) and 20%(220) acrylamide contents, according to the molecular weight ratio, respectively. The flexural strength and flexural modulus were measured by a three-point bending test. The data obtained were statistically analyzed by Kruskal-Wallis test (a50.05) to determine significant differences between the groups. The chemical structures of the resins were characterized by the nuclear magnetic resonance spectroscopy. Thermal stabilities were determined by thermogravimetric analysis (TGA) with a heating rate of 10 6C?min21 from 35 6C to 600 6C. Control groups from both acrylic resins showed the lowest flexural strength values. Qc-15 showed significant increase in the flexural strength when compared to Qc-c (P,0.01). Ac-10 and Ac-15 showed significance when compared to Ac-c (P,0.01). Acrylamide incorporation increased the elastic modulus in Qc-10, Qc-15 and Qc-20 when compared to Qc-c (P,0.01). Also significant increase was observed in Ac-10, Ac-15 and Ac-20 copolymer groups when compared to Ac-c (P,0.01). According to the 1H-nuclear magnetic resonance (NMR) results, acrylamide copolymerization was confirmed in the experimental groups. TGA results showed that the thermal stability of PMMA is increased by the insertion of AAm.

  18. [Effect of surface pretreatment with chemical etchants on bond strength between a silicone-based resilient liner and denture base resin].

    Science.gov (United States)

    Zhang, Ying; Zhang, Huai-qin; Ma, Jun-chi; Jin, Si-yuan

    2011-12-01

    To evaluate the effect of denture base resin surface pretreatment with chemical etchants on microleakage and bond strength between silicone-based resilient liner and denture base resin. The initial bending strength of denture base resin after surface pretreatment was also examined. Thirty-six polymethyl methacrylate (PMMA) denture base resin blocks (30 mm × 30 mm × 2 mm) were prepared and divided into three groups: group acetone, group methyl methy acrylate (MMA) and group control. Subsequently, a 2 mm silicone-based resilient liner was applied between every two blocks. After 5000 cycles in the thermal cycler (5 and 55°C), they were immersed in the (131) I solution for 24 hours and γ-ray counts were measured. Another 36 PMMA resin blocks (30 mm × 10 mm × 7.5 mm) were prepared. The blocks were divided into three groups and treated as mentioned above. A 3 mm silicone-based resilient liner was applied between every two blocks. After 5000 thermal cycles, tensile bond strength of the sample was measured in a universal testing machine. Another 18 PMMA resin blocks (65 mm × 10 mm × 3.3 mm) were prepared. They were divided into 3 groups and treated in the same way. After an adhesive was applied, the bending strength was measured with three-piont bending test. Two experimental groups showed lower microleakage (520.0 ± 562.2 and 493.5 ± 447.9) and higher tensile bond strength [(1.5 ± 0.4) and (1.4 ± 0.5) MPa] than the group control [microleakage: (1369.5 ± 590.2); tensile bond strength: (0.9 ± 0.2) MPa, P 0.05). There was no statistically significant difference in bending strength among the three groups (P > 0.05). Treating the denture base resin surface with acetone and MMA decreased the microleakage, increased the tensile bond strength between the two materials and did not make the initial bending strength of denture base resin decline.

  19. The second green revolution? Production of plant-based biodegradable plastics.

    Science.gov (United States)

    Mooney, Brian P

    2009-03-01

    Biodegradable plastics are those that can be completely degraded in landfills, composters or sewage treatment plants by the action of naturally occurring micro-organisms. Truly biodegradable plastics leave no toxic, visible or distinguishable residues following degradation. Their biodegradability contrasts sharply with most petroleum-based plastics, which are essentially indestructible in a biological context. Because of the ubiquitous use of petroleum-based plastics, their persistence in the environment and their fossil-fuel derivation, alternatives to these traditional plastics are being explored. Issues surrounding waste management of traditional and biodegradable polymers are discussed in the context of reducing environmental pressures and carbon footprints. The main thrust of the present review addresses the development of plant-based biodegradable polymers. Plants naturally produce numerous polymers, including rubber, starch, cellulose and storage proteins, all of which have been exploited for biodegradable plastic production. Bacterial bioreactors fed with renewable resources from plants--so-called 'white biotechnology'--have also been successful in producing biodegradable polymers. In addition to these methods of exploiting plant materials for biodegradable polymer production, the present review also addresses the advances in synthesizing novel polymers within transgenic plants, especially those in the polyhydroxyalkanoate class. Although there is a stigma associated with transgenic plants, especially food crops, plant-based biodegradable polymers, produced as value-added co-products, or, from marginal land (non-food), crops such as switchgrass (Panicum virgatum L.), have the potential to become viable alternatives to petroleum-based plastics and an environmentally benign and carbon-neutral source of polymers.

  20. Novel acrylic resin denture base with enhanced mechanical properties by the incorporation of PMMA-modified hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    Yingying Pan; Fengwei Liu; Dan Xu; Xiaoze Jiang; Hao Yu; Meifang Zhu

    2013-01-01

    A kind of novel acrylic resin denture base enhanced by PMMA-modified hydroxyapatite (M-HAP) was prepared and the modification effect of HAP on the mechanical properties of denture base material was investigated in the present study. HAP whiskers were prepared by hydrothermal homogeneous precipitation process and were silanized by the coupling agent, 3-methacryloxy propyl trimethoxyl silane (g-MPS), to induce the vinyl groups onto its surface. Methyl methacrylate (MMA) were then modified outside the vinyl functionalized HAP via polymerization to build a similar chemical structure with the acrylic matrix. A novel acrylic resin denture base was obtained through self-curing process with the incorporation of this PMMA-modified HAP, and the content of which ranged from 0 wt% to 0.8 wt%. Thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and universal testing apparatus were used to characterize M-HAP and corresponding denture base. The results showed that PMMA were successfully grafted onto the surface of HAP whiskers with up to 15 wt% and the modification turned out to be useful for the dispersion and compatibility of whiskers in the acrylic resin matrix. The mechanical properties of the prepared denture base samples were enhanced greatly after incorporating with M-HAP fillers. The optimal incorporated content of M-HAP was also investigated.

  1. Detecting Tweet-Based Sentiment Polarity of Plastic Surgery Treatment

    Directory of Open Access Journals (Sweden)

    Marvi Jokhio

    2015-10-01

    Full Text Available Sentiment analysis is a growing research these days. Many companies perform this analysis on public opinions to get a general idea about any product or service. This paper presents a novel approach to get views or comments of Twitter users about plastic surgery treatments. The proposed approach uses machine-learning technique embedded with the naïve Bayesian classifier to assign polarities (i.e. positive, negative or neutral to the tweets, collected from ?Twitter micro-blogging website?. The accuracy of the obtained results has been validated using precision, recall and F-score measures. It has been observed from 25000 tweets dataset that people tend to have positive as well as substantial negative opinions regarding particular treatments. The experimental results show the effectiveness of the proposed approach

  2. Cell death effects of resin-based dental material compounds and mercurials in human gingival fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Reichl, Franz-Xaver [Walther-Straub-Institute of Pharmacology and Toxicology, Munich (Germany); Ludwig-Maximilians-University, Department of Operative Dentistry and Periodontology, Munich (Germany); Esters, Magali; Simon, Sabine; Seiss, Mario [Walther-Straub-Institute of Pharmacology and Toxicology, Munich (Germany); Kehe, Kai [Bundeswehr Institute of Pharmacology and Toxicology, Munich (Germany); Kleinsasser, Norbert [University of Regensburg, Head and Neck Surgery, Department of Otolaryngology, Regensburg (Germany); Folwaczny, Matthias; Glas, Juergen; Hickel, Reinhard [Ludwig-Maximilians-University, Department of Operative Dentistry and Periodontology, Munich (Germany)

    2006-06-15

    In order to test the hypothesis that released dental restorative materials can reach toxic levels in human oral tissues, the cytotoxicities of the resin-based dental (co)monomers hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (BisGMA) compared with methyl mercury chloride (MeHgCl) and the amalgam component mercuric chloride (HgCl{sub 2}) were investigated on human gingival fibroblasts (HGF) using two different test systems: (1) the modified XTT-test and (2) the modified H 33342 staining assay. The HGF were exposed to various concentrations of the test-substances in all test systems for 24 h. All tested (co)monomers and mercury compounds significantly (P<0.05) decreased the formazan formation in the XTT-test. EC{sub 50} values in the XTT assay were obtained as half-maximum-effect concentrations from fitted curves. Following EC{sub 50} values were found (mean [mmol/l]; s.e.m. in parentheses; n=12; * significantly different to HEMA): HEMA 11.530 (0.600); TEGDMA* 3.460 (0.200); UDMA* 0.106 (0.005); BisGMA* 0.087 (0.001); HgCl{sub 2}* 0.013 (0.001); MeHgCl* 0.005 (0.001). Following relative toxicities were found: HEMA 1; TEGDMA 3; UDMA 109; BisGMA 133; HgCl{sub 2} 887; MeHgCl 2306. A significant (P<0.05) increase of the toxicity of (co)monomers and mercurials was found in the XTT-test in the following order: HEMA < TEGDMA < UDMA < BisGMA < HgCl{sub 2} < MeHgCl. TEGDMA and MeHgCl induced mainly apoptotic cell death. HEMA, UDMA, BisGMA, and HgCl{sub 2} induced mainly necrotic cell death. The results of this study indicate that resin composite components have a lower toxicity than mercury from amalgam in HGF. HEMA, BisGMA, UDMA, and HgCl{sub 2} induced mainly necrosis, but it is rather unlikely that eluted substances (solely) can reach concentrations, which might induce necrotic cell death in the human physiological situation, indicating that other (additional) factors may be involved in

  3. Synthesis of Boron Modified Phenolic Resin and the Mechanic Performance of Its Molding Plastics%硼改性酚醛树脂的合成及其模塑料力学性能研究∗

    Institute of Scientific and Technical Information of China (English)

    易新龙; 冯安妮; 邵文尧; 肖宗源

    2015-01-01

    The effects of boracic acid dosage on the properties of modified phenolic resin were studied.The structure and thermal property of boron modified phenolic resin were characterized with infrared spectroscopy (IR) and thermogravimetric analyzer (TGA),respectively.It was shown that the residual carbon rate of the boron modified phenolic resin was 10.92% and 67.82%,respectively under the air and nitrogen conditions,when n(phenol)∶n(for-maldehyde)∶n(boron acid)= 1 ∶ 1.4 ∶ 0.4.Also,the mechanic properties,such as tensile,flexural and impact strength of the molding plastics prepared by boron modified phenolic resin were investigated.With the consideration of thermal and mechanic properties,the optimum molar ratio was obtained as n(phenol)∶n(formaldehyde)∶n(boracic acid)=1∶1.4∶0.3.Besides,the effects of filler kind and content for the molding plastics on its mechanic properties were investigated.It was shown that short glass fiber as filler was much better than long glass fiber and wood pow-der,and when wood powder and long glass fiber were used as the mixing filler,the optimum mass ratio of long glass fiber to wood powder was 3∶1.%研究了硼酸加入量对所合成硼改性酚醛树脂性能的影响。通过红外光谱和热重等分析手段对硼改性酚醛树脂的结构和热性能进行表征,分别考察其在氮气和空气氛围下的残炭率,获知当苯酚、甲醛和硼酸之间的物质的量比为1∶1.4∶0.4时,硼改性酚醛树脂的残炭率最高,分别为67.82%和10.92%。此外,以硼改性酚醛树脂为基体树脂制备模塑料并考察其拉伸强度、弯曲强度和抗冲击强度等力学性能。综合考虑以上热性能和力学性能,确定苯酚、甲醛和硼酸之间的最佳物质的量比为1∶1.4∶0.3。最后,研究了添加不同种类和不同含量的填料对酚醛模塑料力学性能的影响。研究结果表明:以短玻璃纤维为填料时,酚醛模塑料的力学性能优于

  4. Thin and thick layers of resin-based sealer cement bonded to root dentine compared: Adhesive behaviour.

    Science.gov (United States)

    Pane, Epita S; Palamara, Joseph E A; Messer, Harold H

    2015-12-01

    This study aims to evaluate tensile and shear bond strengths of one epoxy (AH) and two methacrylate resin-based sealers (EZ and RS) in thin and thick layers bonded to root dentine. An alignment device was prepared for accurate positioning of 20 root dentine cylinders in a predefined gap of 0.1 or 1 mm. Sealer was placed in the interface. Bond strength tests were conducted. Mode of failures and representative surfaces were evaluated. Data were analysed using anova and post-hoc tests, with P layer of sealer produced higher bond strength, except for the shear bond strength of EZ. Significant differences between thin and thick layers were found only in tensile bond strengths of AH and RS. Mixed type of failure was constantly found with all sealers. Bond strengths of thick layers of resin-based sealers to root dentine tended to be higher than with thin layers.

  5. Bonding of a mica-based castable ceramic material with a tri-n-butylborane-initiated adhesive resin.

    Science.gov (United States)

    Morikawa, T; Matsumura, H; Atsuta, M

    1996-07-01

    Adhesive bonding of a mica-based castable ceramic material (Olympus Castable Ceramics, OCC) was evaluated in vitro with the use of a silane primer in conjunction with an adhesive luting material. The primer contained a silane coupler and 4-methacryloxyethyl trimellitate anhydride (4-META), while the methyl methacrylate (MMA)-based luting agent was initiated with a tri-n-butylborane derivative (TBB) and contained 4-META (4-META/MMA-TBB resin). Ceramic specimens were sanded with No. 600 silicon carbide paper followed by blasting with alumina and/or etching with ammonium bifluoride. The specimens were bonded with various combinations and shear bond strengths were determined. Both priming and alumina blasting enhanced the bond between 4-META resin and OCC. Although etching with ammonium bifluoride roughened the ceramic surface, this procedure did not improve the bond strength. Electron probe microanalysis of the ceramic surface revealed a decrease in silicon and aluminium elements after etching with ammonium bifluoride.

  6. Selective degradation of organic dyes by a resin modified Fe-based metal-organic framework under visible light irradiation

    Science.gov (United States)

    Araya, Tirusew; Chen, Chun-cheng; Jia, Man-ke; Johnson, David; Li, Ruiping; Huang, Ying-ping

    2017-02-01

    Metal organic frameworks (MOFs), a new class of porous crystalline materials have attracted attention because of potential applications in environmental remediation. In this work, an Fe-based MOF, FeBTC (BTC = 1,3,5-tricarboxylic acid), was successfully modified with Amberlite IRA-200 resin to yield a novel heterogeneous photocatalyst, A@FeBTC. The modification resulted in higher photocatalytic activity than FeBTC under the same conditions. After 60 min of visible light illumination (λ ≥ 420 nm) 99% of rhodamine B was degraded. The modification lowers the zeta potential, enhancing charge-based selective adsorption and subsequent photocatalytic degradation of cationic dye pollutants. The composite also improved catalyst stability and recyclability by significantly reducing loss of iron leaching. Photoluminescence studies show that introduction of the resin reduces the recombination rate of photogenerated charge carriers thereby improving the photocatalytic activity of the composite. Finally, a plausible photocatalytic reaction mechanism is proposed.

  7. Characteristics of low polymerization shrinkage flowable resin composites in newly-developed cavity base materials for bulk filling technique.

    Science.gov (United States)

    Nitta, Keiko; Nomoto, Rie; Tsubota, Yuji; Tsuchikawa, Masuji; Hayakawa, Tohru

    2017-06-23

    The purpose of this study was to evaluate polymerization shrinkage and other physical properties of newly-developed cavity base materials for bulk filling technique, with the brand name BULK BASE (BBS). Polymerization shrinkage was measured according to ISO/FDIS 17304. BBS showed the significantly lowest polymerization shrinkage and significantly higher depth of cure than conventional flowable resin composites (p<0.05). The Knoop hardness, flexural strength and elastic modulus of that were significantly lower than conventional flowable resin composites (p<0.05). BBS had the significantly greatest filler content (p<0.05). SEM images of the surface showed failure of fillers. The lowest polymerization shrinkage was due to the incorporation of a new type of low shrinkage monomer, which has urethane moieties. There were no clear correlations between inorganic filler contents and polymerization shrinkage, flexural strength and elastic modulus. In conclusion, the low polymerization shrinkage of BBS will be useful for cavity treatment in dental clinics.

  8. China Plastics Industry (2011) China Plastics Processing Industry Association

    Institute of Scientific and Technical Information of China (English)

    Li Ying

    2012-01-01

    General situation of China plastics industry in 2011 was reviewed, including the output and export/import of plastics products, synthetic resins,and plastics processing machinery, as well as major economic data, such as the total industrial values, sales and profits of plastics products, etc. Analysis of the market of plastics products in 2011 was made, and the developing trend of China plastics industry in 2012 was proposed.

  9. In vitro tensile bond strength of denture repair acrylic resins to primed base metal alloys using two different processing techniques.

    Science.gov (United States)

    Banerjee, Sarmistha; Engelmeier, Robert L; O'Keefe, Kathy L; Powers, John M

    2009-12-01

    Approximately 38% of removable partial denture (RPD) failures involve fracture at the alloy/acrylic interface. Autopolymerizing resin is commonly used to repair RPDs. Poor chemical bonding of repair acrylic to base metal alloys can lead to microleakage and failure of the bond. Therefore, ideal repair techniques should provide a strong, adhesive bond. This investigation compared the tensile bond strength between cobalt-chromium (Super Cast, Pentron Laboratory Technologies, Llc., Wallingford, CT) and nickel-chromium (Rexalloy, Pentron Laboratory Technologies, Llc.) alloys and autopolymerized acrylic resin (Dentsply Repair Material, Dentsply Int, Inc, York, Pa) using three primers containing different functional monomers [UBar (UB), Sun Medical Co., Ltd., Shiga, Japan: Alloy Primer (AP) Kuraray Medical Inc., Okayama, Japan; and MR Bond (MRB) Tokyuyama Dental Corp., Tokyo, Japan] and two processing techniques (bench cure and pressure-pot cure). One hundred and twenty eight base metal alloy ingots were polished, air abraded, and ultrasonically cleaned. The control group was not primed. Specimens in the test groups were primed with one of the three metal primers. Autopolymerized acrylic resin material was bonded to the metal surfaces. Half the specimens were bench cured, and the other half were cured in a pressure pot. All specimens were stored in distilled water for 24 hours at 37 degrees C. The specimens were debonded under tension at a crosshead speed of 0.05 cm/min. The forces at which the bond failed were noted. Data were analyzed using ANOVA. Fisher's PLSD post hoc test was used to determine significant differences (p effect on bond strength of all specimens except Co-Cr alloy primed with UB. The highest bond strength was observed for both Co-Cr and Ni-Cr alloys that were sandblasted, primed with MRB, and pressure-pot cured. Co-Cr alloys primed with UB had the lowest bond strength whether bench cured or pressure-pot cured. Primed specimens generally experienced

  10. Determining the bio-based content of bio-plastics used in Thailand by radiocarbon analysis

    Science.gov (United States)

    Ploykrathok, T.; Chanyotha, S.

    2017-06-01

    Presently, there is an increased interest in the development of bio-plastic products from agricultural materials which are biodegradable in order to reduce the problem of waste disposal. Since the amount of modern carbon in bio-plastics can indicate how much the amount of agricultural materials are contained in the bio-plastic products, this research aims to determine the modern carbon in bio-plastic using the carbon dioxide absorption method. The radioactivity of carbon-14 contained in the sample is measured by liquid scintillation counter (Tri-carb 3110 TR, PerkinElmer). The percentages of bio-based content in the samples were determined by comparing the observed modern carbon content with the values contained in agricultural raw materials. The experimental results show that only poly(lactic acid) samples have the modern carbon content of 97.4%, which is close to the agricultural materials while other bio-plastics types are found to have less than 50% of the modern carbon content. In other words, most of these bio-plastic samples were mixed with other materials which are not agriculturally originated.

  11. Analysis of localized shear deformation of ductile metal based on gradient-dependent plasticity

    Institute of Scientific and Technical Information of China (English)

    王学滨; 代树红; 海龙; 潘一山

    2003-01-01

    Shear localization in linear strain softening heterogeneous material under simple shear was investigated analytically.The closed-form solutions obtained based on gradient plasticity theory considering interactions and interplaying among microstructures due to heterogeneity of metal material show that in the normal direction of shear band,elastic shear displacement is linear; while plastic and total shear displacement are non-linear.Elastic shear strain in the band is uniform and the non-uniformity of total shear displacement stems from localized plastic shear displacement.In the center of the band,plastic and total shear displacement all reach their maximum values.In strain-softening process,elastic displacement decreases as flow shear stress decreases.Contrarily,plastic and total shear displacement increase and manifest shear localization occurs progressively.Under the same shear stress level,plastic and total shear displacement increase as strain softening modulus and elastic shear modulus decrease.The present analytical solutions were compared with many experimental results and the agreement is good.

  12. Microbial enzymes for the recycling of recalcitrant petroleum-based plastics: how far are we?

    Science.gov (United States)

    Wei, Ren; Zimmermann, Wolfgang

    2017-03-28

    Petroleum-based plastics have replaced many natural materials in their former applications. With their excellent properties, they have found widespread uses in almost every area of human life. However, the high recalcitrance of many synthetic plastics results in their long persistence in the environment, and the growing amount of plastic waste ending up in landfills and in the oceans has become a global concern. In recent years, a number of microbial enzymes capable of modifying or degrading recalcitrant synthetic polymers have been identified. They are emerging as candidates for the development of biocatalytic plastic recycling processes, by which valuable raw materials can be recovered in an environmentally sustainable way. This review is focused on microbial biocatalysts involved in the degradation of the synthetic plastics polyethylene, polystyrene, polyurethane and polyethylene terephthalate (PET). Recent progress in the application of polyester hydrolases for the recovery of PET building blocks and challenges for the application of these enzymes in alternative plastic waste recycling processes will be discussed. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  13. Influence of surface preparation on fracture load of resin composite-based repairs

    Science.gov (United States)

    Mateos-Palacios, Rocío; Román-Rodríguez, Juan-Luis; Solá-Ruíz, María-Fernanda; Fons-Font, Antonio

    2015-01-01

    The purpose of the present study is to evaluate the fracture load of composite-based repairs to fractured zirconium oxide (Z) crowns and to ceramic-fused-to-metal (CM) crowns, comparing different mechanical surface preparation methods. A total of 75 crowns were repaired; samples then underwent dynamic loading and thermocycling. Final fracture load values for failure of the repaired crowns were measured and the type of fracture registered. Group I: CM: Surface preparation with a diamond bur + 9.5% Hydrofluoric Acid (HF) etching; Group II): CM: air-particle (Al2O3) + 9.5% HF; Group III: CM: Silica coating (SiO2); Group IV): Z: air-particle (Al2O3) + HF 9.5%; Group V) Z: Silica coating (SiO2). Of the three CM groups, Group I (CM-diamond bur) showed the highest mean failure value, with significant difference in comparison with Group III (CM-silica coating). For the zirconia groups, the highest value was obtained by Group V (silica coating). Key words:Crown, ceramic-fused-to-metal, zirconia, resin-composite, ceramic covering. PMID:25810848

  14. Influence of surface preparation on fracture load of resin composite-based repairs.

    Science.gov (United States)

    Agustín-Panadero, Rubén; Mateos-Palacios, Rocío; Román-Rodríguez, Juan-Luis; Solá-Ruíz, María-Fernanda; Fons-Font, Antonio

    2015-02-01

    The purpose of the present study is to evaluate the fracture load of composite-based repairs to fractured zirconium oxide (Z) crowns and to ceramic-fused-to-metal (CM) crowns, comparing different mechanical surface preparation methods. A total of 75 crowns were repaired; samples then underwent dynamic loading and thermocycling. Final fracture load values for failure of the repaired crowns were measured and the type of fracture registered. Group I: CM: Surface preparation with a diamond bur + 9.5% Hydrofluoric Acid (HF) etching; Group II): CM: air-particle (Al2O3) + 9.5% HF; Group III: CM: Silica coating (SiO2); Group IV): Z: air-particle (Al2O3) + HF 9.5%; Group V) Z: Silica coating (SiO2). Of the three CM groups, Group I (CM-diamond bur) showed the highest mean failure value, with significant difference in comparison with Group III (CM-silica coating). For the zirconia groups, the highest value was obtained by Group V (silica coating). Key words:Crown, ceramic-fused-to-metal, zirconia, resin-composite, ceramic covering.

  15. Influence of fluoride- or triclosan-based desensitizing agents on adhesion of resin cements to dentin.

    Science.gov (United States)

    Dündar, Mine; Cal, Ebru; Gökçe, Bülent; Türkün, Murat; Ozcan, Mutlu

    2010-10-01

    Effect of desensitizers on the bond strength of resin cements to dentin was evaluated. Intact premolars (N = 90) were embedded in polymethyl methacrylate; dentin surfaces were exposed, and they were randomly divided into two main groups of cements (Duolink (D), Variolink II (V); n = 45 per group) and then into three desensitizer subgroups (n = 15 per subgroup). Teeth in controls (C) were treated according to cements' adhesion protocols; the other two groups received either fluoride- [Aqua-Prep F (F)] or triclosan-based [Seal&Protect (T)] desensitizers. Ceramic disks (Empress 2) were adhered; specimens were thermocycled (×5,000 cycles, 5-55 ± 1°C, dwell time 30 s) and subjected to shear bond strength test (MPa ± SD) in a universal testing machine (crosshead speed 1 mm/min). Failure types were classified using scanning electron microscope. For V, application of both desensitizers (29.6 ± 7.8 and 22.8 ± 2.8 for F and T, respectively) did not present significantly different results than that of the VC (21.2 ± 2.3; p > 0.05, one-way ANOVA). In D, F (20.6 ± 2.4) showed significantly higher results (p types.

  16. Study on Synthesis of Resin Used for UV Plastic Coating%用于UV塑胶涂料的树脂合成研究

    Institute of Scientific and Technical Information of China (English)

    葛文成; 罗侃; 马希海; 曹磊

    2012-01-01

    The two functional groups of UV curable polyurethane acrylate (PUA)was synthesized by using diol, isophorone diisocyanate(IPDI)and monomer (A-99, own preparation)as raw materials. The influence of synthesis of resin such as different structures of the polyols,ratio of reactants ,reaction time and selection of inhibitor were studied.%以二元醇、异佛尔酮二异氰酸酯(IPDI)和自制单体(A-99)为原料合成了二官能团UV固化聚氨酯丙烯酸酯(PUA)。研究了不同结构的多元醇、反应物配比、反应时间和阻聚剂的选取等对树脂合成的影响。

  17. Influence of zirconium hydrophosphate nanoparticles on porous structure and sorption capacity of the composites based on ion exchange resin

    OpenAIRE

    Dzyazko, Yuliya; Ponomarova, Ludmila; Volfkovich, Yurii; Tsirina, Valentina; Sosenkin, Valentin; Nikolska, Nadiya; Belyakov, Volodimir

    2016-01-01

    Evolution of swelling of gel-like strongly acidic resin and organic-inorganic composites based on this ionexchanger was investigated. Non-aggregated nanoparticles of zirconium hydrophosphate were found to provide size invariability of the polymer pores, which contain functional groups (up to 20 nm), the nanoparticle aggregates squeeze these pores (down to 3 nm). Owing to this, the nanocomposite shows higher break-through capacity during removal of Ni2+ from water, than the sample modified onl...

  18. A new approach to influence contact angle and surface free energy of resin-based dental restorative materials.

    Science.gov (United States)

    Rüttermann, Stefan; Trellenkamp, Taina; Bergmann, Nora; Raab, Wolfgang H-M; Ritter, Helmut; Janda, Ralf

    2011-03-01

    The purpose of the present study was to identify novel delivery systems and active agents which increase the water contact angle and reduce the surface free energy when added to resin-based dental restorative materials. Two delivery systems based on zeolite or novel polymeric hollow beads (Poly-Pore), loaded with two low surface tension active agents (hydroxy functional polydimethylsiloxane and polydimethylsiloxane) or a polymerizable active agent (silicone polyether acrylate) were used to modify commonly formulated experimental dental resin composites. The non-modified resin was used as a standard (ST). Flexural strength, flexural modulus, water sorption, solubility, polymerization shrinkage, surface roughness Ra, contact angle θ, total surface free energy γS, and the apolar γSLW, polar γSAB, Lewis acid γS+ and base γS- components, and the active agents surface tensions γL were determined (Pmaterials had significantly higher θ but significantly lower γS, γSAB and γS- than the ST. A Poly-Pore/polydimethyl siloxane delivery system yielded the highest θ (110.9±3.5°) acceptable physical properties and the lowest values for γSLW and γS-. Among the modified materials the polymerizable materials containing active agents had the lowest γAB and the highest γS+ and γS-. Although not significant, both of the zeolite delivery systems yielded higher γSLW, γS+ and γS- but lower γSAB than the Poly-Pore delivery systems. Poly-Pore based delivery systems highly loaded with low surface tension active agents were found not to influence the physical properties but to significantly increase the water contact angle and thus reduce surface free energy of dental resin composites.

  19. Detection and quantification of monomers in unstimulated whole saliva after treatment with resin-based composite fillings in vivo.

    Science.gov (United States)

    Michelsen, Vibeke B; Kopperud, Hilde B M; Lygre, Gunvor B; Björkman, Lars; Jensen, Einar; Kleven, Inger S; Svahn, Johanna; Lygre, Henning

    2012-02-01

    Resin-based dental restorative materials contain allergenic methacrylate monomers, which may be released into saliva after restorative treatment. Monomers from resin-based composite materials have been demonstrated in saliva in vitro; however, studies analyzing saliva after restorative therapy are scarce. The aim of this study was to quantify methacrylate monomers in saliva after treatment with a resin-based composite filling material. Saliva was collected from 10 patients at four start points--before treatment, and 10 min, 24 h, and 7 d after treatment--and analysed by combined chromatography/mass spectrometry. The monomers bisphenol-A diglycidyl methacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), and urethane dimethacrylate (UDMA) were detected and quantified in the samples collected shortly (10 min) after treatment. The amounts detected ranged from 0.028 to 9.65 μg ml(-1) for Bis-GMA, from 0.015 to 0.19 μg ml(-1) for HEMA, and from 0.004 to 1.2 μg ml(-1) for UDMA. Triethyleneglycol dimethacrylate (TEGDMA) was detected in four of the samples. Ethoxylated bisphenol-A dimethacrylate (Bis-EMA) was not detected. Monomers were not detected in saliva samples collected before treatment, or 24 h or 7 d after treatment, with the exception of one sample, 24 h after treatment, in which HEMA was detected. In conclusion, monomers from the investigated resin-based composite and adhesive system were present in saliva shortly after treatment. One week after treatment, no monomers could be detected in patients' saliva samples.

  20. Use of polycarbonate plastic products and human health

    OpenAIRE

    R. K. Srivastava; Sushila Godara

    2013-01-01

    As plastic and plastic products are being used in day to day at the cost of environment pollution, the human and wild life health and has become a global concern. Researchers found link between abnormal liver enzymes in the people and Bisphenol-A (BPA). Changes in insulin resistance, reproduction system, cardiovascular and brain function are also reported. BPA is used in the production of epoxy resins, polycarbonate resins, and polyester resins. BPA can leach out of certain plastic products i...

  1. Efficacy and tolerability of a polysaccharide-resin-honey based cough syrup as compared to carbocysteine syrup for children with colds: a randomized, single-blinded, multicenter study

    National Research Council Canada - National Science Library

    Cohen, Herman Avner; Hoshen, Moshe; Gur, Shmuel; Bahir, Arie; Laks, Yoseph; Blau, Hannah

    2017-01-01

    .... The objective of this trial is to compare the effects of a polysaccharide-resin-honey based cough syrup, and carbocysteine syrups on nocturnal and daytime cough associated with childhood upper...

  2. Face recognition via edge-based Gabor feature representation for plastic surgery-altered images

    Science.gov (United States)

    Chude-Olisah, Chollette C.; Sulong, Ghazali; Chude-Okonkwo, Uche A. K.; Hashim, Siti Z. M.

    2014-12-01

    Plastic surgery procedures on the face introduce skin texture variations between images of the same person (intra-subject), thereby making the task of face recognition more difficult than in normal scenario. Usually, in contemporary face recognition systems, the original gray-level face image is used as input to the Gabor descriptor, which translates to encoding some texture properties of the face image. The texture-encoding process significantly degrades the performance of such systems in the case of plastic surgery due to the presence of surgically induced intra-subject variations. Based on the proposition that the shape of significant facial components such as eyes, nose, eyebrow, and mouth remains unchanged after plastic surgery, this paper employs an edge-based Gabor feature representation approach for the recognition of surgically altered face images. We use the edge information, which is dependent on the shapes of the significant facial components, to address the plastic surgery-induced texture variation problems. To ensure that the significant facial components represent useful edge information with little or no false edges, a simple illumination normalization technique is proposed for preprocessing. Gabor wavelet is applied to the edge image to accentuate on the uniqueness of the significant facial components for discriminating among different subjects. The performance of the proposed method is evaluated on the Georgia Tech (GT) and the Labeled Faces in the Wild (LFW) databases with illumination and expression problems, and the plastic surgery database with texture changes. Results show that the proposed edge-based Gabor feature representation approach is robust against plastic surgery-induced face variations amidst expression and illumination problems and outperforms the existing plastic surgery face recognition methods reported in the literature.

  3. Effect of artificial saliva and pH on shear bond strength of resin cements to zirconia-based ceramic.

    Science.gov (United States)

    Geramipanah, F; Majidpour, M; Sadighpour, L; Fard, M J Kharazi

    2013-03-01

    The aim of the present study was to evaluate the effect of media with different pH on shear and strength of resin cements to zirconia-based ceramics. Sixty rectangularly shaped specimens made of a zirconia based ceramic (Cercon, Dentsply) were prepared, air-blasted with 110 microm aluminum oxide particles (Al203) and randomly assigned into three groups (n = 30). A universal resin composite (Filtek Z250, 3M/ESPE) was bonded to each specimen using one of the following three cements: Calibra (Dentsply), Panavia F2 (kurary) and Unicem (3M/ESPE). Specimens were thermal cycled and stored in one of the following three media for two weeks: water at pH = 7, saliva at pH = 7 and saliva at pH = 3.5. The mean shear bond strength of each group was analyzed using the Kruskal-Wallis test (alpha = 0.05). The modes of failure were recorded using a streomicroscope. All specimens in the Calibra groups showed premature debonding. No significant difference was found between the two other cements or different media. The failure modes in the two latter cements were predominantly adhesive. Despite the adverse effect of acidic media on the properties of restorative materials, the media did not significantly influence the bond strength of MDP-containing resin cement and a self-adhesive cement to a zirconia- based ceramic.

  4. Bacterial Leakage Assessment for Different Types of Resin-Based Dental Restorations Applied Using Various Placement Methods

    Directory of Open Access Journals (Sweden)

    Horieh Moosavi

    2014-09-01

    Full Text Available Introduction: Although composite resins have improved greatly since their introduction, microleakage is one of the most frequently encountered problems. This study compared the effects of different monomer systems and layering techniques on the bacterial leakage of Cl I composite resin restorations. Methods: Eighty-two sound human third molars were used. The teeth were randomly divided into six groups of 12 teeth each and two positive and negative control groups of five teeth. Class I cavities, measuring 4×4×2 mm, were prepared. The first three groups were filled with a silorane-based composite (Filtek P90 using three different methods of filling (bulk, incremental and snowplow and the remaining three groups were filled with a methacrylate-based composite (Clearfil AP-X using the same techniques. The specimens were stored for 24 hours at 37°C and then thermocycled up to 1000 cycles. The bacterial leakage of the specimens was assessed in a microbiological laboratory and statistical analyses of data were performed by Fisher’s exact and chi-squared tests (P0.05. Conclusion: Leakage occurred similarly in both silorane- and methacrylate-based composite resins and three filling techniques.  

  5. Influence of radiopaque fillers on physicochemical properties of a model epoxy resin-based root canal sealer

    Directory of Open Access Journals (Sweden)

    Fabricio Mezzomo COLLARES

    2013-12-01

    Full Text Available Objective: To verify the influence of radiopaque fillers on an epoxy resin-based sealer. Material and Methods: Experimental sealers were formulated by adding 20%, 40%, 60%, 80%, 100% and 120% of calcium tungstate, ytterbium trifluoride or barium sulphate by weight to an epoxy-resin-base. Setting time, flow, film thickness, radiopacity, sorption, solubility, pH and push-out bond strength were evaluated. Results: The setting time ranged from 373 to 612.66 min, the flow varied from 13.81±0.49 to 22.49±0.37 mm, and the film thickness ranged from 16.67±5.77 to 33.33±11.54 µm. The lowest pH was 5.47±0.53, and the highest was 6.99±0.03. Radiopacity varied from 0.38±0.04 to 2.57±0.21 mmAl and increased with the amount of filler. Calcium tungstate sealers had a higher sorption and solubility than other sealers. There was no significant difference in the push-out bond strength among the fillers at the 120% concentration. CONCLUSION: The inorganic fillers evaluated and their concentrations affect the physicochemical properties of an epoxy resin-based root canal sealer.

  6. Plastic lubricants on the base of an aluminum system

    Energy Technology Data Exchange (ETDEWEB)

    Trubac, K.

    1980-01-01

    Aluminum system lubricants (ASL) are mainly produced from oxystearic acid, as well as from other highly molecular acids and from benzoic acid. The ASL have a high boiling point, excellent water resistance, good thermal and colloidal stability, and high resistance in respect to shift. The ASL accept additives well. In respect to boiling point (greater than 250/sup 0/C), the ASL surpass lithium plastic lubricants by 50 to 100/sup 0/C. To produce a complex soap, it is possible to use two forms of active aluminum: alcoholate (commonly isopropylate) or a corresponding trimer of aluminum soap can be used as the accepted acid: caprilic, caprinic, lauric, myristic, palmitic, stearic (I), 12-oxy-I, arachinic, melissinic, oleic or linoleic (better than I and oxy-I) acids, or carbonic acid and oxides of the C/sub 14/--C/sub 22/ (usually C/sub 16/--C/sub 18/) acids. Oleophobi anions are mainly carbohydrates of C/sub 7/--C/sub 12/ with aromatic rings, for example, the proton acids such as benzoic, toluenic, dimethylbenzoic, phenylacetic, phenylpropionic, alicylic, and so forth, better to have acids of C/sub 7/--C/sub 9/ with a COOH group, connected to the benzoic nucleus. The necessary properties of the ASL depend on the structure of the complex soap, as well as on the relative solubility of the complex soap in the liquid phase of the lubricant.

  7. SWELLING AND WETTABILITY OF LIGHT-CURED METHACRYLATE-BASED DENTAL RESINS PREPARED FROM CHOLIC ACID

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    2 '-methacryloxy-3α, 7α 12α- trimethacryloyl cholic acid ethyl ester (CAGE4MA) has been prepared from cholic acid. Photo-polymeric resins were prepared from CAGE4MA. 2,2-bis[4-(2-hydroxy-3-methacrylyloxypropoxy)phenyl]propane (bis-GMA) was used for comparison, triethyleneglycol dimethacrylate (TEGDMA) was used as diluent. The polymerization was initiated by camphoroquinone (CQ)/N, N-dimethylaminoethyl methacrylate (DMAEMA) system. The conversion of CAGE4MA was 39% when the reaction time is 60s, which is lower than bis-GMA and TEGDMA.The swelling value of CAGE4MA resin was 0.41% in distilled water, which is much lower than those of bis-GMA resin (2.04%) and TEGDMA resin (4.77%) under the same conditions. Copolymers from CAGE4MA and TEGDMA have been prepared. With the increase of TEGDMA in mixture, the degree of conversion of CA GE4MA and swelling value increased. The swelling values of photocured resins in 0. 1mol/L HCl were also measured.

  8. Effect of root canal filling techniques on the bond strength of epoxy resin-based sealers.

    Science.gov (United States)

    Rached-Júnior, Fuad Jacob Abi; Souza, Angélica Moreira; Macedo, Luciana Martins Domingues; Raucci-Neto, Walter; Baratto-Filho, Flares; Silva, Bruno Marques; Silva-Sousa, Yara Teresinha Corrêa

    2016-01-01

    The aim of this study was to evaluate the effects of different root canal filling techniques on the bond strength of epoxy resin-based sealers. Sixty single-rooted canines were prepared using ProTaper (F5) and divided into the following groups based on the root filling technique: Lateral Compaction (LC), Single Cone (SC), and Tagger Hybrid Technique (THT). The following subgroups (n = 10) were also created based on sealer material used: AH Plus and Sealer 26. Two-millimeter-thick slices were cut from all the root thirds and subjected to push-out test. Data (MPa) was analyzed using ANOVA and Tukey's test (α = 0.05). The push-out values were significantly affected by the sealer, filling technique, and root third (p < 0.05). AH Plus (1.37 ± 1.04) exhibited higher values than Sealer 26 (0.92 ± 0.51), while LC (1.80 ± 0.98) showed greater bond strength than THT (1.16 ± 0.50) and SC (0.92 ± 0.25). The cervical (1.45 ± 1.14) third exhibited higher bond strength, followed by the middle (1.20 ± 0.72) and apical (0.78 ± 0.33) thirds. AH Plus/LC (2.26 ± 1.15) exhibited the highest bond strength values, followed by AH Plus/THT (1.32 ± 0.61), Sealer 26/LC (1.34 ± 0.42), and Sealer 26/THT (1.00 ± 0.27). The lowest values were obtained with AH Plus/SC and Sealer 26/SC. Thus, it can be concluded that the filling technique affects the bond strength of sealers. LC was associated with higher bond strength between the material and intra-radicular dentine than THT and SC techniques.

  9. Mechanical characteristics of plastic base Ports and impact on flushing efficacy

    Directory of Open Access Journals (Sweden)

    Guiffant G

    2017-01-01

    Full Text Available Gérard Guiffant,1 Patrice Flaud,1 Laurent Royon,1 Espérie Burnet,2 Jacques Merckx1–3 1University Paris Diderot, Biofluidic Group, UMR CNRS, 2Pulmonary Department and Adult Cystic Fibrosis Centre, Cochin Hospital, 3University Teaching Hospital, Necker-Enfants Malades, Paris, France Background: Three types of totally implantable venous access devices, Ports, are currently in use: titanium, plastic (polyoxymethylene, POM, and mixed (titanium base with a POM shell. Physics theory suggests that the interaction between a non-coring needle (NCN, made of stainless steel and a plastic base would lead to the stronger material (steel altering the more malleable material (plastic. Objectives: To investigate whether needle impacts can alter a plastic base’s surface, thus potentially reducing flushing efficacy. Study design and methods: A Port made of POM was punctured 200 times with a 19-gauge NCN. Following the existing guidelines, the needle tip pricked the base with each puncture. The Port’s base was then examined using a two-dimensional optical instrument, and a bi-dimensional numerical simulation using COMSOL® was performed to investigate potential surface irregularities and their impact on fluid flow. Results: Each needle impact created a hole (mean depth, 0.12 mm with a small bump beside it (mean height, 0.02 mm the Reynolds number Rek≈10. A numerical simulation of the one hole/bump set showed that the flushing efficacy was 60% that of flushing along a flat surface. Discussion: In clinical practice, the number of times a Port is punctured depends on patient and treatment characteristics, but each needle impact on the plastic base may increase the risk of decreased flushing effectiveness. Therefore, the more a plastic Port is accessed, the greater the risk of microorganisms, blood products, and medication accumulation. Conclusions: Multiple needle impacts created an irregular surface on the Port’s base, which decreased flushing efficacy

  10. Effect of Heat Treatment Temperature on Properties of Chinese Calcined Flint Clay Based Plastic Refractories

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; DAI Wenyong; YU Xinfeng; LI Liang

    2009-01-01

    Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material,aluminum sulfate and fireclay as binding system.The results showed that with temperature rising,Chinese calcined flint clay based plastic refractories shrinked firstly and then expanded.The modulus of rupture (MOR) and the cold crushing strength (CCS) increased firstly and then decreased from 110 ℃ to 600 ℃,then increased obviously.Thermal expansion coefficient increased from 110 ℃ to 760 ℃,decreased from 760 ℃ to 1 300 ℃,and increased from 1 300 ℃ to 1 500 ℃.

  11. SOVIET TRENDS IN ORIENTED GLASS-FIBER REINFORCED PLASTICS

    Science.gov (United States)

    GLASS TEXTILES, *PLASTICS, *REINFORCING MATERIALS, ADHESION, BINDERS, DEFORMATION, ELASTIC PROPERTIES, EPOXY RESINS , FIBERS, PHYSICAL PROPERTIES, POLYMERS, PROCESSING, SILICATES, STYRENES, TEXTILES, VISCOSITY

  12. Streptococcus mutans counts in plaque adjacent to orthodontic brackets bonded with resin-modified glass ionomer cement or resin-based composite

    Directory of Open Access Journals (Sweden)

    Solange Machado Mota

    2008-03-01

    Full Text Available This study investigated the number of Streptococcus mutans CFU (colony forming units in the saliva and plaque adjacent to orthodontic brackets bonded with a glass ionomer cement - GIC (Fuji Ortho or a resin-based composite - RC (Concise. Twenty male and female patients, aged 12 to 20 years, participated in the study. Saliva was collected before and after placement of appliances. Plaque was collected from areas adjacent to brackets and saliva was again collected on the 15th, 30th, and 45th day after placement. On the 30th day, 0.4% stannous fluoride gel was applied for 4 minutes. No significant modification in the number of Streptococcus mutans CFU in saliva was observed after placement of the fixed orthodontic appliances. On the 15th day, the percentage of Streptococcus mutans CFU in plaque was statistically lower in sites adjacent to GIC-bonded brackets (mean = 0.365 than in those adjacent to RC-bonded brackets (mean = 0.935. No evidence was found of a contribution of GIC to the reduction of CFU in plaque after the 15th day. Topical application of stannous fluoride gel on the 30th day reduced the number of CFU in saliva, but not in plaque. This study suggests that the antimicrobial activity of GIC occurs only in the initial phase and is not responsible for a long-term anticariogenic property.

  13. Monitoring of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of southern Luxembourg using XAD-2 resin-based passive samplers.

    Science.gov (United States)

    Schummer, Claude; Appenzeller, Brice M; Millet, Maurice

    2014-02-01

    XAD-2 resin-based passive samplers (PAS) with dimensions adapted to 100 mL accelerated solvent extraction cells were used to study the temporal and spatial variations of 17 PAHs on five sites in the atmosphere of southern Luxembourg. This new design allowed extracting the PAS without emptying the resin from the shelter. PAH analyses were done with gas chromatography-tandem mass spectrometry. PAS were deployed for 1 year with varying sampling periodicities, and 16 PAHs were detected with concentrations ranging from 1 ng/PAS for chrysene to 9,727 ng/PAS for naphthalene. The PAS were found adapted to the monitoring of temporal and spatial variations for lightweight PAHs (up to four aromatic rings) though not for heavy PAHs with five aromatic rings or more, as these compounds are preferably in the particle phase of the atmosphere and the amount of these PAHs trapped on the PAS will be too low.

  14. Industrial resin inspection for display production using automated fluid-inspection based on multimodal optical detection techniques

    Science.gov (United States)

    Wijesinghe, Ruchire Eranga; Park, Kibeom; Jung, Yeongri; Kim, Pilun; Jeon, Mansik; Kim, Jeehyun

    2017-09-01

    The large-scale liquid-crystal display (LCD) industry requires an accurate inspection system for identifying defects, as the LCD quality can be drastically degraded because of defects. In particular, the refractive index of LCD panels can be changed by internal micrometer-range substances, which form as a result of defectiveness and the insufficient solidification of industrial liquid resins. Intrinsically, the defect inspection of the raw materials must be performed prior to the LCD manufacturing process. Thus, optical coherence tomography (OCT) based automated fluid-inspection (AFI) methodology was introduced to demarcate and enumerate the defects in industrial liquid resins and the final product (LCD smartphone). The accuracy of the method was enhanced by implementing an intensity-detection algorithm. Subsequently, the optimal solidification rates of liquid resins were investigated using a fluorescence sensor-based ultraviolet hardening method to prevent the formation of defects between the internal layers of the LCD panel. Therefore, AFI can be implemented as an effective and cost-saving method in the smartphone industry for improving the quality of the final product.

  15. The impact of fluorescent dyes on the performances of polystyrene-based plastic scintillators

    Science.gov (United States)

    Zhu, Jun; Deng, Cheng; Jiang, Huimin; Zheng, Zhanlong; Gong, Rui; Bi, Yutie; Zhang, Lin; Lin, Runxiong

    2016-11-01

    To investigate the influence of both the first luminescent additive and the wavelength-shifter on the performance of plastic scintillator, a series of polystyrene-based scintillator had been prepared by thermal polymerization. Three first luminescent additives (PPO, p-TP and b-PBD) and four wavelength-shifters (POPOP, Bis-MSB, Me-MSB and DPA) were added to the scintillators respectively. The comparison results showed that PPO and POPOP were the most adequate fluorescent dyes for the polystyrene-based plastic scintillator. Moreover, with the increase of the concentration of PPO and POPOP, the fluorescence intensity and light yield were increased firstly and then decreased. The plastic scintillator containing 2% PPO and 0.02% POPOP had the highest fluorescence intensity and light yield.

  16. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials

    Energy Technology Data Exchange (ETDEWEB)

    Magalhães Filho, T.R.; Weig, K.M. [Faculdade de Odontologia, Universidade Federal Fluminense, Rua São Paulo 28, CEP 24020-150 Niterói (Brazil); Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Costa, M.F. [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Werneck, M.M. [Engenharia Elétrica (COPPE), Universidade Federal do Rio de Janeiro, CP 68504, CEP: 21941-972 Rio de Janeiro (Brazil); Barthem, R.B. [Instituto de Física, Universidade Federal do Rio de Janeiro, CP 68528, CEP: 21941-972 Rio de Janeiro (Brazil); Costa Neto, C.A., E-mail: celio@metalmat.ufrj.br [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil)

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8 mm diameter and 2 mm thickness were produced and polymerized by 20 s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. - Highlights: • A resin based composite (RBC) was polymerized by three different Light Emitting Diodes. • Each LED had its beam profile visually, wavelength and power analyzed. • The effective polymerization power (EPP) varied from 28% to 52% of the total beam power. • Wavelength seems to be as relevant as power in the light curing process. • Mechanical properties depend on the simultaneous effect of wavelength and power.

  17. Effect of resin content and substrate on the emission of BTEX and carbonyls from low-VOC water-based wall paint.

    Science.gov (United States)

    Zhao, Ping; Cheng, Yu-Hsiang; Lin, Chi-Chi; Cheng, Yu-Lin

    2016-02-01

    The primary aim of this work is to explore the effect of resin content and the effect of substrate on the emission of benzene, toluene, ethylbenzene, and xylene (BTEX) and carbonyls from low-VOC water-based wall paint. Four low-volatile organic compound (VOC) paints include paints A (20% acrylic), B (30% acrylic), C (20% polyvinyl acetate), and D (30% polyvinyl acetate) were painted on stainless steel specimen for the study of resin effect. Green calcium silicate, green cement, and stainless steel were painted with paints A and C for the study of substrate effect. Concentrations of the VOCs in the chamber decreased with the elapsed time. Both resin type and resin quantity in paint had effects on VOC emissions. Paints with acrylic resin emitted less BTEX and carbonyls than paints with polyvinyl acetate resin. However, the effects of resin quantity varied with VOCs. Porous substrates were observed to interact more strongly with paints than inert substrates. Both green calcium silicate and green cement substrates have strong power of adsorption of VOCs from wall paints, namely toluene, formaldehyde, acetaldehyde, 2-butanone, methacrolein, butyraldehyde, and benzaldehyde. Some compounds like toluene, formaldehyde, and butyaldehyde were desorbed very slowly from green calcium silicate and green cement substrates.

  18. Embedding, serial sectioning and staining of zebrafish embryos using JB-4 resin.

    Science.gov (United States)

    Sullivan-Brown, Jessica; Bisher, Margaret E; Burdine, Rebecca D

    2011-01-01

    Histological techniques are critical for observing tissue and cellular morphology. In this paper, we outline our protocol for embedding, serial sectioning, staining and visualizing zebrafish embryos embedded in JB-4 plastic resin-a glycol methacrylate-based medium that results in excellent preservation of tissue morphology. In addition, we describe our procedures for staining plastic sections with toluidine blue or hematoxylin and eosin, and show how to couple these stains with whole-mount RNA in situ hybridization. We also describe how to maintain and visualize immunofluorescence and EGFP signals in JB-4 resin. The protocol we outline-from embryo preparation, embedding, sectioning and staining to visualization-can be accomplished in 3 d. Overall, we reinforce that plastic embedding can provide higher resolution of cellular details and is a valuable tool for cellular and morphological studies in zebrafish.

  19. Epoxy resins.

    Science.gov (United States)

    Bray, P G

    1999-01-01

    Epoxy resins have an extraordinarily broad range of commercial applications, especially as protective surface coatings and adhesives. Epoxy resin systems include combinations of epoxy monomers, hardeners, reactive diluents, and/or a vast array of other additives. As a result, an epoxy resin system may have a number of chemical ingredients with the potential for attendant health hazards. Most, but not all, of these health hazards arise in the occupational setting. The most frequent adverse effects are irritation or allergic mechanisms involving the dermal and respiratory systems. Sensitization usually is caused by low molecular weight or short-chain compounds. This review discusses the diagnosis, treatment, and prevention of epoxy resin-related adverse health effects.

  20. Sifat fisik hidroksiapatit sintesis kalsit sebagai bahan pengisi pada sealer saluran akar resin epoxy (Physical properties of calcite synthesized hydroxyapatite as the filler of epoxy-resin-based root canal sealer

    Directory of Open Access Journals (Sweden)

    Ema Mulyawati

    2013-12-01

    Full Text Available Background: The filler addition to resin based sealers will enhance the physical properties of the polymer. Because of its biological properties, the synthetic hydroxyapatite (HA has been proposed as filler for dental material such as composite resin. The calcite synthesized HA is the HA produced of calcite minerals that came from many Indonesian mining. Purpose: The aim of study was to determine the effect of different concentration of calcite synthesized HA as the filler of the epoxy-resin-based root canal sealer on the physical properties such as its contact angle, the film thickness and the microhardness. Methods: The crystal of the calcite synthesized hydroxyapatite with the size between 77.721-88.710 nm and the ratio of Ca/P 1.6886 were synthesized at Ceramic Laboratory, Mechanical Engineering, using wet method of hydrothermal microwave. The powders of the epoxy- resin were prepared by added the synthesized hydroxyapatite crystal in 5 different weight ratios (e.g.: HA-10%, HA-20%, HA-30%, HA-40% and HA-50%. Each of these was mixed with the paste of 3:1 ratio using spatula on a glass plate until homogen and then measuring the contact angle and the film thickness. Microhardness test was conducted after the mixture of experimental sealer was stored for 24 hrs at 37 oC to reach perfect polymerization. Results: All of contact angles were <90o and were not significantly different to each other (p= 0.510. All groups had a film thickness in accordance with ISO 6876 (<50 um and with no statistical difference (p= 0.858. In the HA of 10%, 20%, 30% seen that the microhardness were increased, while in the HA-50% was decreased and in the HA-40% has the same microhardness to the control groups (HA-0%. Conclusion: Calcite synthesized HA as the filler did not affect contact angle and film thickness of the sealer. Microhardness of the epoxy-resin based sealer could be increased using maximum 30% of the calcite synthesized HA as the filler.Latar belakang

  1. The use of plasticizing additives based on recycled raw materials in the petrochemical rubber mixtures

    Directory of Open Access Journals (Sweden)

    Z. S. Shashok

    2016-01-01

    Full Text Available At present, the development of alternative products for elastomers based on recycling petrochemical raw materials is a new trend of the rubber industry progress. Petrochemical raw materials include spent lubricants and motor oils are among such recycling products. In this context, the influence of the products of recycling waste engine oil (DVCH and RA in comparison with industrial oil (I-20 on the technological properties of filled elastomeric compositions was investigated. The elastomeric compositions were based on poly isoprene and divinyl rubbers. The plasticizing components were manufactured by IOOO “DVCH-Menedzhment”. They are mixture of hydro-carbons, C16–C20 and differ from each other in the content of linear and branched paraffin. Plastic-elastic properties of rubber compounds on the shear disk viscometer MV2000 in accordance with GOST 10722–76 was carried out. Kinetics of vulcanization on the rheometer ODR2000 according to GOST 12535–84 was defined. It is shown that the introduction of RA test plasticizing component provides a significant effect on Mooney viscosity, as compared to elastomeric compositions containing a plasticizer and I-20 and plasticizing additive DVCH. It revealed that the administration of all components in the studied plasticizing elastomer compositions based on a combination poly isoprene and divinyl rubbers has no significant effect on the rate of relaxation of stress of rubber compounds. It is found that elastomeric compositions containing as additives investigated processing waste oil products (DVCH and RA are characterized by a slightly smaller value of time to reach an optimal degree of vulcanization.

  2. Influence of Coating with Some Natural Based Materials on the Erosion Wear Behavior of Glass Fiber Reinforced Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Aseel Basim Abdul Hussein

    2015-06-01

    Full Text Available In the present study, composites were prepared by Hand lay-up molding. The composites constituents were epoxy resin as a matrix, 6% volume fractions of glass fibers (G.F as reinforcement and 3%, 6% volume fractions of preparation natural material (Rice Husk Ash, Carrot Powder, and Sawdust as filler. Studied the erosion wear behavior and coating by natural wastes (Rice Husk Ash with epoxy resin after erosion. The results showed the non – reinforced epoxy have lower resistance erosion than natural based material composites and the specimen (Epoxy+6%glass fiber+6%RHA has higher resistance erosion than composites reinforced with carrot powder and sawdust at 30cm , angle 60°, grin size of sand 425µm , temperature 30Ċ , 300 gm salt content in 2liter of water and 15 hour. Coating specimen with mixed epoxy resin -RHA with particles size in the range (1.4-4.2 µm improves erosion wear resistance characteristics of the coated specimen, coating thickness was (16 ± 1 μm and after erosion at (15 hour the thickness was (10 μm .

  3. Influence of light-curing mode on the cytotoxicity of resin-based surface sealants

    Science.gov (United States)

    2014-01-01

    Background Surface sealants have been successfully used in the prevention of erosive tooth wear. However, when multiple tooth surfaces should be sealed, the light-curing procedure is very time-consuming. Therefore, the aim of this study was to investigate whether reduced light-curing time (while maintaining similar energy density) has an influence on resin-based surface sealant cytotoxicity. Methods Bovine dentine discs were treated as follows: group 1: untreated, groups 2–5: Seal&Protect and groups 6–9: experimental sealer. Groups 2 and 6 were light-cured (VALO LED light-curing device) for 40 s (1000 mW/cm2), groups 3 and 7 for 10 s (1000 mW/cm2), groups 4 and 8 for 7 s (1400 mW/cm2) and groups 5 and 9 for 3 s (3200 mW/cm2). Later, materials were extracted in culture medium for 24 h, and released lactate dehydrogenase (LDH) activity as a measure of cytotoxicity was determined photometrically after cells (dental pulp cells and gingival fibroblasts) were exposed to the extracts for 24 h. Three independent experiments, for both sample preparation and cytotoxicity testing, were performed. Results Overall, lowest cytotoxicity was observed for the unsealed control group. No significant influence of light-curing settings on the cytotoxicity was observed (p = 0.537 and 0.838 for pulp cells and gingival fibroblasts, respectively). No significant difference in the cytotoxicity of the two sealants was observed after light-curing with same light-curing settings (group 2 vs. 6, 3 vs. 7, 4 vs. 8 and 5 vs. 9: p > 0.05, respectively). Conclusions Shortening the light-curing time, while maintaining constant energy density, resulted in no higher cytotoxicity of the investigated sealants. PMID:24885810

  4. Comparison of cytotoxicity test models for evaluating resin-based composites.

    Science.gov (United States)

    Lim, S M; Yap, Auj; Loo, Csl; Ng, J; Goh, C Y; Hong, Chl; Toh, W S

    2017-04-01

    This study compared different cytotoxicity test models for evaluating resin-based composites (RBCs) and assessed the biocompatibility of standard and bulk-fill RBCs. A standard (spectrum TPH) and a bulk-fill (smart dentin replacement (SDR)) RBC were selected. Disc-shaped specimens (7 mm diameter) of 2 and 4 mm thickness were polymerized for 20 s with a LED curing light of 700 mW/cm(2) irradiance. The specimens ( n = 5) were subjected to micro-hardness testing and three cytotoxicity test models (direct contact, indirect contact and extract tests) with the established L-929 cell line. Hardness ratios of top and bottom surfaces of specimens were computed to assess the effectiveness of cure. For the direct and indirect contact tests, the cells were stained and zones of inhibition were analyzed after material contact for 24 h. For the extract test, cells were exposed to extracts for 24 h, and cell viability was measured. Data was analyzed using analysis of variance/Scheffe's post hoc test and Pearson's correlation ( p cytotoxicity were observed for TPH at 4 mm. At 4-mm thickness, SDR was found to be biocompatible with all three models. Correlations between hardness ratio and cell viability ranged from r = 0.89-0.96 for the various tests. A significant correlation ( r = 0.97) was also observed between the three test models. Our data indicated consistency between direct contact, indirect contact and extract test models for cytotoxicity testing of RBCs. Bulk placement and curing at 4 mm for the bulk-fill RBC evaluated did not result in undue cytotoxicity.

  5. Development of palm oil-based UV-curable epoxy acrylate and urethane acrylate resins for wood coating application

    Energy Technology Data Exchange (ETDEWEB)

    Tajau, Rida; Mahmood, Mohd Hilmi; Salleh, Mek Zah; Salleh, Nik Ghazali Nik [Radiation Processing Technology Division, Malaysian Nuclear Agency (Nuclear Malaysia), Bangi, 43000 Kajang, Selangor (Malaysia); Ibrahim, Mohammad Izzat [Faculty of Science, University of Malaya (UM), 50603 Kuala Lumpur (Malaysia); Yunus, Nurulhuda Mohd [Faculty of Science and Technology, National University Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

    2014-02-12

    The trend of using renewable sources such as palm oil as raw material in radiation curing is growing due to the demand from the market to produce a more environmental friendly product. In this study, the radiation curable process was done using epoxy acrylate and urethane acrylate resins which are known as epoxidised palm olein acrylate (EPOLA) and palm oil based urethane acrylate (POBUA), respectively. The purpose of the study was to investigate curing properties and the application of this UV-curable palm oil resins for wood coating. Furthermore, the properties of palm oil based coatings are compared with the petrochemical-based compound such as ebecryl (EB) i.e. EB264 and EB830. From the experiment done, the resins from petrochemical-based compounds resulted higher degree of crosslinking (up to 80%) than the palm oil based compounds (up to 70%), where the different is around 10-15%. The hardness property from this two type coatings can reached until 50% at the lower percentage of the oligomer. However, the coatings from petrochemical-based have a high scratch resistance as it can withstand at least up to 3.0 Newtons (N) compared to the palm oil-based compounds which are difficult to withstand the load up to 1.0 N. Finally, the test on the rubber wood substrate showed that the coatings containing benzophenone photoinitiator give higher adhesion property and their also showed a higher glosiness property on the glass substrate compared to the coatings containing irgacure-819 photoinitiator. This study showed that the palm oil coatings can be a suitable for the replacement of petrochemicals compound for wood coating. The palm oil coatings can be more competitive in the market if the problems of using high percentage palm oil oligomer can be overcome as the palm oil price is cheap enough.

  6. Development of palm oil-based UV-curable epoxy acrylate and urethane acrylate resins for wood coating application

    Science.gov (United States)

    Tajau, Rida; Ibrahim, Mohammad Izzat; Yunus, Nurulhuda Mohd; Mahmood, Mohd Hilmi; Salleh, Mek Zah; Salleh, Nik Ghazali Nik

    2014-02-01

    The trend of using renewable sources such as palm oil as raw material in radiation curing is growing due to the demand from the market to produce a more environmental friendly product. In this study, the radiation curable process was done using epoxy acrylate and urethane acrylate resins which are known as epoxidised palm olein acrylate (EPOLA) and palm oil based urethane acrylate (POBUA), respectively. The purpose of the study was to investigate curing properties and the application of this UV-curable palm oil resins for wood coating. Furthermore, the properties of palm oil based coatings are compared with the petrochemical-based compound such as ebecryl (EB) i.e. EB264 and EB830. From the experiment done, the resins from petrochemical-based compounds resulted higher degree of crosslinking (up to 80%) than the palm oil based compounds (up to 70%), where the different is around 10-15%. The hardness property from this two type coatings can reached until 50% at the lower percentage of the oligomer. However, the coatings from petrochemical-based have a high scratch resistance as it can withstand at least up to 3.0 Newtons (N) compared to the palm oil-based compounds which are difficult to withstand the load up to 1.0 N. Finally, the test on the rubber wood substrate showed that the coatings containing benzophenone photoinitiator give higher adhesion property and their also showed a higher glosiness property on the glass substrate compared to the coatings containing irgacure-819 photoinitiator. This study showed that the palm oil coatings can be a suitable for the replacement of petrochemicals compound for wood coating. The palm oil coatings can be more competitive in the market if the problems of using high percentage palm oil oligomer can be overcome as the palm oil price is cheap enough.

  7. An Improved Plasticity-Based Distortion Analysis Method for Large Welded Structures

    Science.gov (United States)

    Yang, Yu-Ping; Athreya, Badrinarayan P.

    2013-05-01

    The plasticity-based distortion prediction method was improved to address the computationally intensive nature of welding simulations. Plastic strains, which are typically first computed using either two-dimensional (2D) or three-dimensional (3D) thermo-elastic-plastic analysis (EPA) on finite element models of simple weld geometry, are mapped to the full structure finite element model to predict distortion by conducting a linear elastic analysis. To optimize welding sequence to control distortion, a new theory was developed to consider the effect of weld interactions on plastic strains. This improved method was validated with experimental work on a Tee joint and tested on two large-scale welded structures—a light fabrication and a heavy fabrication—by comparing against full-blown distortion predictions using thermo-EPA. 3D solid and shell models were used for the heavy and light fabrications, respectively, to compute plastic strains due to each weld. Quantitative comparisons between this method and thermo-EPA indicate that this method can predict distortions fairly accurately—even for different welding sequences—and is roughly 1-2 orders of magnitude faster. It was concluded from these findings that, with further technical development, this method can be an ideal solver for optimizing welding sequences.

  8. Perubahan warna lempeng resin akrilik yang direndam dalam larutan desinfektan sodium hipoklorit dan klorhexidin (The color changes of acrylic resins denture base material which are immersed in Sodium hypochlorite and chlorhexidine

    Directory of Open Access Journals (Sweden)

    David David

    2006-03-01

    Full Text Available One of the acrylic resins properties is the water absorption including color fluids and chemically fluids that affect on the color changes of the acrylic resins. This laboratory experiments studied sodium hypochlorite and chlorhexidine effect on the color changes of acrylic denture base resins material. The study was conducted by immersing heat cured acrylic plate samples of 26 mm of diameter and 0.4 mm of thickness in sodium hypochlorite for 10; 70 and 140 minutes and chlorhexidine for 15; 105 and 210 minutes. Seven samples were used for each experiment. An optical spectrometer BPX-47 type photo cell and a digital microvoltage were used for the color changes observation. The statistical test used were t-test, One-way ANOVA and LSD with 0.05 significance degree level. The results of the studied showed that the color of acrylic resins denture base plate changed after immersion in sodium hypochlorite for 70 and 140 minutes and chlorhexidine for 105 and 210 minute of immersion.

  9. PARAMETRIC VARIATIONAL PRINCIPLE BASED ELASTIC-PLASTIC ANALYSIS OF COSSERAT CONTINUUM

    Institute of Scientific and Technical Information of China (English)

    Zhang Hongwu; Wang Hui; Chen Biaosong; Xie Zhaoqian

    2007-01-01

    A new algorithm is developed based on the parametric variational principle for elastic-plastic analysis of Cosserat continuum. The governing equations of the classic elastic-plastic problem are regularized by adding rotational degrees of freedom to the conventional translational degrees of freedom in conventional continuum mechanics. The parametric potential energy principle of the Cosserat theory is developed, from which the finite element formulation of the Cosserat theory and the corresponding parametric quadratic programming model are constructed. Strain localization problems are computed and the mesh independent results are obtained.

  10. A novel polishing technology for epoxy resin based on 355 nm UV laser

    Science.gov (United States)

    Meng, Xinling; Tao, Luqi; Liu, Zhaolin; Yang, Yi; Ren, Tianling

    2017-06-01

    The electromagnetic shielding film has drawn much attention due to its wide applications in the integrated circuit package, which demands a high surface quality of epoxy resin. However, gaseous Cu will splash and adhere to epoxy resin surface when the Cu layer in PCB receives enough energy in the process of laser cutting, which has a negative effect on the quality of the shielding film. Laser polishing technology can solve this problem and it can effectively improve the quality of epoxy resin surface. The paper studies the mechanism of Cu powder spraying on the compound surface by 355 nm ultraviolet (UV) laser, including the parameters of laser polishing process and the remains of Cu content on compound surface. The results show that minimal Cu content can be realized with a scanning speed of 700 mm/s, a laser frequency of 50 kHz and the distance between laser focus and product top surface of -1.3 mm. This result is important to obtain an epoxy resin surface with high quality. Project supported by the National Natural Science Foundation of China (Nos. 61574083, 61434001), the National Basic Research Program (No. 2015CB352100), the National Key Project of Science and Technology (No. 2011ZX02403-002), the Special Fund for Agroscientic Research in the Public Interest of China (No 201303107), the support of the Independent Research Program of Tsinghua University (No. 2014Z01006), and Advanced Sensor and Integrated System Lab of Tsinghua University Graduate School at Shenzhen (No. ZDSYS20140509172959969).

  11. Fluorinated Epoxy Resins-based Sorbent Coating Materials for Quartz Piezoelectric Crystal Detector

    Directory of Open Access Journals (Sweden)

    D. C Gupta

    2004-04-01

    Full Text Available Fluorinated epoxy resins were synthesised and evaluated as sorbent coating materials for the detection of organophosphorus compounds using quartz piezoelectric crystal detector. These resins were prepared by reacting excess of epichlorohydrin with each of or in combination of fluorinated diols, ie, a, a, a', a' tetrakis (trifluoromethyl 1,3 benzene dimethanol (TTFMBD, 4,4'bis-2-hydroxy hexafluoro isopropyl biphenyl (BHHFIBP, 4,4'dihydroxyocta fluorodiphenyl (DHOFDP and 2,2,3,3,4,4 hexafluoro 1,5 pentanediol (HFPD in the presence of sodium hydroxide at reflux temperature. These polymers were extracted in organic solvents and dried. Each of these fluoroepoxy resins were coated over quartz piezoelectric crystal by solution-casting method and tested using dimethylmethyl phosphonate (DMMP as model compound. Change in the  frequency (AF of quartz piezoelectric crystal oscillator was recorded. Sensitive and potential fluorinated epoxy resins, ie, diglycidylethers (DGE of HFPD-TTFMBD (in the molar ratio 6:4 and DGE (HFPD-BHHFIBP in the molar ratio 4:6 were characterised by viscosity, number average molecular weight (Mn, epoxy equivalent, infrared spectroscopy, and thermal stability.

  12. Resins and additives for powder coatings and alkyd paints, based on renewable resources

    NARCIS (Netherlands)

    Haveren, van J.; Oostveen, E.A.; Micciche, F.; Noordover, B.A.J.; Koning, C.E.; Benthem, van R.A.T.M.; Frissen, A.E.; Weijnen, J.G.J.

    2007-01-01

    Due to limited fossil resources and an increased need for environmentally friendly, sustainable technologies, the importance of using renewable feedstocks in the paint and coatings area will increase in the decades to come. This paper highlights some of the perspectives in this area. Alkyd resins

  13. Fatty Acid-Based Monomers as Styrene Replacements for Liquid Molding Resins

    Science.gov (United States)

    2005-05-01

    methacrylation of diglycidyl ether of bisphenol A ( DGEBA ) [8] (Fig. 1) catalyzed using AMC-2 (Aerojet Chemicals, Rancho Cordova, CA), which is a... DGEBA , and its methacrylated analog is dubbed VE 828. The effect of VE molecular weight on the properties of VE/FA resins was not tested, but will be

  14. Resins and additives for powder coatings and alkyd paints, based on renewable resources

    NARCIS (Netherlands)

    Haveren, van J.; Oostveen, E.A.; Micciche, F.; Noordover, B.A.J.; Koning, C.E.; Benthem, van R.A.T.M.; Frissen, A.E.; Weijnen, J.G.J.

    2007-01-01

    Due to limited fossil resources and an increased need for environmentally friendly, sustainable technologies, the importance of using renewable feedstocks in the paint and coatings area will increase in the decades to come. This paper highlights some of the perspectives in this area. Alkyd resins fo

  15. Novel Ag nanocrystals based dental resin composites with enhanced mechanical and antibacterial properties

    Institute of Scientific and Technical Information of China (English)

    Fengwei Liu; Ruili Wang; Yuyuan Shi; Xiaoze Jiang; Bin Sun; Meifang Zhu

    2013-01-01

    The aim of this work was to investigate the effect of trace addition of oleic acid coated Ag nanocrystals (Ag NCs) on mechanical and antibacterial properties of dental resin composites. Composites (70 wt%of silica loading) with 25 ppm, 50 ppm, 75 ppm and 100 ppm (wt) Ag NCs were prepared and the composite without Ag NCs served as a control. The experimental results showed that the addition of Ag NCs significantly improved the strength and modulus of the resin composite without compromising the shade. For the composite with 50 ppm Ag NCs, flexural strength (140.3 MPa), modulus (13.2 GPa) and compressive strength (347.2 MPa) were increased by 4.1%, 22.2%, 13.3%, respectively, compared with the control. The antibacterial test demonstrated that trace Ag NCs provided the resin composites with an antibacterial effect. Such strong and antibacterial dental resin composites might be advantageous to prevent secondary caries and be potential for future clinical applications.

  16. Plastic Fishes

    CERN Multimedia

    Trettnak, Wolfgang

    2015-01-01

    In terms of weight, the plastic pollution in the world’s oceans is estimated to be around 300,000 tonnes. This plastic comes from both land-based and ocean-based sources. A lecture at CERN by chemist Wolfgang Trettnak addressed this issue and highlighted the role of art in raising people’s awareness. The slideshow below gives you a taste of the artworks by Wolfgang Trettnak and Margarita Cimadevila.

  17. Low-cost rapid prototyping of flexible plastic paper based microfluidic devices

    KAUST Repository

    Fan, Yiqiang

    2013-04-01

    This research presents a novel rapid prototyping method for paper-based flexible microfluidic devices. The microchannels were fabricated using laser ablation on a piece of plastic paper (permanent paper), the dimensions of the microchannels was carefully studied for various laser powers and scanning speeds. After laser ablation of the microchannels on the plastic paper, a transparent poly (methyl methacrylate)(PMMA) film was thermally bonded to the plastic paper to enclose the channels. After connection of tubing, the device was ready to use. An example microfluidic device (droplet generator) was also fabricated using this technique. Due to the flexibility of the fabricated device, this technique can be used to fabricate 3D microfluidic devices. The fabrication process was simple and rapid without any requirement of cleanroom facilities. © 2013 IEEE.

  18. Mechanistic aspects of fracture and fatigue in resin based dental restorative composites

    Science.gov (United States)

    Shah, Minalben B.

    For resin based dental restorative composites, one of the major challenges is to optimize the balance between mechanical and optical properties. Although fracture is the second leading cause of dental restorative failures, very limited mechanistic understanding exists on a microscopic level. In the present study, the fracture properties and mechanisms of two commercial dental resin composites with different microstructures are examined using double notched four point beam bending and pre-cracked compact-tension, C(T), specimens. Four point bend flexural strength was also measured using un-notched beam samples. The first material is a microhybrid composite that combines a range of nano and micro scale filler particles to give an average particle size of 0.6 mum, while the second is a nanofill composite reinforced entirely with nano particles and their agglomerates. The influences of 60 days water hydration and a post-cure heat treatment were also examined. Fracture resistance curve (R-curve) experiments have demonstrated the microhybrid composite to be more fracture resistant than the nanofill composite in both as-processed and hydrated conditions. Rising fracture resistance with crack extension was observed in all specimens, independent of the environmental conditions. Compared to the as-processed condition, a significant reduction in the peak toughness was observed for the nanofill composite after 60 days of water aging. Hydration lowered flexural strength of both composites which was attributed to hydrolytic matrix degradation with additional interfacial debonding causing larger strength decrease in the nanofill. Optical and SEM observations revealed an interparticle matrix crack path promoting crack deflection as a toughening mechanism in all cases except the hydrated nanofill which showed particle-matrix debonding. Crack bridging was another observed extrinsic toughening mechanism that was believed to be responsible for the rising fracture resistance curve (R

  19. Resin-based preparation of HTGR fuels: operation of an engineering-scale uranium loading system

    Energy Technology Data Exchange (ETDEWEB)

    Haas, P.A.

    1977-10-01

    The fuel particles for recycle of /sup 233/U to High-Temperature Gas-Cooled Reactors are prepared from uranium-loaded carboxylic acid ion exchange resins which are subsequently carbonized, converted, and refabricated. The development and operation of individual items of equipment and of an integrated system are described for the resin-loading part of the process. This engineering-scale system was full scale with respect to a hot demonstration facility, but was operated with natural uranium. The feed uranium, which consisted of uranyl nitrate solution containing excess nitric acid, was loaded by exchange with resin in the hydrogen form. In order to obtain high loadings, the uranyl nitrate must be acid deficient; therefore, nitric acid was extracted by a liquid organic amine which was regenerated to discharge a NaNO/sub 3/ or NH/sub 4/NO/sub 3/ solution waste. Water was removed from the uranyl nitrate solution by an evaporator that yielded condensate containing less than 0.5 ppM of uranium. The uranium-loaded resin was washed with condensate and dried to a controlled water content via microwave heating. The loading process was controlled via in-line measurements of the pH and density of the uranyl nitrate. The demonstrated capacity was 1 kg of uranium per hour for either batch loading contractors or a continuous column as the resin loading contractor. Fifty-four batch loading runs were made without a single failure of the process outlined in the chemical flowsheet or any evidence of inability to control the conditions dictated by the flowsheet.

  20. Adiabatic Shear Localization for Steels Based on Johnson-Cook Model and Second- and Fourth-Order Gradient Plasticity Models

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-bin

    2007-01-01

    To consider the effects of the interactions and interplay among microstructures, gradient-dependent models of second- and fourth-order are included in the widely used phenomenological Johnson-Cook model where the effects of strain-hardening, strain rate sensitivity, and thermal-softening are successfully described. The various parameters for 1006 steel, 4340 steel and S-7 tool steel are assigned. The distributions and evolutions of the local plastic shear strain and deformation in adiabatic shear band (ASB) are predicted. The calculated results of the second- and fourth-order gradient plasticity models are compared. S-7 tool steel possesses the steepest profile of local plastic shear strain in ASB, whereas 1006 steel has the least profile. The peak local plastic shear strain in ASB for S-7 tool steel is slightly higher than that for 4340 steel and is higher than that for 1006 steel. The extent of the nonlinear distribution of the local plastic shear deformation in ASB is more apparent for the S-7 tool steel, whereas it is the least apparent for 1006 steel. In fourth-order gradient plasticity model, the profile of the local plastic shear strain in the middle of ASB has a pronounced plateau whose width decreases with increasing average plastic shear strain, leading to a shrink of the portion of linear distribution of the profile of the local plastic shear deformation. When compared with the second-order gradient plasticity model, the fourth-order gradient plasticity model shows a lower peak local plastic shear strain in ASB and a higher magnitude of plastic shear deformation at the top or base of ASB, which is due to wider ASB. The present numerical results of the second- and fourth-order gradient plasticity models are consistent with the previous numerical and experimental results at least qualitatively.

  1. Tuning the Mechanical Properties of Tapioca Starch by Plasticizers, Inorganic Fillers and Agrowaste-Based Fillers

    OpenAIRE

    Edwin Azwar; Minna Hakkarainen

    2012-01-01

    Mechanical properties of tapioca starch-based films were tuned by different additives and additive combinations. The additives included plasticizers (glycerol, sorbitol, and citric acid), inorganic fillers (halloysite and kaolin), and agrowaste-based fillers (milled wood flour and rice bran). In addition, new biobased additives were prepared from wood flour and rice bran through liquefaction reaction. Through different additive combinations, starch-based materials with significant differences...

  2. Effect of silica coating combined to a MDP-based primer on the resin bond to Y-TZP ceramic.

    Science.gov (United States)

    May, Liliana Gressler; Passos, Sheila Pestana; Capelli, Diana Barca; Ozcan, Mutlu; Bottino, Marco Antonio; Valandro, Luiz Felipe

    2010-10-01

    The aim of this study was to evaluate the influence of silica coating and 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based primer applications upon the bonding durability of a MDP-based resin cement to a yttrium stabilized tetragonal zirconia (Y-TZP) ceramic. Ninety-six Y-TZP tabs were embedded in an acrylic resin (free surface for adhesion: 5 × 5 mm(2)), ground finished and randomly divided into four groups (N = 24) according to the ceramic surface conditioning: (1) cleaning with isopropanol (ALC); (2) ALC + phosphoric acid etching + MDP-based primer application (MDP-primer); (3) silica coating + 3-methacryloyloxypropyl trimethoxysilane (MPS)-based coupling agent application (SiO2 + MPS-Sil); and (4) SiO2 + MDP-primer. The MDP-based resin cement was applied on the treated surface using a cylindrical mold (diameter= 3 mm). Half of the specimens from each surface conditioning were stored in distilled water (37 °C, 24 h) before testing. Another half of the specimens were stored (90 days) and thermo-cycled (12,000 x) during this period (90 d/TC) before testing. A shear bond strength (SBS) test was performed at a crosshead speed of 0.5 mm/min. Two factors composed the experimental design: ceramic conditioning strategy (in four levels) and storage condition (in two levels), totaling eight groups. After 90 d/TC (Tukey; p MDP-primer (24.40 MPa) promoted the highest SBS. The ALC and MDP-primer groups debonded spontaneously during 90 d/TC. Bonding values were higher and more stable in the SiO2 groups. The use of MDP-primer after silica coating increased the bond strength.

  3. A QSPR for the plasticization efficiency of polyvinylchloride plasticizers.

    Science.gov (United States)

    Chandola, Mridula; Marathe, Sujata

    2008-01-01

    A simple quantitative structure property relationship (QSPR) for correlating the plasticization efficiency of 25 polyvinylchloride (PVC) plasticizers was obtained using molecular modeling. The plasticizers studied were-aromatic esters (phthalate, terephthalate, benzoate, trimellitate), aliphatic esters (adipate, sebacate, azelate), citrates and a phosphate. The low temperature flex point, Tf, of plasticized polyvinylchloride resins was considered as an indicator of plasticization efficiency. Initially, we attempted to predict plasticization efficiency of PVC plasticizers from physical and structural descriptors derived from the plasticizer molecule alone. However, the correlation of these descriptors with Tf was not very good with R=0.78 and r2=0.613. This implied that the selected descriptors were unable to predict all the interactions between PVC and plasticizer. Hence, to account for these interactions, a model containing two polyvinylchloride (PVC) chain segments along with a plasticizer molecule in a simulation box was constructed, using molecular mechanics. A good QSPR equation correlating physical and structural descriptors derived from the model to Tf of the plasticized resins was obtained with R=0.954 and r2=0.909.

  4. Study on Impact Acoustic—Visual Sensor-Based Sorting of ELV Plastic Materials

    Science.gov (United States)

    Huang, Jiu; Tian, Chuyuan; Ren, Jingwei; Bian, Zhengfu

    2017-01-01

    This paper concentrates on a study of a novel multi-sensor aided method by using acoustic and visual sensors for detection, recognition and separation of End-of Life vehicles’ (ELVs) plastic materials, in order to optimize the recycling rate of automotive shredder residues (ASRs). Sensor-based sorting technologies have been utilized for material recycling for the last two decades. One of the problems still remaining results from black and dark dyed plastics which are very difficult to recognize using visual sensors. In this paper a new multi-sensor technology for black plastic recognition and sorting by using impact resonant acoustic emissions (AEs) and laser triangulation scanning was introduced. A pilot sorting system which consists of a 3-dimensional visual sensor and an acoustic sensor was also established; two kinds commonly used vehicle plastics, polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) and two kinds of modified vehicle plastics, polypropylene/ethylene-propylene-diene-monomer (PP-EPDM) and acrylonitrile-butadiene-styrene/polycarbonate (ABS-PC) were tested. In this study the geometrical features of tested plastic scraps were measured by the visual sensor, and their corresponding impact acoustic emission (AE) signals were acquired by the acoustic sensor. The signal processing and feature extraction of visual data as well as acoustic signals were realized by virtual instruments. Impact acoustic features were recognized by using FFT based power spectral density analysis. The results shows that the characteristics of the tested PP and ABS plastics were totally different, but similar to their respective modified materials. The probability of scrap material recognition rate, i.e., the theoretical sorting efficiency between PP and PP-EPDM, could reach about 50%, and between ABS and ABS-PC it could reach about 75% with diameters ranging from 14 mm to 23 mm, and with exclusion of abnormal impacts, the actual separation rates were 39.2% for PP, 41

  5. The influence of resin flexural modulus on the magnitude of ceramic strengthening.

    LENUS (Irish Health Repository)

    Fleming, Garry J P

    2012-07-01

    The aim was to determine the magnitude of ceramic resin-strengthening with resin-based materials with varying flexural moduli using a regression technique to assess the theoretical strengthening at a \\'zero\\' resin-coating thickness. The hypothesis tested was that experimentally, increasing resin flexural modulus results in increased resin-strengthening observed at a theoretical \\'zero\\' resin-coating thickness.

  6. Properties evaluation of silorane, low-shrinkage, non-flowable and flowable resin-based composites in dentistry

    Directory of Open Access Journals (Sweden)

    Rodrigo R. Maia

    2015-06-01

    Full Text Available Purpose. This study tested the null hypothesis that different classes of direct restorative dental materials: silorane-based resin, low-shrinkage and conventional (non-flowable and flowable resin-based composite (RBC do not differ from each other with regard to polymerization shrinkage, depth of cure or microhardness.Methods. 140 RBC samples were fabricated and tested by one calibrated operator. Polymerization shrinkage was measured using a gas pycnometer both before and immediately after curing with 36 J/cm2 light energy density. Depth of cure was determined, using a penetrometer and the Knoop microhardness was tested from the top surface to a depth of 5 mm.Results. Considering polymerization shrinkage, the authors found significant differences (p < 0.05 between different materials: non-flowable RBCs showed lower values compared to flowable RBCs, with the silorane-based resin presenting the smallest shrinkage. The low shrinkage flowable composite performed similarly to non-flowable with significant statistical differences compared to the two other flowable RBCs. Regarding to depth of cure, low-shrinkage flowable RBC, were most effective compared to other groups. Microhardness was generally higher for the non-flowable vs. flowable RBCs (p < 0.05. However, the values for low-shrinkage flowable did not differ significantly from those of non-flowable, but were significantly higher than those of the other flowable RBCs.Clinical Significance. RBCs have undergone many modifications as they have evolved and represent the most relevant restorative materials in today’s dental practice. This study of low-shrinkage RBCs, conventional RBCs (non-flowable and flowable and silorane-based composite—by in vitro evaluation of volumetric shrinkage, depth of cure and microhardness—reveals that although filler content is an important determinant of polymerization shrinkage, it is not the only variable that affects properties of materials that were tested in

  7. Properties evaluation of silorane, low-shrinkage, non-flowable and flowable resin-based composites in dentistry.

    Science.gov (United States)

    Maia, Rodrigo R; Reis, Rodrigo S; Moro, André F V; Perez, Cesar R; Pessôa, Bárbara M; Dias, Katia R H C

    2015-01-01

    Purpose. This study tested the null hypothesis that different classes of direct restorative dental materials: silorane-based resin, low-shrinkage and conventional (non-flowable and flowable) resin-based composite (RBC) do not differ from each other with regard to polymerization shrinkage, depth of cure or microhardness. Methods. 140 RBC samples were fabricated and tested by one calibrated operator. Polymerization shrinkage was measured using a gas pycnometer both before and immediately after curing with 36 J/cm(2) light energy density. Depth of cure was determined, using a penetrometer and the Knoop microhardness was tested from the top surface to a depth of 5 mm. Results. Considering polymerization shrinkage, the authors found significant differences (p flowable RBCs showed lower values compared to flowable RBCs, with the silorane-based resin presenting the smallest shrinkage. The low shrinkage flowable composite performed similarly to non-flowable with significant statistical differences compared to the two other flowable RBCs. Regarding to depth of cure, low-shrinkage flowable RBC, were most effective compared to other groups. Microhardness was generally higher for the non-flowable vs. flowable RBCs (p flowable did not differ significantly from those of non-flowable, but were significantly higher than those of the other flowable RBCs. Clinical Significance. RBCs have undergone many modifications as they have evolved and represent the most relevant restorative materials in today's dental practice. This study of low-shrinkage RBCs, conventional RBCs (non-flowable and flowable) and silorane-based composite-by in vitro evaluation of volumetric shrinkage, depth of cure and microhardness-reveals that although filler content is an important determinant of polymerization shrinkage, it is not the only variable that affects properties of materials that were tested in this study.

  8. Co-Curing of CFRP-Steel Hybrid Joints Using the Vacuum Assisted Resin Infusion Process

    Science.gov (United States)

    Streitferdt, Alexander; Rudolph, Natalie; Taha, Iman

    2017-01-01

    This study focuses on the one-step co-curing process of carbon fiber reinforced plastics (CFRP) joined with a steel plate to form a hybrid structure. In this process CFRP laminate and bond to the metal are realized simultaneously by resin infusion, such that the same resin serves for both infusion and adhesion. For comparison, the commonly applied two-step process of adhesive bonding is studied. In this case, the CFRP laminate is fabricated in a first stage through resin infusion of Non Crimp Fabric (NCF) and joined to the steel plate in a further step through adhesive bonding. For this purpose, the commercially available epoxy-based Betamate 1620 is applied. CFRP laminates were fabricated using two different resin systems, namely the epoxy (EP)-based RTM6 and a newly developed fast curing polyurethane (PU) resin. Results show comparable mechanical performance of the PU and EP based CFRP laminates. The strength of the bond of the co-cured samples was in the same order as the samples adhesively bonded with the PU resin and the structural adhesive. The assembly adhesive with higher ductility showed a weaker performance compared to the other tests. It could be shown that the surface roughness had the highest impact on the joint performance under the investigated conditions.

  9. Performance-based plastic design method for steel concentric braced frames

    Science.gov (United States)

    Banihashemi, M. R.; Mirzagoltabar, A. R.; Tavakoli, H. R.

    2015-09-01

    This paper presents a performance-based plastic design (PBPD) methodology for the design of steel concentric braced frames. The design base shear is obtained based on energy-work balance equation using pre-selected target drift and yield mechanism. To achieve the intended yield mechanism and behavior, plastic design is applied to detail the frame members. For validity, three baseline frames (3, 6, 9-story) are designed according to AISC (Seismic Provisions for Structural Steel Buildings, American Institute of Steel Construction, Chicago, 2005) seismic provisions (baseline frames). Then, the frames are redesigned based on the PBPD method. These frames are subjected to extensive nonlinear dynamic time-history analyses. The results show that the PBPD frames meet all the intended performance objectives in terms of yield mechanisms and target drifts, whereas the baseline frames show very poor response due to premature brace fractures leading to unacceptably large drifts and instability.

  10. The study of mechanical properties of pineapple leaf fibre reinforced tapioca based bioplastic resin composite

    Directory of Open Access Journals (Sweden)

    Mathivanan D.

    2016-01-01

    Full Text Available Natural fibre reinforced composite has brought the material engineering to a high new level of research. Natural fibres are compatible with matrices like polypropylene and can be used as reinforcement material to reduce the composition of plastic in a material. Natural fibres such as kenaf, pineapple leaf, and coir already found its importance in reducing the dependence of petroleum based products. However the biodegradability of the product at the end of the intended lifespan is still questionable. This has led many researches to look for a suitable replacement for synthetic fibres and achieve better adhesion between fibre and matrix. In this study, fiber and matrix which are hydrophilic in nature was used and the mixture was extruded and hot compressed to acquire better mechanical properties. The specimens were fabricated and tested according to ASTM D638. The 30% composition illustrates the best average modulus value among other composition and from this result it can be concluded that the increase of PALF fibre in TBR composite increases the modulus strength of the composite.

  11. Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units

    Directory of Open Access Journals (Sweden)

    Sayed-Mostafa Mousavinasab

    2014-08-01

    Full Text Available Objectives Light-curing of resin-based materials (RBMs increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs of three different RBMs using quartz tungsten halogen (QTH and light-emitting diode (LED units (LCUs. Materials and Methods Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12 during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey, a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE, and a giomer (Beautifil II, Shofu GmbH, was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. Results The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p 0.05. Conclusions Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

  12. Tensile bond strength of silicone-based soft denture liner to two chemically different denture base resins after various surface treatments.

    Science.gov (United States)

    Akin, Hakan; Tugut, Faik; Guney, Umit; Kirmali, Omer; Akar, Turker

    2013-01-01

    This study evaluated the effect of various surface treatments on the tensile bond strength of a silicone-based soft denture liner to two chemically different denture base resins, heat-cured polymethyl methacrylate (PMMA), and light-activated urethane dimethacrylate or Eclipse denture base resin. PMMA test specimens were fabricated and relined with a silicone-based soft denture liner (group AC). Eclipse test specimens were prepared according to the manufacturer's recommendation. Before they were relined with a silicone-based soft denture liner, each received one of three surface treatments: untreated (control, group EC), Eclipse bonding agent applied (group EB), and laser-irradiated (group EL). Tensile bond strength tests (crosshead speed = 5 mm/min) were performed for all specimens, and the results were analyzed using the analysis of variance followed by Tukey's test (p = 0.05). Eclipse denture base and PMMA resins presented similar bond strengths to the silicone-based soft denture liner. The highest mean force was observed in group EL specimens, and the tensile bond strengths in group EL were significantly different (p < 0.05) from those in the other groups.

  13. Scintillation Particle Detectors Based on Plastic Optical Fibres and Microfluidics

    CERN Document Server

    Mapelli, Alessandro; Renaud, Philippe

    2011-01-01

    This thesis presents the design, development, and experimental validation of two types of scintillation particle detectors with high spatial resolution. The first one is based on the well established scintillating fibre technology. It will complement the ATLAS (A Toroidal Large ApparatuS) detector at the CERN Large Hadron Collider (LHC). The second detector consists in a microfabricated device used to demonstrate the principle of operation of a novel type of scintillation detector based on microfluidics. The first part of the thesis presents the work performed on a scintillating fibre tracking system for the ATLAS experiment. It will measure the trajectory of protons elastically scattered at very small angles to determine the absolute luminosity of the CERN LHC collider at the ATLAS interaction point. The luminosity of an accelerator characterizes its performance. It is a process-independent parameter that is completely determined by the properties of the colliding beams and it relates the cross section of a ...

  14. [Acrylic resin removable partial dentures

    NARCIS (Netherlands)

    Baat, C. de; Witter, D.J.; Creugers, N.H.J.

    2011-01-01

    An acrylic resin removable partial denture is distinguished from other types of removable partial dentures by an all-acrylic resin base which is, in principle, solely supported by the edentulous regions of the tooth arch and in the maxilla also by the hard palate. When compared to the other types of

  15. Comparison of Cashew Nut Shell Liquid (CNS Resin with Polyester Resin in Composite Development

    Directory of Open Access Journals (Sweden)

    C. C. Ugoamadi

    2013-12-01

    Full Text Available Natural resins can compete effectively with the synthetic ones in composite development. In this research, cashew nuts were picked and processed for the extraction of the resin content. The resin (natural resin so obtained was mixed with cobalt amine (accelerator, methyl ethyl ketone peroxide (catalyst to develop two sets of composite specimens – specimens without fibres and specimens reinforced with glass fibres. This method of sample specimen development was repeated with polyester (synthetic resin. Compressive and tensile strength tests conducted proved that composites developed with cashew nut shell liquid (CNSL resin were comparable to those developed with polyester resin. In the results, CNSL has an ultimate compressive strength of 55MPa compared to that of polyester resin with an ultimate strength of 68MPa. The result of tensile strength proved cashew nut shell liquid resin (with ultimate strength of 44MPa to be better than polyester resin with 39MPa as ultimate tensile strength. This means that natural resins could be a better substitute for the synthetic ones when the required quantities of fibers (reinforcements and fillers are used in the fibre-reinforced plastic composite developments.

  16. Flexural Strength of Acrylic Resin Denture Bases Processed by Two Different Methods

    Directory of Open Access Journals (Sweden)

    Jafar Gharechahi

    2014-09-01

    Full Text Available Background and aims. The aim of this study was to compare flexural strength of specimens processed by conventional and injection-molding techniques. Materials and methods. Conventional pressure-packed PMMA was used for conventional pressure-packed and injection-molded PMMA was used for injection-molding techniques. After processing, 15 specimens were stored in distilled water at room temperature until measured. Three-point flexural strength test was carried out. Statistical analysis was carried out by SPSS using t-test. Statistical significance was defined at P<0.05. Results. Flexural strength of injection-polymerized acrylic resin specimens was higher than that of theconventional method (P=0.006. This difference was statistically significant (P=0.006. Conclusion. Within the limitations of this study, flexural strength of acrylic resin specimens was influenced by the mold-ing technique.

  17. Flexural strength of acrylic resin denture bases processed by two different methods.

    Science.gov (United States)

    Gharechahi, Jafar; Asadzadeh, Nafiseh; Shahabian, Foad; Gharechahi, Maryam

    2014-01-01

    Background and aims. The aim of this study was to compare flexural strength of specimens processed by conventional and injection-molding techniques. Materials and methods. Conventional pressure-packed PMMA was used for conventional pressure-packed and injection-molded PMMA was used for injection-molding techniques. After processing, 15 specimens were stored in distilled water at room temperature until measured. Three-point flexural strength test was carried out. Statistical analysis was carried out by SPSS using t-test. Statistical significance was defined at P<0.05. Results. Flexural strength of injection-polymerized acrylic resin specimens was higher than that of the conventional method (P=0.006). This difference was statistically significant (P=0.006). Conclusion. Within the limitations of this study, flexural strength of acrylic resin specimens was influenced by the molding technique.

  18. Optical waveguide BTX gas sensor based on polyacrylate resin thin film.

    Science.gov (United States)

    Kadir, Razak; Yimit, Abliz; Ablat, Hayrensa; Mahmut, Mamtimin; Itoh, Kiminori

    2009-07-01

    An optical sensor sensitive to BTX has been developed by spin coating a thin film of polyacrylate resin onto a tin- diffused glass optical waveguide. A pair of prism coupler was employed for optical coupling matched with diiodomethane (CH2l2). The guided wave transmits in waveguide layer and passes through the film as an evanescent wave. Polyacrylate film has a strong capacity of absorbing oil gases. The film is stable in N2 but benzene exposure at room temperature can result in rapid and reversible changes of transmittance (7) and refractive index (n1) of this film. It has been demonstrated that the sensor containing a 10 mm boardand about a hundred nanometers thick resin film can detect lower than 8 ppm BTX.

  19. PHOTOCURING STUDY OF NEW DENTAL RESINS BASED ON MULTIFUNCTIONAL ACRYLIC ISOCYANURATE BY PHOTOCALORIMETRY

    Institute of Scientific and Technical Information of China (English)

    Jun Nie; Wen-hui Zhou; Miao-zhen Li; Er-jian Wang; L.A. Linden; J.F. Rabek

    1999-01-01

    Photocuring of new dental resins composed of tri(2-hydroxyethyl) isocyanurate triacrylate (THITA)alone and its mixtures with trimethylolpropane triacrylate (TMPTA) or pentaerythritol triacrylate (PETA) initiated by camphorquinone/amine system was studied by photocalorimetry. Among several different amines as coinitiators, 2-ethyl-4-dimethylaminobenzoate (AM-3), N,N-dimethylbenzylamine (AM-5) and 2,4,6-[tri(dimethylaminomethyl)]phenol (AM-6) are most effective. Upon irradiation, photopolymerization can occur immediately and no induction period appears in N2 nor in air. Comparing the THITA/TMPTA and THITA/PETA mixtures, the parameters of photopolymerization and hardness of photocured samples show a small difference and only change slightly with varying molar ratios of mixture. In the presence of inorganic filler, the hardness of photocuring resins is almost the same as that for commercial products.

  20. Outcome-based residency education: teaching and evaluating the core competencies in plastic surgery.

    Science.gov (United States)

    Bancroft, Gregory N; Basu, C Bob; Leong, Mimi; Mateo, Carol; Hollier, Larry H; Stal, Samuel

    2008-06-01

    Through its oversight of residency education in the United States, the Accreditation Council for Graduate Medical Education has mandated new structural changes in resident education with its newly created core competencies and an emphasis on outcomes-based education. These core competencies represent the central areas in which the Accreditation Council for Graduate Medical Education believes a plastic surgery resident should receive adequate and appropriate education and training. In addition, as part of this outcomes-based education, residents are to be evaluated on their level of mastery in these core competencies. Increasingly, the Accreditation Council for Graduate Medical Education will assess the ability of residency programs to integrate the teaching and evaluating of the core competencies in their accreditation process of plastic surgery residency programs. This shift in residency evaluation initiated by the Outcomes Project by the Accreditation Council for Graduate Medical Education will have a significant impact in how plastic surgery residents are taught and, as importantly, evaluated in the coming years. The objectives of this work were as follows: (1) to outline the different methods available to foster a core competency-based plastic surgery training curriculum and (2) to serve as a primer to help both full-time academic and clinical faculty to further develop their curriculum to successfully teach and constructively evaluate their residents in the core competencies in accordance with the Accreditation Council for Graduate Medical Education guidelines. At the conclusion of this review, the reader should have a better understanding of what is necessary to formulate and help foster a plastic surgery core competency curriculum, particularly with an emphasis on the contemporary methods used for outcomes evaluations.

  1. The surface-forming energy release rate based fracture criterion for elastic-plastic crack propagation

    Science.gov (United States)

    Xiao, Si; Wang, He-Ling; Liu, Bin; Hwang, Keh-Chih

    2015-11-01

    The J-integral based criterion is widely used in elastic-plastic fracture mechanics. However, it is not rigorously applicable when plastic unloading appears during crack propagation. One difficulty is that the energy density with plastic unloading in the J-integral cannot be defined unambiguously. In this paper, we alternatively start from the analysis on the power balance, and propose a surface-forming energy release rate (ERR), which represents the energy available for separating the crack surfaces during the crack propagation and excludes the loading-mode-dependent plastic dissipation. Therefore the surface-forming ERR based fracture criterion has wider applicability, including elastic-plastic crack propagation problems. Several formulae are derived for calculating the surface-forming ERR. From the most concise formula, it is interesting to note that the surface-forming ERR can be computed using only the stress and deformation of the current moment, and the definition of the energy density or work density is avoided. When an infinitesimal contour is chosen, the expression can be further simplified. For any fracture behaviors, the surface-forming ERR is proven to be path-independent, and the path-independence of its constituent term, so-called Js-integral, is also investigated. The physical meanings and applicability of the proposed surface-forming ERR, traditional ERR, Js-integral and J-integral are compared and discussed. Besides, we give an interpretation of Rice paradox by comparing the cohesive fracture model and the surface-forming ERR based fracture criterion.

  2. Shear bond strength of a denture base acrylic resin and gingiva-colored indirect composite material to zirconia ceramics.

    Science.gov (United States)

    Kubochi, Kei; Komine, Futoshi; Fushiki, Ryosuke; Yagawa, Shogo; Mori, Serina; Matsumura, Hideo

    2017-04-01

    To evaluate the shear bond strengths of two gingiva-colored materials (an indirect composite material and a denture base acrylic resin) to zirconia ceramics and determine the effects of surface treatment with various priming agents. A gingiva-colored indirect composite material (CER) or denture base acrylic resin (PAL) was bonded to zirconia disks with unpriming (UP) or one of seven priming agents (n=11 each), namely, Alloy Primer (ALP), Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB+Act), Metal Link (MEL), Meta Fast Bonding Liner (MFB), MR. bond (MRB), and V-Primer (VPR). Shear bond strength was determined before and after 5000 thermocycles. The data were analyzed with the Kruskal-Wallis test and Steel-Dwass test. The mean pre-/post-thermalcycling bond strengths were 1.0-14.1MPa/0.1-12.1MPa for the CER specimen and 0.9-30.2MPa/0.1-11.1MPa for the PAL specimen. For the CER specimen, the ALP, CPB, and CPB+Act groups had significantly higher bond strengths among the eight groups, at both 0 and 5000 thermocycles. For the PAL specimen, shear bond strength was significantly lower after thermalcycling in all groups tested. After 5000 thermocycles, bond strengths were significantly higher in the CPB and CPB+Act groups than in the other groups. For the PAL specimens, bond strengths were significantly lower after thermalcycling in all groups tested. The MDP functional monomer improved bonding of a gingiva-colored indirect composite material and denture base acrylic resin to zirconia ceramics. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  3. A defect density-based constitutive crystal plasticity framework for modeling the plastic deformation of Fe-Cr-Al cladding alloys subsequent to irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Patra, Anirban [Los Alamos National Laboratory; Wen, Wei [Los Alamos National Laboratory; Martinez Saez, Enrique [Los Alamos National Laboratory; Tome, Carlos [Los Alamos National Laboratory

    2016-02-05

    It is essential to understand the deformation behavior of these Fe-Cr-Al alloys, in order to be able to develop models for predicting their mechanical response under varied loading conditions. Interaction of dislocations with the radiation-induced defects governs the crystallographic deformation mechanisms. A crystal plasticity framework is employed to model these mechanisms in Fe-Cr-Al alloys. This work builds on a previously developed defect density-based crystal plasticity model for bcc metals and alloys, with necessary modifications made to account for the defect substructure observed in Fe-Cr-Al alloys. The model is implemented in a Visco-Plastic Self Consistent (VPSC) framework, to predict the mechanical behavior under quasi-static loading.

  4. Effects of Bio-based Plasticizers on Mechanical and Thermal Properties of PVC/Wood Flour Composites

    Directory of Open Access Journals (Sweden)

    Zhenhua Xie

    2014-10-01

    Full Text Available Poly(vinyl chloride/wood flour (WPVC composites with dioctyl phthalate (DOP, dibutyl phthalate (DBP, cardanol acetate (CA, or epoxy fatty acid methyl ester (EFAME were prepared using twin-screw extrusion. The effects of plasticizers on the mechanical, dynamic mechanical, and melt rheological properties of composites and the thermal migration of plasticizers were characterized. The results demonstrated that WPVC/ DBP and WPVC/EFAME composites had better elongation at break; however, composites with bio-based plasticizers exhibited significantly higher impact strength. The morphology indicated that the compatibility between CA and WPVC was poor, while the surface of the composites showed good plasticity with the addition of DBP or EFAME. The PVC matrix with a plasticizer of higher molecular weight exhibited a higher glass transition temperature (Tg. The dynamic rheological test showed that WPVC/EFAME composites had the lowest storage modulus, loss modulus, and complex viscosity, but EFAME migrated more easily from composites than other plasticizers.

  5. Plastic Bridge

    Institute of Scientific and Technical Information of China (English)

    履之

    1994-01-01

    Already ubiquitous in homes and cars, plastic is now appearing inbridges. An academic-industrial consortium based at the University ofCalifornia in San Diego is launching a three-year research program aimed atdeveloping the world’s first plastic highway bridge, a 450-foot span madeentirely from glass-,carbon,and polymer-fiber-reinforced composite mate-rials, the stuff of military aircraft. It will cross Interstate 5 to connect thetwo sides of the school’s campus.

  6. Research progress in bio-based epoxy resins%生物基环氧树脂的研究进展

    Institute of Scientific and Technical Information of China (English)

    马松琪; 刘小青; 朱锦

    2014-01-01

    In oder to solve the unsustainability and toxicity problems of the traditional bisphenol A type epoxy resins,one of the best solutions is synthesizing the epoxy resins with the bio-based raw materials.Our researchers in the bio-based polymer material research group of Ningbo Institute of Materials Technology&Engineering (Chinese Academy of Science) have done a lot of work in preparation of the bio-based epoxy resins.Based on the progress in home and abroad,this paper introduced the research work in preparing the bio-based epoxy resins with rosin, itaconic acid and gallic acid as the raw materials,and presented the raises prospect of future development in the bio-based epoxy resins.%以生物基原料合成环氧树脂是目前解决双酚A环氧树脂原料不可持续性和毒性问题最切实可行的方案。在综述国内外生物基环氧树脂研究进展的基础上,对最近几年我们基于松香、衣康酸、没食子酸合成生物基环氧树脂方面的研究进展进行了介绍,在此基础上进行了总结和展望。

  7. High Performance Fatty Acid-Based Vinyl Ester Resin for Liquid Molding

    Science.gov (United States)

    2007-07-01

    novolac epoxy, and Epon 828, a diglycidyl ether of bisphenol A ( DGEBA ), were purchased from Hexion Specialty Chemicals and was used to synthesize vinyl... DGEBA vinyl ester resins with n~0.1 and containing no styrene, CN 151 and RDX 26936, were obtained from Sartomer and Cytec Surface Specialties Inc...Diglycidyl ether of bisphenol-A ( DGEBA ) Methacrylic Acid Figure 1: The reaction of DGEBA and methacrylic acid to produce the vinyl ester 2.3

  8. Taylor-plasticity-based analysis of length scale effects in void growth

    KAUST Repository

    Liu, Junxian

    2014-09-25

    We have studied the void growth problem by employing the Taylor-based strain gradient plasticity theories, from which we have chosen the following three, namely, the mechanism-based strain gradient (MSG) plasticity (Gao et al 1999 J. Mech. Phys. Solids 47 1239, Huang et al 2000 J. Mech. Phys. Solids 48 99-128), the Taylor-based nonlocal theory (TNT; 2001 Gao and Huang 2001 Int. J. Solids Struct. 38 2615) and the conventional theory of MSG (CMSG; Huang et al 2004 Int. J. Plast. 20 753). We have addressed the following three issues which occur when plastic deformation at the void surface is unconstrained. (1) Effects of elastic deformation. Elasticity is essential for cavitation instability. It is therefore important to guarantee that the gradient term entering the Taylor model is the effective plastic strain gradient instead of the total strain gradient. We propose a simple elastic-plastic decomposition method. When the void size approaches the minimum allowable initial void size related to the maximum allowable geometrically necessary dislocation density, overestimation of the flow stress due to the negligence of the elastic strain gradient is on the order of lεY/R0 near the void surface, where l, εY and R0 are, respectively, the intrinsic material length scale, the yield strain and the initial void radius. (2) MSG intrinsic inconsistency, which was initially mentioned in Gao et al (1999 J. Mech. Phys. Solids 47 1239) but has not been the topic of follow-up studies. We realize that MSG higher-order stress arises due to the linear-strain-field approximation within the mesoscale cell with a nonzero size, lε. Simple analysis shows that within an MSG mesoscale cell near the void surface, the difference between microscale and mesoscale strains is on the order of (lε/R0)2, indicating that when lε/R0 ∼ 1.0, the higher-order stress effect can make the MSG result considerably different from the TNT or CMSG results. (3) Critical condition for cavitation instability

  9. Heat-resistant thermosetting resins and maleimido prepolymers based on a novel tetrakisaminophenoxycyclotriphosphazene

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, D.; Gupta, A.D.; Khullar, M. [Univ. of Delhi (India)

    1993-12-31

    A novel monomer, 2,2,4,4-tetrakis(4`-aminophenoxy)-6,6-diphenylcyclotriphosphazene (IV), useful for producing a variety of heat- and fire-resistant polymers, has been synthesized in good yield. Its synthesis involve Friedel-Frafts reaction of hexachlorocyclotriphosphazene (I) with benzene followed by the reaction of 2,2,4,4-tetrachloro-6,6-diphenylcyclotriphosphazene (II) with potassium 4-nitrophenoxide. The reduction of the obtained 2,2,4,4-tetrakis(4`-nitrophenoxy)-6, 6-diphenylcyclotriphosphazene (III) with molecular hydrogen in presence of PtO{sub 2} gave the tetrakisamine (IV). Heat-resistant thermosetting resins (X) and (XI) were synthesized by the reaction of tetrakisamine (IV) with maleic anhydride followed by insitu cyclodehydration and polymerization of the prepolymers (VIII) and (IX) at 235{+-}5{degrees}C for 1.5 and 290{degrees}C for 0.5 h. The TGA analysis of the developed cyclotriphosphazene containing cyclomatrix resins showed their thermal-stability up to 350{degrees}C and char yield of 71% in nitrogen at 800{degrees}C and 65% in air at 700{degrees}C. The structure of the synthesized monomer and intermediates were characterized by FT-IR, {sup 1}H-NMR, {sup 31}P-NMR, mass spectroscopy, DSC and elemental analysis. These resins are potential candidates for the development of heat-resistant composites, laminates, and adhesives in space, aerospace, and electronic industry.

  10. Cavity Adaptation of Water-Based Restoratives Placed as Liners under a Resin Composite

    Directory of Open Access Journals (Sweden)

    Sheela B. Abraham

    2017-01-01

    Full Text Available Purpose. To investigate the cavity adaptation of mineral trioxide (ProRoot MTA/MT, tricalcium silicate (Biodentine/BD, and glass ionomer (Equia Fil/EF cements used as liners and the interfacial integrity between those liners and a composite resin placed as the main restorative material. Materials and Methods. Standardized class I cavities (n: 8 per group were prepared in upper premolars. Cavities were lined with a 1 mm thick layer of each of the tested materials and restored with Optibond FL adhesive and Herculite Precis composite resin. Cavity adaptation of the restorations was investigated by computerized X-ray microtomography. The regions of interest (ROI were set at the cavity-liner (CL interface and the liner-resin (LR interface. The percentage void volume fraction (%VVF in the ROI was calculated. The specimens were then sectioned and the interfaces were evaluated by reflection optical microscopy, to measure the % length (%LD of the interfacial gaps. Selected samples were further evaluated by scanning electron microscopy. Statistical analysis was performed by two-way ANOVA and Student-Newman-Keuls multiple comparison test (a=0.05. Results. MT showed significantly higher %VVF and %LD values in CL interfaces than BD and EF (p<0.05. No significant differences were found among the materials for the same values at the LR interfaces. Conclusions. When used as a composite liner, ProRoot MTA showed inferior cavity adaptation at dentin/liner interface when compared to Biodentine and Equia Fil.

  11. Cavity Adaptation of Water-Based Restoratives Placed as Liners under a Resin Composite

    Science.gov (United States)

    Gaintantzopoulou, Maria D.; Eliades, George

    2017-01-01

    Purpose. To investigate the cavity adaptation of mineral trioxide (ProRoot MTA/MT), tricalcium silicate (Biodentine/BD), and glass ionomer (Equia Fil/EF) cements used as liners and the interfacial integrity between those liners and a composite resin placed as the main restorative material. Materials and Methods. Standardized class I cavities (n: 8 per group) were prepared in upper premolars. Cavities were lined with a 1 mm thick layer of each of the tested materials and restored with Optibond FL adhesive and Herculite Precis composite resin. Cavity adaptation of the restorations was investigated by computerized X-ray microtomography. The regions of interest (ROI) were set at the cavity-liner (CL) interface and the liner-resin (LR) interface. The percentage void volume fraction (%VVF) in the ROI was calculated. The specimens were then sectioned and the interfaces were evaluated by reflection optical microscopy, to measure the % length (%LD) of the interfacial gaps. Selected samples were further evaluated by scanning electron microscopy. Statistical analysis was performed by two-way ANOVA and Student-Newman-Keuls multiple comparison test (a = 0.05). Results. MT showed significantly higher %VVF and %LD values in CL interfaces than BD and EF (p Biodentine and Equia Fil. PMID:28465685

  12. Resin composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Peutzfeldt, Anne; Lussi, Adrian;

    2014-01-01

    OBJECTIVE: To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading. METHODS: Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity...... of resin composite (p=0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (p....008). CONCLUSIONS: The resin composite with the highest modulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures. CLINICAL SIGNIFICANCE: The results from this study suggest that the marginal quality of restorations can...

  13. Synthesis and properties of a bio-based epoxy resin with high epoxy value and low viscosity.

    Science.gov (United States)

    Ma, Songqi; Liu, Xiaoqing; Fan, Libo; Jiang, Yanhua; Cao, Lijun; Tang, Zhaobin; Zhu, Jin

    2014-02-01

    A bio-based epoxy resin (denoted TEIA) with high epoxy value (1.16) and low viscosity (0.92 Pa s, 258C) was synthesized from itaconic acid and its chemical structure was confirmed by 1H NMR and 13C NMR spectroscopy. Its curing reaction with poly(propylene glycol) bis(2-aminopropyl ether) (D230) and methyl hexahydrophthalic anhydride (MHHPA) was investigated. For comparison, the commonly used diglycidyl ether of bisphenol A (DGEBA) was also cured with the same curing agents. The results demonstrated that TEIA showed higher curing reactivity towards D230/MHHPA and lower viscosity compared with DGEBA, resulting in the better processability. Owing to its high epoxy value and unique structure, comparable or better glass transition temperature as well as mechanical properties could be obtained for the TEIA-based network relative to the DGEBA-based network. The results indicated that itaconic acid is a promising renewable feedstock for the synthesis of bio-based epoxy resin with high performance.

  14. Adhesion properties of styrene-butadiene rubber (SBR/Standard Malaysian Rubber (SMR L-based adhesives in the presence of phenol formaldehyde resin

    Directory of Open Access Journals (Sweden)

    2007-10-01

    Full Text Available The adhesion properties, i. e. viscosity, tack and peel strength of styrene-butadiene rubber (SBR/Standard Malaysian Rubber (SMR L-based pressure-sensitive adhesive was studied using phenol formaldehyde resin as the tackifying resin. Toluene was used as the solvent throughout the experiment. SBR composition in SBR/SMR L blend used was 0, 20, 40, 60, 80, 100%. Three different resin loadings, i. e. 40, 80 and 120 parts per hundred parts of rubber (phr were used in the adhesive formulation. The viscosity of adhesive was determined by a HAAKE Rotary Viscometer whereas loop tack and peel strength of paper/polyethylene terephthalate (PET film were measured using a Lloyd Adhesion Tester operating at 30 cm/min. Results indicate that the viscosity of adhesive decreases with increasing % SBR whereas loop tack passes through a maximum value at 20% SBR for all resin loadings. Except for the control sample (without resin, the peel strength shows a maximum value at 60% SBR for the three modes of peel tests. For a fixed % SBR, adhesive sample containing 40 phr phenol formaldehyde resin always exhibits the highest loop tack and peel strength, an observation which is associated to the optimum wettability of adhesive on the substrate.

  15. Effect of surface modified TiO2 nanoparticles on thermal, barrier and mechanical properties of long oil alkyd resin-based coatings

    Directory of Open Access Journals (Sweden)

    T. S. Radoman

    2015-10-01

    Full Text Available Novel soy alkyd-based nanocomposites (NCs were prepared using TiO2 nanoparticles (NPs surface modified with different gallates, and for the first time with imine obtained from 3,4-dihydroxybenzaldehyde and oleylamine (DHBAOA. Unmodified and surface modified anatase TiO2 NPs were characterized by transmission electron microscopy (TEM, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and ultraviolet-visible (UV-Vis spectroscopy, while the amount of adsorbed ligands was calculated from thermogravimetric analysis (TGA results. Surface modification of TiO2 NPs was confirmed by FTIR and UV-Vis spectra. The influence of the TiO2 surface modification on the dispersion of TiO2 NPs in alkyd resin, thermal, barrier and mechanical properties and chemical resistance of alkyd resin/TiO2 NC coatings was investigated. The obtained results revealed that glass transition temperature of all investigated NCs is lower than for pure resin, that the presence of TiO2 NPs surface modified with gallates had no significant influence on the thermooxidative stability of alkyd resin, while TiO2-DHBAOA NPs slightly improved alkyd resin thermooxidative stability. Also, the presence of surface modified TiO2 NPs improved barrier properties, increased stress and strain at break and hardness and chemical resistance and decreased modulus of elasticity and abrasion resistance of alkyd resin.

  16. Jute fibre reinforced plastic: evaluation of application based properties

    Directory of Open Access Journals (Sweden)

    J. B. Sajin

    2015-01-01

    Full Text Available A fibre extracted from jute is a budding component identified for its potential application in composites. It is imperative to evaluate the parametric and property based features to determine its suitability. In this research study, considering the possible application of the fibre composites, the aptness of these fibres are examined with respect to their physical, mechanical [by layered manufacturing technique(LM] and thermal properties. This study focuses on evaluating the properties and behaviour of raw Jute fibres and NaOH surface treated fibres. Subsequently, the fibres are subjected to thermo-gravimetry tests. The outcome of the thermal analysis clearly indicates that the temperature peak shifts to a higher region in the treated fibre compared to raw fibre. The overall observation strongly emphasize that the physical properties and the thermal behaviour of jute fibre are enhanced after surface treatments which makes it more feasible for its application in composite structures.

  17. Paucity of Nanolayering in Resin-Dentin Interfaces of MDP-based Adhesives.

    Science.gov (United States)

    Tian, F; Zhou, L; Zhang, Z; Niu, L; Zhang, L; Chen, C; Zhou, J; Yang, H; Wang, X; Fu, B; Huang, C; Pashley, D H; Tay, F R

    2016-04-01

    Self-assembled nanolayering structures have been reported in resin-dentin interfaces created by adhesives that contain 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP). These structures have been hypothesized to contribute to bond durability. The objective of the present study was to determine the extent of nanolayering in resin-dentin interfaces after application of commercialized 10-MDP-containing self-etch and universal adhesives to human dentin. Seven commercialized adhesives were examined: Adhese Universal (Ivoclar-Vivadent), All-Bond Universal (Bisco, Inc.), Clearfil SE Bond 2, Clearfil S3 Bond Plus, Clearfil Universal Bond (all from Kuraray Noritake Dental Inc.), G-Premio Bond (GC Corp.), and Scotchbond Universal (3M ESPE). Each adhesive was applied in the self-etch mode on midcoronal dentin according to the respective manufacturer's instructions. Bonded specimens (n = 6) were covered with flowable resin composite, processed for transmission electron microscopy, and examined at 30 random sites without staining. Thin-film glancing angle X-ray diffraction (XRD) was used to detect the characteristic peaks exhibited by nanolayering (n = 4). The control consisted of 15%wt, 10%wt, and 5%wt 10-MDP (DM Healthcare Products, Inc.) dissolved in a mixed solvent (ethanol and water weight ratio 9:8, with photoinitiators). Experimental primers were applied to dentin for 20 s, covered with hydrophobic resin layer, and examined in the same manner. Profuse nanolayering with highly ordered periodicity (~3.7 nm wide) was observed adjacent to partially dissolved apatite crystallites in dentin treated with the 15% 10-MDP primer. Three peaks in the 2θ range of 2.40° (3.68 nm), 4.78° (1.85 nm), and 7.18° (1.23 nm) were identified from thin-film XRD. Reduction in the extent of nanolayering was observed in the 10% and 5% 10-MDP experimental primer-dentin interface along with lower intensity XRD peaks. Nanolayering and characteristic XRD peaks were rarely observed in

  18. Thermosetting polyimide resin matrix composites with interpenetrating polymer networks for precision foil resistor chips based on special mechanical performance requirements

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.Y., E-mail: wxy@tju.edu.cn [School of Electronic Information Engineering, Tianjin University, Tianjin 300072 (China); Ma, J.X.; Li, C.G. [School of Electronic Information Engineering, Tianjin University, Tianjin 300072 (China); Wang, H.X. [ZHENGHE electronics Co., Ltd, Jining 272023 (China)

    2014-04-01

    Highlights: • Macromolecular materials were chosen to modify thermosetting polyimide (TSPI). • The formation of IPN structure in TSPI composite polymers was discussed. • The special mechanical properties required were the main study object. • The desired candidate materials should have proper hardness and toughness. • The specific mechanical data are quantitatively determined by experiments. - Abstract: Based on interpenetrating networks (IPNs) different macromolecular materials such as epoxy, phenolic, and silicone resin were chosen to modify thermosetting polyimide (TSPI) resin to solve the lack of performance when used for protecting precision foil resistor chips. Copolymerization modification, controlled at curing stage, was used to prepare TSPI composites considering both performance and process requirements. The mechanical properties related to trimming process were mainly studied due to the special requirements of the regularity of scratch edges caused by a tungsten needle. The analysis on scratch edges reveals that the generation and propagation of microcracks caused by scratching together with crack closure effect may lead to regular scratch traces. Experiments show that the elongation at break of TSPI composites is the main reason that determines the special mechanical properties. The desired candidate materials should have proper hardness and toughness, and the specific mechanical data are that the mean elongation at break and tensile strength of polymer materials are in the range of 9.2–10.4% and 100–107 MPa, respectively. Possible reasons for the effect of the modifiers chosen on TSPI polymers, the reaction mechanisms on modified TSPI resin and the IPN structure in TSPI composite polymers were discussed based on IR and TG analysis.

  19. A study of an assisting robot for mandible plastic surgery based on augmented reality.

    Science.gov (United States)

    Shi, Yunyong; Lin, Li; Zhou, Chaozheng; Zhu, Ming; Xie, Le; Chai, Gang

    2017-02-01

    Mandible plastic surgery plays an important role in conventional plastic surgery. However, its success depends on the experience of the surgeons. In order to improve the effectiveness of the surgery and release the burden of surgeons, a mandible plastic surgery assisting robot, based on an augmented reality technique, was developed. Augmented reality assists surgeons to realize positioning. Fuzzy control theory was used for the control of the motor. During the process of bone drilling, both the drill bit position and the force were measured by a force sensor which was used to estimate the position of the drilling procedure. An animal experiment was performed to verify the effectiveness of the robotic system. The position error was 1.07 ± 0.27 mm and the angle error was 5.59 ± 3.15°. The results show that the system provides a sufficient accuracy with which a precise drilling procedure can be performed. In addition, under the supervision's feedback of the sensor, an adequate safety level can be achieved for the robotic system. The system realizes accurate positioning and automatic drilling to solve the problems encountered in the drilling procedure, providing a method for future plastic surgery.

  20. Crack detection in plastic pipe using piezoelectric transducers based on nonlinear ultrasonic modulation

    Science.gov (United States)

    Hong, Xiaobin; Lin, Xiaohui; Yang, Bo; Li, Maodong

    2017-10-01

    As a common kind of failure, crack damages account for major losses in plastic pipeline systems, which are now increasingly being used. In this study, a crack detection method for plastic pipes using piezoelectric transducers based on nonlinear ultrasonic modulation is developed. First, the low frequency and the high frequency (HF) inputs generated by two lead zirconate titanate (PZT) transducers that are bonded to the outer surface of a plastic pipe are used to induce stress waves along the pipe. For the response signal detected by another PZT, the first spectral sideband is extracted using filtering and synchronous demodulation and then modified by a proposed mean equalization method. Subsequently, by applying wavelet packet analysis, the wavelet energy of the signal can be obtained and is used as an index to determine the damaged state. Finally, a series of experiments on plastic pipes of different crack damaged states were conducted using several ways to verify their effectiveness. Experimental results show that wavelet energy of the response signal decreases as the crack grows and it is mainly determined by the HF component of the response signal, while the wavelet energy of the modified first spectral sideband tends to become larger when the crack grows. Among the investigated approaches, it is found that the first spectral sideband can detect the crack damage state effectively.

  1. Consumer Exposure to Bisphenol A from Plastic Bottles

    Science.gov (United States)

    Bidabadi, Fatemeh

    2013-01-01

    Bisphenol A (BPA) is a plastic monomer and plasticizer and is a chemical that has one of the highest volume production worldwide, with more than six billion pounds each year. Its primary use is the production of polycarbonate plastics, epoxy resins used to line metal cans in a host of plastic consumer products such as toys, water pipes, drinking…

  2. A simple enzyme based biosensor on flexible plastic substrate

    Science.gov (United States)

    Kanakamedala, Senaka K.; Alshakhouri, Haidar T.; Agarwal, Mangilal; Fang, Ji; DeCoster, Mark A.

    2010-08-01

    An enzyme based biosensor was fabricated by employing a simple, inexpensive and rapid xurography fabrication process. The electrodes and channel were made from the conducting polymer poly(3,4-ethyelenedioxythiphene) poly(styrene sulfonate) (PEDOT:PSS). PEDOT:PSS was selectively deposited using a polyimide tape mask. The tape mask was peeled off from the substrate after annealing the polymer in vacuum. Polymer wells of defined dimensions were made and were attached to the device to accommodate the solutions. This sensor utilizes the change in current as a parameter to measure different analyte concentrations. Initial experiments were done by using the sensor for glucose detection. The sensor is able to detect the glucose concentrations approximately from 1 μM to 10 mM range covering glucose in human saliva (8-210 μM). The glucose oxidase activity was independently measured using colorimetric method and the results indicate that the sensor retains the enzyme activity and can be used as a biosensor to detect various analytes. The analyte of interest can be measured by preloading the corresponding enzyme into the wells.

  3. Short and long term behaviour of externally bonded fibre reinforced polymer laminates with bio-based resins for flexural strengthening of concrete beams

    Science.gov (United States)

    McSwiggan, Ciaran

    The use of bio-based resins in composites for construction is emerging as a way to reduce of embodied energy produced by a structural system. In this study, two types of bio-based resins were explored: an epoxidized pine oil resin blend (EP) and a furfuryl alcohol resin (FA) derived from corn cobs and sugar cane. Nine large-scale reinforced concrete beams strengthened using externally bonded carbon and glass fibre reinforced bio-based polymer (CFRP and GFRP) sheets were tested. The EP resin resulted in a comparable bond strength to conventional epoxy (E) when used in wet layup, with a 7% higher strength for CFRP. The FA resin, on the other hand, resulted in a very weak bond, likely due to concrete alkalinity affecting curing. However, when FA resin was used to produce prefabricated cured CFRP plates which were then bonded to concrete using conventional epoxy paste, it showed an excellent bond strength. The beams achieved an increase in peak load ranging from 18-54% and a 9-46% increase in yielding load, depending on the number of FRP layers and type of fibres and resin. Additionally, 137 concrete prisms with a mid-span half-depth saw cut were used to test CFRP bond durability, and 195 CFRP coupons were used to examine tensile strength durability. Specimens were conditioned in a 3.5% saline solution at 23, 40 or 50°C, for up to 240 days. Reductions in bond strength did not exceed 15%. Bond failure of EP was adhesive with traces of cement paste on CFRP, whereas that of FA was cohesive with a thicker layer of concrete on CFRP, suggesting that the bond between FA and epoxy paste is excellent. EP tension coupons had similar strength and modulus to E resin, whereas FA coupons had a 9% lower strength and 14% higher modulus. After 240 days of exposure, maximum reductions in tensile strength were 8, 19 and 10% for EP, FA and E resins, respectively. Analysis of Variance (ANOVA) was also performed to assess the significance of the reductions observed. High degrees of

  4. [Allergic contact eczema from epoxy resin].

    Science.gov (United States)

    Calzado, Leticia; Ortiz-de Frutos, Francisco J; del Prado Sánchez-Caminero, María; Galera, Carmen María; Valverde, Ricardo; Vanaclocha, Francisco

    2005-11-01

    Epoxy resins are plastics that are widely used as electrical insulation, in coatings, and as adhesives and paints. They have strong sensitizing power and are one of the main causes of allergic contact eczema, both in the workplace and elsewhere. We present the case of a worker at a plastics/chemical plant, who handled aeronautical components in the process of manufacturing fuselage parts. He consulted his physician because of eczematous lesions on his fingers, hands and forearms which had developed over a two-year period and were clearly related to his work. The standard battery of skin tests was performed, along with the plastics and adhesives series and tests using the products from his workplace. Positivity was shown to epoxy resins (standard battery) and to the products from his workplace, which included different fiberglass and carbon fiber sheets impregnated with epoxy resins and epoxy adhesives.

  5. Comparison of the Effects of Two Different Drinks on Microhardness of a Silorane-based Composite Resin

    Directory of Open Access Journals (Sweden)

    Sedighe Sadat HashemiKamangar

    2015-09-01

    Full Text Available Statement of the Problem: Acidic foods and drinks can erode composite resins. Silorane-based composite is a new low shrinkage composite with higher hydrophobicity which might resist the erosive effect of beverages. Purpose: The aim of this study was to determine the effects of 100% orange juice and non-alcoholic carbonated beer on microhardness of a silorane-based composite in comparison with two methacrylate-based composite resins. Materials and Method: Ninety disc-shaped composite specimens were fabricated of Filtek P90, Filtek Z350 XT Enamel and Filtek Z250 (3M-ESPE (n=30 and randomly divided into 3 subgroups of 10.Group 1 was immersed in distilled water, group 2 in 100% orange juice, and group 3 in non-alcoholic beer for 3 h/day. Primary, secondary and final Vickers microhardness tests were performed at the beginning of the study and 7 and 28 days later. Surface of 2 specimens in each group was evaluated under scanning electron microscope on day 28. Data were analyzed using repeated measures of ANOVA model (α=0.05. Results: The primary and secondary microhardness of P90 was significantly lower than that of Z350, and Z250 (p 0.05. Conclusion: Although 28 days of immersion in 100% orange juice and non-alcoholic beer decreased the microhardness of all specimens, P90 experienced the greatest reduction of microhardness and non-alcoholic beer had the highest effect on reducing microhardness.

  6. STUDIES ON THE ADSORPTION OF PHENOLIC COMPOUNDS ON A PS-BASED RESIN MODIFIED BY NITRO FUNCTIONAL GROUPS

    Institute of Scientific and Technical Information of China (English)

    Jin-nan Wang; Ai-min Li; Sheng Zhong; Wei-ben Yan; Quan-xing Zhang

    2008-01-01

    A new adsorbent (JN-01) was prepared by modifying resin NDA-1800 with nitro functional groups.The adsorption capacities of resins XAD-4,NDA-1800 and JN-01 were investigated,and the results indicated that the modified resin JN-01 was much better in adsorbing phenol,p-nitrophenol and p-cresol.The adsorption capacities of the resin JN-01 were higher than those of the resins XAD-4 and NDA-1800 within a temperature range of 283-323 K,which might be attributed to the higher surface area and the partial polarity on its matrix.The new adsorbent could be widely used in wastewater treatment.

  7. Decoupling Conditions for Elasto-plastic Consolidation Question Based onNumerical Modeling Method

    Institute of Scientific and Technical Information of China (English)

    Cheng Tao; Wang Jingtao; Dong Bichang

    2005-01-01

    Elasto-plastic consolidation is one of the classic coupling questions in geomechanics. To solve this problem, an elasto-plastic constitutive model is derived based on the numerical modeling method. The model is applied to Biot's consolidation theory. Incremental governing partial differential equations are established using this method. According to the stress path, the decoupling condition of these equations is discussed. Based on these conditions, an incremental diffusion equation and uncoupling governing equations are presented. The method is then applied to numerical analyses of three examples. The results show that (1) the effect of the stress path should be taken into account in the simulation of the soil consolidation question; (2) this decoupling method can predict the evolvement of pore water pressure; (3) the settlement using cam-clay model is less than that using numerical model because of dilatancy.

  8. ELASTO-PLASTICITY ANALYSIS BASED ON COLLOCATION WITH THE MOVING LEAST SQUARE METHOD

    Institute of Scientific and Technical Information of China (English)

    SongKangzu; ZhangXiong; LuMiugwau

    2003-01-01

    A meshless approach based on the moving least square method is developed for elasto-plasticity analysis, in which the incremental formulation is used. In this approach, the displacement shape functions are constructed by using the moving least square approximation, and the discrete governing equations for elasto-plastic material are constructed with the direct collocation method. The boundary conditions are also imposed by collocation. The method established is a truly meshless one, as it does not need any mesh, either for the purpose of interpolation of the solution variables, or for the purpose of construction of the discrete equations. It is simply formulated and very efficient, and no post-processing procedure is required to compute the derivatives of the unknown variables, since the solution from this method based on the moving least square approximation is already smooth enough. Numerical examples are given to verify the accuracy of the meshless method proposed for elasto-rdasticity analysis.

  9. Color Stability of Nanofilled and Microhybrid Resin-Based Composites following Exposure to Chlorhexidine Mouthrinses: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Mahmood Khosravi

    2016-10-01

    Full Text Available Objectives: This study aimed to evaluate the effects of chlorhexidine mouthrinses on color stability of nanofilled and micro-hybrid resin-based composites.Materials and Methods: In this in-vitro study, 160 disc-shaped specimens (7x2mm were fabricated of Filtek Z250 and Filtek Z350XT Enamel (A2 shade. The samples of each group were randomly divided into eight subgroups (n=10. The specimens were incubated in artificial saliva at 37˚C for 24 hours. The baseline color values (L*, a*, b* of each specimen were measured according to CIE LAB system using a reflection spectrophotometer. After baseline color measurements, the control samples were immersed in saliva and the test groups were immersed in Kin (Cosmodent, Vi-One (Rozhin, Epimax (Emad, Hexodine (Donyaye Behdasht, Chlorhexidine (Shahrdaru, Najo (Najo and Behsa (Behsa mouthrinses once a day for two minutes. The specimens were then immersed again in saliva. This process was repeated for two weeks. Color measurements were made on days seven and 14. Two-way and one-way ANOVA and Tukey’s post hoc test, t-test and paired t-test were used to analyze data at a significance level of 0.05.Results: All specimens displayed color change after immersion in the mouthrinses. Significant interactions were found between the effects of materials and mouthrinses on color change.Conclusions: All composite resins tested showed acceptable color change after immersion in different mouthrinses. Filtek Z350XT showed less color change than Filtek Z250. Mouthrinses containing alcohol (Behsa and Najo and citric acid (Vi-One caused greater discoloration of composites.Keywords: Chlorhexidine; Color; Composite Resins; Mouthwashes

  10. Light-cured dimethacrylate-based resins and their composites: comparative study of mechanical strength, water sorption and ion release

    Science.gov (United States)

    O’Donnell, J.N.R.; Langhorst, S.E.; Fow, M.D.; Antonucci, J.M.; Skrtic, D.

    2008-01-01

    This study explored how resin type affects selected physicochemical properties of complex methacrylate copolymers and their amorphous calcium phosphate (ACP)-filled and glass-filled composites. Two series of photo-polymerizable resin matrices were formulated employing 2,2-bis[p-(2’-hydroxy-3’-methacryloxypropoxy)phenyl]propane (Bis-GMA) or an ethoxylated bisphenol A dimethacrylate (EBPADMA) as the base monomer, Unfilled copolymers and composites filled with a mass fraction with 40 %, 35 % and 30 %, respectively, of ACP or the un-silanized glass were assessed for biaxial flexure strength (BFS), water sorption (WS) and mineral ion release upon immersion in HEPES-buffered saline solution for up to six months. Substituting EBPADMA for Bis-GMA significantly reduced the WS while only marginally affected the BFS of both dry and wet copolymers. Independent of the filler level, both dry and wet ACP composites formulated with either BTHM or ETHM resins were mechanically weaker than the corresponding copolymers. The BFS of ACP composite specimens after 1 month in saline did not further decrease with further aqueous exposure. The BFS of glass-filled composites decreased with the increased level of the glass filler and the time of aqueous exposure. After 6 months of immersion, the BFS of glass-filled BTHM and ETHM composites, respectively, remained 58 % and 41 % higher than the BFS of the corresponding ACP composites. Ion release data indicated that a minimum mass fraction of 35 % ACP was required to attain the desired solution supersaturation with respect to hydroxyapatite for both the BTHM and ETHM derived composites. PMID:18607513

  11. UV-curable nanocomposite based on methacrylic-siloxane resin and surface-modified TiO2 nanocrystals.

    Science.gov (United States)

    Ingrosso, Chiara; Esposito Corcione, Carola; Striani, Raffaella; Comparelli, Roberto; Striccoli, Marinella; Agostiano, Angela; Curri, M Lucia; Frigione, Mariaenrica

    2015-07-22

    A novel UV-light-curable nanocomposite material formed of a methacrylic-siloxane resin loaded with 1 wt % oleic acid and 3-(trimethoxysilyl)propyl methacrylate silane (OLEA/MEMO)-coated TiO2 nanorods (NRs) has been manufactured as a potential self-curing structural coating material for protection of monuments and artworks, optical elements, and dental components. OLEA-coated TiO2 NRs, presynthesized by a colloidal chemistry route, have been surface-modified by a treatment with the methacrylic-based silane coupling agent MEMO. The resulting OLEA/MEMO-capped TiO2 NRs have been dispersed in MEMO; that is a monomer precursor of the organic formulation, used as a "common solvent" for transferring the NRs in prepolymer components of the formulation. Differential scanning calorimetry and Fourier transform infrared spectroscopy have allowed investigation of the effects of the incorporation of the OLEA/MEMO-capped TiO2 NRs on reactivity and photopolymerization kinetics of the nanocomposite, demonstrating that the embedded NRs significantly increase curing reactivity of the neat organic formulation both in air and inert atmosphere. Such a result has been explained on the basis of the photoactivity of the nanocrystalline TiO2 which behaves as a free-radical donor photocatalyst in the curing reaction, finally turning out more effective than the commonly used commercial photoinitiator. Namely, the NRs have been found to accelerate the cure rate and increase cross-linking density, promoting multiple covalent bonds between the resin prepolymers and the NR ligand molecules, and, moreover, they limit inhibition effect of oxygen on photopolymerization. The NRs distribute uniformly in the photocurable matrix, as assessed by transmission electron microscopy analysis, and increase glass transition temperature and water contact angle of the nanocomposite with respect to the neat resin.

  12. Shock induced shear strength in an HMX based plastic bonded explosive

    Science.gov (United States)

    Millett, J. C. F.; Taylor, P.; Appleby-Thomas, G.

    2017-01-01

    The shock induced mechanical response of an HMX based plastic bonded explosive (PBX) has been investigated in terms of the shear strength. Results show that shear strength increases with impact stress. However comparison with the calculated elastic response of both the PBX and pure HMX suggests that the overall mechanical response is controlled by the HMX crystals, with the near liquid like nature of the binder phase having a minimal contribution.

  13. Emerging sustainable technology for epoxidation directed toward plant oil-based plasticizers

    DEFF Research Database (Denmark)

    Chua, Seong-Chea; Xu, Xuebing; Guo, Zheng

    2012-01-01

    The chemical industry is increasingly looking toward sustainable technology to reduce the environmental impact and minimize the footprint of a chemical process. This work, which presents emerging technologies in academia and industry, discusses the development of advanced processes...... for the production of epoxidized plant oil-based plasticizers. The effects of the substrate structure, oxygen-donor properties, catalysts and biocatalysts on the specificity of the epoxidation reaction are intensively discussed. The progress in enzymatic epoxidation and the application of neoteric media...

  14. Polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials--a comparative study.

    Science.gov (United States)

    Rüttermann, Stefan; Krüger, Sören; Raab, Wolfgang H-M; Janda, Ralf

    2007-10-01

    To investigate the polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials. The densities of SureFil (SU), CeramXMono (CM), Clearfil AP-X (CF), Solitaire 2 (SO), TetricEvoCeram (TE), and Filtek P60 (FT) were measured using the Archimedes' principle prior to and 15min after curing for 20, 40 and 60s and after 1h, 24h, 7 d, and 30 d storage at 37 degrees C in water. Volumetric changes (DeltaV) in percent after polymerization and after each storage period in water were calculated from the changes of densities. Water sorption and solubility were determined after 30 d for all specimens and their curing times. Two-way ANOVA was calculated for shrinkage and repeated measures ANOVA was calculated for hygroscopic expansion (p<0.05). DeltaV depended on filler load but not on curing time (SU approximately -2.0%, CM approximately -2.6%, CF approximately -2.1%, SO approximately -3.3%, TE approximately -1.7%, FT approximately -1.8%). Hygroscopic expansion depended on water sorption and solubility. Except for SU, all materials showed DeltaV approximately +1% after water storage. Polymerization shrinkage depended on the type of resin-based filling material but not on curing time. Shrinkage was not compensated by hygroscopic expansion.

  15. Evaluation of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental dental resin-based materials.

    Science.gov (United States)

    Oliveira, Dayane Carvalho Ramos Salles de; Souza-Junior, Eduardo José; Dobson, Adam; Correr, Ana Rosa Costa; Brandt, William Cunha; Sinhoreti, Mário Alexandre Coelho

    2016-01-01

    To evaluate the influence of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental resin-based materials photoactivated using different light curing units (LCUs). Experimental resin-based materials with the same organic matrix (60:40 wt% BisGMA:TEGDMA) were mechanically blended using a centrifugal mixing device. To this blend, different photoinitiator systems were added in equimolar concentrations with aliphatic amine doubled by wt%: 0.4 wt% CQ; 0.38 wt% PPD; or 0.2 wt% CQ and 0.19 wt% PPD. The degree of conversion (DC), flexural strength (FS), Young's modulus (YM), Knoop hardness (KNH), crosslinking density (CLD), and yellowing (Y) were evaluated (n=10). All samples were light cured with the following LCUs: a halogen lamp (XL 2500), a monowave LED (Radii), or a polywave LED (Valo) with 16 J/cm2. The results were analysed by two-way ANOVA and Tukey's test (α=0.05). No statistical differences were found between the different photoinitiator systems to KNH, CLS, FS, and YM properties (p≥0.05). PPD/CQ association showed the higher DC values compared with CQ and PPD isolated systems when photoactivated by a polywave LED (p≤0.05). Y values were highest for the CQ compared with the PPD systems (p≤0.05). PPD isolated system promoted similar chemical and mechanical properties and less yellowing compared with the CQ isolated system, regardless of the LCU used.

  16. Film Thickness and Flow Properties of Resin-Based Cements at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Bagheri R.

    2013-06-01

    Full Text Available Statement of Problem: For a luting agent to allow complete seating of prosthetic restorations, it must obtain an appropriate flow rate maintaining a minimum film thickness. The performance of recently introduced luting agents in this regard has not been evaluated. Purpose: To measure and compare the film thickness and flow properties of seven resin-containing luting cements at different temperatures (37°C, 25°C and10°C. Material and Methods: Specimens were prepared from five resin luting cements; seT (SDI, Panavia F (Kuraray, Varioloink II (Ivoclar, Maxcem (Kerr, Nexus2 (Kerr and two resin-modified glass-ionomer luting cements (RM-GICs; GC Fuji Plus (GC Corporation, and RelyX Luting 2 (3 M/ESPE. The film thickness and flow rate of each cement (n=15 was determined using the test described in ISO at three different temperatures. Results: There was a linear correlation between film thickness and flow rate for most of the materials. Cooling increased fluidity of almost all materials while the effect of temperature on film thickness was material dependent. At 37°C, all products revealed a film thickness of less than 25µm except for GC Fuji Plus. At 25°C, all cements pro-duced a film thickness of less than 27 µm except for seT. At 10°C, apart from seT and Rely X Luting 2, the remaining cements showed a film thickness smaller than 20 µm.Conclusion: Cooling increased fluidity of almost all materials, however. the film thickness did not exceed 35 µm in either condition, in spite of the lowest film thickness being demonstrated at the lowest temperature.

  17. Performance Based Plastic Design of Concentrically Braced Frame attuned with Indian Standard code and its Seismic Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Sejal Purvang Dalal

    2015-12-01

    Full Text Available In the Performance Based Plastic design method, the failure is predetermined; making it famous throughout the world. But due to lack of proper guidelines and simple stepwise methodology, it is not quite popular in India. In this paper, stepwise design procedure of Performance Based Plastic Design of Concentrically Braced frame attuned with the Indian Standard code has been presented. The comparative seismic performance evaluation of a six storey concentrically braced frame designed using the displacement based Performance Based Plastic Design (PBPD method and currently used force based Limit State Design (LSD method has also been carried out by nonlinear static pushover analysis and time history analysis under three different ground motions. Results show that Performance Based Plastic Design method is superior to the current design in terms of displacement and acceleration response. Also total collapse of the frame is prevented in the PBPD frame.

  18. Influence of Cumulative Plastic Deformation on Microstructure of the Fe-Al Intermetallic Phase Base Alloy

    Directory of Open Access Journals (Sweden)

    Bednarczyk I.

    2014-10-01

    Full Text Available This article is part of the research on the microstructural phenomena that take place during hot deformation of intermetallic phase-based alloy. The research aims at design an effective thermo - mechanical processing technology for the investigated intermetallic alloy. The iron aluminides FeAl have been among the most widely studied intermetallics because their low cost, low density, good wear resistance, easy of fabrication and resistance to oxidation and corrosion. There advantages create wide prospects for their industrial applications for components of machines working at a high temperature and in corrosive environment. The problem restricting their application is their low plasticity and their brittle cracking susceptibility, hampers their development as construction materials. Consequently, the research of intermetallic-phase-based alloys focuses on improvement their plasticity by hot working proceses. The study addresses the influence of deformation parameters on the structure of an Fe-38% at. Al alloy with Zr, B Mo and C microadditions, using multi – axis deformation simulator. The influence of deformation parameters on microstructure and substructure was determined. It was revealed that application of cumulative plastic deformation method causes intensive reduction of grain size in FeAl phase base alloy.

  19. A Fuzzy Mathematics Based Fault Auto-diagnosis System for Vacuum Resin Shot Dosing Equipment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    On the basis of the analysis of faults and their causes of vacuum resin shot dosing equipment, the fuzzy model of fault diagnosis for the equipment is constructed, and the fuzzy relationship matrix, the symptom fuzzy vector, the fuzzy compound arithmetic operator, and the diagnosis principle of the model are determined. Then the fault auto-diagnosis system for the equipment is designed, and the functions for real-time monitoring its operation condition and for fault auto-diagnosis are realized. Finally, the experiments of fault auto-diagnosis are conducted in practical production and the veracity of the system is verified.

  20. Prediction of the viscosity reduction due to dissolved CO2 of and an elementary approach in the supercritical CO2 assisted continuous particle production of a polyester resin

    NARCIS (Netherlands)

    Nalawade, Sameer P.; Nieborg, Vincent H. J.; Picchioni, Francesco; Janssen, L. P. B. M.

    2006-01-01

    The dissolution of CO2 in a polymer causes plasticization of the polymer and hence, its viscosity is reduced. A model based on the free volume theory has been used for a polyester resin, which shows a considerable reduction in the viscosity due to dissolved M. Therefore, superctitical CO2 has been u

  1. Comparison of protaper and mtwo retreatment systems for working time in the removal of resin-based root canal obturation materials during retreatment

    OpenAIRE

    İriboz, Emre; Sazak Öveçoğlu, Hesna

    2013-01-01

    Objective: The aim of this study is to evaluate the working time of ProTaper and Mtwo retreatment systems for removal of three different resin-based filling materials during simulated retreatment. Methods: 160 extracted maxillary anterior teeth were enlarged using two different rotary systems; ProTaper and Mtwo. The teeth were randomly divided into 8 groups of 20 specimens each. Six groups were filled with 3 different resin-based obturation materials, two groups were filled with an eugenol-ba...

  2. Adsorption of heavy metal ions and azo dyes by crosslinked nanochelating resins based on poly(methylmethacrylate-co-maleic anhydride

    Directory of Open Access Journals (Sweden)

    M. Ghaemy

    2014-03-01

    Full Text Available Chelating resins are suitable materials for the removal of heavy metals in water treatments. A copolymer, Poly(MMA-co-MA, was synthesized by radical polymerization of maleic anhydride (MA and methyl methacrylate (MMA, characterized and transformed into multifunctional nanochelating resin beads (80–150 nm via hydrolysis, grafting and crosslink reactions. The resin beads were characterized by swelling studies, field emission scanning electron microscopy (FESEM and Fourier transform infrared spectroscopy (FTIR. The main purpose of this work was to determine the adsorption capacity of the prepared resins (swelling ratio ~55% towards metal ions such as Hg2+, Cd2+, Cu2+ from water at three different pH values (3, 6 and 9. Variations in pH and types of metal ions have not significantly affected the chelation capacity of these resins. The maximum chelation capacity of one of the prepared resin beads (Co-g-AP3 for Hg2+ was 63, 85.8 and 71.14 mg/g at pH 3, 6 and 9, respectively. Approximately 96% of the metal ions could be desorbed from the resin. Adsorption capacity of these resins towards three commercial synthetic azo dyes was also investigated. The maximum adsorption of dye AY42 was 91% for the resin Co-g-AP3 at room temperature. This insures the applicability of the synthesized resins for industrial applications.

  3. Selective separation of biobutanol from acetone-butanol-ethanol fermentation broth by means of sorption methodology based on a novel macroporous resin.

    Science.gov (United States)

    Lin, Xiaoqing; Wu, Jinglan; Jin, Xiaohong; Fan, Jiansheng; Li, Renjie; Wen, Qingshi; Qian, Wenbin; Liu, Dong; Chen, Xiaochun; Chen, Yong; Xie, Jingjing; Bai, Jianxin; Ying, Hanjie

    2012-07-01

    The traditional distillation method for recovery of butanol from fermentation broth is an energy-intensive process. Separation of butanol based on adsorption methodology has advantages in terms of biocompatibility and stability, as well as economy, and therefore gains much attention. However, the application of the commercial adsorbents in the integrated acetone-butanol-ethanol (ABE) fermentation process is restricted due to the low recovery (less than 85%) and the weak capability of enrichment in the eluent (3-4 times). In this study, we investigated the sorption properties of butanol onto three kinds of adsorbents with different polarities developed in our laboratory, that is, XD-41, H-511, and KA-I resin. The sorption behaviors of single component and ABE ternary mixtures presented in the fermentation broths on KA-I resin were investigated. KA-I resin had higher affinity for butanol than for acetone, ethanol, glucose, acetic acid, and butyric acid. Multicomponent ABE sorption on KA-I resin was modeled using a single site extended Langmuir isotherm model. In a desorption study, all the adsorbed components were desorbed in one bed volume of methanol, and the recovery of butanol from KA-I resin was 99.7%. The concentration of butanol in the eluent was increased by a factor of 6.13. In addition, KA-I resin was successfully regenerated by two bed volumes of water. Because of its quick sorption, high sorption capacity, low cost, and ease of desorption and regeneration, KA-I resin exhibits good potential for compatibility with future ABE fermentation coupled with in situ recovery product removal techniques. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  4. PARAMETRIC VARIATIONAL PRINCIPLE BASED ELASTIC-PLASTIC ANALYSIS OF HETEROGENEOUS MATERIALS WITH VORONOI FINITE ELEMENT METHOD

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-wu; WANG Hui

    2006-01-01

    The Voronoi cell finite element method (VCFEM) is adopted to overcome the limitations of the classic displacement based finite element method in the numerical simulation of heterogeneous materials. The parametric variational principle and quadratic programming method are developed for elastic-plastic Voronoi finite element analysis of two-dimensional problems. Finite element formulations are derived and a standard quadratic programming model is deduced from the elastic-plastic equations. Influence of microscopic heterogeneities on the overall mechanical response of heterogeneous materials is studied in detail. The overall properties of heterogeneous materials depend mostly on the size, shape and distribution of the material phases of the microstructure. Numerical examples are presented to demonstrate the validity and effectiveness of the method developed.

  5. Simultaneous Sterilization With Surface Modification Of Plastic Bottle By Plasma-Based Ion Implantation

    Science.gov (United States)

    Sakudo, N.; Ikenaga, N.; Ikeda, F.; Nakayama, Y.; Kishi, Y.; Yajima, Z.

    2011-01-01

    Dry sterilization of polymeric material is developed. The technique utilizes the plasma-based ion implantation which is same as for surface modification of polymers. Experimental data for sterilization are obtained by using spores of Bacillus subtilis as samples. On the other hand we previously showed that the surface modification enhanced the gas barrier characteristics of plastic bottles. Comparing the implantation conditions for the sterilization experiment with those for the surface modification, we find that both sterilization and surface modification are simultaneously performed in a certain range of implantation conditions. This implies that the present bottling system for plastic vessels will be simplified and streamlined by excluding the toxic peroxide water that has been used in the traditional sterilization processes.

  6. Synthesis of Petroleum-Based Fuel from Waste Plastics and Performance Analysis in a CI Engine

    Directory of Open Access Journals (Sweden)

    Christine Cleetus

    2013-01-01

    Full Text Available The present work involves the synthesis of a petroleum-based fuel by the catalytic pyrolysis of waste plastics. Catalytic pyrolysis involves the degradation of the polymeric materials by heating them in the absence of oxygen and in the presence of a catalyst. In the present study different oil samples are produced using different catalysts under different reaction conditions from waste plastics. The synthesized oil samples are subjected to a parametric study based on the oil yield, selectivity of the oil, fuel properties, and reaction temperature. Depending on the results from the above study, an optimization of the catalyst and reaction conditions was done. Gas chromatography-mass spectrometry of the selected optimized sample was done to find out its chemical composition. Finally, performance analysis of the selected oil sample was carried out on a compression ignition (CI engine. Polythene bags are selected as the source of waste plastics. The catalysts used for the study include silica, alumina, Y zeolite, barium carbonate, zeolite, and their combinations. The pyrolysis reaction was carried at polymer to catalyst ratio of 10 : 1. The reaction temperature ranges between 400°C and 550°C. The inert atmosphere for the pyrolysis was provided by using nitrogen as a carrier gas.

  7. Comparative evaluation of surface hardness and depth of cure of silorane and methacrylate-based posterior composite resins: An in vitro study

    Directory of Open Access Journals (Sweden)

    Abhishek Agrawal

    2015-01-01

    Full Text Available Aim: This in vitro study was carried out to compare the effect of LED light curing system on polymerization and hardness of silorane-based and methacrylate-based posterior composite resin. Materials and Methods: A total of 40 samples, 20 of silorane-based composite Filtek P-90 and 20 of methacrylate-based composite Heliomolar HB measuring 2 mm thickness and 8 mm diameter were prepared using Teflon molds and cured using LED curing light. The samples were polished and tested in Knoop hardness tester using a 50-gram load and dwell time of 15 seconds on top and bottom surfaces. The percentage depth of cure was calculated, and statistical analysis was performed using two-way ANOVA test and Student t- test. Results: Higher statistically significant values were seen for both the top and bottom surface hardness in silorane-based resins than methacrylate-based resins on LED light curing. Conclusion: Greater depth of cure was achieved in silorane-based posterior composite than in methacrylate-based posterior composite resins with a statistically significant difference.

  8. Effect of an acrylic resin-based resilient liner applied to mandibular complete dentures on satisfaction ratings among edentulous patients.

    Science.gov (United States)

    Kimoto, Suguru; Kimoto, Katsuhiko; Murakami, Hiroshi; Atsuko, Gunji; Ogawa, Akina; Kawai, Yasuhkio

    2014-01-01

    The aim of this study was to investigate whether an acrylic resin-based resilient liner (ARL) could improve the satisfaction ratings of complete denture wearers. The null hypothesis was that no difference exists between the satisfaction ratings of conventional acrylic resin denture (CARD) wearers and those of ARL denture (ARLD) wearers. From April 2004 to July 2006, a randomized controlled trial was conducted at two centers, including 74 edentulous patients. Of these, 37 patients were each randomly allocated to the ARLD and CARD groups. All of the patients rated their satisfaction with dentures, including general satisfaction and satisfaction with chewing ability, speaking, cleaning, stability, retention, comfort, and esthetics. These satisfaction ratings were measured by a 100-mm visual analog scale. Perceived chewing ability of different foods, divided into five grades, was measured using a questionnaire. The mastication index (MI) was calculated for each grade. General satisfaction, satisfaction with chewing, and satisfaction with speaking were significantly higher in the ARLD than in the CARD group (P = .049, .025, and .049, respectively). The chewing satisfaction with maxillary dentures in the ARLD group was significantly higher than that of the CARD group (P = .02). No significant difference existed between the MI of the ARLD (69.2 ± 17.0) and CARD groups (66.7 ± 18.7). Within its limitations, this study showed that the ARL improves a complete denture wearer's satisfaction ratings.

  9. Comparative evaluation of dental resin composites based on micron- and submicron-sized monomodal glass filler particles.

    Science.gov (United States)

    Valente, Lisia L; Peralta, Sonia L; Ogliari, Fabrício A; Cavalcante, Larissa M; Moraes, Rafael R

    2013-11-01

    A model resin composite containing a novel monomodal inorganic filler system based on submicron-sized Ba-Si-Al glass particles (NanoFine NF180; Schott) was formulated and compared with an experimental composite containing micron-sized particles (UltraFine UF1.0; Schott). The filler particles were characterized using X-ray microanalysis and granulometry, while the composites were characterized in terms of filler-resin morphology, radiopacity, degree of CC conversion, hardness, flexural strength/modulus, work-of-fracture, surface roughness and gloss (before and after simulated toothbrushing abrasion), and bulk compressive creep. The composites were formulated from the same photoactivated dimethacrylate co-monomer, incorporating mass fractions of 75% micron- and 78% submicron-sized particles. Quantitative data were analyzed at a significance level of pcomposites were similar in radiopacity, flexural strength, work-of-fracture, and creep. The submicron composite was harder but had lower flexural modulus and CC conversion. No significant differences in roughness were observed before brushing, although the submicron composite had higher gloss. Brushing increased roughness and decreased gloss on both materials, but the submicron composite retained higher gloss after brushing. The monomodal submicron glass filler system demonstrated potential for use in restorative dental composites, particularly due to improved esthetic properties. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Chemical characterization and bioactivity of epoxy resin and Portland cement-based sealers with niobium and zirconium oxide radiopacifiers.

    Science.gov (United States)

    Viapiana, Raqueli; Guerreiro-Tanomaru, Juliane Maria; Hungaro-Duarte, Marco Antonio; Tanomaru-Filho, Mário; Camilleri, Josette

    2014-09-01

    The purpose of this study was to characterize and to evaluate the bioactivity potential of experimental root canal sealers (ES) based on Portland cement, epoxy resin with nano- and micro-particles of niobium or zirconium oxide used as radiopacifiers in comparison to AH Plus and MTA Fillapex. Specimens of the sealers (10 mm in diameter×1 mm thick) were prepared and the radiopacity was evaluated according to ISO 6876 (2012) specifications. Characterization of the sealers was performed under the scanning electron microscope (SEM) immediately after setting and after immersion for 28 days in Hank's balanced salt solution (HBSS). In addition X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were also performed. The pH and calcium ion release were measured after 1, 7, 14, 21 and 28 days after completion of seating using a digital pH meter and an atomic absorption spectrophotometer, respectively. The experimental sealers exhibited an average radiopacity of 2.5 mm thickness of aluminum, which was similar to MTA Fillapex (P>0.05) and inferior to AH Plus (Pepoxy resin and radiopacifier exhibited a degree of bioactivity although no evidence of cement hydration was demonstrated on material characterization. The radiopacifier particle size had limited effect on the sealer microstructure and chemical properties. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. Method for estimating the stress field from seismic moment tensor data based on the flow rule in plasticity theory

    Science.gov (United States)

    Matsumoto, S.

    2016-09-01

    The stress field is a key factor controlling earthquake occurrence and crustal evolution. In this study, we propose an approach for determining the stress field in a region using seismic moment tensors, based on the classical equation in plasticity theory. Seismic activity is a phenomenon that relaxes crustal stress and creates plastic strain in a medium because of faulting, which suggests that the medium could behave as a plastic body. Using the constitutive relation in plastic theory, the increment of the plastic strain tensor is proportional to the deviatoric stress tensor. Simple mathematical manipulation enables the development of an inversion method for estimating the stress field in a region. The method is tested on shallow earthquakes occurring on Kyushu Island, Japan.

  12. Effect of Beverages on the Hardness and Tensile Bond Strength of Temporary Acrylic Soft Liners to Acrylic Resin Denture Base

    Directory of Open Access Journals (Sweden)

    Safari A.

    2013-12-01

    Full Text Available Statement of Problem: Two potential problems commonly identified with a denture base incorporating a resilient liner are failure of the bond between acrylic resin and soft liner material, and loss of resiliency of the soft liner over time. Since patients may drink different beverages, it is important to evaluate their effects on physical properties of soft lining materials.Purpose: The objective of this in vitro study was to evaluate the effect of different beverages on the hardness of two temporary acrylic-based soft lining materials and their bond strength to the denture base resin.Materials and Method: For the hardness test; a total of 80 rectangular specimens (40mm×10mm×3mm were fabricated from a heat-polymerized polymethylmethacrylate. Two commercially auto-polymerized acrylic resin-based resilient liners; Coe-Soft and Visco-gel were prepared according to the manufacturers’ instructions and applied on the specimens. For the tensile test, 160 cylindrical specimens (30mm×10mm were prepared. The liners were added between specimens with a thickness of 3 mm. The specimens of both soft liners were divided into 4 groups (n=10 and immersed in distilled water as the control group, Coca-Cola, 8% and 50% ethanol. All groups were stored in separate containers at 37oC for 12 days. All beverages were changed daily. The hardness was determined using a Shore A durometer and tensile bond strength was determined in a ZwickRoell testing machine at a cross-head speed of 5mm/min. The results were analyzed using two-way ANOVA.Results: There was no significant interaction between the soft liners and the drinks for both hardness (p= 0.748 and bond strength (p= 0.902. There were statistically signifi-cant differences between all drinks for both hardness (p< 0.001 and bond strength (p< 0.05.Conclusion: Within the limitations of this study, it seems that drinking Coca-Cola and alcoholic beverages would not be potentially causing any problems for the temporary

  13. Effect of Plasticizer Type and Concentration on Tensile, Thermal and Barrier Properties of Biodegradable Films Based on Sugar Palm (Arenga pinnata Starch

    Directory of Open Access Journals (Sweden)

    Muhammed L. Sanyang

    2015-06-01

    Full Text Available The use of starch based films as a potential alternative choice to petroleum derived plastics is imperative for environmental waste management. This study presents a new biopolymer (sugar palm starch for the preparation of biodegradable packaging films using a solution casting technique. The effect of different plasticizer types (glycerol (G, sorbitol (S and glycerol-sorbitol (GS combination with varying concentrations (0, 15, 30 and 45, w/w% on the tensile, thermal and barrier properties of sugar palm starch (SPS films was evaluated. Regardless of plasticizer types, the tensile strength of plasticized SPS films decreased, whereas their elongation at break (E% increased as the plasticizer concentrations were raised. However, the E% for G and GS-plasticized films significantly decreased at a higher plasticizer concentration (45% w/w due to the anti-plasticization effect of plasticizers. Change in plasticizer concentration showed an insignificant effect on the thermal properties of S-plasticized films. The glass transition temperature of SPS films slightly decreased as the plasticizer concentration increased from 15% to 45%. The plasticized films exhibited increased water vapor permeability values from 4.855 × 10−10 to 8.70 × 10−10 g·m−1·s−1·Pa−1, irrespective of plasticizer types. Overall, the current study manifested that plasticized sugar palm starch can be regarded as a promising biopolymer for biodegradable films.

  14. A Series of Zr-Based Bulk Metallic Glasses with Room Temperature Plasticity

    Directory of Open Access Journals (Sweden)

    Anhui Cai

    2016-05-01

    Full Text Available A group of plastic Zr-Al-Ni-Cu bulk metallic glasses (BMGs with low Zr content was developed and their thermal and mechanical properties were investigated. The results show that these Zr-based BMGs have a single crystallization event for all heating rates in the studied temperature region. The glass transition temperature Tg decreases with increasing Zr content for all heating rates. There are two melting procedures for the BMGs whose Zr content is less than 52 at %, while three melting procedures for the other Zr-based BMGs. The second melting procedure is split into two melting procedures for Zr52.5Al12.2Ni12.6Cu22.7 and Zr53Al11.6Ni11.7Cu23.7 BMGs, while the first melting procedure is split into two melting procedures for the other BMGs. The activation energy decreases with increasing sensitivity index β for the studied Zr-based BMGs. The plastic strain εp is in the region of 0.2%–19.1% for these Zr-based BMGs. Both yield strength σy and fracture strength σf are smallest for Zr55Al8.9Ni7.3Cu28.8 BMG whose εp is largest among all studied Zr-based BMGs and reaches up to 19.1%. In addition, the mechanism for the large difference of the plasticity among the studied Zr-based BMGs is also discussed.

  15. In vitro comparison of antibacterial properties of bioceramic-based sealer, resin-based sealer and zinc oxide eugenol based sealer and two mineral trioxide aggregates

    Science.gov (United States)

    Singh, Gurpreet; Gupta, Iti; Elshamy, Faheim M. M.; Boreak, Nezar; Homeida, Husham Elraih

    2016-01-01

    Objective: Our goal of the study was to evaluate the antibacterial properties of endodontic sealers against the E. faecalis. Materials and Methods: Six millimeters wells were made for each material in all the preinoculated petri plates. Then, the petri plates were incubated for 24 h. The zones of inhibition appeared were measured, and the measurements were put to statistical analysis. Results: EndoSequence BC Sealer, MM-mineral trioxide aggregate (MTA), and ProRoot MTA showed maximum means of diameter of zones of inhibition, whereas MM-seal and Endoseal did not show any zones of inhibition. Conclusion: EndoSequence BC Sealer was found to be a better endodontic sealer as compared to resin-based and zinc oxide-eugenol-based sealer. PMID:27403055

  16. Predicting the Viscosity of Low VOC Vinyl Ester and Fatty Acid-Based Resins

    Science.gov (United States)

    2005-12-01

    gelation and reducing diffusion limitations (3). These properties provided by the reactive diluent also allow for the use of low cost composite...have been used as plasticizers and toughening agents (12). In fact, the largest non- food use of triglycerides is the use of epoxidized soybean and...the high molecular weight Epon 100XF. Addition of styrene during the methacrylation reaction normally causes gelation . Therefore, hydroquinone

  17. A Coupled Creep Plasticity Model for Residual Stress Relaxation of a Shot Peened Nickel-Base Superalloy (Postprint)

    Science.gov (United States)

    2008-09-01

    McLean, M. “Tension- Compression creep asymmetry in a turbine disc superalloy : roles of internal stress and thermal ageing,” Acta Materialia, 52, 2004...AFRL-RX-WP-TP-2009-4156 A COUPLED CREEP PLASTICITY MODEL FOR RESIDUAL STRESS RELAXATION OF A SHOT PEENED NICKEL-BASE SUPERALLOY (POSTPRINT...SUBTITLE A COUPLED CREEP PLASTICITY MODEL FOR RESIDUAL STRESS RELAXATION OF A SHOT PEENED NICKEL-BASE SUPERALLOY (POSTPRINT) 5a. CONTRACT NUMBER

  18. Study on the Plastic Bottle Recycling Based on Evolution Tree for Technical System

    OpenAIRE

    Yuedong Xiong; Huadong Huang

    2014-01-01

    Technical system theory of evolution tree was used in the study of the plastic bottle recycling, and established the evolutionary line of plastic bottle recycling on the basis of the analysis of plastic bottle recycling recovery evolution tree, and summed up a new smart plastic bottle recycling program. The new recovery recovers and smashes the plastic bottles through technical system, and communicates with users through automatically reward system and rewards the latter. The experimental pro...

  19. ACCELERATED THERMAL AGEING OF ACRYLIC COPOLYMERS, CYCLOHEXANONE-BASED AND UREA-ALDEHYDE RESINS USED IN PAINTINGS CONSERVATION

    OpenAIRE

    Farmakalidis, Helen Velonika; Douvas, Antonios M.; Karatasios, Ioannis; Sotiropoulou, Sophia; Boyatzis, Stamatis; Argitis, Panagiotis; Chryssoulakis, Yannis; Kilikoglou, Vassilis

    2016-01-01

    The monitoring of performance characteristics of resins was always an issue for the conservation community, since the stability of the art objects depends on the service life of conservation materials used. Among the resins commonly applied in the field of paintings conservation, four of the most popular ones, Paraloid B72, Primal AC33 (acrylic polymers), Ketone Resin N (cyclohexanone) and Laropal A81 (ureaaldehyde) were selected to be comparatively studied under accelerated ageing conditions...

  20. 3D animation of facial plastic surgery based on computer graphics

    Science.gov (United States)

    Zhang, Zonghua; Zhao, Yan

    2013-12-01

    More and more people, especial women, are getting desired to be more beautiful than ever. To some extent, it becomes true because the plastic surgery of face was capable in the early 20th and even earlier as doctors just dealing with war injures of face. However, the effect of post-operation is not always satisfying since no animation could be seen by the patients beforehand. In this paper, by combining plastic surgery of face and computer graphics, a novel method of simulated appearance of post-operation will be given to demonstrate the modified face from different viewpoints. The 3D human face data are obtained by using 3D fringe pattern imaging systems and CT imaging systems and then converted into STL (STereo Lithography) file format. STL file is made up of small 3D triangular primitives. The triangular mesh can be reconstructed by using hash function. Top triangular meshes in depth out of numbers of triangles must be picked up by ray-casting technique. Mesh deformation is based on the front triangular mesh in the process of simulation, which deforms interest area instead of control points. Experiments on face model show that the proposed 3D animation facial plastic surgery can effectively demonstrate the simulated appearance of post-operation.