WorldWideScience

Sample records for biodegradable polymer compositions

  1. Polyethylene Modification as Biodegradable Composite Polymer for Packing Materials

    International Nuclear Information System (INIS)

    Deswita; Aloma KK; Sudirman; Indra Gunawan

    2008-01-01

    The synthesis of biodegradable polymer using blending method has been done. The aim of this research is to synthesize kinds of biodegradable composite polymer materials which could be applied in many kinds of requirements such as environmental friendly packaging and degradable. In this paper, the synthetic of biodegradable composite polymer was performed by adding biodegradable filler to the synthetic polymer using blending method. In this experiment Low Linier Density Polyethylene (LLDPE), High Density Polyethylene (HDPE) and filler of tapioca were used. The variation of tapioca meal composition were 50 in weight percent, 55 in weight percent, 60 in weight percent, 65 in weight percent, 70 in weight percent and 75 in weight percent. The characterization was done by means of thermal test, microstructure test, biodegradable and mechanical test. The result showed that the mechanical properties of the materials decreased with increasing composition of tapioca but did not show significant change to the polymer composite materials. For burrying time inside the ground of 8 weeks, all specimens based on polymer LLDPE for all composition of tapioca filler were degraded inside the ground, where as for all specimens based on polymer HDPE with all composition of tapioca filler did not show any degradation. (author)

  2. Biodegradable Polymers

    OpenAIRE

    Vroman, Isabelle; Tighzert, Lan

    2009-01-01

    Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. ...

  3. Effect of Material Parameters on Mechanical Properties of Biodegradable Polymers/Nanofibrillated Cellulose (NFC) Nano Composites

    Science.gov (United States)

    Yottha Srithep; Ronald Sabo; Craig Clemons; Lih-Sheng Turng; Srikanth Pilla; Jun Peng

    2012-01-01

    Using natural cellulosic fibers as fillers for biodegradable polymers can result in fully biodegradable composites. Biodegradable composites were prepared using nanofibrillated cellulose (NFC) as the reinforcement and poly (3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV) as the polymer matrix. The objective of this study was to determine how various additives (i.e.,...

  4. Biodegradation of New Polymer Foundry Binders for the Example of the Composition Polyacrylic Acid/Starch

    Directory of Open Access Journals (Sweden)

    Beata Grabowska

    2011-04-01

    Full Text Available The investigations on the biodegradation process pathway of the new polymer binders for the example of water soluble compositionpolyacrylic acid/starch are presented in the hereby paper. Degradation was carried out in water environment and in a soil. Thedetermination of the total oxidation biodegradation in water environment was performed under laboratory conditions in accordance with the static water test system (Zahn-Wellens method, in which the mixture undergoing biodecomposition contained inorganic nutrient,activated sludge and the polymer composition, as the only carbon and energy source. The biodecomposition progress of the polymercomposition sample in water environment was estimated on the basis of the chemical oxygen demand (COD measurements and thedetermination the biodegradation degree, Rt, during the test. These investigations indicated that the composition polyacrylic acid/starchconstitutes the fully biodegradable material in water environment. The biodegradation degree Rt determined in the last 29th day of the test duration achieved 65%, which means that the investigated polymer composition can be considered to be fully biodegradable.During the 6 months biodegradation process of the cross-linked sample of the polymer composition in a garden soil several analysis ofsurface and structural changes, resulting from the sample decomposition, were performed. Those were: thermal analyses (TG-DSC,structural analyses (Raman spectroscopy and microscopic analyses (optical microscopy, AFM.

  5. Computational modeling of biodegradable starch based polymer composites

    Science.gov (United States)

    Joshi, Sachin Sudhakar

    2007-12-01

    Purpose. The goal of this study is to improve the favorable molecular interactions between starch and PPC by addition of grafting monomers MA and ROM as compatibilizers, which would advance the mechanical properties of starch/PPC composites. Methodology. DFT and semi-empirical methods based calculations were performed on three systems: (a) starch/PPC, (b) starch/PPC-MA, and (c) starch-ROM/PPC. Theoretical computations involved the determination of optimal geometries, binding-energies and vibrational frequencies of the blended polymers. Findings. Calculations performed on five starch/PPC composites revealed hydrogen bond formation as the driving force behind stable composite formation, also confirmed by the negative relative energies of the composites indicating the existence of binding forces between the constituent co-polymers. The interaction between starch and PPC is also confirmed by the computed decrease in stretching CO and OH group frequencies participating in hydrogen bond formation, which agree qualitatively with the experimental values. A three-step mechanism of grafting MA on PPC was proposed to improve the compatibility of PPC with starch. Nine types of 'blends' produced by covalent bond formation between starch and MA-grafted PPC were found to be energetically stable, with blends involving MA grafted at the 'B' and 'C' positions of PPC indicating a binding-energy increase of 6.8 and 6.2 kcal/mol, respectively, as compared to the non-grafted starch/PPC composites. A similar increase in binding-energies was also observed for three types of 'composites' formed by hydrogen bond formation between starch and MA-grafted PPC. Next, grafting of ROM on starch and subsequent blend formation with PPC was studied. All four types of blends formed by the reaction of ROM-grafted starch with PPC were found to be more energetically stable as compared to the starch/PPC composite and starch/PPC-MA composites and blends. A blend of PPC and ROM grafted at the '

  6. Morphology and transport in biodegradable polymer compositions based on poly(3-hydroxybutyrate) and polyamide 54C

    Energy Technology Data Exchange (ETDEWEB)

    Zhul' kina, A. L.; Ivantsova, E. L.; Filatova, A. G.; Kosenko, R. Yu.; Gumargalieva, K. Z.; Iordanskii, A. L., E-mail: iordan@chph.ras.ru [Russian Academy of Sciences, Semenov Institute of Chemical Physics (Russian Federation)

    2009-05-15

    Complex investigation of the equilibrium sorption of water, diffusive transport of antiseptic, and morphology of mixed compositions based on polyoxybutirate and polyamide resin 54C has been performed to develop and analyze new biodegradable polymer compositions for controlled release of medicinal substances. Samples of mixtures were prepared by two methods: pressing under pressure and solvent evaporation from a polymer solution. The samples were compared and their morphology was analyzed by scanning electron microscopy. It is shown that the component ratio in the obtained mixtures affects their morphological, transport, and sorption characteristics.

  7. Morphology and transport in biodegradable polymer compositions based on poly(3-hydroxybutyrate) and polyamide 54C

    International Nuclear Information System (INIS)

    Zhul'kina, A. L.; Ivantsova, E. L.; Filatova, A. G.; Kosenko, R. Yu.; Gumargalieva, K. Z.; Iordanskii, A. L.

    2009-01-01

    Complex investigation of the equilibrium sorption of water, diffusive transport of antiseptic, and morphology of mixed compositions based on polyoxybutirate and polyamide resin 54C has been performed to develop and analyze new biodegradable polymer compositions for controlled release of medicinal substances. Samples of mixtures were prepared by two methods: pressing under pressure and solvent evaporation from a polymer solution. The samples were compared and their morphology was analyzed by scanning electron microscopy. It is shown that the component ratio in the obtained mixtures affects their morphological, transport, and sorption characteristics.

  8. Tuning particle biodegradation through polymer-peptide blend composition.

    Science.gov (United States)

    Gunawan, Sylvia T; Kempe, Kristian; Such, Georgina K; Cui, Jiwei; Liang, Kang; Richardson, Joseph J; Johnston, Angus P R; Caruso, Frank

    2014-12-08

    We report the preparation of polymer-peptide blend replica particles via the mesoporous silica (MS) templated assembly of poly(ethylene glycol)-block-poly(2-diisopropylaminoethyl methacrylate-co-2-(2-(2-(prop-2-ynyloxy)ethoxy)ethoxy)ethyl methacrylate) (PEG45-b-P(DPA55-co-PgTEGMA4)) and poly(l-histidine) (PHis). PEG45-b-P(DPA55-co-PgTEGMA4) was synthesized by atom transfer radical polymerization (ATRP), and was coinfiltrated with PHis into poly(methacrylic acid) (PMA)-coated MS particles assembled from different peptide-to-polymer ratios (1:1, 1:5, 1:10, or 1:15). Subsequent removal of the sacrificial templates and PMA resulted in monodisperse, colloidally stable, noncovalently cross-linked polymer-peptide blend replica particles that were stabilized by a combination of hydrophobic interactions between the PDPA and the PHis, hydrogen bonding between the PEG and PHis backbone, and π-π stacking of the imidazole rings of PHis side chains at physiological pH (pH ∼ 7.4). The synergistic charge-switchable properties of PDPA and PHis, and the enzymatic degradability of PHis, make these particles responsive to pH and enzymes. In vitro studies, in simulated endosomal conditions and inside cells, demonstrated that particle degradation kinetics could be engineered (from 2 to 8 h inside dendritic cells) based on simple adjustment of the peptide-to-polymer ratio used.

  9. Composite implants coated with biodegradable polymers prevent stimulating tumor progression

    Energy Technology Data Exchange (ETDEWEB)

    Litviakov, N. V., E-mail: nvlitv72@yandex.ru; Tsyganov, M. M., E-mail: TsyganovMM@yandex.ru; Cherdyntseva, N. V., E-mail: nvch@oncology.tomsk.ru [Tomsk Cancer Research Institute, Tomsk, 634050 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Tverdokhlebov, S. I., E-mail: tverd@tpu.ru; Bolbasov, E. N., E-mail: ebolbasov@gmail.com [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Perelmuter, V. M., E-mail: pvm@ngs.ru; Kulbakin, D. E., E-mail: kulbakin2012@gmail.com [Tomsk Cancer Research Institute, Tomsk, 634050 (Russian Federation); Zheravin, A. A., E-mail: zheravin2010@yandex.ru [Tomsk Cancer Research Institute, Tomsk, 634050 (Russian Federation); Academician E.N. Meshalkin Novosibirsk State Research Institute of Circulation Pathology, Novosibirsk (Russian Federation); Svetlichnyi, V. A., E-mail: v-svetlichnyi@bk.ru [National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2016-08-02

    In this experiment we studied oncologic safety of model implants created using the solution blow spinning method with the use of the PURASORB PL-38 polylactic acid polymer and organic mineral filler which was obtained via laser ablation of a solid target made of dibasic calcium phosphate dihydrate. For this purpose the implant was introduced into the area of Wistar rats’ iliums, and on day 17 after the surgery the Walker sarcoma was transplanted into the area of the implant. We evaluated the implant’s influence on the primary tumor growth, hematogenous and lymphogenous metastasis of the Walker sarcoma. In comparison with sham operated animals the implant group demonstrated significant inhibition of hematogenous metastasis on day 34 after the surgery. The metastasis inhibition index (MII) equaled 94% and the metastases growth inhibition index (MGII) equaled 83%. The metastasis frequency of the Walker sarcoma in para aortic lymph nodes in the implant group was not statistically different from the control frequency; there was also no influence of the implant on the primary tumor growth noted. In case of the Walker sarcoma transplantation into the calf and the palmar pad of the ipsilateral limb to the one with the implant in the ilium, we could not note any attraction of tumor cells to the implant area, i.e. stimulation of the Walker sarcoma relapse by the implant. Thus, the research concluded that the studied implant meets the requirements of oncologic safety.

  10. Mechanical, Thermomechanical and Reprocessing Behavior of Green Composites from Biodegradable Polymer and Wood Flour.

    Science.gov (United States)

    Morreale, Marco; Liga, Antonio; Mistretta, Maria Chiara; Ascione, Laura; Mantia, Francesco Paolo La

    2015-11-11

    The rising concerns in terms of environmental protection and the search for more versatile polymer-based materials have led to an increasing interest in the use of polymer composites filled with natural organic fillers (biodegradable and/or coming from renewable resources) as a replacement for traditional mineral inorganic fillers. At the same time, the recycling of polymers is still of fundamental importance in order to optimize the utilization of available resources, reducing the environmental impact related to the life cycle of polymer-based items. Green composites from biopolymer matrix and wood flour were prepared and the investigation focused on several issues, such as the effect of reprocessing on the matrix properties, wood flour loading effects on virgin and reprocessed biopolymer, and wood flour effects on material reprocessability. Tensile, Dynamic-mechanical thermal (DMTA), differential scanning calorimetry (DSC) and creep tests were performed, pointing out that wood flour leads to an improvement of rigidity and creep resistance in comparison to the pristine polymer, without compromising other properties such as the tensile strength. The biopolymer also showed a good resistance to multiple reprocessing; the latter even allowed for improving some properties of the obtained green composites.

  11. Mechanical, Thermomechanical and Reprocessing Behavior of Green Composites from Biodegradable Polymer and Wood Flour

    Directory of Open Access Journals (Sweden)

    Marco Morreale

    2015-11-01

    Full Text Available The rising concerns in terms of environmental protection and the search for more versatile polymer-based materials have led to an increasing interest in the use of polymer composites filled with natural organic fillers (biodegradable and/or coming from renewable resources as a replacement for traditional mineral inorganic fillers. At the same time, the recycling of polymers is still of fundamental importance in order to optimize the utilization of available resources, reducing the environmental impact related to the life cycle of polymer-based items. Green composites from biopolymer matrix and wood flour were prepared and the investigation focused on several issues, such as the effect of reprocessing on the matrix properties, wood flour loading effects on virgin and reprocessed biopolymer, and wood flour effects on material reprocessability. Tensile, Dynamic-mechanical thermal (DMTA, differential scanning calorimetry (DSC and creep tests were performed, pointing out that wood flour leads to an improvement of rigidity and creep resistance in comparison to the pristine polymer, without compromising other properties such as the tensile strength. The biopolymer also showed a good resistance to multiple reprocessing; the latter even allowed for improving some properties of the obtained green composites.

  12. Effect of sterilization dose on electron beam irradiated biodegradable polymers and coconut fiber based composites

    International Nuclear Information System (INIS)

    Kodama, Yasko; Machado, Luci D.B.; Oishi, Akihiro; Nakayama, Kazuo; Nagasawa, Naotsugu; Tamada, Masao

    2009-01-01

    In Brazil, annual production of coconut fruit is 1.5 billion in a cultivated area of 2.7 million ha. Coconut fiber applications as reinforcement for polymer composites, besides reducing the coconut waste, would reduce cost of the composite. On the other hand, biodegradable polymers have been receiving much attention due to the plastic waste problem. Poly(e-caprolactone), PCL, and poly(lactic acid), PLA, besides being biodegradable aliphatic polyesters, are biocompatible polymers. Considering the biomedical application of PLA and PCL, their products must be sterilized for use, and ionizing radiation has been widely used for medical devices sterilization. It is important to study the effect of ionizing radiation on the blends and composites due to the fact that they are based on biocompatible polymers. Is this research, hot pressed samples based on PLA:PCL (80:20, ratio of weight:weight) blend and the composites containing chemically treated or untreated coconut fiber (5, 10%) were irradiated by electron beams and gamma radiation from Co-60 source at doses in the range up to 200 kGy. Thermal mechanical analysis (TMA) and gel fraction measurements were performed in irradiated samples. From TMA curves it can be observed that thermal stability of samples with untreated coconut fiber slightly decreased with increasing fiber content. On the other hand, deformation increased with increasing fiber content. Acetylated coconut fibers slightly decreased thermal stability of samples. It seems that no interaction occurs between the natural fibers and the polymeric matrix due to irradiation. PLLA undergoes to main chain scission under ionizing irradiation according to thermal stability results and also because no gel fraction was observed. In contrast, PCL cross-linking is induced by ionizing radiation that increases thermal stability and decreases deformation. (author)

  13. Effect of sterilization dose on electron beam irradiated biodegradable polymers and coconut fiber based composites

    Energy Technology Data Exchange (ETDEWEB)

    Kodama, Yasko; Machado, Luci D.B., E-mail: ykodama@ipen.b, E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Oishi, Akihiro; Nakayama, Kazuo, E-mail: a.oishi@aist.go.j, E-mail: kazuo-nakayama@jcom.home.ne.j [National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki-ken (Japan). Research Institute for Sustainable Chemical Innovation; Nagasawa, Naotsugu; Tamada, Masao, E-mail: nagasawa.naotsugu@jaea.go.j [Japan Atomic Energy Agency (JAEA), Gunma-ken (Japan). Quantum Beam Science Directorate

    2009-07-01

    In Brazil, annual production of coconut fruit is 1.5 billion in a cultivated area of 2.7 million ha. Coconut fiber applications as reinforcement for polymer composites, besides reducing the coconut waste, would reduce cost of the composite. On the other hand, biodegradable polymers have been receiving much attention due to the plastic waste problem. Poly(e-caprolactone), PCL, and poly(lactic acid), PLA, besides being biodegradable aliphatic polyesters, are biocompatible polymers. Considering the biomedical application of PLA and PCL, their products must be sterilized for use, and ionizing radiation has been widely used for medical devices sterilization. It is important to study the effect of ionizing radiation on the blends and composites due to the fact that they are based on biocompatible polymers. Is this research, hot pressed samples based on PLA:PCL (80:20, ratio of weight:weight) blend and the composites containing chemically treated or untreated coconut fiber (5, 10%) were irradiated by electron beams and gamma radiation from Co-60 source at doses in the range up to 200 kGy. Thermal mechanical analysis (TMA) and gel fraction measurements were performed in irradiated samples. From TMA curves it can be observed that thermal stability of samples with untreated coconut fiber slightly decreased with increasing fiber content. On the other hand, deformation increased with increasing fiber content. Acetylated coconut fibers slightly decreased thermal stability of samples. It seems that no interaction occurs between the natural fibers and the polymeric matrix due to irradiation. PLLA undergoes to main chain scission under ionizing irradiation according to thermal stability results and also because no gel fraction was observed. In contrast, PCL cross-linking is induced by ionizing radiation that increases thermal stability and decreases deformation. (author)

  14. Effect of degumming time on silkworm silk fibre for biodegradable polymer composites

    Science.gov (United States)

    Ho, Mei-po; Wang, Hao; Lau, Kin-tak

    2012-02-01

    Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm fibre), animal-based fibre is a kind of sustainable natural materials for making novel composites. Silkworm silk fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing silk fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the silk fibre's properties, making the silk fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah silk are affected by the degumming time due to the change of the fibre structure and fibroin alignment.

  15. Radiation processing of indigenous natural polymers. Properties of radiation modified blends from sago-starch for biodegradable composite

    International Nuclear Information System (INIS)

    Ghazali, Z.; Dahlan, K.Z.; Wongsuban, B.; Idris, S.; Muhammad, K.

    2001-01-01

    Research and development on biodegradable polymer blends and composites have gained wider interest to offer alternative eco-friendly products. Natural polysaccharide such as sago-starch offers the most promising raw material for the production of biodegradable composites. The potential of sago, which is so abundant in Malaysia, to produce blends for subsequent applications in composite material, was evaluated and explored. Blends with various formulations of sago starch and polyvinyl alcohol (PVA), and polyvinyl pyrrolidone (PVP) polymers were prepared and subjected to radiation modification using electron beam irradiation. The effect of irradiation on the sago and its blends was evaluated and their properties were characterized. The potential of producing composite from sago blends was explored. Foams from these blends were produced using microwave oven while films were produced through casting method. The properties such as mechanical, water absorption, expansion ratio, and biodegradability were characterized and reported in this paper. (author)

  16. Core–shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Oka, Chiemi; Ushimaru, Kazunori [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Horiishi, Nanao [Bengala Techno Laboratory, 9-5-1006, 1-1 Kodai, Miyamae-ku, Kawasaki 216-0007 (Japan); Tsuge, Takeharu [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Kitamoto, Yoshitaka, E-mail: kitamoto.y.aa@m.titech.ac.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)

    2015-05-01

    Core–shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core–shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body. - Highlights: • Core−shell composites with biodegradability and magnetism are prepared. • O/W emulsion stabilized by iron oxide nanoparticles is utilized for the preparation. • The nanoparticle's dispersibility is crucial for controlling the composite structure. • Composites loading a model drug are also prepared. • The model drug is released with decomposition of the composites.

  17. Core–shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

    International Nuclear Information System (INIS)

    Oka, Chiemi; Ushimaru, Kazunori; Horiishi, Nanao; Tsuge, Takeharu; Kitamoto, Yoshitaka

    2015-01-01

    Core–shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core–shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body. - Highlights: • Core−shell composites with biodegradability and magnetism are prepared. • O/W emulsion stabilized by iron oxide nanoparticles is utilized for the preparation. • The nanoparticle's dispersibility is crucial for controlling the composite structure. • Composites loading a model drug are also prepared. • The model drug is released with decomposition of the composites

  18. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  19. Nanocomposites with biodegradable polymers synthesis properties and future perspectives

    CERN Document Server

    2011-01-01

    Polymers are used in practically every facet of daily life. Most polymers come from fossil fuels and are not biodegradable, causing long-term environmental hazards. Biodegradable polymers provide an alternative class of materials. Composites of such polymers have high potential within a wide spectrum of applications.

  20. Casein and soybean protein-based thermoplastics and composites as alternative biodegradable polymers for biomedical applications

    NARCIS (Netherlands)

    Vaz, C.M.; Fossen, M.; Tuil, van R.F.; Graaf, de L.A.; Reis, R.L.; Cunha, A.M.

    2003-01-01

    This work reports on the development and characterization of novel meltable polymers and composites based on casein and soybean proteins. The effects of inert (Al2O3) and bioactive (tricalcium phosphate) ceramic reinforcements over the mechanical performance, water absorption, and bioactivity

  1. Biodegradability and mechanical properties of PP/HMSPP and natural polymers bio-composites in function of gamma-irradiation

    International Nuclear Information System (INIS)

    Cardoso, Elisabeth C.L.; Scagliusi, Sandra R.; Lima, Luis F.C.P.; Bueno, Nelson R.; Parra, Duclerc F.; Lugao, Ademar B.

    2013-01-01

    PP, expressed as C n H 2n , is one of the most widely used linear hydrocarbon polymers; its versatility arises from the fact that it is made from cheap petrochemical feed stocks through efficient catalytic polymerization process and easy processing to various products. Thus, enormous production and utilization of polymers, in general, lead to their accumulation in the environment, since they are not easily degraded by microorganisms, presenting a serious source of pollution affecting both flora and fauna. These polymers are very bio-resistant due to the involvement of only carbon atoms in main chain with no hydrolyzable functional group. Non-degradable plastics accumulate in the environment at a rate of 25 million tons per year. In recent years, as a result of growing environmental awareness, natural polymers have been increasingly used as reinforcing fillers in thermoplastic composite materials. Sugarcane bagasse was used as reinforcing filler, considering that Brazil is the largest world producer of this crop, with a 101 Mt main agro-industrial residue of sugarcane processing from 340 Mt of sugarcane. Bio-composites were compounded on a twin-screw extruder and samples collected directly from the die. This study aims to investigate mechanical properties of PP/HMSPP-sugarcane bagasse 10, 15, 30 and 50% blends gamma-irradiated at 50, 100, 150 and 200 kGy doses. Degradation essays will comprise DSC and TGA tests and biodegradability behavior will be indicated by Laboratory Soil Burial Test. The main objective of this work is to support the application of these composites as environmentally friendly materials, without prejudicing mechanicals properties, in spite of applied gamma-irradiation. (author)

  2. Biodegradability and mechanical properties of PP/HMSPP and natural polymers bio-composites in function of gamma-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Elisabeth C.L.; Scagliusi, Sandra R.; Lima, Luis F.C.P.; Bueno, Nelson R.; Parra, Duclerc F.; Lugao, Ademar B., E-mail: eclcardo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    PP, expressed as C{sub n}H{sub 2n}, is one of the most widely used linear hydrocarbon polymers; its versatility arises from the fact that it is made from cheap petrochemical feed stocks through efficient catalytic polymerization process and easy processing to various products. Thus, enormous production and utilization of polymers, in general, lead to their accumulation in the environment, since they are not easily degraded by microorganisms, presenting a serious source of pollution affecting both flora and fauna. These polymers are very bio-resistant due to the involvement of only carbon atoms in main chain with no hydrolyzable functional group. Non-degradable plastics accumulate in the environment at a rate of 25 million tons per year. In recent years, as a result of growing environmental awareness, natural polymers have been increasingly used as reinforcing fillers in thermoplastic composite materials. Sugarcane bagasse was used as reinforcing filler, considering that Brazil is the largest world producer of this crop, with a 101 Mt main agro-industrial residue of sugarcane processing from 340 Mt of sugarcane. Bio-composites were compounded on a twin-screw extruder and samples collected directly from the die. This study aims to investigate mechanical properties of PP/HMSPP-sugarcane bagasse 10, 15, 30 and 50% blends gamma-irradiated at 50, 100, 150 and 200 kGy doses. Degradation essays will comprise DSC and TGA tests and biodegradability behavior will be indicated by Laboratory Soil Burial Test. The main objective of this work is to support the application of these composites as environmentally friendly materials, without prejudicing mechanicals properties, in spite of applied gamma-irradiation. (author)

  3. Biobased and biodegradable polymer nanocomposites

    Science.gov (United States)

    Qiu, Kaiyan

    In this dissertation, various noncrosslinked and crosslinked biobased and biodegradable polymer nanocomposites were fabricated and characterized. The properties of these polymer nanocomposites, and their relating mechanisms and corresponding applications were studied and discussed in depth. Chapter 1 introduces the research background and objectives of the current research. Chapter 2 presents the development of a novel low cost carbon source for bacterial cellulose (BC) production and fabrication and characterization of biobased polymer nanocomposites using produced BC and soy protein based resins. The carbon source, soy flour extract (SFE), was obtained from defatted soy flour (SF) and BC yield achieved using SFE medium was high. The results of this study showed that SFE consists of five sugars and Acetobacter xylinum metabolized sugars in a specific order. Chapter 3 discusses the fabrication and characterization of biodegradable polymer nanocomposites using BC and polyvinyl alcohol (PVA). These polymer nanocomposites had excellent tensile and thermal properties. Crosslinking of PVA using glutaraldehyde (GA) not only increased the mechanical and thermal properties but the water-resistance. Chapter 4 describes the development and characterization of microfibrillated cellulose (MFC) based biodegradable polymer nanocomposites by blending MFC suspension with PVA. Chemical crosslinking of the polymer nanocomposites was carried out using glyoxal to increase the mechanical and thermal properties as well as to make the PVA partially water-insoluble. Chapter 5 reports the development and characterization of halloysite nanotube (HNT) reinforced biodegradable polymer nanocomposites utilizing HNT dispersion and PVA. Several separation techniques were used to obtain individualized HNT dispersion. The results indicated uniform dispersion of HNTs in both PVA and malonic acid (MA) crosslinked PVA resulted in excellent mechanical and thermal properties of the materials, especially

  4. Synthetic biodegradable functional polymers for tissue engineering: a brief review.

    Science.gov (United States)

    BaoLin, Guo; Ma, Peter X

    2014-04-01

    Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly (glycerol sebacate) are summarized in this article. New developments in conducting polymers, photoresponsive polymers, amino-acid-based polymers, enzymatically degradable polymers, and peptide-activated polymers are also discussed. In addition to chemical functionalization, the scaffold designs that mimic the nano and micro features of the extracellular matrix (ECM) are presented as well, and composite and nanocomposite scaffolds are also reviewed.

  5. Toward biodegradable nanogel star polymers via organocatalytic ROP.

    Science.gov (United States)

    Appel, Eric A; Lee, Victor Y; Nguyen, Timothy T; McNeil, Melanie; Nederberg, Frederik; Hedrick, James L; Swope, William C; Rice, Jullia E; Miller, Robert D; Sly, Joseph

    2012-06-21

    Organocatalytic ring opening polymerization (OROP) is used to effect the rapid, scalable, room temperature formation of size-controlled, highly uniform, polyvalent, nanogel star polymer nanoparticles of biodegradable composition.

  6. CLASSIFICATION OF BIODEGRADABLE POLYMERS

    Directory of Open Access Journals (Sweden)

    I. I. Karpunin

    2015-01-01

    Full Text Available The executed investigations have made it possible to ascertain that a morphological structure of starch granules mainly determine technological peculiarities of starch isolation from raw material, its modification and its later use. Morphological structure of starch granules primarily depends on type of plant starch-containing raw material which has been used for its isolation. Class of raw material exerts a strong impact on the shape and size of the granules. Linear “light” amylose chains and “heavy” amylopectin branch chains form a starch granule ultrastructure. X-ray research has proved that starch granules are characterized by presence of interlacing amorphous and crystalline regions. In this case polymer orientation using stretching of the obtained end product influences on its physical and mechanical  indices which are increasing due to polymer orientation. For the purpose of packaging orientation of polymer films can solve such important problems as significant improvement of operational properties, creation of  thermosetting film materials, improvement of qualitative indices of the recycled film.Results of the conducted research have proved the fact that it is necessary to make changes in technology in order to increase biological degradability of the recycled packaging made from polymers and improve physical and mechanical indices. In this regard film production technology presupposes usage of such substances as stark and others which are characterized by rather large presence of branch chains of molecules and interlacing amorphous and crystalline regions. Such approach makes it possible to obtain after-use package which is strong and quickly degradable by micro-organisms.

  7. A model for simultaneous crystallisation and biodegradation of biodegradable polymers.

    Science.gov (United States)

    Han, Xiaoxiao; Pan, Jingzhe

    2009-01-01

    This paper completes the model of biodegradation for biodegradable polymers that was previously developed by Wang et al. (Wang Y, Pan J, Han X, Sinka, Ding L. A phenomenological model for the degradation of biodegradable polymers. Biomaterials 2008;29:3393-401). Crystallisation during biodegradation was not considered in the previous work which is the topic of the current paper. For many commonly used biodegradable polymers, there is a strong interplay between crystallisation and hydrolysis reaction during biodegradation - the chain cleavage caused by the hydrolysis reaction provides an extra mobility for the polymer chains to crystallise and the resulting crystalline phase becomes more resistant to further hydrolysis reaction. This paper presents a complete theory to describe this interplay. The fundamental equations in the Avrami's theory for crystallisation are modified and coupled to the diffusion-reaction equations that were developed in our previous work. The mathematical equations are then applied to three biodegradable polymers for which long term degradation data are available in the literature. It is shown that the model can capture the behavior of the major biodegradable polymers very well.

  8. Engineered biosynthesis of biodegradable polymers.

    Science.gov (United States)

    Jambunathan, Pooja; Zhang, Kechun

    2016-08-01

    Advances in science and technology have resulted in the rapid development of biobased plastics and the major drivers for this expansion are rising environmental concerns of plastic pollution and the depletion of fossil-fuels. This paper presents a broad view on the recent developments of three promising biobased plastics, polylactic acid (PLA), polyhydroxyalkanoate (PHA) and polybutylene succinate (PBS), well known for their biodegradability. The article discusses the natural and recombinant host organisms used for fermentative production of monomers, alternative carbon feedstocks that have been used to lower production cost, different metabolic engineering strategies used to improve product titers, various fermentation technologies employed to increase productivities and finally, the different downstream processes used for recovery and purification of the monomers and polymers.

  9. Synthetic biodegradable functional polymers for tissue engineering: a brief review

    OpenAIRE

    BaoLin, GUO; MA, Peter X.

    2014-01-01

    Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly (glyce...

  10. Biodegradable polymers derived from amino acids.

    Science.gov (United States)

    Khan, Wahid; Muthupandian, Saravanan; Farah, Shady; Kumar, Neeraj; Domb, Abraham J

    2011-12-08

    In the past three decades, the use of polymeric materials has increased dramatically for biomedical applications. Many α-amino acids derived biodegradable polymers have also been intensely developed with the main goal to obtain bio-mimicking functional biomaterials. Polymers derived from α-amino acids may offer many advantages, as these polymers: (a) can be modified further to introduce new functions such as imaging, molecular targeting and drugs can be conjugated chemically to these polymers, (b) can improve on better biological properties like cell migration, adhesion and biodegradability, (c) can improve on mechanical and thermal properties and (d) their degradation products are expected to be non-toxic and readily metabolized/excreted from the body. This manuscript focuses on biodegradable polymers derived from natural amino acids, their synthesis, biocompatibility and biomedical applications. It is observed that polymers derived from α-amino acids constitute a promising family of biodegradable materials. These provide innovative multifunctional polymers possessing amino acid side groups with biological activity and with innumerous potential applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Biodegradation of Moringa oleifera's polymer blends.

    Science.gov (United States)

    Finzi-Quintão, Cristiane Medina; Novack, Kátia Monteiro; Bernardes-Silva, Ana Cláudia; Silva, Thais D; Moreira, Lucas E S; Braga, Luiza E M

    2017-11-10

    Vegetable oils are used as a base for the synthesis of polymers and monomers with structures similar to that of petroleum, as plasticizers for conventional polymers and biodegrading additives. The Moringa oleifera oil was extracted from seeds and polymerized after being submitted to 16 h of microwave irradiation without catalysers. This polymer was characterized and the efficiency of the oil polymerization was verified by the reduction of double bonds and the increase of molecular weight up to 50,000 g mol -1 . Films produced by a mixture of low-density polyethylene (LDPE) with poly(butylene adipate-co-terephthalate)/poly(lactic acid) (PBAT/PLA) present low tensile resistance and low biodegradation behaviour. In order to improve those properties, the Moringa polymer (PMO) was mixed with LDPE and PBAT/PLA in specific mass concentrations. The films produced with this mixture were characterized and submitted to biodegradation analysis. The PMO behaves as a compatibilizer by improving thermal properties, reducing the crystalline phase and improving the biodegradation behaviour. The biodegradation improved up to five times in comparison to conventional polymers and it restores the mechanical properties.

  12. Biodegradable Polymers and Stem Cells for Bioprinting

    Directory of Open Access Journals (Sweden)

    Meijuan Lei

    2016-04-01

    Full Text Available It is imperative to develop organ manufacturing technologies based on the high organ failure mortality and serious donor shortage problems. As an emerging and promising technology, bioprinting has attracted more and more attention with its super precision, easy reproduction, fast manipulation and advantages in many hot research areas, such as tissue engineering, organ manufacturing, and drug screening. Basically, bioprinting technology consists of inkjet bioprinting, laser-based bioprinting and extrusion-based bioprinting techniques. Biodegradable polymers and stem cells are common printing inks. In the printed constructs, biodegradable polymers are usually used as support scaffolds, while stem cells can be engaged to differentiate into different cell/tissue types. The integration of biodegradable polymers and stem cells with the bioprinting techniques has provided huge opportunities for modern science and technologies, including tissue repair, organ transplantation and energy metabolism.

  13. Biodegradable Polymers and Stem Cells for Bioprinting.

    Science.gov (United States)

    Lei, Meijuan; Wang, Xiaohong

    2016-04-29

    It is imperative to develop organ manufacturing technologies based on the high organ failure mortality and serious donor shortage problems. As an emerging and promising technology, bioprinting has attracted more and more attention with its super precision, easy reproduction, fast manipulation and advantages in many hot research areas, such as tissue engineering, organ manufacturing, and drug screening. Basically, bioprinting technology consists of inkjet bioprinting, laser-based bioprinting and extrusion-based bioprinting techniques. Biodegradable polymers and stem cells are common printing inks. In the printed constructs, biodegradable polymers are usually used as support scaffolds, while stem cells can be engaged to differentiate into different cell/tissue types. The integration of biodegradable polymers and stem cells with the bioprinting techniques has provided huge opportunities for modern science and technologies, including tissue repair, organ transplantation and energy metabolism.

  14. Biodegradable Shape Memory Polymers in Medicine.

    Science.gov (United States)

    Peterson, Gregory I; Dobrynin, Andrey V; Becker, Matthew L

    2017-11-01

    Shape memory materials have emerged as an important class of materials in medicine due to their ability to change shape in response to a specific stimulus, enabling the simplification of medical procedures, use of minimally invasive techniques, and access to new treatment modalities. Shape memory polymers, in particular, are well suited for such applications given their excellent shape memory performance, tunable materials properties, minimal toxicity, and potential for biodegradation and resorption. This review provides an overview of biodegradable shape memory polymers that have been used in medical applications. The majority of biodegradable shape memory polymers are based on thermally responsive polyesters or polymers that contain hydrolyzable ester linkages. These materials have been targeted for use in applications pertaining to embolization, drug delivery, stents, tissue engineering, and wound closure. The development of biodegradable shape memory polymers with unique properties or responsiveness to novel stimuli has the potential to facilitate the optimization and development of new medical applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Biodegradable Poly(polyol sebacate) Polymers

    OpenAIRE

    Bruggeman, Joost P.; de Bruin, Berend-Jan; Bettinger, Christopher J.; Langer, Robert

    2008-01-01

    We have developed a family of synthetic biodegradable polymers that are composed of structural units endogenous to the human metabolism, designated poly(polyol sebacates) (PPS) polymers. Material properties of PPS polymers can be tuned by altering the polyol monomer and reacting stiochiometric ratio of sebacic acid. These thermoset networks exhibited tensile Young’s moduli ranging from 0.37 ± 0.08 to 378 ± 33 MPa with maximum elongations at break from 10.90 ± 1.37 to 205.16 ± 55.76%, and glas...

  16. Biodegradable Poly(polyol sebacate) Polymers

    Science.gov (United States)

    Bruggeman, Joost P.; de Bruin, Berend-Jan; Bettinger, Christopher J.; Langer, Robert

    2010-01-01

    We have developed a family of synthetic biodegradable polymers that are composed of structural units endogenous to the human metabolism, designated poly(polyol sebacates) (PPS) polymers. Material properties of PPS polymers can be tuned by altering the polyol monomer and reacting stiochiometric ratio of sebacic acid. These thermoset networks exhibited tensile Young’s moduli ranging from 0.37 ± 0.08 to 378 ± 33 MPa with maximum elongations at break from 10.90 ± 1.37 to 205.16 ± 55.76%, and glass-transition temperatures ranged from ~7 to 46 °C. In vitro degradation under physiological conditions was slower than in vivo degradation rates observed for some PPS polymers. PPS polymers demonstrated similar in vitro and in vivo biocompatibility compared to poly(L-lactic-co-glycolic acid) (PLGA). PMID:18824260

  17. Biodegradable polymers in Quebec; Les polymeres biodegradables au Quebec

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    Poly-hydroxy-alkanoates (PHA) are natural polymers made from renewable resources and are easily recyclable, hydrolyzable and biodegradable. Thanks to genetic technologies, PHA can be synthesized from plants or bacteria and can be used in various domains ranging from the manufacturing of packing materials to medical applications. Moreover, their properties make them good substitutes of equivalent petroleum-derived compounds. This report makes a status of Quebec's research work on PHAs and presents the three main research centers in which such studies are carried out: the biotechnology research institute, the Mc Gill university and the Polytechnique school of Montreal. (J.S.)

  18. Effect of electron beam irradiation on the enzymatic degradation of composites based on biodegradable polymers and coconut fiber

    Energy Technology Data Exchange (ETDEWEB)

    Kodama, Yasko; Bardi, Marcelo Augusto Goncalves; Machado, Luci Diva Brocardo, E-mail: ykodama@ipen.b, E-mail: marcelo.bardi@usp.b, E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Rosa, Derval dos Santos, E-mail: derval.rosa@ufabc.edu.b [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2011-07-01

    The development of polymeric materials that are susceptible to microbiological degradation and that have properties similar to the conventional polymers would reduce waste deposit. Degradable plastics suffer significant change on chemical structure when submitted to specific environmental condition. PCL and PLLA have been extensively investigated due to their bio-assimilation and because they are considered as eco-friendly. So the degradation of PCL and PLLA homopolymers, PCL:PLLA 20:80 (w:w) blend and coconut fiber-modified composites were studied by means of their degradation under lipase enzyme from Pseudomonas cepacia. Non-irradiated and EB-irradiated samples at 50 kGy and 100 kGy were exposed during 24, 72, 120 and 168 hours to the enzyme-buffer solution and the retained mass of dried samples was accompanied over time. The results were compared to the not submitted to the enzyme solution samples. Degradation rate of PCL was higher than PLLA in the presence of Pseudomonas lipase. PLLA presence reduced PCL's enzymatic degradation in the PCL:PLLA 20:80 w:w blend. After 120 h exposure, blend mass loss variation approached pure PLLA behavior. Composites degradation behavior through time was similar to the blend. Values of retained mass for composites were superior to the blends suggesting that coconut fiber did not significantly degrade in the period of test. Degradation rate of 50 kGy-irradiated PCL slightly reduced, and it was observed increase of degradation rate of samples irradiated with 100 kGy, probably attributed to its crystallinity decrease. Degradation rate of irradiated composite was similar to the blend, suggesting that fiber presence did not affect significantly this parameter. Samples tested during 168 h were affected by the water absorption by PLLA or coconut fibers through time testing. Studied samples degraded accentuatedly in the enzyme presence and were not negatively affected by the radiation processing. (author)

  19. Effect of electron beam irradiation on the enzymatic degradation of composites based on biodegradable polymers and coconut fiber

    International Nuclear Information System (INIS)

    Kodama, Yasko; Bardi, Marcelo Augusto Goncalves; Machado, Luci Diva Brocardo; Rosa, Derval dos Santos

    2011-01-01

    The development of polymeric materials that are susceptible to microbiological degradation and that have properties similar to the conventional polymers would reduce waste deposit. Degradable plastics suffer significant change on chemical structure when submitted to specific environmental condition. PCL and PLLA have been extensively investigated due to their bio-assimilation and because they are considered as eco-friendly. So the degradation of PCL and PLLA homopolymers, PCL:PLLA 20:80 (w:w) blend and coconut fiber-modified composites were studied by means of their degradation under lipase enzyme from Pseudomonas cepacia. Non-irradiated and EB-irradiated samples at 50 kGy and 100 kGy were exposed during 24, 72, 120 and 168 hours to the enzyme-buffer solution and the retained mass of dried samples was accompanied over time. The results were compared to the not submitted to the enzyme solution samples. Degradation rate of PCL was higher than PLLA in the presence of Pseudomonas lipase. PLLA presence reduced PCL's enzymatic degradation in the PCL:PLLA 20:80 w:w blend. After 120 h exposure, blend mass loss variation approached pure PLLA behavior. Composites degradation behavior through time was similar to the blend. Values of retained mass for composites were superior to the blends suggesting that coconut fiber did not significantly degrade in the period of test. Degradation rate of 50 kGy-irradiated PCL slightly reduced, and it was observed increase of degradation rate of samples irradiated with 100 kGy, probably attributed to its crystallinity decrease. Degradation rate of irradiated composite was similar to the blend, suggesting that fiber presence did not affect significantly this parameter. Samples tested during 168 h were affected by the water absorption by PLLA or coconut fibers through time testing. Studied samples degraded accentuatedly in the enzyme presence and were not negatively affected by the radiation processing. (author)

  20. State-of-the-art of biodegradable composite materials; Etat de l'art sur les materiaux composites biodegradables

    Energy Technology Data Exchange (ETDEWEB)

    Baley, Ch.; Grohens, Y.; Pillin, I. [Universite de Bretagne Sud, Lab. Polymeres, Proprietes aux Interfaces et Composites, 56 - Lorient (France)

    2004-07-01

    Nowadays, the market demand for environment friendly materials is in strong growth. The biodegradable composites (biodegradable fibres and polymers) mainly extracted from renewable resources will be a major contributor to the production of new industrial high performance products partially solving the problem of waste management. At the end of the lifetime, a structural bio-composite could be be crushed and recycled through a controlled industrial composting process. This the state-of-the-art report focuses on the biopolymers the vegetable fibres properties, the mechanisms of biodegradation and the examples of biodegradable composites. Eco-design of new products requires these new materials for which a life cycle analysis is nevertheless necessary to validate their environmental benefits. (authors)

  1. Tribology of natural fiber polymer composites

    CERN Document Server

    Chand, N

    2008-01-01

    Environmental concerns are driving demand for bio-degradable materials such as plant-based natural fiber reinforced polymer composites. These composites are fast replacing conventional materials in many applications, especially in automobiles, where tribology (friction, lubrication and wear) is important. This book covers the availability and processing of natural fiber polymer composites and their structural, thermal, mechanical and, in particular, tribological properties.Chapter 1 discusses sources of natural fibers, their extraction and surface modification. It also reviews the ther

  2. Microgel polymer composite fibres

    OpenAIRE

    Kehren, Dominic

    2014-01-01

    In this thesis some novel ideas and advancements in the field of polymer composite fibres, specifically microgel-based polymer composite fibres have been achieved. The main task was to investigate and understand the electrospinning process of microgels and polymers and the interplay of parameter influences, in order to fabricate reproducible and continuously homogenous composite fibres. The main aim was to fabricate a composite material which combines the special properties of polymer fibres ...

  3. Development of aliphatic biodegradable photoluminescent polymers.

    Science.gov (United States)

    Yang, Jian; Zhang, Yi; Gautam, Santosh; Liu, Li; Dey, Jagannath; Chen, Wei; Mason, Ralph P; Serrano, Carlos A; Schug, Kevin A; Tang, Liping

    2009-06-23

    None of the current biodegradable polymers can function as both implant materials and fluorescent imaging probes. The objective of this study was to develop aliphatic biodegradable photoluminescent polymers (BPLPs) and their associated cross-linked variants (CBPLPs) for biomedical applications. BPLPs are degradable oligomers synthesized from biocompatible monomers including citric acid, aliphatic diols, and various amino acids via a convenient and cost-effective polycondensation reaction. BPLPs can be further cross-linked into elastomeric cross-linked polymers, CBPLPs. We have shown representatively that BPLP-cysteine (BPLP-Cys) and BPLP-serine (BPLP-Ser) offer advantages over the traditional fluorescent organic dyes and quantum dots because of their preliminarily demonstrated cytocompatibility in vitro, minimal chronic inflammatory responses in vivo, controlled degradability and high quantum yields (up to 62.33%), tunable fluorescence emission (up to 725 nm), and photostability. The tensile strength of CBPLP-Cys film ranged from 3.25 +/- 0.13 MPa to 6.5 +/- 0.8 MPa and the initial Modulus was in a range of 3.34 +/- 0.15 MPa to 7.02 +/- 1.40 MPa. Elastic CBPLP-Cys could be elongated up to 240 +/- 36%. The compressive modulus of BPLP-Cys (0.6) (1:1:0.6 OD:CA:Cys) porous scaffold was 39.60 +/- 5.90 KPa confirming the soft nature of the scaffolds. BPLPs also possess great processability for micro/nano-fabrication. We demonstrate the feasibility of using BPLP-Ser nanoparticles ("biodegradable quantum dots") for in vitro cellular labeling and noninvasive in vivo imaging of tissue engineering scaffolds. The development of BPLPs and CBPLPs represents a new direction in developing fluorescent biomaterials and could impact tissue engineering, drug delivery, bioimaging.

  4. Biodegradable Polymers in Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Leon E. Govaert

    2009-07-01

    Full Text Available The use ofdegradable polymers in medicine largely started around the mid 20th century with their initial use as in vivo resorbing sutures. Thorough knowledge on this topic as been gained since then and the potential applications for these polymers were, and still are, rapidly expanding. After improving the properties of lactic acid-based polymers, these were no longer studied only from a scientific point of view, but also for their use in bone surgery in the 1990s. Unfortunately, after implanting these polymers, different foreign body reactions ranging from the presence of white blood cells to sterile sinuses with resorption of the original tissue were observed. This led to the misconception that degradable polymers would, in all cases, lead to inflammation and/or osteolysis at the implantation site. Nowadays, we have accumulated substantial knowledge on the issue of biocompatibility of biodegradable polymers and are able to tailor these polymers for specific applications and thereby strongly reduce the occurrence of adverse tissue reactions. However, the major issue of biofunctionality, when mechanical adaptation is taken into account, has hitherto been largely unrecognized. A thorough understanding of how to improve the biofunctionality, comprising biomechanical stability, but also visualization and sterilization of the material, together with the avoidance of fibrotic tissue formation and foreign body reactions, may greatly enhance the applicability and safety of degradable polymers in a wide area of tissue engineering applications. This review will address our current understanding of these biofunctionality factors, and will subsequently discuss the pitfalls remaining and potential solutions to solve these problems.

  5. Electrospun biodegradable polymers loaded with bactericide agents

    Directory of Open Access Journals (Sweden)

    Ramaz Katsarava

    2016-03-01

    Full Text Available Development of materials with an antimicrobial activity is fundamental for different sectors, including medicine and health care, water and air treatment, and food packaging. Electrospinning is a versatile and economic technique that allows the incorporation of different natural, industrial, and clinical agents into a wide variety of polymers and blends in the form of micro/nanofibers. Furthermore, the technique is versatile since different constructs (e.g. those derived from single electrospinning, co-electrospinning, coaxial electrospinning, and miniemulsion electrospinning can be obtained to influence the ability to load agents with different characteristics and stability and to modify the release behaviour. Furthermore, antimicrobial agents can be loaded during the electrospinning process or by a subsequent coating process. In order to the mitigate burst release effect, it is possible to encapsulate the selected drug into inorganic nanotubes and nanoparticles, as well as in organic cyclodextrine polysaccharides. In the same way, processes that involve covalent linkage of bactericide agents during surface treatment of electrospun samples may also be considered. The present review is focused on more recent works concerning the electrospinning of antimicrobial polymers. These include chitosan and common biodegradable polymers with activity caused by the specific load of agents such as metal and metal oxide particles, quaternary ammonium compounds, hydantoin compounds, antibiotics, common organic bactericides, and bacteriophages.

  6. Critical evaluation of biodegradable polymers used in nanodrugs

    Science.gov (United States)

    Marin, Edgar; Briceño, Maria Isabel; Caballero-George, Catherina

    2013-01-01

    Use of biodegradable polymers for biomedical applications has increased in recent decades due to their biocompatibility, biodegradability, flexibility, and minimal side effects. Applications of these materials include creation of skin, blood vessels, cartilage scaffolds, and nanosystems for drug delivery. These biodegradable polymeric nanoparticles enhance properties such as bioavailability and stability, and provide controlled release of bioactive compounds. This review evaluates the classification, synthesis, degradation mechanisms, and biological applications of the biodegradable polymers currently being studied as drug delivery carriers. In addition, the use of nanosystems to solve current drug delivery problems are reviewed. PMID:23990720

  7. Critical evaluation of biodegradable polymers used in nanodrugs.

    Science.gov (United States)

    Marin, Edgar; Briceño, Maria Isabel; Caballero-George, Catherina

    2013-01-01

    Use of biodegradable polymers for biomedical applications has increased in recent decades due to their biocompatibility, biodegradability, flexibility, and minimal side effects. Applications of these materials include creation of skin, blood vessels, cartilage scaffolds, and nanosystems for drug delivery. These biodegradable polymeric nanoparticles enhance properties such as bioavailability and stability, and provide controlled release of bioactive compounds. This review evaluates the classification, synthesis, degradation mechanisms, and biological applications of the biodegradable polymers currently being studied as drug delivery carriers. In addition, the use of nanosystems to solve current drug delivery problems are reviewed.

  8. Partial Discharge Degradation of Several Biodegradable Polymers

    Science.gov (United States)

    Fuse, Norikazu; Fujita, Shinjiro; Hirai, Naoshi; Tanaka, Toshikatsu; Kozako, Masahiro; Kohtoh, Masanori; Okabe, Shigemitsu; Ohki, Yoshimichi

    Partial discharge (PD) resistance was examined by applying a constant voltage for four kinds of biodegradable polymers, i.e. poly-L-lactic acid (PLLA), polyethylene terephthalate succinate (PETS), poly ε-caprolactone butylene succinate (PCL-BS), and polybutylene succinate (PBS), and the results were compared with those of low density polyethylene (LDPE) and crosslinked low density polyethylene (XLPE). The PD resistance is determined by the erosion depth and the surface roughness caused by PDs, and is ranked as LDPE ≅ XLPE > PLLA ≅ PETS > PBS > PCL-BS. This means that the sample with a lower permittivity has better PD resistance. Furthermore, observations of the sample surface by a polarization microscope and a laser confocal one reveal that crystalline regions with spherulites are more resistant to PDs than amorphous regions. Therefore, good PD resistance can be achieved by the sample with a high crystallinity and a low permittivity.

  9. Biodegradable and biocompatible polymers for tissue engineering application: a review.

    Science.gov (United States)

    Asghari, Fatemeh; Samiei, Mohammad; Adibkia, Khosro; Akbarzadeh, Abolfazl; Davaran, Soodabeh

    2017-03-01

    Since so many years ago, tissue damages that are caused owing to various reasons attract scientists' attention to find a practical way to treat. In this regard, many studies were conducted. Nano scientists also suggested some ways and the newest one is called tissue engineering. They use biodegradable polymers in order to replace damaged structures in tissues to make it practical. Biodegradable polymers are dominant scaffolding materials in tissue engineering field. In this review, we explained about biodegradable polymers and their application as scaffolds.

  10. Control of colloidal CaCO3 suspension by using biodegradable polymers during fabrication

    Directory of Open Access Journals (Sweden)

    Nemany Abdelhamid Nemany Hanafy

    2015-03-01

    The aim of this work was to investigate the synthesis process of CaCO3 particles in different experimental conditions: calcium carbonate was produced in presence and in absence of water and with addition of appropriate polymers. In particular, chitosan (CHI and poly acrylic acid (PAA were chosen as biodegradable polymers whereas PSS and PAH were chosen as non-biodegradable polymers. Shape and diameter of particles were investigated by using transmission and scanning electron microscopy, elemental composition was inferred by energy dispersive X-ray analyses whereas their charges were explored by using zeta potential.

  11. A comprehensive NMR methodology to assess the composition of biobased and biodegradable polymers in contact with food

    International Nuclear Information System (INIS)

    Gratia, Audrey; Merlet, Denis; Ducruet, Violette; Lyathaud, Cédric

    2015-01-01

    Highlights: • A methodological approach by NMR was developed to assess the safety of food contact materials. • Additives from PLA were rapidly identified by an automatic NMR methodology coupled with dedicated database. • Quantitative NMR (qNMR) allowed to quantify 12 additives in three types of polylactide. • qNMR is as sensitive as chromatographic methods to quantify additives in PLA. - Abstract: A nuclear magnetic resonance (NMR) methodology was assessed regarding the identification and quantification of additives in three types of polylactide (PLA) intended as food contact materials. Additives were identified using the LNE/NMR database which clusters NMR datasets on more than 130 substances authorized by European Regulation No. 10/2011. Of the 12 additives spiked in the three types of PLA pellets, 10 were rapidly identified by the database and correlated with spectral comparison. The levels of the 12 additives were estimated using quantitative NMR combined with graphical computation. A comparison with chromatographic methods tended to prove the sensitivity of NMR by demonstrating an analytical difference of less than 15%. Our results therefore demonstrated the efficiency of the proposed NMR methodology for rapid assessment of the composition of PLA

  12. Modern mass spectrometry in the characterization and degradation of biodegradable polymers

    Energy Technology Data Exchange (ETDEWEB)

    Rizzarelli, Paola, E-mail: paola.rizzarelli@cnr.it; Carroccio, Sabrina

    2014-01-15

    Graphical abstract: -- Highlights: •Recent trends in the structural characterization of biodegradable polymers by MALDI and ESI MS are discussed. •MALDI MS as a noteworthy tool to follow the synthetic polymerization route of biodegradable materials is evidenced. •Elucidation of degradation mechanisms by modern MS techniques is examined. •ESI MS and HPLC–ESI MS are highlighted as highly suitable methods for structural and quantitative analysis of water-soluble biodegradation products. •Novel MS methods developed ad hoc and new MALDI matrices for biodegradable polymers are reviewed. -- Abstract: In the last decades, the solid-waste management related to the extensively growing production of plastic materials, in concert with their durability, have stimulated increasing interest in biodegradable polymers. At present, a variety of biodegradable polymers has already been introduced onto the market and can now be competitive with non biodegradable thermoplastics in different fields (packaging, biomedical, textile, etc.). However, a significant economical effort is still directed in tailoring structural properties in order to further broaden the range of applications without impairing biodegradation. Improving the performance of biodegradable materials requires a good characterization of both physico-chemical and mechanical parameters. Polymer analysis can involve many different features including detailed characterization of chemical structures and compositions as well as average molecular mass determination. It is of outstanding importance in troubleshooting of a polymer manufacturing process and for quality control, especially in biomedical applications. This review describes recent trends in the structural characterization of biodegradable materials by modern mass spectrometry (MS). It provides an overview of the analytical tools used to evaluate their degradation. Several successful applications of MALDI-TOF MS (matrix assisted laser desorption ionization

  13. New biocomposites based on bioplastic flax fibers and biodegradable polymers.

    Science.gov (United States)

    Wróbel-Kwiatkowska, Magdalena; Czemplik, Magdalena; Kulma, Anna; Zuk, Magdalena; Kaczmar, Jacek; Dymińska, Lucyna; Hanuza, Jerzy; Ptak, Maciej; Szopa, Jan

    2012-01-01

    A new generation of entirely biodegradable and bioactive composites with polylactic acid (PLA) or poly-ε-caprolactone (PCL) as the matrix and bioplastic flax fibers as reinforcement were analyzed. Bioplastic fibers contain polyhydroxybutyrate and were obtained from transgenic flax. Biochemical analysis of fibers revealed presence of several antioxidative compounds of hydrophilic (phenolics) and hydrophobic [cannabidiol (CBD), lutein] nature, indicating their high antioxidant potential. The presence of CBD and lutein in flax fibers is reported for the first time. FTIR analysis showed intermolecular hydrogen bonds between the constituents in composite PLA+flax fibers which were not detected in PCL-based composite. Mechanical analysis of prepared composites revealed improved stiffness and a decrease in tensile strength. The viability of human dermal fibroblasts on the surface of composites made of PLA and transgenic flax fibers was the same as for cells cultured without composites and only slightly lower (to 9%) for PCL-based composites. The amount of platelets and Escherichia coli cells aggregated on the surface of the PLA based composites was significantly lower than for pure polymer. Thus, composites made of PLA and transgenic flax fibers seem to have bacteriostatic, platelet anti-aggregated, and non-cytotoxic effect. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  14. Methods for Evaluating the Biodegradability of Environmentally Degradable Polymers

    NARCIS (Netherlands)

    Zee, van der M.

    2014-01-01

    This chapter presents an overview of the current knowledge on experimental methods for monitoring the biodegradability of polymeric materials. The focus is, in particular, on the biodegradation of materials under environmental conditions. Examples of in vivo degradation of polymers used in

  15. Computational analysis for biodegradation of exogenously depolymerizable polymer

    Science.gov (United States)

    Watanabe, M.; Kawai, F.

    2018-03-01

    This study shows that microbial growth and decay in a biodegradation process of exogenously depolymerizable polymer are controlled by consumption of monomer units. Experimental outcomes for residual polymer were incorporated in inverse analysis for a degradation rate. The Gauss-Newton method was applied to an inverse problem for two parameter values associated with the microbial population. A biodegradation process of polyethylene glycol was analyzed numerically, and numerical outcomes were obtained.

  16. DNA polyplexes formed using PEGylated biodegradable hyperbranched polymers.

    Science.gov (United States)

    Tao, Lei; Chou, William C; Tan, Beng H; Davis, Thomas P

    2010-06-11

    A novel PEGylated biodegradable hyperbranched PEG-b-PDMAEMA has been synthesized. The low toxicity, small molecular weight PDMAEMA chains were crosslinked using a biodegradable disulfide-based dimethacrylate (DSDMA) agent to yield higher molecular weight hyperbranched polymers. PEG chains were linked onto the polymer surface, masking the positive charge (as shown by Zeta potential measurements) and reducing the toxicity of the polymer. The hyperbranched structures were also cleaved under reducing conditions and analyzed, confirming the expected component structures. The hyperbranched polymer was mixed with DNA and efficient binding was shown to occur through electrostatic interactions. The hyperbranched structures could be reduced easily, generating lower toxicity oligomer chains.

  17. Modern mass spectrometry in the characterization and degradation of biodegradable polymers.

    Science.gov (United States)

    Rizzarelli, Paola; Carroccio, Sabrina

    2014-01-15

    In the last decades, the solid-waste management related to the extensively growing production of plastic materials, in concert with their durability, have stimulated increasing interest in biodegradable polymers. At present, a variety of biodegradable polymers has already been introduced onto the market and can now be competitive with non biodegradable thermoplastics in different fields (packaging, biomedical, textile, etc.). However, a significant economical effort is still directed in tailoring structural properties in order to further broaden the range of applications without impairing biodegradation. Improving the performance of biodegradable materials requires a good characterization of both physico-chemical and mechanical parameters. Polymer analysis can involve many different features including detailed characterization of chemical structures and compositions as well as average molecular mass determination. It is of outstanding importance in troubleshooting of a polymer manufacturing process and for quality control, especially in biomedical applications. This review describes recent trends in the structural characterization of biodegradable materials by modern mass spectrometry (MS). It provides an overview of the analytical tools used to evaluate their degradation. Several successful applications of MALDI-TOF MS (matrix assisted laser desorption ionization time of flight) and ESI MS (electrospray mass spectrometry) for the determination of the structural architecture of biodegradable macromolecules, including their topology, composition, chemical structure of the end groups have been reported. However, MS methodologies have been recently applied to evaluate the biodegradation of polymeric materials. ESI MS represents the most useful technique for characterizing water-soluble polymers possessing different end group structures, with the advantage of being easily interfaced with solution-based separation techniques such as high-performance liquid

  18. Biodegradable polymers for targeted delivery of anti-cancer drugs.

    Science.gov (United States)

    Doppalapudi, Sindhu; Jain, Anjali; Domb, Abraham J; Khan, Wahid

    2016-06-01

    Biodegradable polymers have been used for more than three decades in cancer treatment and have received increased interest in recent years. A range of biodegradable polymeric drug delivery systems designed for localized and systemic administration of therapeutic agents as well as tumor-targeting macromolecules has entered into the clinical phase of development, indicating the significance of biodegradable polymers in cancer therapy. This review elaborates upon applications of biodegradable polymers in the delivery and targeting of anti-cancer agents. Design of various drug delivery systems based on biodegradable polymers has been described. Moreover, the indication of polymers in the targeted delivery of chemotherapeutic drugs via passive, active targeting, and localized drug delivery are also covered. Biodegradable polymer-based drug delivery systems have the potential to deliver the payload to the target and can enhance drug availability at desired sites. Systemic toxicity and serious side effects observed with conventional cancer therapeutics can be significantly reduced with targeted polymeric systems. Still, there are many challenges that need to be met with respect to the degradation kinetics of the system, diffusion of drug payload within solid tumors, targeting tumoral tissue and tumor heterogeneity.

  19. An entropy spring model for the Young's modulus change of biodegradable polymers during biodegradation.

    Science.gov (United States)

    Wang, Ying; Han, Xiaoxiao; Pan, Jingzhe; Sinka, Csaba

    2010-01-01

    This paper presents a model for the change in Young's modulus of biodegradable polymers due to hydrolysis cleavage of the polymer chains. The model is based on the entropy spring theory for amorphous polymers. It is assumed that isolated polymer chain cleavage and very short polymer chains do not affect the entropy change in a linear biodegradable polymer during its deformation. It is then possible to relate the Young's modulus to the average molecular weight in a computer simulated hydrolysis process of polymer chain sessions. The experimental data obtained by Tsuji [Tsuji, H., 2002. Autocatalytic hydrolysis of amorphous-made polylactides: Effects of L-lactide content, tacticity, and enantiomeric polymer blending. Polymers 43, 1789-1796] for poly(L-lactic acid) and poly(D-lactic acid) are examined using the model. It is shown that the model can provide a common thread through Tsuji's experimental data. A further numerical case study demonstrates that the Young's modulus obtained using very thin samples, such as those obtained by Tsuji, cannot be directly used to calculate the load carried by a device made of the same polymer but of various thicknesses. This is because the Young's modulus varies significantly in a biodegradable device due to the heterogeneous nature of the hydrolysis reaction. The governing equations for biodegradation and the relation between the Young's modulus and average molecular weight can be combined to calculate the load transfer from a degrading device to a healing bone.

  20. Acceleration of biodegradation by ultraviolet femtosecond laser irradiation to biodegradable polymer

    Science.gov (United States)

    Shibata, Akimichi; Yada, Shuhei; Kondo, Naonari; Terakawa, Mitsuhiro

    2017-02-01

    Biodegradability is a key property of biodegradable polymers for tissue scaffold applications. Among the methods to control biodegradability, laser processing is a simple technique, which enables the alteration of biodegradability even after molding. Since ultrafast laser processing realizes precise processing of biodegradable polymer with less heat affected zone, ultrafast laser processing has the potential to fabricate tissue scaffolds and to control its biodegradability. In this study, we investigate the effect of femtosecond laser wavelength on the biodegradability of PLGA. We evaluated the biodegradability of PLGA irradiated with femtosecond laser pulses at the wavelength of 800, 400, 266 nm by the measurement of the change in mass of PLGA during water immersion. The results of degradation tests indicate that PLGA irradiated with the shorter wavelength show faster water absorption as well as rapid mass decrease. Since the results of X-ray photoelectron spectroscopy analysis indicate that the chemical bonds of PLGA irradiated with the shorter wavelength are dissociated more significantly, the acceleration of the biodegradation could be attributable to the decrease in molecular weight by chemical bond breaking.

  1. Novel biodegradable calcium phosphate/polymer composite coating with adjustable mechanical properties formed by hydrothermal process for corrosion protection of magnesium substrate.

    Science.gov (United States)

    Kaabi Falahieh Asl, Sara; Nemeth, Sandor; Tan, Ming Jen

    2016-11-01

    Ceramic type coatings on metallic implants, such as calcium phosphate (Ca-P), are generally stiff and brittle, potentially leading to the early failure of the bone-implant interface. To reduce material brittleness, polyacrylic acid and carboxymethyl cellulose were used in this study to deposit two types of novel Ca-P/polymer composite coatings on AZ31 magnesium alloy using a one-step hydrothermal process. X-ray diffraction and scanning electron microscopy showed that the deposited Ca-P crystal phase and morphology could be controlled by the type and concentration of polymer used. Incorporation of polymer in the Ca-P coatings reduced the coating elastic modulus bringing it close to that of magnesium and that of human bone. Nanoindentation test results revealed significantly decreased cracking tendency with the incorporation of polymer in the Ca-P coating. Apart from mechanical improvements, the protective composite layers had also enhanced the corrosion resistance of the substrate by a factor of 1000 which is sufficient for implant application. Cell proliferation studies indicated that the composite coatings induced better cell attachment compared with the purely inorganic Ca-P coating, confirming that the obtained composite materials could be promising candidates for surface protection of magnesium for implant application with the multiple functions of corrosion protection, interfacial stress reduction, and cell attachment/cell growth promotion. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1643-1657, 2016. © 2015 Wiley Periodicals, Inc.

  2. [Progress and prospect of synthetic biodegradable polymers for bone repair and reconstruction].

    Science.gov (United States)

    Zhao, Zenghui; Jiang, Dianming

    2010-03-01

    To review the latest researches of synthetic biodegradable polymers for bone repair and reconstruction, to predict the progress of bone substitute materials and bone tissue engineering scaffolds in future. The literature concerning synthetic biodegradable polymers as bone substitute materials or bone tissue engineering scaffolds was collected and discussed. Aliphatic polyester, polyanhydride, polyurethane and poly (amino acids) were the most extensively studied synthetic biodegradable polymers as bone substitutes and the scaffolds. Each polymer was of good biological safety and biocompatibility, and the degradation products were nontoxic to human body. The mechanical properties and degradation rate of the polymers could be adjusted by the type or number of the monomers and different synthetic methods. Therefore, the polymers with suitable mechanical strength and degradation rate could be produced according to the different requirements for bone grafting. Preliminary studies in vivo showed their favorable capacity for bone repair. The synthetic biodegradable polymers, especially the copolymers, composite materials and those carrying bone growth factors are expected to be the most promising and ideal biomaterials for bone repair and reconstruction.

  3. Biodegradable polymers for electrospinning: towards biomedical applications.

    Science.gov (United States)

    Kai, Dan; Liow, Sing Shy; Loh, Xian Jun

    2014-12-01

    Electrospinning has received much attention recently due to the growing interest in nano-technologies and the unique material properties. This review focuses on recent progress in applying electrospinning technique in production of biodegradable nanofibers to the emerging field of biomedical. It first introduces the basic theory and parameters of nanofibers fabrication, with focus on factors affecting the morphology and fiber diameter of biodegradable nanofibers. Next, commonly electrospun biodegradable nanofibers are discussed, and the comparison of the degradation rate of nanoscale materials with macroscale materials are highlighted. The article also assesses the recent advancement of biodegradable nanofibers in different biomedical applications, including tissue engineering, drug delivery, biosensor and immunoassay. Future perspectives of biodegradable nanofibers are discussed in the last section, which emphasizes on the innovation and development in electrospinning of hydrogels nanofibers, pore size control and scale-up productions. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Bio-Based Polymers with Potential for Biodegradability

    Directory of Open Access Journals (Sweden)

    Thomas F. Garrison

    2016-07-01

    Full Text Available A variety of renewable starting materials, such as sugars and polysaccharides, vegetable oils, lignin, pine resin derivatives, and proteins, have so far been investigated for the preparation of bio-based polymers. Among the various sources of bio-based feedstock, vegetable oils are one of the most widely used starting materials in the polymer industry due to their easy availability, low toxicity, and relative low cost. Another bio-based plastic of great interest is poly(lactic acid (PLA, widely used in multiple commercial applications nowadays. There is an intrinsic expectation that bio-based polymers are also biodegradable, but in reality there is no guarantee that polymers prepared from biorenewable feedstock exhibit significant or relevant biodegradability. Biodegradability studies are therefore crucial in order to assess the long-term environmental impact of such materials. This review presents a brief overview of the different classes of bio-based polymers, with a strong focus on vegetable oil-derived resins and PLA. An entire section is dedicated to a discussion of the literature addressing the biodegradability of bio-based polymers.

  5. Study on the Antimicrobial Properties of Citrate-Based Biodegradable Polymers.

    Science.gov (United States)

    Su, Lee-Chun; Xie, Zhiwei; Zhang, Yi; Nguyen, Kytai Truong; Yang, Jian

    2014-01-01

    Citrate-based polymers possess unique advantages for various biomedical applications since citric acid is a natural metabolism product, which is biocompatible and antimicrobial. In polymer synthesis, citric acid also provides multiple functional groups to control the crosslinking of polymers and active binding sites for further conjugation of biomolecules. Our group recently developed a number of citrate-based polymers for various biomedical applications by taking advantage of their controllable chemical, mechanical, and biological characteristics. In this study, various citric acid derived biodegradable polymers were synthesized and investigated for their physicochemical and antimicrobial properties. Results indicate that citric acid derived polymers reduced bacterial proliferation to different degrees based on their chemical composition. Among the studied polymers, poly(octamethylene citrate) showed ~70-80% suppression to microbe proliferation, owing to its relatively higher ratio of citric acid contents. Crosslinked urethane-doped polyester elastomers and biodegradable photoluminescent polymers also exhibited significant bacteria reduction of ~20 and ~50% for Staphylococcus aureus and Escherichia coli , respectively. Thus, the intrinsic antibacterial properties in citrate-based polymers enable them to inhibit bacteria growth without incorporation of antibiotics, silver nanoparticles, and other traditional bacteria-killing agents suggesting that the citrate-based polymers are unique beneficial materials for wound dressing, tissue engineering, and other potential medical applications where antimicrobial property is desired.

  6. Zotarolimus-eluting durable-polymer-coated stent versus a biolimus-eluting biodegradable-polymer-coated stent in unselected patients undergoing percutaneous coronary intervention (SORT OUT VI)

    DEFF Research Database (Denmark)

    Raungaard, Bent; Jensen, Lisette Okkels; Tilsted, Hans-Henrik

    2015-01-01

    -polymer zotarolimus-eluting stent or the biodegradable-polymer biolimus-eluting stent. The primary endpoint was a composite of safety (cardiac death and myocardial infarction not clearly attributable to a non-target lesion) and efficacy (target-lesion revascularisation) at 12 months, analysed by intention to treat...

  7. Study on the Antimicrobial Properties of Citrate-Based Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Lee-Chun eSu

    2014-07-01

    Full Text Available Citrate-based polymers possess unique advantages for various biomedical applications since citric acid is a natural metabolism product, which is biocompatible and antimicrobial. In polymer synthesis, citric acid also provides multiple functional groups to control the crosslinking of polymers and active binding sites for further conjugation of biomolecules. Our group recently developed a number of citrate-based polymers for various biomedical applications by taking advantage of their controllable chemical, mechanical, and biological characteristics. In this study, various citric acid derived biodegradable polymers were synthesized and investigated for their physicochemical and antimicrobial properties. Results indicate that citric acid derived polymers reduced bacterial proliferation to different degrees based on their chemical composition. Among the studied polymers, poly(octamethylene citrate (POC showed approximately 70-80% suppression to microbe proliferation, owing to its relatively higher ratio of citric acid contents. Crosslinked urethane-doped polyester elastomers (CUPEs and biodegradable photoluminescent polymers (BPLPs also exhibited significant bacteria reduction of ~20% and ~50% for Staphylococcus aureus and Escherichia coli, respectively. Thus, the intrinsic antibacterial properties in citrate-based polymers enable them to inhibit bacteria growth without incorporation of antibiotics, silver nanoparticles, and other traditional bacteria-killing agents suggesting that they are unique beneficial materials for wound dressing, tissue engineering, and other potential medical applications where antimicrobial property is desired.

  8. A review on introduction and applications of starch and its biodegradable polymers

    OpenAIRE

    Shanta Pokhrel

    2015-01-01

    Biodegradable polymers play a very important role in plastic engineering by replacing non biodegradable, non renewable petrol based polymers. Starch is a renewable, biodegradable, low cost natural polymer with high availability. Natural polymers can be blended with synthetic polymers to improve their properties significantly. This article reviews advance in starch and starch based blends and presents their numerous potential applications. Therefore, this review helps to understand the importa...

  9. Biodegradation of Synthetic Polymers by Composting and Fungal Treatment

    Czech Academy of Sciences Publication Activity Database

    Šašek, Václav; Vitásek, J.; Chromcová, D.; Prokopová, I.; Brožek, J.; Náhlík, J.

    2006-01-01

    Roč. 51, č. 5 (2006), s. 425-430 ISSN 0015-5632 R&D Projects: GA ČR GA203/03/0508 Institutional research plan: CEZ:AV0Z50200510 Keywords : biodegradation * composting * synthetic polymers Subject RIV: EE - Microbiology, Virology Impact factor: 0.963, year: 2006

  10. The use of biodegradable polymers for the stabilization of copper ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 5. The use of biodegradable polymers for the stabilization of copper nanoparticles synthesized by chemical reduction method. ALI OLAD MAHNAZ ... However, agglomerated copper nanoparticles were obtained bythis chemical reduction method. Hence, the ...

  11. Introduction of environmentally degradable parameters to evaluate the biodegradability of biodegradable polymers.

    Science.gov (United States)

    Guo, Wenbin; Tao, Jian; Yang, Chao; Song, Cunjiang; Geng, Weitao; Li, Qiang; Wang, Yuanyuan; Kong, Meimei; Wang, Shufang

    2012-01-01

    Environmentally Degradable Parameter ((Ed)K) is of importance in the describing of biodegradability of environmentally biodegradable polymers (BDPs). In this study, a concept (Ed)K was introduced. A test procedure of using the ISO 14852 method and detecting the evolved carbon dioxide as an analytical parameter was developed, and the calculated (Ed)K was used as an indicator for the ultimate biodegradability of materials. Starch and polyethylene used as reference materials were defined as the (Ed)K values of 100 and 0, respectively. Natural soil samples were inoculated into bioreactors, followed by determining the rates of biodegradation of the reference materials and 15 commercial BDPs over a 2-week test period. Finally, a formula was deduced to calculate the value of (Ed)K for each material. The (Ed)K values of the tested materials have a positive correlation to their biodegradation rates in the simulated soil environment, and they indicated the relative biodegradation rate of each material among all the tested materials. Therefore, the (Ed)K was shown to be a reliable indicator for quantitatively evaluating the potential biodegradability of BDPs in the natural environment.

  12. Introduction of Environmentally Degradable Parameters to Evaluate the Biodegradability of Biodegradable Polymers

    Science.gov (United States)

    Yang, Chao; Song, Cunjiang; Geng, Weitao; Li, Qiang; Wang, Yuanyuan; Kong, Meimei; Wang, Shufang

    2012-01-01

    Environmentally Degradable Parameter (Ed K) is of importance in the describing of biodegradability of environmentally biodegradable polymers (BDPs). In this study, a concept Ed K was introduced. A test procedure of using the ISO 14852 method and detecting the evolved carbon dioxide as an analytical parameter was developed, and the calculated Ed K was used as an indicator for the ultimate biodegradability of materials. Starch and polyethylene used as reference materials were defined as the Ed K values of 100 and 0, respectively. Natural soil samples were inoculated into bioreactors, followed by determining the rates of biodegradation of the reference materials and 15 commercial BDPs over a 2-week test period. Finally, a formula was deduced to calculate the value of Ed K for each material. The Ed K values of the tested materials have a positive correlation to their biodegradation rates in the simulated soil environment, and they indicated the relative biodegradation rate of each material among all the tested materials. Therefore, the Ed K was shown to be a reliable indicator for quantitatively evaluating the potential biodegradability of BDPs in the natural environment. PMID:22675455

  13. Precursor polymer compositions comprising polybenzimidazole

    Energy Technology Data Exchange (ETDEWEB)

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  14. Microencapsulation of mildronate in biodegradable and non-biodegradable polymers.

    Science.gov (United States)

    Loca, Dagnija; Sevostjanovs, Eduards; Makrecka, Marina; Zharkova-Malkova, Olga; Berzina-Cimdina, Liga; Tupureina, Velta; Sokolova, Marina

    2014-01-01

    The extremely high hygroscopicity (solubility in water ≥2 g/ml) of the pharmaceutical preparation mildronate defines specific requirements to both packaging material and storage conditions. To overcome the above mentioned inconveniences, microencapsulated form of mildronate was developed using polystyrene (PS) and poly (lactic acid) (PLA) as watertight coating materials. Drug/polymer interaction as well as influence of the microencapsulation process variables on microparticle properties was studied in detail. Water-in-oil-in-water double emulsion technique was adapted and applied for the preparation of PS/mildronate microparticles with total drug load up to 77 %wt and PLA/mildronate microparticles with total drug load up to 80 %wt. The repeatability of the microencapsulation process was ±4% and the encapsulation efficiency of the active ingredient reached 60 %wt. The drug release kinetics from the obtained microparticles was evaluated and it was found that drug release in vivo could be successfully sustained if polystyrene matrix has been used.

  15. Novel biodegradable polymers for local growth factor delivery.

    Science.gov (United States)

    Amsden, Brian

    2015-11-01

    Growth factors represent an important therapeutic protein drug class, and would benefit significantly from formulations that provide sustained, local release to realize their full clinical potential. Biodegradable polymer-based delivery platforms have been examined to achieve this end; however, formulations based on conventional polymers have yet to yield a clinical product. This review examines new polymer biomaterials that have been developed for growth factor delivery. The dosage forms are discussed in terms of their mechanism of release, the stability of the released growth factor, their method of preparation, and their potential for clinical translation. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Resonant infrared pulsed laser deposition of thin biodegradable polymer films

    DEFF Research Database (Denmark)

    Bubb, D.M.; Toftmann, B.; Haglund Jr., R.F.

    2002-01-01

    Thin films of the biodegradable polymer poly(DL-lactide-co-glycolide) (PLGA) were deposited using resonant infrared pulsed laser deposition (RIR-PLD). The output of a free-electron laser was focused onto a solid target of the polymer, and the films were deposited using 2.90 (resonant with O...... absorbance spectrum of the films is nearly identical with that of the native polymer, the average molecular weight of the films is a little less than half that of the starting material. Potential strategies for defeating this mass change are discussed....

  17. Identification of market bags composition for biodegradable and oxo-biodegradable samples through thermal analysis in inert and oxidizer atmosphere

    International Nuclear Information System (INIS)

    Finzi-Quintao, Cristiane M.; Novack, Katia M.

    2015-01-01

    Plastic films used to make market bags are based on polymers such as polyethylene, polystyrene and polypropylene, these materials require a long time to degrade in the environment. The alternative technologies of polymers have been developed to reduce the degradation time and the impact on the environment caused by the conventional materials, using pro-degrading additives or by the development biodegradable polymers. In Brazil, the laws of some municipalities require the use of biodegradable material in the production of market bags but the absence of specific surveillance policies makes its chemical composition unknown. In this paper, we analyzed 7 samples that was obtained from a a trading company and commercial market of Belo Horizonte . The samples were characterized by TGA / DTA , XRF , FTIR and MEV which allowed the identification and evaluation of the thermal behavior of the material in inert and oxidizing atmosphere. (author)

  18. Enhancing blood compatibility of biodegradable polymers by introducing sulfobetaine.

    Science.gov (United States)

    Cao, Jun; Chen, Yuan-Wei; Wang, Xin; Luo, Xiang-Lin

    2011-06-15

    Novel biodegradable polycaprolactone containing N,N'-bis (2-hydroxyethyl) methylamine ammonium propane sulfonate (PCL-APS) was synthesized by ring-opening polymerization. The resulting polymers were characterized by nuclear magnetic resonance spectrum (NMR), Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatograph (GPC), differential scanning calorimetry (DSC), and water contact angle (WCA). These measurements showed that the APS unit was introduced into polymers. The hydrolysis of PCL-APS was evaluated by soaking the polymer membranes in a pH = 3.20 acid solution. The rate of weight loss was increased with the content of APS increasing in polymer. The compatibility of polymers were evaluated by platelet adhesion, hemolytic test, and activated partial thromboplastic time (APTT) and prothrombin time (PT) experiments. Results showed that adhered platelets deceased after introducing sulfobetaine as compared to the control PCL, little hemolysis took place on PCL-APS, and APTT of PCL-APS polymers was prolonged than that of control PCL. Therefore, polycaprolactone containing sulfobetaine is a promising biodegradable polymer with good blood compatibility. Copyright © 2011 Wiley Periodicals, Inc.

  19. Biodegradability and biodegradation rate of poly(caprolactone)-starch blend and poly(butylene succinate) biodegradable polymer under aerobic and anaerobic environment.

    Science.gov (United States)

    Cho, H S; Moon, H S; Kim, M; Nam, K; Kim, J Y

    2011-03-01

    The biodegradability and the biodegradation rate of two kinds biodegradable polymers; poly(caprolactone) (PCL)-starch blend and poly(butylene succinate) (PBS), were investigated under both aerobic and anaerobic conditions. PCL-starch blend was easily degraded, with 88% biodegradability in 44 days under aerobic conditions, and showed a biodegradation rate of 0.07 day(-1), whereas the biodegradability of PBS was only 31% in 80 days under the same conditions, with a biodegradation rate of 0.01 day(-1). Anaerobic bacteria degraded well PCL-starch blend (i.e., 83% biodegradability for 139 days); however, its biodegradation rate was relatively slow (6.1 mL CH(4)/g-VS day) compared to that of cellulose (13.5 mL CH(4)/g-VS day), which was used as a reference material. The PBS was barely degraded under anaerobic conditions, with only 2% biodegradability in 100 days. These results were consistent with the visual changes and FE-SEM images of the two biodegradable polymers after the landfill burial test, showing that only PCL-starch blend had various sized pinholes on the surface due to attack by microorganisms. This result may be use in deciding suitable final disposal approaches of different types of biodegradable polymers in the future. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Conductive Polymer Composites

    OpenAIRE

    Pierini, Filippo

    2013-01-01

    In recent years, nanotechnologies have led to the production of materials with new and sometimes unexpected qualities through the manipulation of nanoscale components. This research aimed primarily to the study of the correlation between hierarchical structures of hybrid organic-inorganic materials such as conductive polymer composites (CPCs). Using a bottom-up methodology, we could synthesize a wide range of inorganic nanometric materials with a high degree of homogeneity and purity, ...

  1. Novel bio-based and biodegradable polymer blends

    Science.gov (United States)

    Yang, Shengzhe

    Most plastic materials, including high performance thermoplastics and thermosets are produced entirely from petroleum-based products. The volatility of the natural oil markets and the increasing cost of petroleum have led to a push to reduce the dependence on petroleum products. Together with an increase in environmental awareness, this has promoted the use of alternative, biorenewable, environmentally-friendly products, such as biomass. The growing interest in replacing petroleum-based products by inexpensive, renewable, natural materials is important for sustainable development into the future and will have a significant impact on the polymer industry and the environment. This thesis involved characterization and development of two series of novel bio-based polymer blends, namely polyhydroxyalkanoate (PHA)/polyamide (PA) and poly(lactic acid) (PLA)/soy protein. Blends with different concentrations and compatible microstructures were prepared using twin-screw extruder. For PHA/PA blends, the poor mechanical properties of PHA improved significantly with an excellent combination of strength, stiffness and toughness by adding PA. Furthermore, the effect of blending on the viscoelastic properties has been investigated using small-amplitude oscillatory shear flow experiments as a function of blend composition and angular frequency. The elastic shear modulus (G‧) and complex viscosity of the blends increased significantly with increasing the concentration of PHA. Blending PLA with soy protein aims at reducing production cost, as well as accelerating the biodegradation rate in soil medium. In this work, the mechanical, thermal and morphological properties of the blends were investigated using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests.

  2. Biodegradable thermogelling polymers: working towards clinical applications.

    Science.gov (United States)

    Dou, Qing Qing; Liow, Sing Shy; Ye, Enyi; Lakshminarayanan, Rajamani; Loh, Xian Jun

    2014-07-01

    As society ages, aging medical problems such as organ damage or failure among senior citizens increases, raising the demand for organ repair technologies. Synthetic materials have been developed and applied in various parts of human body to meet the biomedical needs. Hydrogels, in particular, have found extensive applications as wound healing, drug delivery and controlled release, and scaffold materials in the human body. The development of the next generation of soft hydrogel biomaterials focuses on facile synthetic methods, efficacy of treatment, and tunable multi-functionalities for applications. Supramolecular 3D entities are highly attractive materials for biomedical application. They are assembled by modules via various non-covalent bonds (hydrogen bonds, p-p stacking and/or van der Waals interactions). Biodegradable thermogels are a class of such supramolecular assembled materials. Their use as soft biomaterials and their related applications are described in this Review. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Nanofibers extraction from palm mesocarp fiber for biodegradable polymers incorporation

    International Nuclear Information System (INIS)

    Kuana, Vanessa A.; Rodrigues, Vanessa B.; Takahashi, Marcio C.; Campos, Adriana de; Sena Neto, Alfredo R.; Mattoso, Luiz H.C.; Marconcini, Jose M.

    2015-01-01

    The palm mesocarp fibers are residues produced by the palm oil industries. The objective of this paper is to determine an efficient treatment to extract crystal cellulose nanofibers from the palm mesocarp fibers to be incorporated in biodegradable polymeric composites. The fibers were saponified, bleached and analyzed with thermal gravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. (author)

  4. Protection of marble surfaces by using biodegradable polymers as coating agent

    OpenAIRE

    Ocak, Yılmaz; Sofuoğlu, Aysun; Tıhmınlıoğlu, Funda; Böke, Hasan

    2009-01-01

    Biodegradable polymers have been replaced over the synthetic polymers in many applications due to their good properties such as reversibility and biodegradability. Therefore they allow new treatment on the surface of the material to be protected and they fulfil the principles generally accepted by the International Conservation Community of Historic Monuments and Buildings. In this study, the efficiency of four different biodegradable polymers as protective coatings on marble-SO2 reaction was...

  5. Application of Composite Polymer Electrolytes

    National Research Council Canada - National Science Library

    Scrosati, Bruno

    2001-01-01

    ...)PEO-based composite polymer electrolytes, by a series of specifically addressed electrochemical tests which included the determination of the conductivity and of the lithium transference number...

  6. Biodegradable-Polymer Biolimus-Eluting Stents versus Durable-Polymer Everolimus-Eluting Stents at One-Year Follow-Up: A Registry-Based Cohort Study.

    Science.gov (United States)

    Parsa, Ehsan; Saroukhani, Sepideh; Majlessi, Fereshteh; Poorhosseini, Hamidreza; Lofti-Tokaldany, Masoumeh; Jalali, Arash; Salarifar, Mojtaba; Nematipour, Ebrahim; Alidoosti, Mohammad; Aghajani, Hassan; Amirzadegan, Alireza; Kassaian, Seyed Ebrahim

    2016-04-01

    We compared outcomes of percutaneous coronary intervention patients who received biodegradable-polymer biolimus-eluting stents with those who received durable-polymer everolimus-eluting stents. At Tehran Heart Center, we performed a retrospective analysis of the data from January 2007 through December 2011 on 3,270 consecutive patients with coronary artery disease who underwent percutaneous coronary intervention with the biodegradable-polymer biolimus-eluting stent or the durable-polymer everolimus-eluting stent. We excluded patients with histories of coronary artery bypass grafting or percutaneous coronary intervention, acute ST-segment-elevation myocardial infarction, or the implantation of 2 different stent types. Patients were monitored for 12 months. The primary endpoint was a major adverse cardiac event, defined as a composite of death, nonfatal myocardial infarction, and target-vessel and target-lesion revascularization. Durable-polymer everolimus-eluting stents were implanted in 2,648 (81%) and biodegradable-polymer biolimus-eluting stents in 622 (19%) of the study population. There was no significant difference between the 2 groups (2.7% vs 2.7%; P=0.984) in the incidence of major adverse cardiac events. The cumulative adjusted probability of major adverse cardiac events in the biodegradable-polymer biolimus-eluting stent group did not differ from that of such events in the durable-polymer everolimus-eluting stent group (hazard ratio=0.768; 95% confidence interval, 0.421-1.44; P=0.388). We conclude that in our patients the biodegradable-polymer biolimus-eluting stent was as effective and safe, during the 12-month follow-up period, as was the durable-polymer everolimus-eluting stent.

  7. Radiation processing of biodegradable polymer and hydrogel

    International Nuclear Information System (INIS)

    Yoshii, Fumio

    2000-01-01

    Poly(ε-caprolactone), PCL, (melting temperature 60degC) was gamma-irradiated in the solid state at 30 to 55degC, the molten state, and the supercooled state(irradiation at 45 to 55degC after melting, 80degC) under vacuum to improve its heat resistance. Irradiation of PCL in the supercooled state led to the highest gel content and this polymer has high heat resistance. On the other hand, relatively smaller doses such as 15 and 30 kGy were effective to improve processability of PCL by formation of branch structure during irradiation. It was found that carboxymethylcellulose with relatively high degree of substitution led crosslinking at high concentration in aqueous solution such as 10% by irradiation. (author)

  8. Measuring the Biodegradability of Plastic Polymers in Olive-Mill Waste Compost with an Experimental Apparatus

    Directory of Open Access Journals (Sweden)

    Francesco Castellani

    2016-01-01

    Full Text Available The use of biodegradable polymers is spreading in agriculture to replace those materials derived from petroleum, thus reducing the environmental concerns. However, to issue a significant assessment, biodegradation rate must be measured in case-specific standardized conditions. In accordance with ISO 14855-1, we designed and used an experimental apparatus to evaluate the biodegradation rate of three biopolymers based on renewable resources, two poly(ε-caprolactone (PCL composites, and a compatibilized polylactic acid and polybutyrate (PLA/PBAT blend. Biodegradation tests were carried out under composting condition using mature olive-mill waste (OMW compost as inoculum. Carbon dioxide emissions were automatically recorded by infrared gas detectors and also trapped in saturated Ba(OH2 solution and evaluated via a standard titration method to check the results. Some of the samples reached more than 80% biodegradation in less than 20 days. Both the experimental apparatus and the OMW compost showed to be suitable for the cases studied.

  9. Wear of polymers and composites

    CERN Document Server

    Abdelbary, Ahmed

    2015-01-01

    In the field of tribology, the wear behaviour of polymers and composite materials is considered a highly non-linear phenomenon. Wear of Polymers and Composites introduces fundamentals of polymers and composites tribology. The book suggests a new approach to explore the effect of applied load and surface defects on the fatigue wear behaviour of polymers, using a new tribometer and thorough experiments. It discusses effects of surface cracks, under different static and cyclic loading parameters on wear, and presents an intelligent algorithm, in the form of a neural network, to map the relations

  10. Wood and concrete polymer composites

    International Nuclear Information System (INIS)

    Singer, K.

    1974-01-01

    There are several ways to prepare and use wood and concrete polymer composites. The most important improvements in the case of concrete polymer composites are obtained for compressive and tensile strengths. The progress in this field in United States and other countries is discussed in this rview. (M.S.)

  11. Biodegradable Polymer-Based Scaffolds for Bone Tissue Engineering

    CERN Document Server

    Sultana, Naznin

    2013-01-01

    This book addresses the principles, methods and applications of biodegradable polymer based scaffolds for bone tissue engineering. The general principle of bone tissue engineering is reviewed and the traditional and novel scaffolding materials, their properties and scaffold fabrication techniques are explored. By acting as temporary synthetic extracellular matrices for cell accommodation, proliferation, and differentiation, scaffolds play a pivotal role in tissue engineering. This book does not only provide the comprehensive summary of the current trends in scaffolding design but also presents the new trends and directions for scaffold development for the ever expanding tissue engineering applications.

  12. Multilayer Electroactive Polymer Composite Material

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2011-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  13. The Recent Developments in Biobased Polymers toward General and Engineering Applications : Polymers that Are Upgraded from Biodegradable Polymers, Analogous to Petroleum-Derived Polymers, and Newly Developed

    NARCIS (Netherlands)

    Nakajima, Hajime; Dijkstra, Peter; Loos, Katja

    2017-01-01

    The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering

  14. The use of biodegradable polymers in design of cellular scaffolds.

    Science.gov (United States)

    Orłowska, Joanna; Kurczewska, Urszula; Derwińska, Katarzyna; Orłowski, Wojciech; Orszulak-Michalak, Daria

    2015-03-05

    The objective of this work was to demonstrate the usage of biodegradable polymers, made of calcium alginate and dibutyrylchitin, in the design of cellular scaffolds having broad application in reconstructive therapy (dentistry, orthopedics). To visualize cells seeded on calcium alginate and dibutyrylchitin polymers DAPI staining of fibroblasts nuclei was used. The cytotoxicity of the materials and microscopic evaluation of the viability of seeded cells was tested with a PKH 67 fluorescent dye. To assess the cellular toxicity the proliferation of fibroblasts adjacent to the tested polymers was examined. The vitability of cells seeded on polymers was also evaluated by measuring the fluorescence intensity of calcein which binds only to live cells. The conducted experiments (DAPI and PKH 67 staining) show that the tested materials have a positive influence on cell adhesion crucial for wound healing - fibroblasts. The self-made dibutyrylchitin dressing do not cause the reduction of viability of cells seeded on them. The in vitro study illustrated the interactions between the tested materials, constructed of calcium alginate or dibutyrylchitin and mouse fibroblasts and proved their usefulness in the design of cellular scaffolds. Examined polymers turned out to be of great interest and promise for cellular scaffolds design.

  15. The use of biodegradable polymers in design of cellular scaffolds

    Directory of Open Access Journals (Sweden)

    Joanna Orłowska

    2015-03-01

    Full Text Available The objective of this work was to demonstrate the usage of biodegradable polymers, made of calcium alginate and dibutyrylchitin, in the design of cellular scaffolds having broad application in reconstructive therapy (dentistry, orthopedics. To visualize cells seeded on calcium alginate and dibutyrylchitin polymers DAPI staining of fibroblasts nuclei was used. The cytotoxicity of the materials and microscopic evaluation of the viability of seeded cells was tested with a PKH 67 fluorescent dye. To assess the cellular toxicity the proliferation of fibroblasts adjacent to the tested polymers was examined. The vitability of cells seeded on polymers was also evaluated by measuring the fluorescence intensity of calcein which binds only to live cells. The conducted experiments (DAPI and PKH 67 staining show that the tested materials have a positive influence on cell adhesion crucial for wound healing – fibroblasts. The self-made dibutyrylchitin dressing do not cause the reduction of viability of cells seeded on them. The in vitro study illustrated the interactions between the tested materials, constructed of calcium alginate or dibutyrylchitin and mouse fibroblasts and proved their usefulness in the design of cellular scaffolds. Examined polymers turned out to be of great interest and promise for cellular scaffolds design.

  16. Co-delivery of daunomycin and oxaliplatin by biodegradable polymers for safer and more efficacious combination therapy.

    Science.gov (United States)

    Xiao, Haihua; Li, Wenliang; Qi, Ruogu; Yan, Lesan; Wang, Rui; Liu, Shi; Zheng, Yonghui; Xie, Zhigang; Huang, Yubin; Jing, Xiabin

    2012-11-10

    An oxaliplatin pro-drug (Oxa(IV)-COOH) with an axial carboxyl group was synthesized and conjugated to biodegradable polymers with pendant hydroxyl groups to prepare polymer-Oxa(IV) conjugates. A hydrophobic anthracycline-based drug, daunorubicin (DRB) was conjugated to similar biodegradable polymers with carboxyl groups to synthesize polymer-DRB conjugates. The two drug conjugates have the similar polymer backbone and are amphiphilic; thus, they can co-assemble into composite micelles. In the composite micelles, the polymer-Oxa(IV) conjugates can release clinically widely used water soluble anticancer drug oxaliplatin (Oxa(II)) upon reduction, while polymer-DRB conjugate is thought to release DRB via acid hydrolysis in the cancer cells. In this way, combination of the hydrophilic platinum drug Oxa(II) and hydrophobic drug DRB can be realized by delivering them in one platform. Moreover, the composite micelles showed reduced systematic toxicity and greater synergistic effect than combination of small molecules of the two anticancer drugs both in vitro and in vivo; thus, this polymer based combination therapy can be useful in future clinic application. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration

    Science.gov (United States)

    Widmer, M. S.; Gupta, P. K.; Lu, L.; Meszlenyi, R. K.; Evans, G. R.; Brandt, K.; Savel, T.; Gurlek, A.; Patrick, C. W. Jr; Mikos, A. G.; hide

    1998-01-01

    We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve

  18. Characterization of biodegradable polymers irradiated with swift heavy ions

    International Nuclear Information System (INIS)

    Salguero, N.G.; Grosso, M.F. del; Durán, H.; Peruzzo, P.J.; Amalvy, J.I.

    2012-01-01

    In view of their application as biomaterials, there is an increasing interest in developing new methods to induce controlled cell adhesion onto polymeric materials. The critical step in all these methods involves the modification of polymer surfaces, to induce cell adhesion, without changing theirs degradation and biocompatibility properties. In this work two biodegradable polymers, polyhydroxybutyrate (PHB) and poly-L-lactide acid (PLLA) were irradiated using carbon and sulfur beams with different energies and fluences. Pristine and irradiated samples were degradated by immersion in a phosphate buffer at pH 7.0 and then characterized. The analysis after irradiation and degradation showed a decrease in the contact angle values and changes in their crystallinity properties.

  19. Characterization of biodegradable polymers irradiated with swift heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Salguero, N.G. [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA, Av. Gral. Paz 1499 (B1650KNA) San Martin, Buenos Aires (Argentina); Grosso, M.F. del, E-mail: delgrosso@tandar.cnea.gov.ar [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA, Av. Gral. Paz 1499 (B1650KNA) San Martin, Buenos Aires (Argentina); CONICET, Av. Rivadavia 1917 C1033AAJ CABA (Argentina); Duran, H. [CONICET, Av. Rivadavia 1917 C1033AAJ CABA (Argentina); Gerencia de Desarrollo Tecnologico y Proyectos Especiales, CNEA, Av. Gral. Paz 1499 (B1650KNA) San Mart Latin-Small-Letter-Dotless-I Acute-Accent n, Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, H. Yrigoyen 3100, CP 1650, San Martin, UNSAM (Argentina); Peruzzo, P.J. [CICPBA - Grupo de Materiales y Nanomateriales Polimericos, Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), CCT La Plata CONICET - Universidad Nacional de La Plata, La Plata (Argentina); Amalvy, J.I. [CICPBA - Grupo de Materiales y Nanomateriales Polimericos, Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), CCT La Plata CONICET - Universidad Nacional de La Plata, La Plata (Argentina); Facultad de Ingenieria, Universidad Nacional de La Plata, Calle 116 y 48 (B1900TAG), La Plata (Argentina); Departamento de Ingenieria Quimica, Facultad Regional La Plata, Universidad Tecnologica Nacional, 60 y 124 (1900), La Plata (Argentina); and others

    2012-02-15

    In view of their application as biomaterials, there is an increasing interest in developing new methods to induce controlled cell adhesion onto polymeric materials. The critical step in all these methods involves the modification of polymer surfaces, to induce cell adhesion, without changing theirs degradation and biocompatibility properties. In this work two biodegradable polymers, polyhydroxybutyrate (PHB) and poly-L-lactide acid (PLLA) were irradiated using carbon and sulfur beams with different energies and fluences. Pristine and irradiated samples were degradated by immersion in a phosphate buffer at pH 7.0 and then characterized. The analysis after irradiation and degradation showed a decrease in the contact angle values and changes in their crystallinity properties.

  20. Characterization of biodegradable polymers irradiated with swift heavy ions

    Science.gov (United States)

    Salguero, N. G.; del Grosso, M. F.; Durán, H.; Peruzzo, P. J.; Amalvy, J. I.; Arbeitman, C. R.; García Bermúdez, G.

    2012-02-01

    In view of their application as biomaterials, there is an increasing interest in developing new methods to induce controlled cell adhesion onto polymeric materials. The critical step in all these methods involves the modification of polymer surfaces, to induce cell adhesion, without changing theirs degradation and biocompatibility properties. In this work two biodegradable polymers, polyhydroxybutyrate (PHB) and poly- L-lactide acid (PLLA) were irradiated using carbon and sulfur beams with different energies and fluences. Pristine and irradiated samples were degradated by immersion in a phosphate buffer at pH 7.0 and then characterized. The analysis after irradiation and degradation showed a decrease in the contact angle values and changes in their crystallinity properties.

  1. Radiation processing of biodegradable polymer hydrogel from cellulose derivatives

    International Nuclear Information System (INIS)

    Wach, Radoslaw A.; Mitomo, Hiroshi; Yoshii, Fumio; Kume, Tamikazu

    2001-01-01

    The effects of high-energy radiation on ethers of cellulose: carboxymethyl-, hydroxypropyl- and hydroxyethylcellulose have been investigated. Polymers were irradiated in solid state and aqueous solution at various concentrations. Degree of substitution (DS), the concentration in the solution and irradiation conditions had a significant impact on the obtained products. Irradiation of polymers in solid and in diluted solution resulted in their degradation. A novel hydrogels of such natural polymers were synthesized, without using any additives, by irradiation at high concentration. It was found that high DS of CMC promoted crosslinking and, for all of the ethers, the gel formation occurred easier for more concentrated solutions. Paste-like form of the initial material, when water plasticised the bulk of polymer mass, along with the high dose rate and preventing oxygen accessibility to the sample during irradiation were favorable for hydrogel preparation. Up to 95% of gel fraction was obtained from 50 and 60% CMC solutions irradiated by gamma rays or by a beam of accelerated electrons (EB). The other polymers were more sensitive to the dose rate and formed gels with higher gel fraction while processed by EB. Moreover, polymers (except CMC) treated by gamma rays were susceptible to degradation after application of a dose over 50-100 kGy. The presence of oxygen in the system during irradiation limited a gel content and was prone to easier degradation of already formed gel. Produced hydrogels swelled markedly by absorption when paced in the solvent. Crosslinked polymers showed susceptibility to degradation by cellulase enzyme and by the action of microorganisms in compost or under natural conditions in soil thus could be included into the group of biodegradable materials. (author)

  2. Radiation processing of biodegradable polymer hydrogel from cellulose derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Wach, Radoslaw A.; Mitomo, Hiroshi [Gunma Univ., Faculty of Engineering, Department of Biological and Chemical Engineering, Kiryu, Gunma (Japan); Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2001-03-01

    The effects of high-energy radiation on ethers of cellulose: carboxymethyl-, hydroxypropyl- and hydroxyethylcellulose have been investigated. Polymers were irradiated in solid state and aqueous solution at various concentrations. Degree of substitution (DS), the concentration in the solution and irradiation conditions had a significant impact on the obtained products. Irradiation of polymers in solid and in diluted solution resulted in their degradation. A novel hydrogels of such natural polymers were synthesized, without using any additives, by irradiation at high concentration. It was found that high DS of CMC promoted crosslinking and, for all of the ethers, the gel formation occurred easier for more concentrated solutions. Paste-like form of the initial material, when water plasticised the bulk of polymer mass, along with the high dose rate and preventing oxygen accessibility to the sample during irradiation were favorable for hydrogel preparation. Up to 95% of gel fraction was obtained from 50 and 60% CMC solutions irradiated by gamma rays or by a beam of accelerated electrons (EB). The other polymers were more sensitive to the dose rate and formed gels with higher gel fraction while processed by EB. Moreover, polymers (except CMC) treated by gamma rays were susceptible to degradation after application of a dose over 50-100 kGy. The presence of oxygen in the system during irradiation limited a gel content and was prone to easier degradation of already formed gel. Produced hydrogels swelled markedly by absorption when paced in the solvent. Crosslinked polymers showed susceptibility to degradation by cellulase enzyme and by the action of microorganisms in compost or under natural conditions in soil thus could be included into the group of biodegradable materials. (author)

  3. Novel 'nano in nano' composites for sustained drug delivery: biodegradable nanoparticles encapsulated into nanofiber non-wovens.

    Science.gov (United States)

    Beck-Broichsitter, Moritz; Thieme, Marcel; Nguyen, Juliane; Schmehl, Thomas; Gessler, Tobias; Seeger, Werner; Agarwal, Seema; Greiner, Andreas; Kissel, Thomas

    2010-12-08

    Novel 'nano in nano' composites consisting of biodegradable polymer nanoparticles incorporated into polymer nanofibers may efficiently modulate drug delivery. This is shown here using a combination of model compound-loaded biodegradable nanoparticles encapsulated in electrospun fibers. The dye coumarin 6 is used as model compound for a drug in order to simulate drug release from loaded poly(lactide-co-glycolide) nanoparticles. Dye release from the nanoparticles occurs immediately in aqueous solution. Dye-loaded nanoparticles which are encapsulated by electrospun polymer nanofibers display a significantly retarded release. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Mucosal delivery of vaccines: role of mucoadhesive/biodegradable polymers.

    Science.gov (United States)

    Garg, Neeraj K; Mangal, Sharad; Khambete, Hemant; Sharma, Pradeep K; Tyagi, Rajeev K

    2010-06-01

    Majority of infectious microorganism make their gateway to the host through mucosal surfaces, such as gastrointestinal tract, nasal and vaginal tract. Mucosal immune response structured as sIgA can effectively prevent the attachment and invasion of the microorganism from mucosal surface and thereby serves as an efficient tool against infectious disease. There has been an increased demand for the development of novel vaccine that leads to the induction of immune response in systemic circulation as well as at mucosal surfaces against infectious disease. Mucosal delivery of vaccine provides basis for induction of both mucosal as well as systemic immune responses against the infectious organisms. However, a variety of factors such as mucociliary clearance, presence of deteriorating enzymes, pH extremes (GIT), low permeation and metabolic degradation limit the mucosal delivery of vaccine. Numerous strategies have been explored in the meadow of mucosal vaccination for the purpose of efficient antigen delivery through mucosal route(s). Polymeric carrier(s) such as nanoparticles and microparticles loaded with the antigen can serve as the basis for creation of important formulations for improved vaccine. Biodegradable and mucoadhesive polymeric carrier(s) seems to be most promising candidate for mucosal vaccine delivery. Several polymers from natural and synthetic origin, such as polylactide-co-glycolide, chitosan, alginate, carbopol, gelatin etc., have been explored for the efficient mucosal vaccine delivery and significant results have been obtained. This review outlines the polymers used in mucosal vaccine delivery with special reference to mucoadhesive/biodegradable polymers. This article also covers the recent patent granted in the field on polymeric carrier mediated mucosal vaccination.

  5. The Recent Developments in Biobased Polymers toward General and Engineering Applications: Polymers that Are Upgraded from Biodegradable Polymers, Analogous to Petroleum-Derived Polymers, and Newly Developed

    OpenAIRE

    Nakajima, Hajime; Dijkstra, Peter; Loos, Katja

    2017-01-01

    The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering applications. This expansion is driven by the remarkable progress in the processes for refining biomass feedstocks to produce biobased building blocks that allow biobased polymers to have more versati...

  6. Layered plasma polymer composite membranes

    Science.gov (United States)

    Babcock, Walter C.

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  7. Imaging the intracellular degradation of biodegradable polymer nanoparticles

    Directory of Open Access Journals (Sweden)

    Anne-Kathrin Barthel

    2014-10-01

    Full Text Available In recent years, the development of smart drug delivery systems based on biodegradable polymeric nanoparticles has become of great interest. Drug-loaded nanoparticles can be introduced into the cell interior via endocytotic processes followed by the slow release of the drug due to degradation of the nanoparticle. In this work, poly(L-lactic acid (PLLA was chosen as the biodegradable polymer. Although common degradation of PLLA has been studied in various biological environments, intracellular degradation processes have been examined only to a very limited extent. PLLA nanoparticles with an average diameter of approximately 120 nm were decorated with magnetite nanocrystals and introduced into mesenchymal stem cells (MSCs. The release of the magnetite particles from the surface of the PLLA nanoparticles during the intracellular residence was monitored by transmission electron microscopy (TEM over a period of 14 days. It was demonstrated by the release of the magnetite nanocrystals from the PLLA surface that the PLLA nanoparticles do in fact undergo degradation within the cell. Furthermore, even after 14 days of residence, the PLLA nanoparticles were found in the MSCs. Additionally, the ultrastructural TEM examinations yield insight into the long term intercellular fate of these nanoparticles. From the statistical analysis of ultrastructural details (e.g., number of detached magnetite crystals, and the number of nanoparticles in one endosome, we demonstrate the importance of TEM studies for such applications in addition to fluorescence studies (flow cytometry and confocal laser scanning microscopy.

  8. Micro fabrication of biodegradable polymer drug delivery devices

    DEFF Research Database (Denmark)

    Nagstrup, Johan

    . Furthermore, they are often degraded before they can be absorbed. The result is low bioavailability of the drugs. To overcome these challenges, better drug delivery systems need to be developed. Recently, micro systems have emerged as promising candidates to solve the challenges of poor solubility, low......The pharmaceutical industry is presently facing several obstacles in developing oral drug delivery systems. This is primarily due to the nature of the discovered drug candidates. The discovered drugs often have poor solubility and low permeability across the gastro intestinal epithelium...... permeability and degradation. These systems are for the majority based on traditional materials used in micro technology, such as SU-8, silicon, poly(methyl methacrylate). The next step in developing these new drug delivery systems is to replace classical micro fabrication materials with biodegradable polymers...

  9. Sintered iron biodegradable materials modified by polymer coating

    International Nuclear Information System (INIS)

    Gorejova, R.; Markusova-Buckova, L.; Orinakova, R.

    2017-01-01

    Devices made from biodegradable materials become a promising alternative to a permanent orthopedic implants. Temporary scaffolds made from these materials can provide desirable results in tissue healing and gradually dissolve in vivo by corrosion processes. This work is dedicated to preparation of iron based metallic structures prepared by powder metallurgy which were modified by polyethyleneglycol (PEG) coatings in different concentration. Corrosion behaviour of the prepared samples was observed in the form of static corrosion and dynamic corrosion in Hank's solution. Results show that the rate of degradation of polymer coated samples was greater than rate of degradation of pure iron. The highest rate of degradation was observed in porous structure covered with PEG with a concentration of 10 wt. %. (authors)

  10. Graphene-polymer composites

    Science.gov (United States)

    Carotenuto, G.; Romeo, V.; Cannavaro, I.; Roncato, D.; Martorana, B.; Gosso, M.

    2012-09-01

    Graphene is a novel nanostructured material that can be conveniently used as filler for thermoplastic polymers or thermosetting resins, and the resulting nanocomposite material has unique mechanical and chemical/physical properties. Industrial production of graphene/polymer materials requires the availability of a chemical route to produce massive amount of graphene. Natural graphite flakes can be the best starting material for a bulk-production of graphene to be used in the polymeric nanocomposite preparation.

  11. Biolimus-eluting biodegradable polymer-coated stent versus durable polymer-coated sirolimus-eluting stent in unselected patients receiving percutaneous coronary intervention (SORT OUT V)

    DEFF Research Database (Denmark)

    Christiansen, Evald Høj; Jensen, Lisette Okkels; Thayssen, Per

    2013-01-01

    Third-generation biodegradable polymer drug-eluting stents might reduce the risk of stent thrombosis compared with first-generation permanent polymer drug-eluting stents. We aimed to further investigate the effects of a biodegradable polymer biolimus-eluting stent compared with a durable polymer...

  12. Biodegradability of PP/HMSPP and natural and synthetic polymers blends in function of gamma irradiation degradation

    Science.gov (United States)

    Cardoso, Elisabeth C. L.; Scagliusi, Sandra R.; Lima, Luis F. C. P.; Bueno, Nelson R.; Brant, Antonio J. C.; Parra, Duclerc F.; Lugão, Ademar B.

    2014-01-01

    Polymers are used for numerous applications in different industrial segments, generating enormous quantities of discarding in the environment. Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. Polypropylene (PP) undergoes crosslinking and extensive main chain scissions when submitted to ionizing irradiation; as one of the most widely used linear hydrocarbon polymers, PP, made from cheap petrochemical feed stocks, shows easy processing leading it to a comprehensive list of finished products. Consequently, there is accumulation in the environment, at 25 million tons per year rate, since polymeric products are not easily consumed by microorganisms. PP polymers are very bio-resistant due to involvement of only carbon atoms in main chain with no hydrolysable functional group. Several possibilities have been considered to minimize the environmental impact caused by non-degradable plastics, subjecting them to: physical, chemical and biological degradation or combination of all these due to the presence of moisture, air, temperature, light, high energy radiation or microorganisms. There are three main classes of biodegradable polymers: synthetic polymers, natural polymers and blends of polymers in which one or more components are readily consumed by microorganisms. This work aims to biodegradability investigation of a PP/HMSPP (high melt strength polypropylene) blended with sugarcane bagasse, PHB (poly-hydroxy-butyrate) and PLA (poly-lactic acid), both synthetic polymers, at a 10% level, subjected to gamma radiation at 50, 100, 150 and 200 kGy doses. Characterization will comprise IR, DSC, TGA, OIT and Laboratory Soil Burial Test (LSBT).

  13. Carbon nanotube-polymer composite actuators

    Science.gov (United States)

    Gennett, Thomas [Denver, CO; Raffaelle, Ryne P [Honeoye Falls, NY; Landi, Brian J [Rochester, NY; Heben, Michael J [Denver, CO

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  14. Implantable biodegradable polymers for radiosensitization of human glioma in vivo

    International Nuclear Information System (INIS)

    Williams, Jeffery; Dillehay, Larry E.; Sipos, Eric; Fahlman, Christian; Tabassi, Kevin; Williams, Jerry; Wharam, Moody; Brem, Henry

    1995-01-01

    Purpose: The potential of halogenated pyrimidines to radiosensitize human gliomas remains unrealized. Higher local delivery and lower systemic exposure may improve the therapeutic ratio. Synthetic, implantable, biodegradable polyanhydride polymers allow local, controlled, and sustained release of therapeutic agents. Their role in radiosensitization of tumors remains unexplored, however. Materials and Methods: In vitro: To measure release, increasing (10%, 30%, 50%) proportions of 5-iodo-2'-deoxyuridine (IUdR) in synthetic [(poly(bis(p-carboxyphenoxy)-propane) (PCPP):sebacic acid (SA) (PCPP:SA ratio 20:80)]polymers (ca. 10 mg; 1x1x3 mm) were incubated (1 ml PBS, 37 deg. C) and the supernatants serially assayed using HPLC. To measure modulation of release by a second, inert, co-loaded compound, 5-125-I-2'-deoxyuridine (125-IUdR) and increasing (10%, 30%, or 50%) proportions of D-glucose were combined in polymers, incubated in PBS, and the supernatants assayed. To test radiosensitization, cells (U251 human malignant glioma) were sequentially exposed to increasing (0, 0.1, 1.0, or 10 uM) concentrations of IUdR and increasing (0, 2.5, 5.0, or 10 Gy) doses of acute radiation. In vivo: To measure release, polymers bearing 125-IUdR were surgically placed in U251 xenografts (0.1 - 0.2 cc) growing in flanks of nude mice. The flanks bearing the tumors and polymers were reproducibly positioned over a collimated scintillation detector and counted. To measure radiosensitization, polymers bearing no (blank) or 50% unlabeled IUdR were placed in the tumor or contralateral flank. After three days tumors were acutely irradiated (500 cGy x 2 daily fractions). Results: In vitro: The initial rates of release of IUdR from polymers were high regardless of the percentage loading of IUdR, while the subsequent rates of release were proportionate to the percentage loading. The percentages of loaded IUdR recovered were 21.5, 23.3, and 18.7% in 6 h and 57.0, 73.5, and 92.4% after 11 days for 10

  15. JTEC monograph on biodegradable polymers and plastics in Japan: Research, development, and applications

    Science.gov (United States)

    Lenz, Robert W.

    1995-01-01

    A fact-finding team of American scientists and engineers visited Japan to assess the status of research and development and applications in biodegradable polymers. The visit was sponsored by the National Science Foundation and industry. In Japan, the team met with representatives of 31 universities, government ministries and institutes, companies, and associations. Japan's national program on biodegradable polymers and plastics evaluates new technologies, testing methods, and potential markets for biodegradables. The program is coordinated by the Biodegradable Plastics Society of Japan, which seeks to achieve world leadership in biodegradable polymer technology and identify commercial opportunities for exploiting this technology. The team saw no major new technology breakthroughs. Japanese scientists and engineers are focusing on natural polymers from renewable resources, synthetic polymers, and bacterially-produced polymers such as polyhydroxyalkanoates, poly(amino acids), and polysaccharides. The major polymers receiving attention are the Zeneca PHBV copolymers, Biopol(registered trademark), poly(lactic acid) from several sources, polycaprolactone, and the new synthetic polyester, Bionolle(registered trademark), from Showa High Polymer. In their present state of development, these polymers all have major deficiencies that inhibit their acceptance for large-scale applications.

  16. The SYNERGY biodegradable polymer everolimus eluting coronary stent: Porcine vascular compatibility and polymer safety study.

    Science.gov (United States)

    Wilson, Gregory J; Marks, Angela; Berg, Kimberly J; Eppihimer, Michael; Sushkova, Natalia; Hawley, Steve P; Robertson, Kimberly A; Knapp, David; Pennington, Douglas E; Chen, Yen-Lane; Foss, Aaron; Huibregtse, Barbara; Dawkins, Keith D

    2015-11-15

    SYNERGY is a novel platinum chromium alloy stent that delivers abluminal everolimus from an ultrathin poly-lactide-co-glycide (PLGA) biodegradable polymer. This study evaluated the in vivo degradation of the polymer coating, everolimus release time course, and vascular compatibility of the SYNERGY stent. SYNERGY stents were implanted in arteries of domestic swine. Devices were explanted at predetermined time points (up to 120 days) and the extent of PLGA coating or everolimus remaining on the stents was quantified. Everolimus levels in the arterial tissue were also evaluated. A pathological analysis on coronary arteries of single and overlapping stents was performed at time points between 5 and 270 days. PLGA bioabsorption began immediately after implantation, and drug release was essentially complete by 90 days; PLGA absorption was substantially complete by 120 days (>90% of polymer was absorbed) leaving a bare metal SYNERGY stent. Vascular response was similar among SYNERGY and control stents (bare metal, polymer-only, and 3× polymer-only). Mild increases in para-strut fibrin were seen for SYNERGY at an early time point with no significant differences in all other morphological and morphometric parameters through 270 days or endothelial function (eNOS immunostaining) at 90 or 180 days. Inflammation was predominantly minimal to mild for all device types. In a swine model, everolimus was released by 90 days and PLGA bioabsorption was complete shortly thereafter. The SYNERGY stent and its biodegradable polymer, even at a 3× safety margin, demonstrated vascular compatibility similar to bare metal stent controls. © 2015 Wiley Periodicals, Inc.

  17. Rice Husk Filled Polymer Composites

    Directory of Open Access Journals (Sweden)

    Reza Arjmandi

    2015-01-01

    Full Text Available Natural fibers from agricultural wastes are finding their importance in the polymer industry due to the many advantages such as their light weight, low cost and being environmentally friendly. Rice husk (RH is a natural sheath that forms around rice grains during their growth. As a type of natural fiber obtained from agroindustrial waste, RH can be used as filler in composites materials in various polymer matrices. This review paper is aimed at highlighting previous works of RH filled polymer composites to provide information for applications and further research in this area. Based on the information gathered, application of RH filled composites as alternative materials in building and construction is highly plausible with both light weight and low cost being their main driving forces. However, further investigations on physical and chemical treatment to further improve the interfacial adhesion with polymeric matrix are needed as fiber-polymer interaction is crucial in determining the final composite properties. Better understanding on how the used polymer blends as the matrix and secondary fillers may affect the properties would provide interesting areas to be explored.

  18. Polyester-Based (Bio)degradable Polymers as Environmentally Friendly Materials for Sustainable Development

    Science.gov (United States)

    Rydz, Joanna; Sikorska, Wanda; Kyulavska, Mariya; Christova, Darinka

    2014-01-01

    This review focuses on the polyesters such as polylactide and polyhydroxyalkonoates, as well as polyamides produced from renewable resources, which are currently among the most promising (bio)degradable polymers. Synthetic pathways, favourable properties and utilisation (most important applications) of these attractive polymer families are outlined. Environmental impact and in particular (bio)degradation of aliphatic polyesters, polyamides and related copolymer structures are described in view of the potential applications in various fields. PMID:25551604

  19. Polymer compositions and methods

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Scott D.; Willkomm, Wayne R.

    2018-02-06

    The present invention encompasses polyurethane compositions comprising aliphatic polycarbonate chains. In one aspect, the present invention encompasses polyurethane foams, thermoplastics and elastomers derived from aliphatic polycarbonate polyols and polyisocyanates wherein the polyol chains contain a primary repeating unit having a structure: ##STR00001## In another aspect, the invention provides articles comprising the inventive foam and elastomer compositions as well as methods of making such compositions.

  20. Polymer compositions and methods

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Scott D.; Willkomm, Wayne R.

    2016-09-27

    The present invention encompasses polyurethane compositions comprising aliphatic polycarbonate chains. In one aspect, the present invention encompasses polyurethane foams, thermoplastics and elastomers derived from aliphatic polycarbonate polyols and polyisocyanates wherein the polyol chains contain a primary repeating unit having a structure: ##STR00001## In another aspect, the invention provides articles comprising the inventive foam and elastomer compositions as well as methods of making such compositions.

  1. Preparation and Characterization of PLA-Starch Biodegradable Composites Via Radiation Processing

    International Nuclear Information System (INIS)

    Hemvichian, K.; Suwanmala, P.; Kungsumrith, W.; Pongprayoon, T.

    2011-01-01

    This research project aims to apply the use of radiation processing to prepare biodegradable composites from poly(lactic acid) or polylactide (PLA) and cassava starch. Cassava starch, a natural polymer that is inexpensive and abundant, especially in Thailand, will be used as starting material. Functional group of cassava starch will be modified first in order to render starch more compatible with PLA. The monomer with desired functional groups will be grafted onto the backbone of starch via radiation-induced grafting polymerization. Different parameters will be examined to determine the optimum conditions for the grafting polymerization. The modified starch will subsequently be blended with PLA, with and without clay, to form biodegradable composites. In order to further improve the thermal properties, the blends and their composites will be subjected to radiation to induce crosslinking between the molecules of PLA and starch derivatives. (author)

  2. Biodegradability of PP/HMSPP and natural and synthetic polymers blends in function of gamma irradiation degradation

    International Nuclear Information System (INIS)

    Cardoso, Elisabeth C.L.; Scagliusi, Sandra R.; Lima, Luis F.C.P.; Bueno, Nelson R.; Brant, Antonio J.C.; Parra, Duclerc F.; Lugão, Ademar B.

    2014-01-01

    Polymers are used for numerous applications in different industrial segments, generating enormous quantities of discarding in the environment. Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. Polypropylene (PP) undergoes crosslinking and extensive main chain scissions when submitted to ionizing irradiation; as one of the most widely used linear hydrocarbon polymers, PP, made from cheap petrochemical feed stocks, shows easy processing leading it to a comprehensive list of finished products. Consequently, there is accumulation in the environment, at 25 million tons per year rate, since polymeric products are not easily consumed by microorganisms. PP polymers are very bio-resistant due to involvement of only carbon atoms in main chain with no hydrolysable functional group. Several possibilities have been considered to minimize the environmental impact caused by non-degradable plastics, subjecting them to: physical, chemical and biological degradation or combination of all these due to the presence of moisture, air, temperature, light, high energy radiation or microorganisms. There are three main classes of biodegradable polymers: synthetic polymers, natural polymers and blends of polymers in which one or more components are readily consumed by microorganisms. This work aims to biodegradability investigation of a PP/HMSPP (high melt strength polypropylene) blended with sugarcane bagasse, PHB (poly-hydroxy-butyrate) and PLA (poly-lactic acid), both synthetic polymers, at a 10% level, subjected to gamma radiation at 50, 100, 150 and 200 kGy doses. Characterization will comprise IR, DSC, TGA, OIT and Laboratory Soil Burial Test (LSBT). - Highlights: • Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. • Landfills will not be enough for an estimated accumulation of 25 million tons per year of plastics. • Incorporation of natural/synthetic polymers in PP/HMSPP to reduce

  3. Carbon-rich wastes as feedstocks for biodegradable polymer (polyhydroxyalkanoate) production using bacteria.

    Science.gov (United States)

    Nikodinovic-Runic, Jasmina; Guzik, Maciej; Kenny, Shane T; Babu, Ramesh; Werker, Alan; O Connor, Kevin E

    2013-01-01

    Research into the production of biodegradable polymers has been driven by vision for the most part from changes in policy, in Europe and America. These policies have their origins in the Brundtland Report of 1987, which provides a platform for a more sustainable society. Biodegradable polymers are part of the emerging portfolio of renewable raw materials seeking to deliver environmental, social, and economic benefits. Polyhydroxyalkanoates (PHAs) are naturally-occurring biodegradable-polyesters accumulated by bacteria usually in response to inorganic nutrient limitation in the presence of excess carbon. Most of the early research into PHA accumulation and technology development for industrial-scale production was undertaken using virgin starting materials. For example, polyhydroxybutyrate and copolymers such as polyhydroxybutyrate-co-valerate are produced today at industrial scale from corn-derived glucose. However, in recent years, research has been undertaken to convert domestic and industrial wastes to PHA. These wastes in today's context are residuals seen by a growing body of stakeholders as platform resources for a biobased society. In the present review, we consider residuals from food, plastic, forest and lignocellulosic, and biodiesel manufacturing (glycerol). Thus, this review seeks to gain perspective of opportunities from literature reporting the production of PHA from carbon-rich residuals as feedstocks. A discussion on approaches and context for PHA production with reference to pure- and mixed-culture technologies is provided. Literature reports advocate results of the promise of waste conversion to PHA. However, the vast majority of studies on waste to PHA is at laboratory scale. The questions of surmounting the technical and political hurdles to industrialization are generally left unanswered. There are a limited number of studies that have progressed into fermentors and a dearth of pilot-scale demonstration. A number of fermentation studies show

  4. Carbon recovery from wastewater through bioconversion into biodegradable polymers.

    Science.gov (United States)

    Valentino, Francesco; Morgan-Sagastume, Fernando; Campanari, Sabrina; Villano, Marianna; Werker, Alan; Majone, Mauro

    2017-07-25

    Polyhydroxyalkanoates (PHA) are biodegradable polyesters that can be produced in bioprocesses from renewable resources in contrast to fossil-based bio-recalcitrant polymers. Research efforts have been directed towards establishing technical feasibility in the use of mixed microbial cultures (MMC) for PHA production using residuals as feedstock, mainly consisting of industrial process effluent waters and wastewaters. In this context, PHA production can be integrated with waste and wastewater biological treatment, with concurrent benefits of resource recovery and sludge minimization. Over the past 15 years, much of the research on MMC PHA production has been performed at laboratory scale in three process elements as follows: (1) acidogenic fermentation to obtain a volatile fatty acid (VFA)-rich stream, (2) a dedicated biomass production yielding MMCs enriched with PHA-storing potential, and (3) a PHA accumulation step where (1) and (2) outputs are combined in a final biopolymer production bioprocess. This paper reviews the recent developments on MMC PHA production from synthetic and real wastewaters. The goals of the critical review are: a) to highlight the progress of the three-steps in MMC PHA production, and as well to recommend room for improvements, and b) to explore the ideas and developments of integration of PHA production within existing infrastructure of municipal and industrial wastewaters treatment. There has been much technical advancement of ideas and results in the MMC PHA rich biomass production. However, clear demonstration of production and recovery of the polymers within a context of product quality over an extended period of time, within an up-scalable commercially viable context of regional material supply, and with well-defined quality demands for specific intent of material use, is a hill that still needs to be climbed in order to truly spur on innovations for this field of research and development. Copyright © 2016 Elsevier B.V. All rights

  5. Poly(ɛ-caprolactone) composites reinforced by biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fiber.

    Science.gov (United States)

    Ju, Dandan; Han, Lijing; Li, Fan; Chen, Shan; Dong, Lisong

    2014-06-01

    Biodegradable and biosourced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fiber was used as a reinforcing agent, and environment friendly poly(ɛ-caprolactone) (PCL) composites were prepared by melt compounding. The mechanical properties, rheological properties, and enzymatic degradation of the PCL composites were investigated in detail. With the addition of PHBV fibers, the PCL composites showed increased tensile yielding strength and modulus. Especially, the storage modulus from the results of dynamic mechanical analysis was increased significantly, suggesting that PCL was obviously reinforced by adding PHBV fibers. With increasing the PHBV fiber content, the complex viscosity and modulus of PCL increased, especially at low frequencies, indicating that a network structure was formed in the composites. The network structure resulted in evident solid-like response due to the restriction of the chain mobility of PCL matrix, which was further confirmed by the Han and Cole-Cole plots. The morphology, evaluated by scanning electron microscopy, indicated PCL and PHBV fiber were not highly incompatible and the interfacial adhesion was good, which was beneficial to the reinforcement effect. The biodegradability of the PCL was significantly promoted after composites preparation. Such studies are of great interest in the development of environment friendly composites from biodegradable polymers. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Poly (1,8 Octanediol-co-Citrate) Hydroxyapatite Composite as Antibacterial Biodegradable Bone Screw

    Science.gov (United States)

    Widiyanti, P.; Sholikhah, I.; Isfandiary, A.; Hasbiyani, NAF; Lazuardi, M. B.; Laksana, R. D.

    2017-05-01

    The high bone fracture rates reaching up to 300-400 cases per month have been treated with surgical procedure of internal fixation. Nevertheless, the commonly used metal screw has shown several weaknesses. Therefore, it is required bone screw of which primary characteristics include being biocompatible, bio-functional, biodegradable, and anticorrosive. The study aimed to synthesize Antibacterial Poly 1,8-Octanediol-co-Citrate (POC) and investigated the effect of chitosan on the antibacterial and compatibility characteristics of POC-HA composite as antibacterial biodegradable bone screw. The characterization were conducted on POC-HA composite to assess its functional cluster, antibacterial activity, cytotoxicity, degradation capacity, and morphology. Pre-polymer POC was composited with 62% nano-HA, followed by post-polymerization treatment. The sample then coated by chitosan with composition variations of 1%, 3%, and 5%. The nano-HA marked with the appearance of phosphate cluster on the wavenumber of 872.17 cm-1 and 559.51 cm-1, while the chitosan marked with C=O stretch cluster of esther at 1729 cm-1 from Fourier Transform Infra-Red (FTIR) measurement. The best result was obtained with 3% chitosan coating. The POC-HA composites showed bacterial inhibiting ability of 16.92 mm with non-toxic characteristics. These results indicated that chitosan coating Poly 1,8-Octanediol-co-Citrate (POC)-Nano Hydroxyapatite composite is a potential candidate for an antibacterial biodegradable bone screw.

  7. Shape-Memory Polymer Composites

    Science.gov (United States)

    Madbouly, Samy A.; Lendlein, Andreas

    The development of shape-memory polymer composites (SMPCs) enables high recovery stress levels as well as novel functions such as electrical conductivity, magnetism, and biofunctionality. In this review chapter the substantial enhancement in mechanical properties of shape-memory polymers (SMPs) by incorporating small amounts of stiff fillers will be highlighted exemplarily for clay and polyhedral oligomeric silsesquioxanes (POSS). Three different functions resulting from adding functional fillers to SMP-matrices will be introduced and discussed: magnetic SMPCs with different types of magnetic nanoparticles, conductive SMPCs based on carbon nanotubes (CNTs), carbon black (CB), short carbon fiber (SCF), and biofunctional SMPCs containing hydroxyapatite (HA). Indirect induction of the shape-memory effect (SME) was realized for magnetic and conductive SMPCs either by exposure to an alternating magnetic field or by application of electrical current. Major challenges in design and fundamental understanding of polymer composites are the complexity of the composite structure, and the relationship between structural parameters and properties/functions, which is essential for tailoring SMPCs for specific applications. Therefore the novel functions and enhanced properties of SMPCs will be described considering the micro-/nanostructural parameters, such as dimension, shape, distribution, volume fraction, and alignment of fillers as well as interfacial interaction between the polymer matrix and dispersed fillers. Finally, an outlook is given describing the future challenges of this exciting research field as well as potential applications including automotive, aerospace, sensors, and biomedical applications.

  8. Graphene reinforced biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate nano-composites

    Directory of Open Access Journals (Sweden)

    V. Sridhar

    2013-04-01

    Full Text Available Novel biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate [PHBV]/graphene nanocomposites were prepared by solution casting. The thermal properties, crystallization behavior, microstructure, and fracture morphology of the composites were investigated. Scanning electron microscope (SEM results show that graphene layers are homogeneously dispersed in the polymer matrix. X-ray diffraction (XRD and dynamic scanning calorimetry (DSC studies show that the well dispersed graphene sheets act as nucleating agent for crystallization. Consequently, the mechanical properties of the composites have been substantially improved as evident from dynamic mechanical and static tensile tests. Differential thermal analysis (DTA showed an increase in temperature of maximum degradation. Soil degradation tests of PHBV/graphene nanocomposites showed that presence of graphene doesn’t interfere in its biodegradability.

  9. Influence of anionic monomer content on the biodegradation and toxicity of polyvinyl-urethane carbonate-ceramic interpenetrating phase composites.

    Science.gov (United States)

    Yang, Liu; Hong, Jason; Wang, Jian; Pilliar, Robert M; Santerre, J Paul

    2005-10-01

    The objective of this study was to characterize a series of anionic biodegradable polymer resins for their compatibility in a biological environment, comparing them with respect to the influence of ionic function on enzyme catalyzed biodegradation when the polymers were incorporated into a porous calcium polyphosphate (CPP) 3-D structure to form an interpenetrating phase composite (IPC). The swelling behavior of the polymers was investigated by immersing the cured polymer resins in growth media at 37 degrees C. In vitro cytotoxicity of the polymer resins was assessed using a HeLa cell line. Cell viability increased when the amount of low molecular weight monomer was minimized. Despite observing that the addition of carboxylic acid groups into the polymer resin chains contributed to an improvement of the chemical bonding between the polymer and the CPP, the addition of high ionic content into the resin led to the greatest loss of bending strength for the samples incubated in phosphate buffer and cholesterol esterase enzyme solutions, when compared to their as made state. The increased degradation for the higher ionic component materials and their loss of physical strength was attributed to enhanced hydrolysis within the materials and by water transport deep within the composites, via the anionic components of the resin. The findings indicated that the introduction of anionic content must be optimized to promote increased mechanical performance for the CPP, balancing the features of polymer CPP bonding versus polymer swelling and cytotoxicity.

  10. Polymer-composite ball lightning.

    Science.gov (United States)

    Bychkov, V L

    2002-01-15

    Investigations into the state of ball lightning (BL) have been made, and both theory and experiments, related to so-called "polymer-composite" ball lightning, are presented. The properties of such a polymeric BL have been described and are that of a long-lived object capable of storing high energy. Results of experiments, starting with polymeric components in erosive gas discharge experiments, are described and discussed. The model of BL as a highly charged polymer-dielectric structure is described. According to this model BL appears as the result of the aggregation of natural polymers, such as lignin and cellulose, soot, polymeric silica and other natural dust particles. Its ability to glow is explained by the appearance over its perimeter of gas discharges near the highly charged BL surface, and electrical breakdown of some regions on the surface, consisting of polymerized and aggregated threads.

  11. Modelling anisotropic water transport in polymer composite ...

    Indian Academy of Sciences (India)

    and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation models were determined by least-square curve fitting to the experimental data. Diffusion parameters of epoxy and vinyl ester resin were used as input during development of finite element (FE) model of polymer composite.

  12. Modelling anisotropic water transport in polymer composite

    Indian Academy of Sciences (India)

    This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation models were ...

  13. Modelling anisotropic water transport in polymer composite ...

    Indian Academy of Sciences (India)

    Abstract. This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation ...

  14. Effects of Ultraviolet Photon Irradiation on the Dielectric Properties of Biodegradable Polymers

    Science.gov (United States)

    Yamaguchi, Yuya; Uchibori, Nao; Ohki, Yoshimichi

    Three kinds of biodegradable polymers, poly-L-lactic acid (PLLA), polybutylene succinate (PBS), and polybutylene succinate adipate (PBSA), and low-density polyethylene (LDPE) as a reference were irradiated for 30 minutes by ultraviolet (UV) photons from a KrCl excimer lamp. It has become clear that the three biodegradable polymers are far more susceptible to UV photons than LDPE since they absorb UV photons very intensely in the vicinity of the irradiated surface. Space charge distribution profiles show that charge carriers are trapped near the irradiated surface. The conduction current increases by the UV-irradiation in all the biodegradable polymers. Instrumental analyses show that the samples were decomposed by photoinduced oxidation. Furthermore, the absorption spectra indicate the appearance of conjugated double bonds. Such structural changes induced seem to be responsible for the higher conductivity and the charge trapping.

  15. Development and characterization of biodegradable polymer blends - PHBV/PCL irradiated with gamma rays

    International Nuclear Information System (INIS)

    Rosario, F.; Casarin, S.A.; Agnelli, J.A.M.; Souza Junior, O.F. de

    2010-01-01

    This paper presents the results of a study that aimed to develop PHBV biodegradable polymer blends, in a major concentration with PCL, irradiate the pure polymers and blends in two doses of gamma radiation and to analyze the changes in chemical and mechanical properties. The blends used in this study were from natural biodegradable copolymer poly (hydroxybutyrate-valerate) (PHBV) and synthetic biodegradable polymer poly (caprolactone) (PCL 2201) with low molar mass (2,000 g/mol). Several samples were prepared in a co-rotating twin-screw extruder and afterwards, the tensile specimens were injected for the irradiation treatment with 50 kGy to 100 kGy doses and for the mechanical tests. The characterization of the samples before and after the irradiation treatments was performed through scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and mechanical tensile tests. (author)

  16. Spectroscopic study on the in vitro degradation of a biodegradable composite periodontal membrane

    Science.gov (United States)

    Taddei, P.; Simoni, R.; Fini, G.

    2001-05-01

    The hydrolithic in vitro degradation of a commercial biodegradable hydroxyapatite (HA)-polymer (poly(ɛ-caprolactone)-poly(oxyethylene)-poly(ɛ-caprolactone) block copolymer, PCL-POE-PCL) composite membrane was investigated by Raman and IR spectroscopies in three aqueous media at 37°C; 0.01 M NaOH solution, saline phosphate buffer (SPB) at pH 7.4 and simulated body fluid (SBF) buffered at pH 7.5. The vibrational results showed that the polymeric component undergoes preferential degradation of POE blocks while HA is removed by the degradation media faster than the polymer. Vibrational spectroscopy appeared to be a valid non-destructive method for investigating the degradation mechanism of the composite membrane.

  17. Sago Starch-Mixed Low-Density Polyethylene Biodegradable Polymer: Synthesis and Characterization

    Directory of Open Access Journals (Sweden)

    Md Enamul Hoque

    2013-01-01

    Full Text Available This research focuses on synthesis and characterization of sago starch-mixed LDPE biodegradable polymer. Firstly, the effect of variation of starch content on mechanical property (elongation at break and Young’s modulus and biodegradability of the polymer was studied. The LDPE was combined with 10%, 30%, 50%, and 70% of sago for this study. Then how the cross-linking with trimethylolpropane triacrylate (TMPTA and electron beam (EB irradiation influence the mechanical and thermal properties of the polymer was investigated. In the 2nd study, to avoid overwhelming of data LDPE polymer was incorporated with only 50% of starch. The starch content had direct influence on mechanical property and biodegradability of the polymer. The elongation at break decreased with increase of starch content, while Young’s modulus and mass loss (i.e., degradation were found to increase with increase of starch content. Increase of cross-linker (TMPTA and EB doses also resulted in increased Young’s modulus of the polymer. However, both cross-linking and EB irradiation processes rendered lowering of polymer’s melting temperature. In conclusion, starch content and modification processes play significant roles in controlling mechanical, thermal, and degradation properties of the starch-mixed LDPE synthetic polymer, thus providing the opportunity to modulate the polymer properties for tailored applications.

  18. Nanocomposite bone scaffolds based on biodegradable polymers and hydroxyapatite.

    Science.gov (United States)

    Becker, Johannes; Lu, Lichun; Runge, M Brett; Zeng, Heng; Yaszemski, Michael J; Dadsetan, Mahrokh

    2015-08-01

    In tissue engineering, development of an osteoconductive construct that integrates with host tissue remains a challenge. In this work, the effect of bone-like minerals on maturation of pre-osteoblast cells was investigated using polymer-mineral scaffolds composed of poly(propylene fumarate)-co-poly(caprolactone) (PPF-co-PCL) and nano-sized hydroxyapatite (HA). The HA of varying concentrations was added to an injectable formulation of PPF-co-PCL and the change in thermal and mechanical properties of the scaffolds was evaluated. No change in onset of degradation temperature was observed due to the addition of HA, however compressive and tensile moduli of copolymer changed significantly when HA amounts were increased in composite formulation. The change in mechanical properties of copolymer was found to correlate well to HA concentration in the constructs. Electron microscopy revealed mineral nucleation and a change in surface morphology and the presence of calcium and phosphate on surfaces was confirmed using energy dispersive X-ray analysis. To characterize the effect of mineral on attachment and maturation of pre-osteoblasts, W20-17 cells were seeded on HA/copolymer composites. We demonstrated that cells attached more to the surface of HA containing copolymers and their proliferation rate was significantly increased. Thus, these findings suggest that HA/PPF-co-PCL composite scaffolds are capable of inducing maturation of pre-osteoblasts and have the potential for use as scaffold in bone tissue engineering. © 2014 Wiley Periodicals, Inc.

  19. Composites incorporated a conductive polymer nanofiber network

    Science.gov (United States)

    Pozzo, Lilo Danielle; Newbloom, Gregory

    2017-04-11

    Methods of forming composites that incorporate networks of conductive polymer nanofibers are provided. Networks of less-than conductive polymers are first formed and then doped with a chemical dopant to provide networks of conductive polymers. The networks of conductive polymers are then incorporated into a matrix in order to improve the conductivity of the matrix. The formed composites are useful as conductive coatings for applications including electromagnetic energy management on exterior surfaces of vehicles.

  20. Integrated transformations of plant biomass to valuable chemicals, biodegradable polymers and nanoporous carbons

    Science.gov (United States)

    Kuznetsov, B. N.; Chesnokov, N. V.; Taraban'ko, V. E.; Kuznetsova, S. A.; Petrov, A. V.

    2013-03-01

    Integrated transformations of wood biomass to valuable chemicals and materials are described. They include the main biomass components separation, the conversion of cellulose to glucose, levulinic acid, biodegradable polymers and lignin - to nanoporous carbons. For wood fractionation on pure cellulose and low molecular mass lignin the methods of catalytic oxidation and exploded autohydrolysis are used. The processes of acid-catalysed hydrolysis of cellulose to glucose and levulinic acid were optimized. New methods of biodegradable polymers synthesis from lactone of levulinic acid and nanoporous carbons from lignin were suggested.

  1. Effect of chemical heterogeneity of biodegradable polymers on surface energy: A static contact angle analysis of polyester model films

    Energy Technology Data Exchange (ETDEWEB)

    Belibel, R.; Avramoglou, T. [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Garcia, A. [CNRS UPR 3407, Laboratoire des Sciences des Procédés et des Matériau, Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Barbaud, C. [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Mora, L., E-mail: Laurence.mora@univ-paris13.fr [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France)

    2016-02-01

    Biodegradable and bioassimilable poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) derivatives were synthesized and characterized in order to develop a new coating for coronary endoprosthesis enabling the reduction of restenosis. The PDMMLA was chemically modified to form different custom groups in its side chain. Three side groups were chosen: the hexyl group for its hydrophobic nature, the carboxylic acid and alcohol groups for their acid and neutral hydrophilic character, respectively. The sessile drop method was applied to characterize the wettability of biodegradable polymer film coatings. Surface energy and components were calculated. The van Oss approach helped reach not only the dispersive and polar acid–base components of surface energy but also acid and basic components. Surface topography was quantified by atomic force microscopy (AFM) and subnanometer average values of roughness (Ra) were obtained for all the analyzed surfaces. Thus, roughness was considered to have a negligible effect on wettability measurements. In contrast, heterogeneous surfaces had to be corrected by the Cassie–Baxter equation for copolymers (10/90, 20/80 and 30/70). The impact of this correction was quantified for all the wettability parameters. Very high relative corrections (%) were found, reaching 100% for energies and 30% for contact angles. - Highlights: • We develop different polymers with various chemical compositions. • Wettability properties were calculated using Cassie corrected contact angles. • Percentage of acid groups in polymers is directly correlated to acid part of SFE. • Cassie corrections are necessary for heterogeneous polymers.

  2. Effect of chemical heterogeneity of biodegradable polymers on surface energy: A static contact angle analysis of polyester model films

    International Nuclear Information System (INIS)

    Belibel, R.; Avramoglou, T.; Garcia, A.; Barbaud, C.; Mora, L.

    2016-01-01

    Biodegradable and bioassimilable poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) derivatives were synthesized and characterized in order to develop a new coating for coronary endoprosthesis enabling the reduction of restenosis. The PDMMLA was chemically modified to form different custom groups in its side chain. Three side groups were chosen: the hexyl group for its hydrophobic nature, the carboxylic acid and alcohol groups for their acid and neutral hydrophilic character, respectively. The sessile drop method was applied to characterize the wettability of biodegradable polymer film coatings. Surface energy and components were calculated. The van Oss approach helped reach not only the dispersive and polar acid–base components of surface energy but also acid and basic components. Surface topography was quantified by atomic force microscopy (AFM) and subnanometer average values of roughness (Ra) were obtained for all the analyzed surfaces. Thus, roughness was considered to have a negligible effect on wettability measurements. In contrast, heterogeneous surfaces had to be corrected by the Cassie–Baxter equation for copolymers (10/90, 20/80 and 30/70). The impact of this correction was quantified for all the wettability parameters. Very high relative corrections (%) were found, reaching 100% for energies and 30% for contact angles. - Highlights: • We develop different polymers with various chemical compositions. • Wettability properties were calculated using Cassie corrected contact angles. • Percentage of acid groups in polymers is directly correlated to acid part of SFE. • Cassie corrections are necessary for heterogeneous polymers.

  3. Biodegradable aliphatic-aromatic copolyester/corn starch blend composite reinforced with coffee parchment husk

    International Nuclear Information System (INIS)

    Silva, Valquiria A.; Teixeira, Jaciele G.; Gomes, Michelle G.; Ortiz, Angel V.; Oliveira, Rene R.; Scapin, Marcos A.; Moura, Esperidiana A.B.; Colombo, Maria A.

    2013-01-01

    In recent years, studies have shown that the addition of natural fiber or proper filler is an effective strategy for achieving improved properties in biodegradable polymer materials. Moreover, is especially important if such fibers are residues of agro-industrial processes. In this work, a promising technique to develop biodegradable polymer matrix composite based on aliphatic-aromatic copolyester/corn starch blend (Evela®) and coffee parchment husk, which is residue from coffee processing is described. The biodegradable polymeric blend (Evela®) with 5 % (w/w) of ball-milled coffee parchment husk fiber powder, with size ≤250 μm, without any modification was prepared by melt-mixing processing, using a twin screw extruder machine and then pelletized. In a second step, the pelletized Evela®)/coffee parchment (Composite) was then dried at 70 ± 2 deg C for 24 h in a circulating air oven, fed into injection molding machine and test specimens were obtained. The Composite specimen samples were irradiated using an electron beam accelerator, at radiation dose of 20 and 40 kGy, at room temperature in presence of air. The irradiated and non-irradiated samples were characterized by means of scanning electron microscopy (SEM), X-Ray diffraction (XRD), tensile tests and sol-gel analysis and the correlation between their properties was discussed. In addition, coffee parchment husk fiber characterization by SEM, EDS, XRD and WDXRF have also been carried out with a view to evaluate its importance in determining the end-use properties of the composite. (author)

  4. Asphaltenes-based polymer nano-composites

    Science.gov (United States)

    Bowen, III, Daniel E

    2013-12-17

    Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

  5. Biodegradable inorganic-organic hybrids of methacrylate star polymers for bone regeneration.

    Science.gov (United States)

    Chung, Justin J; Fujita, Yuki; Li, Siwei; Stevens, Molly M; Kasuga, Toshihiro; Georgiou, Theoni K; Jones, Julian R

    2017-05-01

    Hybrids that are molecular scale co-networks of organic and inorganic components are promising biomaterials, improving the brittleness of bioactive glass and the strength of polymers. Methacrylate polymers have high potential as the organic source for hybrids since they can be produced, through controlled polymerization, with sophisticated polymer architectures that can bond to silicate networks. Previous studies showed the mechanical properties of hybrids can be modified by polymer architecture and molar mass (MM). However, biodegradability is critical if hybrids are to be used as tissue engineering scaffolds, since the templates must be remodelled by host tissue. Degradation by-products have to either completely biodegrade or be excreted by the kidneys. Enzyme, or bio-degradation is preferred to hydrolysis by water uptake as it is expected to give a more controlled degradation rate. Here, branched and star shaped poly(methyl methacrylate-co-3-(trimethoxysilyl)propyl methacrylate) (poly(MMA-co-TMSPMA)) were synthesized with disulphide based dimethacrylate (DSDMA) as a biodegradable branching agent. Biodegradability was confirmed by exposing the copolymers to glutathione, a tripeptide which is known to cleave disulphide bonds. Cleaved parts of the star polymer from the hybrid system were detected after 2weeks of immersion in glutathione solution, and MM was under threshold of kidney filtration. The presence of the branching agent did not reduce the mechanical properties of the hybrids and bone progenitor cells attached on the hybrids in vitro. Incorporation of the DSDMA branching agent has opened more possibilities to design biodegradable methacrylate polymer based hybrids for regenerative medicine. Bioactive glasses can regenerate bone but are brittle. Hybrids can overcome this problem as intimate interactions between glass and polymer creates synergetic properties. Implants have previously been made with synthetic polymers that degrade by water, however, they

  6. Identification of osteoconductive and biodegradable polymers from a combinatorial polymer library.

    Science.gov (United States)

    Brey, Darren M; Chung, Cindy; Hankenson, Kurt D; Garino, Jonathon P; Burdick, Jason A

    2010-05-01

    Combinatorial polymer syntheses are now being utilized to create libraries of materials with potential utility for a wide variety of biomedical applications. We recently developed a library of photopolymerizable and biodegradable poly(beta-amino ester)s (PBAEs) that possess a range of tunable properties. In this study, the PBAE library was assessed for candidate materials that met design criteria (e.g., physical properties such as degradation and mechanical strength and in vitro cell viability and osteoconductive behavior) for scaffolding in mineralized tissue repair. The most promising candidate, A6, was then processed into three-dimensional porous scaffolds and implanted subcutaneously and only presented a mild inflammatory response. The scaffolds were then implanted intramuscularly and into a critical-sized cranial defect either alone or loaded with bone morphogenetic protein-2 (BMP-2). The samples in both locations displayed mineralized tissue formation in the presence of BMP-2, as evident through radiographs, micro-computed tomography, and histology, whereas samples without BMP-2 showed minimal or no mineralized tissue. These results illustrate a process to identify a candidate scaffolding material from a combinatorial polymer library, and specifically for the identification of an osteoconductive scaffold with osteoinductive properties via the inclusion of a growth factor. Copyright 2009 Wiley Periodicals, Inc.

  7. Biodegradable-Polymer-Blend-Based Surgical Sealant with Body-Temperature-Mediated Adhesion.

    Science.gov (United States)

    Behrens, Adam M; Lee, Nora G; Casey, Brendan J; Srinivasan, Priya; Sikorski, Michael J; Daristotle, John L; Sandler, Anthony D; Kofinas, Peter

    2015-12-22

    The development of practical and efficient surgical sealants has the propensity to improve operational outcomes. A biodegradable polymer blend is fabricated as a nonwoven fiber mat in situ. After direct deposition onto the tissue of interest, the material transitions from a fiber mat to a film. This transition promotes polymer-substrate interfacial interactions leading to improved adhesion and surgical sealant performance. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. [Experimental assessment of biodegradable polyglycolic and polylactic acid polymers for medical use].

    Science.gov (United States)

    Kulakov, A A; Grigor'ian, A S; Arkhipov, A V

    2013-01-01

    Interrelations of biodegradable poliglicolic and polilactic acid polymers in various proportions implanted in standardized bone defects were evaluated in animal model with 40 Wister line rats. During 10 month follow-up period bone capsule surrounded all implants, but timing of bone formation and bone quality varied significantly being optimal in LactoSorb group. Destructive features of polymers were also seen in implant-bone contact area defined as inflammation, fibrous tissue formation and cell dystrophy.

  9. Modified hydrotalcite-like compounds as active fillers of biodegradable polymers for drug release and food packaging applications.

    Science.gov (United States)

    Costantino, Umberto; Nocchetti, Morena; Tammaro, Loredana; Vittoria, Vittoria

    2012-11-01

    This review treats the recent patents and related literature, mainly from the Authors laboratories, on biomedical and food packaging applications of nano-composites constituted of biodegradable polymers filled with micro or nano crystals of organically modified Layered Double Hydroxides of Hydrotalcite type. After a brief outline of the chemical and structural aspects of Hydrotalcite-like compounds (HTlc) and of their manipulation via intercalation of functional molecular anions to obtain materials for numerous, sometime unexpected applications, the review approaches the theme in three separated parts. Part 1 deals with the synthetic method used to prepare the pristine Mg-Al and Zn-Al HTlc and with the procedures of their functionalization with anti-inflammatory (diclofenac), antibacterial (chloramphenicol hemisuccinate), antifibrinolytic (tranexamic acid) drugs and with benzoates with antimicrobial activity. Procedures used to form (nano) composites of polycaprolactone, used as an example of biodegradable polymer, and functionalized HTlc are also reported. Part 2 discusses a patent and related papers on the preparation and biomedical use of a controlled delivery system of the above mentioned pharmacologically active substances. After an introduction dealing with the recent progress in the field of local drug delivery systems, the chemical and structural aspects of the patented system constituted of a biodegradable polymer and HTlc loaded with the active substances will be presented together with an extensive discussion of the drug release in physiological medium. Part 3 deals with a recent patent and related papers on chemical, structural and release property of antimicrobial species of polymeric films containing antimicrobial loaded HTlc able to act as active packaging for food products prolonging their shelf life.

  10. BRANCHED BIODEGRADABLE POLYMERS, A MACROMONOMER, PROCESSES FOR THE PREPARATION OF SAME, AND THEIR USE

    NARCIS (Netherlands)

    Zhong, Zhiyuan; Feijen, Jan; Dijkstra, Pieter J.

    2009-01-01

    The present invention relates to a process for the preparation of branched biodegradable polymers comprising of the steps of: (a) preparing a macromonomer by ring-opening polymerization of at least one cyclic ester, cyclic carbonate, and/or cyclic carboxyanhydride in the presence of a branching

  11. Biolimus-eluting stents with biodegradable polymer versus bare-metal stents in acute myocardial infarction

    DEFF Research Database (Denmark)

    Räber, Lorenz; Kelbæk, Henning; Taniwaki, Masanori

    2014-01-01

    BACKGROUND: This study sought to determine whether the 1-year differences in major adverse cardiac event between a stent eluting biolimus from a biodegradable polymer and bare-metal stents (BMSs) in the COMFORTABLE trial (Comparison of Biolimus Eluted From an Erodible Stent Coating With Bare Metal...

  12. Ring-Opening Polymerization of Lactide to Form a Biodegradable Polymer

    Science.gov (United States)

    Robert, Jennifer L.; Aubrecht, Katherine B.

    2008-01-01

    In this laboratory activity for introductory organic chemistry, students carry out the tin(II) bis(2-ethylhexanoate)/benzyl alcohol mediated ring-opening polymerization of lactide to form the biodegradable polymer polylactide (PLA). As the mechanism of the polymerization is analogous to that of a transesterification reaction, the experiment can be…

  13. Implant-associated local drug delivery systems based on biodegradable polymers: customized designs for different medical applications.

    Science.gov (United States)

    Sternberg, Katrin; Petersen, Svea; Grabow, Niels; Senz, Volkmar; Meyer zu Schwabedissen, Henriette; Kroemer, Heyo K; Schmitz, Klaus-Peter

    2013-10-01

    Implants providing controlled, local release of active substances are of interest in different medical applications. Therefore, the focus of the present article is the development of implant-associated diffusion- or chemically controlled local drug delivery (LDD) systems based on biodegradable polymeric drug carriers. In this context, we provide new data and review our own recently published data concerning the drug release behavior of diffusion-controlled LDD systems in relation to the kind of polymer, drug content, coating mass/thickness, and layer composition. We demonstrate that polymers allow a wide range of control over the drug release characteristics. In this regard, we show that the glass transition temperature of a polymer has an impact on its drug release. Additionally, the blending of hydrophobic, semicrystalline polymers with amorphous polymers leads to an increase in the rate of drug release compared with the pure semicrystalline polymer. Moreover, the percentage loading of the embedded drug has a considerable effect on the rate and duration of drug release. Furthermore, we discuss chemically controlled LDD systems designed for the release of biomolecules, such as growth factors, as well as nanoparticle-mediated LDD systems. With our own published data on drug-eluting stents, microstents, and cochlear implants, we highlight exemplary implant-associated LDD systems designed to improve implant performance through the reduction of undesirable effects such as in-stent restenosis and fibrosis.

  14. Matrix-assisted laser desorption/ionization mass spectrometric analysis of aliphatic biodegradable photoluminescent polymers using new ionic liquid matrices.

    Science.gov (United States)

    Serrano, Carlos A; Zhang, Yi; Yang, Jian; Schug, Kevin A

    2011-05-15

    In this study, two novel ionic liquid matrices (ILMs), N,N-diisopropylethylammonium 3-oxocoumarate and N,N-diisopropylethylammonium dihydroxymonooxoacetophenoate, were tested for the structural elucidation of recently developed aliphatic biodegradable polymers by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The polymers, formed by a condensation reaction of three components, citric acid, octane diol, and an amino acid, are fluorescent, but the exact mechanism behind their luminescent properties has not been fully elucidated. In the original studies, which introduced the polymer class (J. Yang et al., Proc. Natl. Acad. Sci. USA 2009, 106, 10086-10091), a hyper-conjugated cyclic structure was proposed as the source for the photoluminescent behavior. With the use of the two new ILMs, we present evidence that supports the presence of the proposed cyclization product. In addition, the new ILMs, when compared with a previously established ILM, N,N-diisopropylethylammonium α-cyano-3-hydroxycinnimate, provided similar signal intensities and maintained similar spectral profiles. This research also established that the new ILMs provided good spot-to-spot reproducibility and high ionization efficiency compared with corresponding crystalline matrix preparations. Many polymer features revealed through the use of the ILMs could not be observed with crystalline matrices. Ultimately, the new ILMs highlighted the composition of the synthetic polymers, as well as the loss of water that was expected for the formation of the proposed cyclic structure on the polymer backbone. Copyright © 2011 John Wiley & Sons, Ltd.

  15. Mechanical, corrosion and biocompatibility behaviour of Mg-3Zn-HA biodegradable composites for orthopaedic fixture accessories.

    Science.gov (United States)

    Jaiswal, Satish; Kumar, R Manoj; Gupta, Pallavi; Kumaraswamy, Murali; Roy, Partha; Lahiri, Debrupa

    2018-02-01

    Development of biodegradable implants has grown into one of the important areas in medical science. Degradability becomes more important for orthopaedic accessories used to support fractured and damaged bones, in order to avoid second surgery for their removal after healing. Clinically available biodegradable orthopaedic materials are mainly made of polymers or ceramics. These orthopaedic accessories have an unsatisfactory mechanical strength, when used in load-bearing parts. Magnesium and its alloys can be suitable candidate for this purpose, due to their outstanding strength to weight ratio, biodegradability, non-toxicity and mechanical properties, similar to natural bone. The major drawback of magnesium is its low corrosion resistance, which also influences its mechanical and physical characteristics in service condition. An effort has been taken in this research to improve the corrosion resistance, bioactivity and mechanical strength of biodegradable magnesium alloys by synthesizing Mg-3wt% Zn matrix composite, reinforced with thermally treated hydroxyapatite(HA) [Ca 10 (PO 4 ) 6 (OH) 2 ], a bioactive and osteogenic ceramic. Addition of 5wt% HA is found effective in reducing the corrosion rate by 42% and improvement in the compressive yield strength of biodegradable magnesium alloy by 23%. In-vitro evaluation, up to 56 days, reveal improved resistance to degradation with HA reinforcement to Mg. Osteoblast cells show better growth and proliferation on HA reinforced surfaces of the composite. Mg-HA composite structure shows impressive potential to be used in orthopaedic fracture fixing accessories. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Biodegradable polymer films from seaweed polysaccharides: A review on cellulose as a reinforcement material

    Directory of Open Access Journals (Sweden)

    H. P. S. Abdul Khalil

    2017-04-01

    Full Text Available Seaweed and cellulose are promising natural polymers. This article reviews the basic information and recent developments of both seaweed and cellulose biopolymer materials as well as analyses the feasible formation of seaweed/cellulose composite films. Seaweed and cellulose both exhibit interesting film-forming properties. Nevertheless, seaweed has poor water vapour barrier and mechanical properties, whereas cellulose is neither meltable nor soluble in water or common organic solvents due to its highly crystalline structure. Therefore, modification of these hydrocolloids has been done to exploit their useful properties. Blending of biopolymers is a must recommended approach to improve the desired characteristics. From the review, seaweed is well compatible with cellulose, which possesses excellent mechanical strength and water resistance properties. Moreover, seaweed/cellulose composite films can prolong a product’s shelf life while maintaining its biodegradability. Additionally, the films show potential in contributing to the bioeconomy. In order to widen seaweed and cellulose in biocomposite application across various industries, some of the viewpoints are highlighted to be focused for future developments and applications.

  17. Bio-degradable highly fluorescent conjugated polymer nanoparticles for bio-medical imaging applications.

    Science.gov (United States)

    Repenko, Tatjana; Rix, Anne; Ludwanowski, Simon; Go, Dennis; Kiessling, Fabian; Lederle, Wiltrud; Kuehne, Alexander J C

    2017-09-07

    Conjugated polymer nanoparticles exhibit strong fluorescence and have been applied for biological fluorescence imaging in cell culture and in small animals. However, conjugated polymer particles are hydrophobic and often chemically inert materials with diameters ranging from below 50 nm to several microns. As such, conjugated polymer nanoparticles cannot be excreted through the renal system. This drawback has prevented their application for clinical bio-medical imaging. Here, we present fully conjugated polymer nanoparticles based on imidazole units. These nanoparticles can be bio-degraded by activated macrophages. Reactive oxygen species induce scission of the conjugated polymer backbone at the imidazole unit, leading to complete decomposition of the particles into soluble low molecular weight fragments. Furthermore, the nanoparticles can be surface functionalized for directed targeting. The approach opens a wide range of opportunities for conjugated polymer particles in the fields of medical imaging, drug-delivery, and theranostics.Conjugated polymer nanoparticles have been applied for biological fluorescence imaging in cell culture and in small animals, but cannot readily be excreted through the renal system. Here the authors show fully conjugated polymer nanoparticles based on imidazole units that can be bio-degraded by activated macrophages.

  18. Biodegradable polymers as encapsulation materials for cosmetics and personal care markets.

    Science.gov (United States)

    Ammala, Anne

    2013-04-01

    The topical and transdermal delivery of active cosmetic ingredients requires safe and non-toxic means of reaching the target sites without causing any irritation. Preservation of the active ingredients is also essential during formulation, storage and application of the final product. As many biologically active substances are not stable and sensitive to temperature, pH, light and oxidation, they require encapsulation to protect against unwanted degradation and also to target specific and controlled release of the active substance. The use of biodegradable polymers as encapsulation materials offers several advantages over other carrier materials. Encapsulation of active ingredients using biodegradable polymeric carriers can facilitate increased efficacy and bioavailability and they are also removed from the body via normal metabolic pathways. This article reviews current research on biodegradable polymers as carrier or encapsulation materials for cosmetic and personal care applications. Some of the challenges and limitations are also discussed. Examples of biodegradable polymers reviewed include polysaccharides, poly α-esters, polyalkylcyanoacrylates and polyamidoamine dendrimers. © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  19. A phenomenological constitutive model for the nonlinear viscoelastic responses of biodegradable polymers

    KAUST Repository

    Khan, Kamran

    2012-11-09

    We formulate a constitutive framework for biodegradable polymers that accounts for nonlinear viscous behavior under regimes with large deformation. The generalized Maxwell model is used to represent the degraded viscoelastic response of a polymer. The large-deformation, time-dependent behavior of viscoelastic solids is described using an Ogden-type hyperviscoelastic model. A deformation-induced degradation mechanism is assumed in which a scalar field depicts the local state of the degradation, which is responsible for the changes in the material\\'s properties. The degradation process introduces another timescale (the intrinsic material clock) and an entropy production mechanism. Examples of the degradation of a polymer under various loading conditions, including creep, relaxation and cyclic loading, are presented. Results from parametric studies to determine the effects of various parameters on the process of degradation are reported. Finally, degradation of an annular cylinder subjected to pressure is also presented to mimic the effects of viscoelastic arterial walls (the outer cylinder) on the degradation response of a biodegradable stent (the inner cylinder). A general contact analysis is performed. As the stiffness of the biodegradable stent decreases, stress reduction in the stented viscoelastic arterial wall is observed. The integration of the proposed constitutive model with finite element software could help a designer to predict the time-dependent response of a biodegradable stent exhibiting finite deformation and under complex mechanical loading conditions. © 2012 Springer-Verlag Wien.

  20. Computed tomography of Lipiodol-loaded biodegradable pasty polymer for implant visualization.

    Science.gov (United States)

    Sosna, Jacob; Havivi, Ehud; Khan, Wahid; Appelbaum, Liat; Nyska, Abraham; Domb, Abraham J

    2014-01-01

    Targeted delivery of drug-loaded implants for regional drug therapy has become an important approach to therapy. Simple and reproducible imaging methodologies to evaluate the implant noninvasively are needed. The goal of this work was to noninvasively evaluate the visibility, shape and degradation of a biodegradable implant containing Lipiodol (an X-ray contrast medium) by computed tomography (CT). For in vitro evaluation, Lipiodol was incorporated in poly(sebacic-co-ricinoleic acid) [P(SA:RA)], a biodegradable injectable pasty polymer, and CT visibility was assessed. For ex vivo evaluation, bovine liver was injected with the polymer-loaded Lipiodol; for in vivo evaluation rats were injected subcutaneously with Lipiodol in polymer and CT was performed. We show that polymer diameter at CT correlates with implant weight and pathological measurements. Polymer formulation containing 5% Lipiodol was visible on CT in vitro. Ex vivo tests showed a round polymer deposit at the injection site compared with free dispersion of Lipiodol alone. Correlation between implant size at CT scan and surgery at 48 h was R(2)  = 0.78. Average CT diameter at 9 days was 14.2 ± 2.8 mm in rats injected with Lipiodol in the polymer formulation, as compared with 7.3 ± 1.1 mm in controls. After 9 days, the implant degraded into several zones containing inflammatory cells seen on CT as areas with increased heterogeneity. In conclusion, Lipiodol incorporated in P(SA:RA) is visible on CT, and polymer degradation can potentially be monitored noninvasively. This method can be widely applied to follow changes in biodegradable implants. Copyright © 2014 John Wiley & Sons, Ltd.

  1. Gene silencing activity of siRNA polyplexes based on biodegradable polymers.

    Science.gov (United States)

    Varkouhi, Amir K; Lammers, Twan; Schiffelers, Raymond M; van Steenbergen, Mies J; Hennink, Wim E; Storm, Gert

    2011-04-01

    Cationic polymers are used as non-viral vectors for nucleic acid delivery. In this study, two biodegradable cationic polymers were evaluated for the purpose of siRNA delivery: pHPMA-MPPM (poly((2-hydroxypropyl) methacrylamide 1-methyl-2-piperidine methanol)) and TMC (O-methyl-free N,N,N-trimethylated chitosan). The silencing activity and the cellular cytotoxicity of polyplexes based on these biodegradable polymers were compared with those based on non-biodegradable pDMAEMA (poly(2-dimethylamino)ethyl methacrylate) and PEI (polyethylenimine) and with the regularly used lipidic transfection agent Lipofectamine. To promote endosomal escape, either the endosomolytic peptide diINF-7 was added to the formulations or photochemical internalization (PCI) was applied. Incubation of H1299 human lung cancer cells expressing firefly luciferase with polyplexes based on pHPMA-MPPM and TMC showed 30-40% silencing efficiency. This silencing activity was equal to or better than that obtained with the standard transfectants. Under all experimental conditions tested, the cytotoxicity of the biodegradable polymers was low. The application of PCI, as well as the addition of the diINF-7 peptide to the formulations increased their silencing activity up to 70-80%. This demonstrates that pHPMA-MPPM- and TMC-based polyplexes benefit substantially from endosomal escape enhancement. Importantly, the polyplexes retained their silencing activity in the presence of serum, and they showed low cytotoxicity. These biodegradable vectors are therefore attractive systems for further in vivo evaluations. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Novel pH-sensitive biodegradable polymeric drug delivery systems based on ketal polymers.

    Science.gov (United States)

    Chen, Daquan; Wang, Hongbo

    2014-01-01

    This article reviews the recent developments on novel pH-sensitive ketal-based biodegradable polymeric drug delivery systems. Due to the degradation of ketal derivatives, neutral alcohols and ketones, ketal derivatives can be used to fabricate pH-degradable polymer with pH-degradable ketal linkages in new drug delivery systems by avoiding inflammatory problems. Due to the novelty of ketal polymers, there were few reports about ketal polymers. The review starts with a brief introduction to the pH-sensitive drug delivery system, followed by the structure, preparation and characterization techniques of ketal polymers. Thereafter, the promising applications in various diseases in relation to micro/nano drug carriers based on ketal polymers are summarized and discussed.

  3. Comparison of Durable-Polymer Zotarolimus-Eluting and Biodegradable-Polymer Biolimus-Eluting Coronary Stents in Patients With Coronary Artery Disease

    DEFF Research Database (Denmark)

    Raungaard, Bent; Christiansen, Evald H; Bøtker, Hans Erik

    2017-01-01

    OBJECTIVES: The authors sought to compare the safety and efficacy of the biocompatible durable-polymer zotarolimus-eluting stent with the biodegradable-polymer biolimus-eluting stent in unselected coronary patients. BACKGROUND: Biodegradable-polymer biolimus-eluting stents are superior to first......:1) to receive either the zotarolimus-eluting (1,502 patients) or the biolimus-eluting (1,497 patients) stent. At 3-year follow-up, MACE occurred in 128 (8.6%) patients assigned to the durable-polymer zotarolimus-eluting stent and in 144 (9.6%) assigned to the biodegradable-polymer biolimus-eluting stent (p = 0...... to the durable-polymer zotarolimus-eluting stent and in 10 (0.7%) assigned to the biodegradable-polymer biolimus-eluting stent (p = 0.33). CONCLUSIONS: At 3-year follow-up, the durable-polymer zotarolimus-eluting stent and the biodegradable-polymer biolimus-eluting stent were similar in clinical outcome...

  4. Study of thermal and mechanical properties of nanocomposites, synthesized from the organoclays and biodegradable polymers

    International Nuclear Information System (INIS)

    Botelho, K.T.; Wiebeck, H.; Valenzuela-Diaz, F.R.

    2011-01-01

    The smectitic clays (MMT-Na + ) have a broad range of industrial applications. The smectitic clays which the exchangeable cation sodium predominates have much more applications in this class of mineral. The sodium smectitic clays are hydrophilic in character with a high water Foster swelling. For uses in organic medium, where a high hydrophobicity and swelling are necessary, we must transform them in the organoclay form. This is accomplished by the cation exchange reaction of the sodium smectitic clay water dispersion with quaternary ammonium salts. In this paper, it was used the smectitic clays (MMT-Na + ) from Argentina with CEC of 120meq/100g and swelling in water close to 20mL. Its modification was made using five quaternary ammonium salts. We characterize both sodium smectitic clay and the organoclay by X-ray diffraction (XRD) providing that occurred a basal expansion at the MMT-Na + for the five quaternary ammonium salts, Foster swelling and Infrared Spectra. After the synthesis, was done extrusion the two biodegradable plastics with the aim to incorporate the organoclay in these polymers. For characterization the biodegradable polymers, the proper choice is the thermal analysis and the mechanical test. Such analysis was effectuated in to pure plastic and the polymers nanocomposite, to proven of the resistance to the high temperature and the increased the mechanical properties of the modificated polymers when compared with the pure biodegradable plastics. (author)

  5. Sustained Release of Antibacterial Lipopeptides from Biodegradable Polymers against Oral Pathogens.

    Science.gov (United States)

    Eckhard, Lea H; Houri-Haddad, Yael; Sol, Asaf; Zeharia, Rotem; Shai, Yechiel; Beyth, Shaul; Domb, Abraham J; Bachrach, Gilad; Beyth, Nurit

    2016-01-01

    The development of antibacterial drugs to overcome various pathogenic species, which inhabit the oral cavity, faces several challenges, such as salivary flow and enzymatic activity that restrict dosage retention. Owing to their amphipathic nature, antimicrobial peptides (AMPs) serve as the first line of defense of the innate immune system. The ability to synthesize different types of AMPs enables exploitation of their advantages as alternatives to antibiotics. Sustained release of AMPs incorporated in biodegradable polymers can be advantageous in maintaining high levels of the peptides. In this study, four potent ultra-short lipopeptides, conjugated to an aliphatic acid chain (16C) were incorporated in two different biodegradable polymers: poly (lactic acid co castor oil) (PLACO) and ricinoleic acid-based poly (ester-anhydride) (P(SA-RA)) for sustained release. The lipopeptide and polymer formulations were tested for antibacterial activity during one week, by turbidometric measurements of bacterial outgrowth, anti-biofilm activity by live/dead staining, biocompatibility by hemolysis and XTT colorimetric assays, mode of action by fluorescence-activated cell sorting (FACS) and release profile by a fluorometric assay. The results show that an antibacterial and anti-biofilm effect, as well as membrane disruption, can be achieved by the use of a formulation of lipopeptide incorporated in biodegradable polymer.

  6. Performance of Biodegradable Polymers used in Mechanically Loaded Implants

    DEFF Research Database (Denmark)

    Andersen, Lonnie Ulrich

    predisposing for early dislocation have not been completely established, making it difficult to take successful preventative measures. The objective of this PhD thesis was to design an implantable, biodegradable device to guard against these dislocations. The hip dislocation preventer should allow for easy...... to be oriented in a 45° angle to the direction of deformation. From the model the initial strain region was predicted to lie between 35-40%, and the tensile force that the fabric can withstand, without going into plastic deformation was between 2000-5000 N. From the analysis and the material tests it was found...

  7. Electron beam processing of polymers and composites

    International Nuclear Information System (INIS)

    Singh, R. P.

    1994-01-01

    Electron beam processing has emerged as one of the foremost techniques for surface treatment of materials. Recently polymers and advanced composites are being treated with the electron beams of 1-10 MeV. In polymers the surface improvement is caused by radiation curing, cross linking and grafting. It has made inroads in vital sector of plastic industries in industrially advanced countries. Advanced composites can also be cured at ambient temperatures thus avoiding emission of volatiles during curing. Details of all these aspects of electron beam processing of polymers and composites are given. (author). 9 refs., 1 fig

  8. Complex Multifunctional Polymer/Carbon-Nanotube Composites

    Science.gov (United States)

    Patel, Pritesh; Balasubramaniyam, Gobinath; Chen, Jian

    2009-01-01

    A methodology for developing complex multifunctional materials that consist of or contain polymer/carbon-nanotube composites has been conceived. As used here, "multifunctional" signifies having additional and/or enhanced physical properties that polymers or polymer-matrix composites would not ordinarily be expected to have. Such properties include useful amounts of electrical conductivity, increased thermal conductivity, and/or increased strength. In the present methodology, these properties are imparted to a given composite through the choice and processing of its polymeric and CNT constituents.

  9. Investigating the crystal growth behavior of biodegradable polymer blend thin films using in situ atomic force microscopy

    CSIR Research Space (South Africa)

    Malwela, T

    2014-01-01

    Full Text Available This article reports the crystal growth behavior of biodegradable polylactide (PLA)/poly[(butylene succinate)-co-adipate] (PBSA) blend thin films using atomic force microscopy (AFM). Currently, polymer thin films have received increased research...

  10. Mechanics of biological polymer composites

    Science.gov (United States)

    Lomakin, Joseph

    2009-12-01

    Cartilage and cuticle are two natural materials capable of remarkable mechanical performance, especially considering the limitations on composition and processing conditions under which they are constructed. Their impressive properties are postulated to be a consequence of their complex multi-scale organization which has commonly been characterized by biochemical and microscopic methods. The objective of this dissertation is to overcome the limitations of such methods with mechanical analysis techniques generally reserved for the study of synthetic polymers. Methods for transient and dynamic mechanical analysis (DMA) of porcine TMJ disc sections and Tribolium castaneum and Tenebrio molitor elytral (modified forewing) cuticle were developed to characterize the mechanical performance of these biomaterials. The TMJ disc dynamic elastic modulus (E') was determined to be a strong function of disc orientation and pretension ranging from 700+/-240 kPa at (1g pretension) in the mediolateral direction to 73+/-8.5 MPa (150g preload) in the anteroposterior direction. Analogous mechanical testing was used to understand the relationship between composition and mechanical properties of beetle elytral cuticle at variable stages of maturation (tanning). Untanned elytra of both beetle species were ductile with a Young's modulus (E) of 44+/-8 MPa, but became brittle with an E of 2400+/-1100 MPa when fully tanned. Significantly, the E' of the TMJ disc and elytral cuticle exhibited a weak power law increase as a function of oscillation frequency. The exponent of the power law fit ( n) was determined to be a sensitive measure of molecular structure within these biomaterials. With increasing cuticular tanning, more so than with drying, the frequency dependence of cuticle E' diminished, suggesting cuticular cross-linking was an important component of tanning, as postulated by the quinone tanning hypothesis. The natural Black phenotype as well as TcADC iRNA suppressed Tribolium cuticle

  11. Irradiatable polymer composition with improved oxidation resistance

    International Nuclear Information System (INIS)

    Lyons, B.J.

    1977-01-01

    A method is described for the incorporation of a substantially insoluble organic phosphite into a polymer composition such as polyolefin polymers or ethylene copolymers to prevent oxidation of the polymer at elevated temperatures after radiation-induced crosslinking. The crosslinking is readily achieved without affecting the antioxidant properties of the organic phosphite. Particularly suitable organic compounds are derivatives of pentaerythritol, dipentaerythritol, and tripentaerythritol in cooncentrations of 1 to 3% of the mixture to be irradiated

  12. Tunable and processable shape memory composites based on degradable polymers

    NARCIS (Netherlands)

    Zhang, Xi; Geven, Mike A.; Grijpma, Dirk W.; Peijs, Ton; Gautrot, Julien E.

    2017-01-01

    Biodegradable shape memory polymers are attractive materials for the design of biomedical scaffolds as they allow deploying implants remotely with minimal intervention, whilst allowing degradation and tissue repair. However, shape memory properties are difficult to design from common degradable

  13. Physical and Degradable Properties of Mulching Films Prepared from Natural Fibers and Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Zhijian Tan

    2016-05-01

    Full Text Available The use of plastic film in agriculture has the serious drawback of producing vast quantities of waste. In this work, films were prepared from natural fibers and biodegradable polymers as potential substitutes for the conventional non-biodegradable plastic film used as mulching material in agricultural production. The physical properties (e.g., mechanical properties, heat preservation, water permeability, and photopermeability and degradation characteristics (evaluated by micro-organic culture testing and soil burial testing of the films were studied in both laboratory and field tests. The experimental results indicated that these fiber/polymer films exhibited favorable physical properties that were sufficient for use in mulching film applications. Moreover, the degradation degree of the three tested films decreased in the following order: fiber/starch (ST film > fiber/poly(vinyl alcohol (PVA film > fiber/polyacrylate (PA film. The fiber/starch and fiber/PVA films were made from completely biodegradable materials and demonstrated the potential to substitute non-biodegradable films.

  14. Poly(dopamine) coating to biodegradable polymers for bone tissue engineering.

    Science.gov (United States)

    Tsai, Wei-Bor; Chen, Wen-Tung; Chien, Hsiu-Wen; Kuo, Wei-Hsuan; Wang, Meng-Jiy

    2014-02-01

    In this study, a technique based on poly(dopamine) deposition to promote cell adhesion was investigated for the application in bone tissue engineering. The adhesion and proliferation of rat osteoblasts were evaluated on poly(dopamine)-coated biodegradable polymer films, such as polycaprolactone, poly(l-lactide) and poly(lactic-co-glycolic acid), which are commonly used biodegradable polymers in tissue engineering. Cell adhesion was significantly increased to a plateau by merely 15 s of dopamine incubation, 2.2-4.0-folds of increase compared to the corresponding untreated substrates. Cell proliferation was also greatly enhanced by poly(dopamine) deposition, indicated by shortened cell doubling time. Mineralization was also increased on the poly(dopamine)-deposited surfaces. The potential of poly(dopamine) deposition in bone tissue engineering is demonstrated in this study.

  15. Biomedical applications of synthetic, biodegradable polymers for the development of anti-infective strategies.

    Science.gov (United States)

    Bertesteanu, Serban; Chifiriuc, Mariana Carmen; Grumezescu, Alexandru Mihai; Printza, Atnanasia G; Marie-Paule, Thill; Grumezescu, Valentina; Mihaela, Vlad; Lazar, Veronica; Grigore, Raluca

    2014-01-01

    The emergence of antibiotic resistance in microbial strains is representing one of the major threats to public health worldwide, due to the decreased or total cancelling of the available antibiotics effectiveness, correlated with the slow development of novel antibiotics. Due to their excellent biodegradability and biocompatibility, the synthetic polymers could find a lot of biomedical applications, such as the development of biomaterials with optimized properties and of drug delivery systems. This review is focusing on the applications of synthetic, biodegradable polymers for the improvement of antiinfective therapeutic and prophylactic agents (i.e., antimicrobial and anti-inflammatory agents and vaccines) activity, as well as for the design of biomaterials with increased biocompatibility and resistance to microbial colonization.

  16. High temperature performance of polymer composites

    CERN Document Server

    Keller, Thomas

    2014-01-01

    The authors explain the changes in the thermophysical and thermomechanical properties of polymer composites under elevated temperatures and fire conditions. Using microscale physical and chemical concepts they allow researchers to find reliable solutions to their engineering needs on the macroscale. In a unique combination of experimental results and quantitative models, a framework is developed to realistically predict the behavior of a variety of polymer composite materials over a wide range of thermal and mechanical loads. In addition, the authors treat extreme fire scenarios up to more than 1000°C for two hours, presenting heat-protection methods to improve the fire resistance of composite materials and full-scale structural members, and discuss their performance after fire exposure. Thanks to the microscopic approach, the developed models are valid for a variety of polymer composites and structural members, making this work applicable to a wide audience, including materials scientists, polymer chemist...

  17. Microwave Processed Multifunctional Polymer Matrix Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has identified polymer matrix composites (PMCs) as a critical need for launch and in-space vehicles, but the significant costs of such materials limits their...

  18. A randomised comparison of a novel abluminal groove-filled biodegradable polymer sirolimus-eluting stent with a durable polymer everolimus-eluting stent: clinical and angiographic follow-up of the TARGET I trial.

    Science.gov (United States)

    Gao, Run-Lin; Xu, Bo; Lansky, Alexandra J; Yang, Yue-Jin; Ma, Chang-Sheng; Han, Ya-Ling; Chen, Shao-Liang; Li, Hui; Zhang, Rui-Yan; Fu, Guo-Sheng; Yuan, Zu-Yi; Jiang, Hong; Huo, Yong; Li, Wei; Zhang, Yao-Jun; Leon, Martin B

    2013-05-20

    The study sought to evaluate the safety and efficacy of FIREHAWK, a novel abluminal groove-filled biodegradable polymer sirolimus-eluting stent (SES) for treating patients with single de novo coronary lesions compared with the durable polymer everolimus-eluting stent (EES) XIENCE V. A total of 458 patients with single de novo native coronary lesions ≤24 mm in length and a coronary artery ≥2.25 to ≤4.0 mm in diameter were enrolled in the TARGET I study, a prospective, randomised, non-inferiority trial. The primary endpoint was in-stent late lumen loss (LLL) at nine-month follow-up. The secondary endpoint, target lesion failure (TLF), was defined as the composite of cardiac death, target vessel myocardial infarction (TVMI), or ischaemia-driven target lesion revascularisation (iTLR). Patients were centrally randomised to treatment with either biodegradable polymer SES (n=227) or durable polymer EES (n=231). The nine-month in-stent LLL of the biodegradable polymer SES was comparable to the EES group (0.13 ± 0.24 mm vs. 0.13 ± 0.18 mm, p=0.94; difference and 95% confidence interval 0.00 [-0.04, 0.04] mm; p for non-inferiority 0.05). No definite/probable stent thrombosis was observed in both of these groups. In the multicentre TARGET I trial, the novel abluminal groove-filled biodegradable polymer SES FIREHAWK was non-inferior to the durable polymer EES XIENCE V with respect to the primary endpoint of in-stent LLL at nine months for treating patients with single de novo coronary lesions. The incidences of clinical endpoints were low in both of the stents at 12-month follow-up. (ClinicalTrials.gov identifier: NCT01196819).

  19. The use of biodegradable polymers for the stabilization of copper ...

    Indian Academy of Sciences (India)

    2017-08-03

    Aug 3, 2017 ... However, agglomerated copper nanoparticles were obtained by this chemical reduction method. Hence, the effects of three polymers of polyvinyl pyrrolidone, polyethylene glycol (PEG) and starch as stabilizers on the size and size distribution of Cu nanoparticles were investigated. According to the results,.

  20. Study of in vitro degradation of biodegradable polymer based thin ...

    African Journals Online (AJOL)

    GREGORY

    2011-12-16

    Dec 16, 2011 ... Science and Biomedical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia. Accepted 7 November, 2011 .... polymers approved by the US Food and Drug. Administration (FDA) for certain ... equation is applicable when the extent of reaction is slow or before the specimen ...

  1. A model for hydrolytic degradation and erosion of biodegradable polymers.

    Science.gov (United States)

    Sevim, Kevser; Pan, Jingzhe

    2018-01-15

    For aliphatic polyesters such as PLAs and PGAs, there is a strong interplay between the hydrolytic degradation and erosion - degradation leads to a critically low molecular weight at which erosion starts. This paper considers the underlying physical and chemical processes of hydrolytic degradation and erosion. Several kinetic mechanisms are incorporated into a mathematical model in an attempt to explain different behaviours of mass loss observed in experiments. In the combined model, autocatalytic hydrolysis, oligomer production and their diffusion are considered together with surface and interior erosion using a set of differential equations and Monte Carlo technique. Oligomer and drug diffusion are modelled using Fick's law with the diffusion coefficients dependent on porosity. The porosity is due to the formation of cavities which are a result of polymer erosion. The model can follow mass loss and drug release up to 100%, which cannot be explained using a simple reaction-diffusion. The model is applied to two case studies from the literature to demonstrate its validity. The case studies show that a critical molecular weight for the onset of polymer erosion and an incubation period for the polymer dissolution are two critical factors that need to be considered when predicting mass loss and drug release. In order to design bioresorbable implants, it is important to have a mathematical model to predict polymer degradation and corresponding drug release. However, very different behaviours of polymer degradation have been observed and there is no single model that can capture all these behaviours. For the first time, the model presented in this paper is capable of capture all these observed behaviours by switching on and off different underlying mechanisms. Unlike the existing reaction-diffusion models, the model presented here can follow the degradation and drug release all the way to the full disappearance of an implant. Crown Copyright © 2017. Published by

  2. Efficacy and safety of biodegradable polymer biolimus-eluting stents versus durable polymer drug-eluting stents: a meta-analysis.

    Science.gov (United States)

    Ye, Yicong; Xie, Hongzhi; Zeng, Yong; Zhao, Xiliang; Tian, Zhuang; Zhang, Shuyang

    2013-01-01

    Drug-eluting stents (DES) with biodegradable polymers have been developed to address the risk of thrombosis associated with first-generation DES. We aimed to determine the efficacy and safety of biodegradable polymer biolimus-eluting stents (BES) versus durable polymer DES. Systematic database searches of MEDLINE (1950 to June 2013), EMBASE (1966 to June 2013), the Cochrane Central Register of Controlled Trials (Issue 6 of 12, June 2013), and a review of related literature were conducted. All randomized controlled trials comparing biodegradable polymer BES versus durable polymer DES were included. Eight randomized controlled trials investigating 11,015 patients undergoing percutaneous coronary interventions were included in the meta-analysis. The risk of major adverse cardiac events did not differ significantly between the patients treated with the biodegradable polymer BES and the durable polymer DES (Relative risk [RR], 0.970; 95% CI, 0.848-1.111; p = 0.662). However, biodegradable polymer BES was associated with reduced risk of very late ST compared with the durable polymer DES, while the risk of early or late ST was similar (RR for early or late ST, 1.167; 95% CI 0.755-1.802; p = 0.487; RR 0.273; 95% CI 0.115-0.652; p = 0.003; p for interaction = 0.003). In this meta-analysis of randomized controlled trials, treatments with biodegradable polymer BES did not significantly reduce the risk of major adverse cardiac events, but demonstrated a significantly lower risk of very late ST when compared to durable polymer DES. This conclusion requires confirmation by further studies with long-term follow-up. http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42013004364#.UnM2lfmsj6J.

  3. Efficacy and safety of biodegradable polymer biolimus-eluting stents versus durable polymer drug-eluting stents: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Yicong Ye

    Full Text Available BACKGROUNDS: Drug-eluting stents (DES with biodegradable polymers have been developed to address the risk of thrombosis associated with first-generation DES. We aimed to determine the efficacy and safety of biodegradable polymer biolimus-eluting stents (BES versus durable polymer DES. METHODS: Systematic database searches of MEDLINE (1950 to June 2013, EMBASE (1966 to June 2013, the Cochrane Central Register of Controlled Trials (Issue 6 of 12, June 2013, and a review of related literature were conducted. All randomized controlled trials comparing biodegradable polymer BES versus durable polymer DES were included. RESULTS: Eight randomized controlled trials investigating 11,015 patients undergoing percutaneous coronary interventions were included in the meta-analysis. The risk of major adverse cardiac events did not differ significantly between the patients treated with the biodegradable polymer BES and the durable polymer DES (Relative risk [RR], 0.970; 95% CI, 0.848-1.111; p = 0.662. However, biodegradable polymer BES was associated with reduced risk of very late ST compared with the durable polymer DES, while the risk of early or late ST was similar (RR for early or late ST, 1.167; 95% CI 0.755-1.802; p = 0.487; RR 0.273; 95% CI 0.115-0.652; p = 0.003; p for interaction = 0.003. CONCLUSIONS: In this meta-analysis of randomized controlled trials, treatments with biodegradable polymer BES did not significantly reduce the risk of major adverse cardiac events, but demonstrated a significantly lower risk of very late ST when compared to durable polymer DES. This conclusion requires confirmation by further studies with long-term follow-up. PROSPERO REGISTER NUMBER: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42013004364#.UnM2lfmsj6J.

  4. Preparation and properties of biodegradable films from Sterculia urens short fiber/celluose green composites

    CSIR Research Space (South Africa)

    Jayaramudu, J

    2013-04-01

    Full Text Available of the composites films is discussed. This paper presents the developments made in the area of biodegradable S. urens short fiber/cellulose (SUSF/cellulose) composite films, buried in the soil and later investigated by the (POM), before and after biodegradation has...

  5. Obtaining and characterization of a biodegradable polymer starting from the tapioca starch

    International Nuclear Information System (INIS)

    Ruiz Aviles, Gladys

    2006-01-01

    This study focuses on the preparation of tapioca starch biodegradable polymer, processed by blends of starch modified with glycerin and water as plasticizers, by using roll mill and a single-screw extruder in the process. During extrusion, there is a series of variables to control namely: the barrel temperature profile, screw torque and screw rotation speed. Tensile test, differential scanning calorimetric (DSC), thermogravimetric analysis (TGA), Fourier transformer infrared spectroscopy (FTIR) and morphology were used in the process

  6. Targeted Gene Delivery to Macrophages by Biodegradable Star-Shaped Polymers.

    Science.gov (United States)

    Zhang, Yajie; Wang, Yafeng; Zhang, Chi; Wang, Jin; Pan, Dejing; Liu, Jianghuai; Feng, Fude

    2016-02-17

    In this report, two biodegradable star-shaped polyasparamide derivatives and four analogues modified with either mannose or folic acid moiety for preferential targeting of a difficult-to-transfect immune cell type, i.e., macrophage, have been synthesized. Each of the prepared star polymers complexes with plasmid DNA to form nanosized particles featuring a core-shell-like morphology. Mannose or folate functionalized star polymers can greatly improve the transfection performance on a macrophage cell line RAW 264.7. As a result, a combination of targeting ligand modification and topological structures of gene carriers is a promising strategy for immune cells-based gene therapy.

  7. Poly(trimethylene carbonate)-based polymers engineered for biodegradable functional biomaterials.

    Science.gov (United States)

    Fukushima, K

    2016-01-01

    Aliphatic polycarbonates have drawn attention as biodegradable polymers that can be applied to a broad range of resorbable medical devices. In particular, poly(trimethylene carbonate) (PTMC), its copolymers, and its derivatives are currently studied due to their unique degradation characteristics that are different from those of aliphatic polyesters. Furthermore, their flexible and hydrophobic nature has driven the application of PTMC-based polymers to soft tissue regeneration and drug delivery. This review presents the diverse applications and functionalization strategies of PTMC-based materials in relation to recent advances in medical technologies and their subsequent needs in clinical settings.

  8. A study on thermal properties of biodegradable polymers using photothermal methods

    Science.gov (United States)

    Siqueira, A. P. L.; Poley, L. H.; Sanchez, R.; da Silva, M. G.; Vargas, H.

    2005-06-01

    In this work is reported the use of photothermal techniques applied to the thermal characterization of biodegradable polymers of Polyhydroxyalkanoates (PHAs) family. This is a family of polymer produced by bacteria using renewable resources. It exhibits thermoplastic properties and therefore it can be an alternative product for engineering plastics, being also applied as packages for food industry and fruits. Thermal diffusivities were determined using the open photoacoustic cell (OPC) configuration. Specific heat capacity measurements were performed monitoring temperature of the samples under white light illumination against time. Typical values obtained for the thermal properties are in good agreement with those found in the literature for other polymers. Due to the incorporation of hydroxyvalerate in the monomer structure, the thermal diffusivity and thermal conductivity increase reaching a saturation value, otherwise the specific thermal capacity decreases as the concentration of the hydroxyvalerate (HV) increases. These results can be explained by polymers internal structure and are allowing new applications of these materials.

  9. Development of partially biodegradable foams from PP/HMSPP blends with natural and synthetic polymers

    International Nuclear Information System (INIS)

    Cardoso, Elizabeth Carvalho Leite

    2014-01-01

    Polymers are used in various application and in different industrial areas providing enormous quantities of wastes in environment. Among diverse components of residues in landfills are polymeric materials, including Polypropylene, which contribute with 20 to 30% of total volume of solid residues. As polymeric materials are immune to microbial degradation, they remain in soil and in landfills as a semi-permanent residue. Environmental concerning in litter reduction is being directed to renewable polymers development for manufacturing of polymeric foams. Foamed polymers are considered future materials, with a wide range of applications; high density structural foams are specially used in civil construction, in replacement of metal, woods and concrete with a final purpose of reducing materials costs. At present development, it was possible the incorporation of PP/HMSPP polymeric matrix blends with sugarcane bagasse, PHB and PLA, in structural foams production. Thermal degradation at 100, 120 and 160 deg C temperatures was not enough to induce biodegradability. Gamma irradiation degradation, at 50, 100, 200 and 500 kGy showed effective for biodegradability induction. Irradiated bagasse blends suffered surface erosion, in favor of water uptake and consequently, a higher biodegradation in bulk structure. (author)

  10. Drilling of polymer-matrix composites

    CERN Document Server

    Krishnaraj, Vijayan; Davim, J Paulo

    2013-01-01

    Polymeric composites are recognised as good candidates for structural components due to their inherent properties. However, they present several kinds of damages while creating holes for assembly. Delamination is considered the most serious damage since it reduces service life of the component. Thrust and delamination can be controlled by proper drill point geometry. Drilling at high speed is also a current requirement of the aerospace industry. This book focus on drilling of polymer matrix composites for aerospace and defence applications. The book presents introduction to machining of polymer composites and discusses drilling as a processing of composites.

  11. Identification of market bags composition for biodegradable and oxo-biodegradable samples through thermal analysis in inert and oxidizer atmosphere; Identificacao da composicao de amostras de sacolas plasticas biodegradaveis e oxobiodegradaveis atraves de analises termicas em atmosfera inerte e oxidante

    Energy Technology Data Exchange (ETDEWEB)

    Finzi-Quintao, Cristiane M., E-mail: inzi@ufsj.edu.br [Universidade Federal de Sao Joao del-Rei (UFSJ), MG (Brazil); Novack, Katia M. [Universidade Federal de Ouro Preto (DEQUI/UFOP), MG (Brazil)

    2015-07-01

    Plastic films used to make market bags are based on polymers such as polyethylene, polystyrene and polypropylene, these materials require a long time to degrade in the environment. The alternative technologies of polymers have been developed to reduce the degradation time and the impact on the environment caused by the conventional materials, using pro-degrading additives or by the development biodegradable polymers. In Brazil, the laws of some municipalities require the use of biodegradable material in the production of market bags but the absence of specific surveillance policies makes its chemical composition unknown. In this paper, we analyzed 7 samples that was obtained from a a trading company and commercial market of Belo Horizonte . The samples were characterized by TGA / DTA , XRF , FTIR and MEV which allowed the identification and evaluation of the thermal behavior of the material in inert and oxidizing atmosphere. (author)

  12. Evaluation of the influence of the use of waste from the processing of rice in physicochemical properties and biodegradability of PHB in composites

    Directory of Open Access Journals (Sweden)

    Ana Paula Wünsch Boitt

    2014-12-01

    Full Text Available The high calorific value of rice husks has elevated its reuse as an energy source; however, the burning of these shells generates a waste ash from rice husk ash (RHA, which makes its disposal a concern. Despite advances, biodegradable polymers are not yet able to compete with those of traditional thermoplastics, which have lower production cost and higher performance. Based on this background, this paper studies the feasibility of reuse of RHA as filler in polymer matrices replacing the conventional filler. This study consists of applying different percentages of RHA in the formulation of polyhydroxybutyrate composite (PHB and the use of talc (TA for comparison purposes as conventional filler. The composites used in this assay were obtained by twin-screw extrusion and injection molding of the polymer plus the fillers under study. Physicochemical and biodegradability properties of the composites were evaluated. The composite PHB/RHA was superior in the biodegradability tests and the properties remain practically unchanged in the presence of the filler. Thus, composites with RHA are promising because they take an abundant residue combined with degradation capacity of the polymer, therefore reducing cost and the environmental impact.

  13. Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

    Science.gov (United States)

    Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

    2015-07-21

    Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

  14. Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

    2017-10-17

    Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

  15. Ferroelectric Polymer Composite with Enhanced Breakdown Strength

    Science.gov (United States)

    Han, Kuo; Gadinski, Matthew; Wang, Qing

    2013-03-01

    Numerous efforts have been made in the past decades to improve the energy storage capability of dielectric capacitors by incorporating ceramic addictives into polymers. Ferroelectric polymers have been particularly interesting as matrix for dielectric composites because of their highest dielectric permittivity and energy density. However, most polymer composites suffer from significantly reduced breakdown strength, which compromises the potential gain in energy density. In this work, various metallic alkoxide were introduced into the functionalized ferroelectric poly(vinylidene fluoride-co- chlorotrifluoroethylene), P(VDF-CTFE), via covalent bonding. The composite with the optimized composition exhibited the Weibull statistical breakdown strength of 504.8 MV/m, 67.6 % higher than the pristine polymer. The enhanced breakdown strength was mainly ascribed to the cross-linking and the formation of deep traps, which effectively reduced the conduction and further lowered the energy loss. Additionally, the homogeneous dispersion of the inorganic phase and the small contrast in permittivity between the polymer and amorphous oxides also contribute to the improved dielectric strength. The dielectric spectra of the composites have been recorded at varied temperatures and frequencies, which revealed the presence of the interfacial polarization layer in the composites.

  16. Biodegradable Polymers Influence the Effect of Atorvastatin on Human Coronary Artery Cells.

    Science.gov (United States)

    Strohbach, Anne; Begunk, Robert; Petersen, Svea; Felix, Stephan B; Sternberg, Katrin; Busch, Raila

    2016-01-22

    Drug-eluting stents (DES) have reduced in-stent-restenosis drastically. Yet, the stent surface material directly interacts with cascades of biological processes leading to an activation of cellular defense mechanisms. To prevent adverse clinical implications, to date almost every patient with a coronary artery disease is treated with statins. Besides their clinical benefit, statins exert a number of pleiotropic effects on endothelial cells (ECs). Since maintenance of EC function and reduction of uncontrolled smooth muscle cell (SMC) proliferation represents a challenge for new generation DES, we investigated the effect of atorvastatin (ATOR) on human coronary artery cells grown on biodegradable polymers. Our results show a cell type-dependent effect of ATOR on ECs and SMCs. We observed polymer-dependent changes in IC50 values and an altered ATOR-uptake leading to an attenuation of statin-mediated effects on SMC growth. We conclude that the selected biodegradable polymers negatively influence the anti-proliferative effect of ATOR on SMCs. Hence, the process of developing new polymers for DES coating should involve the characterization of material-related changes in mechanisms of drug actions.

  17. Shape-memory effect by specific biodegradable polymer blending for biomedical applications.

    Science.gov (United States)

    Cha, Kook Jin; Lih, Eugene; Choi, Jiyeon; Joung, Yoon Ki; Ahn, Dong Jun; Han, Dong Keun

    2014-05-01

    Specific biodegradable polymers having shape-memory properties through "polymer-blend" method are investigated and their shape-switching in body temperature (37 °C) is characterized. Poly(L-lactide-co-caprolactone) (PLCL) and poly(L-lactide-co-glycolide) (PLGA) are dissolved in chloroform and the films of several blending ratios of PLCL/PLGA are prepared by solvent casting. The shape-memory properties of films are also examined using dynamic mechanical analysis (DMA). Among the blending ratios, the PLCL50/PLGA50 film shows good performance of shape-fixity and shape-recovery based on glass transition temperature. It displays that the degree of shape recovery is 100% at 37 °C and the shape recovery proceeds within only 15 s. In vitro biocompatibility studies are shown to have good blood compatibility and cytocompatibility for the PLCL50/PLGA50 films. It is expected that this blended biodegradable polymer can be potentially used as a material for blood-contacting medical devices such as a self-expended vascular polymer stents and vascular closure devices in biomedical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Polymer Composites Corrosive Degradation: A Computational Simulation

    Science.gov (United States)

    Chamis, Christos C.; Minnetyan, Levon

    2007-01-01

    A computational simulation of polymer composites corrosive durability is presented. The corrosive environment is assumed to manage the polymer composite degradation on a ply-by-ply basis. The degradation is correlated with a measured pH factor and is represented by voids, temperature and moisture which vary parabolically for voids and linearly for temperature and moisture through the laminate thickness. The simulation is performed by a computational composite mechanics computer code which includes micro, macro, combined stress failure and laminate theories. This accounts for starting the simulation from constitutive material properties and up to the laminate scale which exposes the laminate to the corrosive environment. Results obtained for one laminate indicate that the ply-by-ply degradation degrades the laminate to the last one or the last several plies. Results also demonstrate that the simulation is applicable to other polymer composite systems as well.

  19. Biodegradable polyester-based shape memory polymers: Concepts of (supramolecular architecturing

    Directory of Open Access Journals (Sweden)

    J. Karger-Kocsis

    2014-06-01

    Full Text Available Shape memory polymers (SMPs are capable of memorizing one or more temporary shapes and recovering to the permanent shape upon an external stimulus that is usually heat. Biodegradable polymers are an emerging family within the SMPs. This minireview delivers an overlook on actual concepts of molecular and supramolecular architectures which are followed to tailor the shape memory (SM properties of biodegradable polyesters. Because the underlying switching mechanisms of SM actions is either related to the glass transition (Tg or melting temperatures (Tm, the related SMPs are classified as Tg- or Tm-activated ones. For fixing of the permanent shape various physical and chemical networks serve, which were also introduced and discussed. Beside of the structure developments in one-way, also those in two-way SM polyesters were considered. Adjustment of the switching temperature to that of the human body, acceleration of the shape recovery, enhancement of the recovery stress, controlled degradation, and recycling aspects were concluded as main targets for the future development of SM systems with biodegradable polyesters.

  20. Formulation and In Vitro Characterization of Composite Biodegradable Magnetic Nanoparticles for Magnetically Guided Cell Delivery

    Science.gov (United States)

    Alferiev, Ivan S.; Fishbein, Ilia; Tengood, Jillian E.; Folchman-Wagner, Zoë; Forbes, Scott P.; Levy, Robert J.

    2012-01-01

    Purpose Cells modified with magnetically responsive nanoparticles (MNP) can provide the basis for novel targeted therapeutic strategies. However, improvements are required in the MNP design and cell treatment protocols to provide adequate magnetic properties in balance with acceptable cell viability and function. This study focused on select variables controlling the uptake and cell compatibility of biodegradable polymer-based MNP in cultured endothelial cells. Methods Fluorescent-labeled MNP were formed using magnetite and polylactide as structural components. Their magnetically driven sedimentation and uptake were studied fluorimetrically relative to cell viability in comparison to non-magnetic control conditions. The utility of surface-activated MNP forming affinity complexes with replication-deficient adenovirus (Ad) for transduction achieved concomitantly with magnetic cell loading was examined using the green fluorescent protein reporter. Results A high-gradient magnetic field was essential for sedimentation and cell binding of albumin-stabilized MNP, the latter being rate-limiting in the MNP loading process. Cell loading up to 160 pg iron oxide per cell was achievable with cell viability >90%. Magnetically driven uptake of MNP-Ad complexes can provide high levels of transgene expression potentially useful for a combined cell/gene therapy. Conclusions Magnetically responsive endothelial cells for targeted delivery applications can be obtained rapidly and efficiently using composite biodegradable MNP. PMID:22274555

  1. Liquid marble formation and solvent vapor treatment of the biodegradable polymers polylactic acid and polycaprolactone.

    Science.gov (United States)

    Schmücker, Christoph; Stevens, Geoffrey W; Mumford, Kathryn A

    2018-03-15

    Liquid Marbles were produced by rolling aqueous droplets on a powder bed of biodegradable polymers, namely polylactic acid (PLA), polycaprolactone (PCL) and blends of these. Solvent vapor treatment was subsequently applied with dichloromethane (DCM). This treatment aligned the polymer chains in order to form a smooth polymeric shell with enhanced mechanical and barrier properties. Whilst a wide range of potential applications for Liquid Marbles exists, the aim here is to encapsulate a solution containing a fertilizer, i.e. urea to produce a controlled release fertilizer. The influences of droplet volume, polymer particle size and solvent vapor treatment time on the liquid marble properties were investigated. Crystallinity and thermal properties were analyzed by differential scanning calorimetry (DSC), surface characteristics and shell thickness by scanning electron microscopy (SEM), mechanical strength and elasticity by compression tests and evaporation rates by thermogravimetric analysis (TGA). Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Engineering Biodegradable Flame Retardant Wood-Plastic Composites

    Science.gov (United States)

    Zhang, Linxi

    Wood-plastic composites (WPCs), which are produced by blending wood and polymer materials, have attracted increasing attentions in market and industry due to the low cost and excellent performance. In this research, we have successfully engineered WPC by melt blending Polylactic Acid (PLA) and Poly(butylene adipate-co-terphthalate) (PBAT) with recycled wood flour. The thermal property and flammability of the composite are significantly improved by introducing flame retardant agent resorcinol bis(biphenyl phosphate) (RDP). The mechanical and morphological properties are also investigated via multiple techniques. The results show that wood material has increased toughness and impact resistance of the PLA/PBAT polymer matrix. SEM images have confirmed that PLA and PBAT are immiscible, but the incompatibility is reduced by the addition of wood. RDP is initially dispersed in the blends evenly. It migrates to the surface of the sample after flame application, and serves as a barrier between the fire and underlying polymers and wood mixture. It is well proved in the research that RDP is an efficient flame retardant agent in the WPC system.

  3. PEO + PVP blended polymer composite

    Indian Academy of Sciences (India)

    Blended polymer films of polyethylene oxide + polyvinyl pyrrolidone (PEO + PVP) containing transition metal (TM) ions like Fe3+, Co2+ and Ni2+ have been synthesized by a solution casting method. For these films, structural, thermal, magnetic and optical properties have been studied. X-ray diffraction results reveal the ...

  4. Biodegradable cyclen-based linear and cross-linked polymers as non-viral gene vectors.

    Science.gov (United States)

    Li, Shuo; Wang, Yu; Wang, Shan; Zhang, Ji; Wu, Shi-Fei; Wang, Bo-Lin; Zhu, Wen; Yu, Xiao-Qi

    2012-02-15

    Several 1,4,7,10-tetraazacyclododecane (cyclen)-based linear (3a-c) and cross-linked (8a-d) polymers containing biodegradable ester or disulfide bonds were described. These polymeric compounds were prepared by ring-opening polymerization from various diol glycidyl ethers. The molecular weights of the title polymers were measured by GPC. Agarose gel retardation assays showed that these compounds have good DNA-binding ability and can completely retard plasmid DNA (pDNA) at weight ratio of 20 for linear polymers and 1.2 for cross-linked polymers. The degradation of these polymers was confirmed by GPC. The formed polyplexes have appropriate sizes around 400 nm and zeta-potential values about 15-40 mV. The cytotoxicities of 8 assayed by MTT are much lower than that of 25 KDa PEI. In vitro transfection toward A549 and 293 cells showed that the transfection efficiency (TE) of 8c-DNA polyplex is close to that of 25 kDa PEI at 8c/DNA weight ratio of 4. Structure-activity relationships (SAR) of these linear and cross-linked polymers were discussed in their DNA-binding, cytotoxicity, and transfection studies. In addition, in the presence of serum, the TE of 8/DNA polyplexes could be improved by introducing chloroquine or Ca(2+) to pretreated cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Comparative in situ biodegradation studies of polyhydroxybutyrate film composites.

    Science.gov (United States)

    Debbarma, Prasenjit; Raghuwanshi, Shikha; Singh, Jyoti; Suyal, Deep Chandra; Zaidi, M G H; Goel, Reeta

    2017-07-01

    Application of polyhydroxybutyrate (PHB) to plastic industry has expanded over the last decades due to its attracting features over petro-based plastic, and therefore, its waste accumulation in nature is inevitable. In the present study, a total of four bacterial strains, viz., MK3, PN12, PW1, and Lna3, were formulated into a consortium and subsequently used as biological tool for degradation of biopolymers. The consortium was tested through λ max shifts under in vitro conditions for utilization of PHB as sole carbon source. Talc-based bioformulations of consortium were used for the degradation of PHB film composites under in situ conditions. After 9 months of incubation, the recovered samples were monitored through Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM), respectively. Analytical data, viz., changes in λ max shifts (212-219 nm), FT-IR spectra, and SEM micrographs, revealed the biodegradation potential of developed consortium against PHB film composites, i.e., higher degradation of copolymer films was found over blend films. The used consortium had enhanced the rate of natural degradation and can be further used as a natural tool to maintain and restore global environmental safety.

  6. Investigation of Bauschinger effect in thermo-plastic polymers for biodegradable stents

    Directory of Open Access Journals (Sweden)

    Schümann Kerstin

    2017-09-01

    Full Text Available The Bauschinger effect is a phenomenon metals show as a result of plastic deformation. After a primary plastic deformation the yield strength in the opposite loading direction decreases. The aim of this study is to investigate if there is a phenomenon similar to Bauschinger effect in thermoplastic polymers for stent application that would influence the mechanical properties of these biodegradable implants. Combined uniaxial tensile with subsequent compression tests as well as conventional compression tests without prior tensile loading were performed using biodegradable polymers for stent application (PLLA and a PLLA based blend. Comparing the results of compression tests with prior tensile loading to the compression-only tests a decrease in compressive strength can be observed for both of the tested materials. The conclusion of the performed experiments is that there is a phenomenon similar to Bauschinger effect not only in metallic materials but also in the examined thermoplastic polymers. The observed reduction of compressive strength as a consequence of prior tensile loading can influence the mechanical behaviour, e.g. the radial strength, of polymeric stents after sustaining a complex load history due to crimping and expansion.

  7. Fabrication of a Delaying Biodegradable Magnesium Alloy-Based Esophageal Stent via Coating Elastic Polymer

    Directory of Open Access Journals (Sweden)

    Tianwen Yuan

    2016-05-01

    Full Text Available Esophageal stent implantation can relieve esophageal stenosis and obstructions in benign esophageal strictures, and magnesium alloy stents are a good candidate because of biodegradation and biological safety. However, biodegradable esophageal stents show a poor corrosion resistance and a quick loss of mechanical support in vivo. In this study, we chose the elastic and biodegradable mixed polymer of Poly(ε-caprolactone (PCL and poly(trimethylene carbonate (PTMC as the coated membrane on magnesium alloy stents for fabricating a fully biodegradable esophageal stent, which showed an ability to delay the degradation time and maintain mechanical performance in the long term. After 48 repeated compressions, the mechanical testing demonstrated that the PCL-PTMC-coated magnesium stents possess good flexibility and elasticity, and could provide enough support against lesion compression when used in vivo. According to the in vitro degradation evaluation, the PCL-PTMC membrane coated on magnesium was a good material combination for biodegradable stents. During the in vivo evaluation, the proliferation of the smooth muscle cells showed no signs of cell toxicity. Histological examination revealed the inflammation scores at four weeks in the magnesium-(PCL-PTMC stent group were similar to those in the control group (p > 0.05. The α-smooth muscle actin layer in the media was thinner in the magnesium-(PCL-PTMC stent group than in the control group (p < 0.05. Both the epithelial and smooth muscle cell layers were significantly thinner in the magnesium-(PCL-PTMC stent group than in the control group. The stent insertion was feasible and provided reliable support for at least four weeks, without causing severe injury or collagen deposition. Thus, this stent provides a new stent for the treatment of benign esophageal stricture and a novel research path in the development of temporary stents in other cases of benign stricture.

  8. Impact Strength and Flexural Properties Enhancement of Methacrylate Silane Treated Oil Palm Mesocarp Fiber Reinforced Biodegradable Hybrid Composites

    Directory of Open Access Journals (Sweden)

    Chern Chiet Eng

    2014-01-01

    Full Text Available Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA/polycaprolactone (PCL/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR, thermogravimetric analysis (TGA, and scanning electron microscopy (SEM. FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.

  9. Impact strength and flexural properties enhancement of methacrylate silane treated oil palm mesocarp fiber reinforced biodegradable hybrid composites.

    Science.gov (United States)

    Eng, Chern Chiet; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Ariffin, Hidayah; Yunus, Wan Md Zin Wan

    2014-01-01

    Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.

  10. Biodegradable polymer DES versus durable polymer everolimus-eluting stents for patients undergoing PCI: a meta-analysis.

    Science.gov (United States)

    Sun, Li-Xia; Zhang, Jing

    2014-06-01

    Everolimus-eluting stents are associated with low risk of stent thrombosis and stent restenosis, and the new generation of stents with biodegradable polymer were designed to reduce that risk. However, the benefits have been variable. Four RCTs with a total of 8282 patients were included. Overall, BP-DES was not inferior to EES with equivalent risk of TVR (relative risk [RR], 1.07; 95% confidence interval [CI], 0.91-1.27; P=0.414; I(2)=0.0%) and ARC definite and/or probable ST (RR, 1.06; 95% CI, 0.66-1.70; P=0.810; I(2)=4.8%). Furthermore, there was no difference in all-cause mortality (RR, 1.06; 95% CI, 0.84-1.33; P=0.651; I(2)=0.0%), myocardial infarction (RR, 1.12; 95% CI, 0.88-1.44; P=0.360; I(2)=0.0%), and MACE (RR, 1.00; 95% CI, 0.87-1.15; P=0.975; I(2)=0.0%) between the two groups. The new generation of biodegradable polymer stents were not inferior to EES for equivalent risk of MACE and ST. Copyright © 2014 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  11. Panorama setorial e perspectivas na área de polímeros biodegradáveis Biodegradable polymers: sectorial overview and prospects

    Directory of Open Access Journals (Sweden)

    Daniele M. B. Falcone

    2007-03-01

    Full Text Available Neste trabalho, envolvendo polímeros biodegradáveis, buscou-se obter indicadores por meio da análise de patentes para avaliar as perspectivas e oportunidades de atuação da área de polímeros. Utilizou-se para tal a base de dados Espacenet e o software Vantage Point. São matéria desse estudo os polímeros: poli(hidroxibutirato - PHB, poli(hidroxibutirato-co-hidroxivalerato - PHBV, poli(ácido lático - PLA, poli(épsilon-caprolactona - PCL e os polihidroxialcanoatos (PHAs, tratados mais detalhadamente por serem a classe geral dos poliésteres microbiais. Verificou-se que a área de polímeros biodegradáveis, apesar de recente e em desenvolvimento, apresenta grande potencial mediante o panorama atual de consumo dos materiais poliméricos. Observou-se, de uma forma geral, uma grande diversidade de temas e oportunidades de estudo em compostos, blendas, biodegradação e aplicações.This work on biodegradable polymers involved an analysis of patents to identify indicators for evaluating the prospects and opportunities of action in the field of polymers. We used the Spacenet database and Vantage Point software. The study encompassed the following polymers: polyhydroxybutyrate - PHB, polyhydroxybutyrate-co-hydroxyvalerate - PHBV, polylactic acid - PLA, poly (epsilon-caprolactone - PCL and the polyhydroxyalkanoates (PHAs, dealt in greater detail because they represent the general class of microbial polyesters. We found that, although the field of biodegradable polymers is new and still under development, it holds great potential in view of present widespread use of polymeric materials. Overall we found a great diversity of themes and opportunities for studies on compounds, blends, biodegradation and applications.

  12. Driving degradation within biodegradable polymers with embedded nanoparticles

    Science.gov (United States)

    Gorga, Russell; Firestone, Gabriel; Fontecha, Daniela; Bochinski, Jason; Clarke, Laura

    The ability to controllably trigger breaking of chemical bonds enables a substance that has robust material properties during use but can be re-worked or deteriorated upon command. Photothermal heating creates intense local heat at isolated nanoparticle locations within a sample and can result in very different material responses than those achievable with conventional (uniform) heating. In this process, irradiation with visible light resonant with the nanoparticle's surface plasmon resonance results in dramatic local heating of the particles and the surrounding material. This work studies intentional thermal degradation of poly ethyl cyanoacrylate-starch composites doped with metal nanoparticles, and explores differences in degradation speed, efficiency, and resultant mechanical properties when heated via the photothermal effect. This work was supported by the National Science Foundation, Grant #: CMMI-1462966.

  13. Polymer/Layered Silicate Nano composites

    International Nuclear Information System (INIS)

    Bakhit, M.E.E.H.

    2012-01-01

    Polymer–clay nano composites have attracted the attention of many researchers and experimental results are presented in a large number of recent papers and patents because of the outstanding mechanical properties and low gas permeabilities that are achieved in many cases. Polymer-clay nano composites are a new class of mineral-field polymer that contain relatively small amounts (<10%) of nanometer-sized clay particles. Polymer/clay nano composites have their origin in the pioneering research conducted at Toyota Central Research Laboratories and the first historical record goes back to 1987. The matrix was nylon-6 and the filler MMT. Because of its many advantages such as high mechanical properties, good gas barrier, flame retardation, etc. polymer/clay nano composites have been intensely investigated and is currently the subject of many research programs. Nano composite materials are commercially important and several types of products with different shapes and applications including food packaging films and containers, engine parts, dental materials, etc. are now available in markets. A number of synthesis routes have been developed in the recent years to prepare these materials, which include intercalation of polymers or prepolymers from solution, in-situ polymerization, melt intercalation etc. In this study, new nano composite materials were produced from the components of rubber (Nbr, SBR and EPDM) as the polymeric matrix and organically modified quaternary alkylammonium montmorillonite in different contents (3, 5, 7, and 10 phr) as the filler by using an extruder then, the rubber nano composite sheets were irradiated at a dose of 0, 50, 75, 100 and 150 KGy using Electron beam Irradiation technique as a crosslinking agent. These new materials can be characterized by using various analytical techniques including X-ray diffractometer XRD, Thermogravimetric analyzer TGA, scanning electron microscope (SEM), transmission electron microscope (TEM),Fourier transform

  14. New Fabrication Technique of Conductive Polymer / Insulating Polymer Composite Films

    Science.gov (United States)

    Abe, Yayoi; Mathur, Paramatma Chandra; Bhatnagar, Pramod Kumar; Tada, Kazuya; Onoda, Mitsuyoshi

    The electrochemical polymerization of pyrrole on an ITO (indium-tin oxide) coated glass electrode with an insulating film of poly(vinyl alcohol), PVA produces a flexible composite polymer film with electrical, optical and electrochemical properties very similar to polypyrrole (PPy). The rate of electrochemical polymerization depends on the diffusion of the electrolyte across the PVA film to the ITO electrode. Especially, the solvent with hydrophilic nature easily penetrates into the PVA film. By applying this new process, we demonstrate a unique method to form electrically conductive pattern in PVA film. It will be possible to develop electrodes for electrical stimulation of the nervous system using conducting polymer, PPy. Then, by using similar technique we have fabricated poly (3,4-ethylenedioxythiophene), PEDOT/PVA composite films and investigated their electrochemical basic properties.

  15. Alternating-current electrophoretic adhesion of biodegradable hydrogel utilizing intermediate polymers.

    Science.gov (United States)

    Asoh, Taka-Aki; Kawai, Wataru; Kikuchi, Akihiko

    2014-11-01

    The adhesion of anionic charged biodegradable hydrogels each other utilizing oppositely charged water-soluble polymers as a binder has been achieved by applying alternating-current (AC) electric fields. The two gelatin based dextran sulfate gels (DS gels) were molecularly sutured together by AC electrophoretic adhesion when cationic charged quaternary ammonium chitosan (TMC) was applied between and held in contact with the two DS gels. The adhesive strength of the gels increased with increasing periodicity when a square wave was applied. Hydrogel constructs composed of DS microgels were prepared simply by AC electrophoretic adhesion utilizing intermediate TMC. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Biodegradable Polymer Releasing Antibiotic Developed for Drainage Catheter of Cerebrospinal Fluid: In Vitro Results

    Science.gov (United States)

    Han, Song Yup; Cho, Ki Hong; Cho, Han Jin; An, Jeong Ho; Ra, Young Sin

    2005-01-01

    The authors developed a biodegradable polymer that releases an antibiotic (nalidixic acid) slowly and continuously, for prevention of catheter-induced infection during drainage of cerebrospinal fluid. We investigated the in vitro antibiotic releasing characteristics and bacterial killing effects of the new polymer against E. coli. The novel fluoroquinolone polymer was prepared using diisopropylcarbodiimide, poly (e-caprolactone) diol, and nalidixic acid. FT-IR, mass spectrometry, and elemental analysis proved that the novel antibacterial polymer was prepared successfully without any side products. Negative MS showed that the released drug has a similar molecular weight (M.W.=232, 350) to pure drug (M.W.=232). In high pressure liquid chromatography, the released drug and drug-oligomer showed similar retention times (about 4.5-5 min) in comparison to pure drug (4.5 min). The released nalidixic acid and nalidixic acid derivatives have antibacterial characteristics against E. coli, Staphylococcus aureus, and Salmonella typhi, of more than 3 months duration. This study suggests the possibility of applying this new polymer to manufacture drainage catheters that resist catheter-induced infection, by delivering antibiotics for a longer period of more than 1 month. PMID:15832004

  17. Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amides

    Directory of Open Access Journals (Sweden)

    Angélica Díaz

    2014-04-01

    Full Text Available Poly(alkylene dicarboxylates constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amides derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

  18. The Study of Starch Seeds Durian (Durio zibethinus Effect as the Filler Material on Tensile Strength and Biodegradation of Polymers Polystyrene (PS

    Directory of Open Access Journals (Sweden)

    Rifka Sudi

    2013-11-01

    Full Text Available The study of starch seeds durian (Durio zibethinus effect as the filler material on tensile strength and biodegradation of polymers polystyrene (PS  has been done. In this study, the sample was made with 5 variations of Polystyrene:Starch:glycerol as follows:(95:0:5; 90:5:5; 85:10:5; 80:15:5 and 75:20:5 %. The samples were made using the hotpress machine and the ASTM D368 standard. The mechanical properties (tensile strength were tested using a tensile tester. The testing for functional groups were using FT-IR. The surface morphology was obtained by AFM and biodegradation through burial the samples for 40 days (time of observation 1, 2, 3, 4 and 5 weeks. As the results showed that the tensile strength values are influenced by variations in the composition of composite materials. The optimum tensile strength values were obtained on samples of PS-2 (90% of PS: 5% of Starch: 5% of glycerol with a tensile strength value of 0.55 kgf / mm². Based on the analysis of functional groups, it was found that there is no chemical reaction, which is characterized by the emergence of new functional groups on the composite sample. The surface morphology observation showed that the variation does not affect the relative composition of the surface morphology of the samples. Biodegradation test results showed that the samples of PS-4 and PS-5 began degraded after burial for 4 weeks.

  19. Method of making metal-polymer composite catalysts

    Science.gov (United States)

    Zelena, Piotr [Los Alamos, NM; Bashyam, Rajesh [Los Alamos, NM

    2009-06-23

    A metal-polymer-carbon composite catalyst for use as a cathode electrocatalyst in fuel cells. The catalyst includes a heteroatomic polymer; a transition metal linked to the heteroatomic polymer by one of nitrogen, sulfur, and phosphorus, and a recast ionomer dispersed throughout the heteroatomic polymer-carbon composite. The method includes forming a heteroatomic polymer-carbon composite and loading the transition metal onto the composite. The invention also provides a method of making a membrane electrode assembly for a fuel cell that includes the metal-polymer-carbon composite catalyst.

  20. Mechanical properties of glass polymer multilayer composite

    Indian Academy of Sciences (India)

    Unknown

    Mechanical properties of glass polymer multilayer composite. A SEAL, N R BOSE, S K DALUI, A K MUKHOPADHYAY*, K K PHANI and. H S MAITI. Central Glass and Ceramic Research Institute, Kolkata 700 032, India. Abstract. The preliminary experimental studies on the comparative behaviour of the deformation ...

  1. Diamond structures grown from polymer composite nanofibers

    Czech Academy of Sciences Publication Activity Database

    Potocký, Štěpán; Kromka, Alexander; Babchenko, Oleg; Rezek, Bohuslav; Martinová, L.; Pokorný, P.

    2013-01-01

    Roč. 5, č. 6 (2013), s. 519-521 ISSN 2164-6627 R&D Projects: GA ČR GAP108/12/0910; GA ČR GAP205/12/0908 Institutional support: RVO:68378271 Keywords : chemical vapour deposition * composite polymer * nanocrystalline diamond * nanofiber sheet * SEM Subject RIV: BM - Solid Matter Physics ; Magnetism

  2. Piezoresistive polymer composites for cantilever readout

    DEFF Research Database (Denmark)

    Lillemose, Michael

    concentrations. No signicant piezoresistive eect was observed for the silver nanoparticle doped composites. Thin lm structures of the intrinsically conductive polymer, polyaniline, have been fabricated and a negative piezoresistive eect was observed. Thin gold lms were investigated, with the aim of measuring...

  3. Characterization and evaluation physical properties biodegradable plastic composite from seaweed (Eucheuma cottonii)

    Science.gov (United States)

    Deni, Glar Donia; Dhaningtyas, Shalihat Afifah; Fajar, Ibnu; Sudarno

    2015-12-01

    The characterization and evaluation of biodegradable plastic composed of a mixture PVA - carrageenan - chitosan was conducted in this study. Obtained data were then compared to commercial biodegradable plastic. Characteristic of plastic was mechanical tested such as tensile - strength and elongation. Plastic degradation was studied using composting method for 7 days and 14 days. The results showed that the increase carrageenan will decrease tensile-strength and elongation plastic composite. In addition, increase carrageenan would increase the degraded plastics composite.

  4. A novel biodegradable nicotinic acid/calcium phosphate composite coating on Mg-3Zn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yingwei, E-mail: ywsong@imr.ac.cn; Shan, Dayong; Han, En-Hou

    2013-01-01

    A novel biodegradable composite coating is prepared to reduce the biodegradation rate of Mg-3Zn alloy. The Mg-3Zn substrate is first immersed into 0.02 mol L{sup -1} nicotinic acid (NA) solution, named as vitamin B{sub 3}, to obtain a pretreatment film, and then the electrodeposition of calcium phosphate coating with ultrasonic agitation is carried out on the NA pretreatment film to obtain a NA/calcium phosphate composite coating. Surface morphology is observed by scanning electron microscopy (SEM). Chemical composition is determined by X-ray diffraction (XRD) and EDX. Protection property of the coatings is evaluated by electrochemical tests. The biodegradable behavior is investigated by immersion tests. The results indicate that a thin but compact bottom layer can be obtained by NA pretreatment. The electrodeposition calcium phosphate coating consists of many flake particles and ultrasonic agitation can greatly improve the compactness of the coating. The composite coating is biodegradable and can reduce the biodegradation rate of Mg alloys in stimulated body fluid (SBF) for twenty times. The biodegradation process of the composite coating can be attributed to the gradual dissolution of the flake particles into chippings. - Highlights: Black-Right-Pointing-Pointer NA/calcium phosphate composite coating is prepared to protect Mg-3Zn alloy implant. Black-Right-Pointing-Pointer Nicotinic acid (vitamin B{sub 3}) is available to obtain a protective bottom film. Black-Right-Pointing-Pointer Ultrasonic agitation greatly improves the compactness of calcium phosphate coating. Black-Right-Pointing-Pointer The composite coating can reduce the biodegradation rate of Mg-3Zn twenty times. Black-Right-Pointing-Pointer The composite coating is biodegraded by the dissolution of flakes into chippings.

  5. Biocompatible or biodegradable hyperbranched polymers: from self-assembly to cytomimetic applications.

    Science.gov (United States)

    Jin, Haibao; Huang, Wei; Zhu, Xinyuan; Zhou, Yongfeng; Yan, Deyue

    2012-09-21

    Self-assembly of amphiphilic hyperbranched polymers (HBPs) is a newly emerging research area and has attracted increasing attention due to the great advantages in biomedical applications. This tutorial review focuses on the self-assembly of biocompatible or biodegradable amphiphilic HBPs and their cytomimetic applications, and specialities or advantages therein owing to the hyperbranched structure have also been summarized. As shown here, various supramolecular structures including micelles, vesicles, tubes, fibers and films have been prepared through the primary self-assembly processes. The primary self-assemblies can be further assembled into more complex structures through hierachical self-assembly processes. Besides, the hyperbranched polymer vesicles have demonstrated great potential to be used as model membranes to mimic cellular behaviors, such as fusion, fission and cell aggregation. Other biomedical applications of HBPs as well as their self-assemblies are also briefly summarized.

  6. Numerical study on injection parameters optimization of thin wall and biodegradable polymers parts

    Science.gov (United States)

    Santos, C.; Mendes, A.; Carreira, P.; Mateus, A.; Malça, C.

    2017-07-01

    Nowadays, the molds industry searches new markets, with diversified and added value products. The concept associated to the production of thin walled and biodegradable parts mostly manufactured by injection process has assumed a relevant importance due to environmental and economic factors. The growth of a global consciousness about the harmful effects of the conventional polymers in our life quality associated with the legislation imposed, become key factors for the choice of a particular product by the consumer. The target of this work is to provide an integrated solution for the injection of parts with thin walls and manufactured using biodegradable materials. This integrated solution includes the design and manufacture processes of the mold as well as to find the optimum values for the injection parameters in order to become the process effective and competitive. For this, the Moldflow software was used. It was demonstrated that this computational tool provides an effective responsiveness and it can constitute an important tool in supporting the injection molding of thin-walled and biodegradable parts.

  7. Nanocellulose based polymer composite for acoustical materials

    Science.gov (United States)

    Farid, Mohammad; Purniawan, Agung; Susanti, Diah; Priyono, Slamet; Ardhyananta, Hosta; Rahmasita, Mutia E.

    2018-04-01

    Natural fibers are biodegradable materials that are innovatively and widely used for composite reinforcement in automotive components. Nanocellulose derived from natural fibers oil palm empty bunches have properties that are remarkable for use as a composite reinforcement. However, there have not been many investigations related to the use of nanocellulose-based composites for wideband sound absorption materials. The specimens of nanocellulose-based polyester composite were prepared using a spray method. An impedance tube method was used to measure the sound absorption coefficient of this composite material. To reveal the characteristics of the nanocellulose-based polyester composite material, SEM (scanning electron microscope), TEM (Transmission Electron Microscope), FTIR (Fourier Transform Infra Red), TGA (Thermogravimetric Analysis), and density tests were performed. Sound absorption test results showed the average value of sound absorption coefficient of 0.36 to 0,46 for frequency between 500 and 4000 Hz indicating that this nanocellulose-based polyester composite materials had a tendency to wideband sound absorption materials and potentially used as automotive interior materials.

  8. Surface Modification of Biodegradable Polymers towards Better Biocompatibility and Lower Thrombogenicity.

    Science.gov (United States)

    Rudolph, Andreas; Teske, Michael; Illner, Sabine; Kiefel, Volker; Sternberg, Katrin; Grabow, Niels; Wree, Andreas; Hovakimyan, Marina

    2015-01-01

    Drug-eluting stents (DES) based on permanent polymeric coating matrices have been introduced to overcome the in stent restenosis associated with bare metal stents (BMS). A further step was the development of DES with biodegradable polymeric coatings to address the risk of thrombosis associated with first-generation DES. In this study we evaluate the biocompatibility of biodegradable polymer materials for their potential use as coating matrices for DES or as materials for fully bioabsorbable vascular stents. Five different polymers, poly(L-lactide) PLLA, poly(D,L-lactide) PDLLA, poly(L-lactide-co-glycolide) P(LLA-co-GA), poly(D,L-lactide-co-glycolide) P(DLLA-co-GA) and poly(L-lactide-co-ε-caprolactone), P(LLA-co-CL) were examined in vitro without and with surface modification. The surface modification of polymers was performed by means of wet-chemical (NaOH and ethylenediamine (EDA)) and plasma-chemical (O2 and NH3) processes. The biocompatibility studies were performed on three different cell types: immortalized mouse fibroblasts (cell line L929), human coronary artery endothelial cells (HCAEC) and human umbilical vein endothelial cells (HUVEC). The biocompatibility was examined quantitatively using in vitro cytotoxicity assay. Cells were investigated immunocytochemically for expression of specific markers, and morphology was visualized using confocal laser scanning (CLSM) and scanning electron (SEM) microscopy. Additionally, polymer surfaces were examined for their thrombogenicity using an established hemocompatibility test. Both endothelial cell types exhibited poor viability and adhesion on all five unmodified polymer surfaces. The biocompatibility of the polymers could be influenced positively by surface modifications. In particular, a reproducible effect was observed for NH3-plasma treatment, which enhanced the cell viability, adhesion and morphology on all five polymeric surfaces. Surface modification of polymers can provide a useful approach to enhance

  9. Surface Modification of Biodegradable Polymers towards Better Biocompatibility and Lower Thrombogenicity

    Science.gov (United States)

    Rudolph, Andreas; Teske, Michael; Illner, Sabine; Kiefel, Volker; Sternberg, Katrin; Grabow, Niels; Wree, Andreas; Hovakimyan, Marina

    2015-01-01

    Purpose Drug-eluting stents (DES) based on permanent polymeric coating matrices have been introduced to overcome the in stent restenosis associated with bare metal stents (BMS). A further step was the development of DES with biodegradable polymeric coatings to address the risk of thrombosis associated with first-generation DES. In this study we evaluate the biocompatibility of biodegradable polymer materials for their potential use as coating matrices for DES or as materials for fully bioabsorbable vascular stents. Materials and Methods Five different polymers, poly(L-lactide) PLLA, poly(D,L-lactide) PDLLA, poly(L-lactide-co-glycolide) P(LLA-co-GA), poly(D,L-lactide-co-glycolide) P(DLLA-co-GA) and poly(L-lactide-co-ε-caprolactone), P(LLA-co-CL) were examined in vitro without and with surface modification. The surface modification of polymers was performed by means of wet-chemical (NaOH and ethylenediamine (EDA)) and plasma-chemical (O2 and NH3) processes. The biocompatibility studies were performed on three different cell types: immortalized mouse fibroblasts (cell line L929), human coronary artery endothelial cells (HCAEC) and human umbilical vein endothelial cells (HUVEC). The biocompatibility was examined quantitatively using in vitro cytotoxicity assay. Cells were investigated immunocytochemically for expression of specific markers, and morphology was visualized using confocal laser scanning (CLSM) and scanning electron (SEM) microscopy. Additionally, polymer surfaces were examined for their thrombogenicity using an established hemocompatibility test. Results Both endothelial cell types exhibited poor viability and adhesion on all five unmodified polymer surfaces. The biocompatibility of the polymers could be influenced positively by surface modifications. In particular, a reproducible effect was observed for NH3-plasma treatment, which enhanced the cell viability, adhesion and morphology on all five polymeric surfaces. Conclusion Surface modification of

  10. Composite Polymer-Garnet Solid State Electrolytes

    Science.gov (United States)

    Villa, Andres; Oduncu, Muhammed R.; Scofield, Gregory D.; Marinero, Ernesto E.; Forbey, Scott

    Solid-state electrolytes provide a potential solution to the safety and reliability issues of Li-ion batteries. We have synthesized cubic-phase Li7-xLa3Zr2-xBixO12 compounds utilizing inexpensive, scalable Sol-gel synthesis and obtained ionic conductivities 1.2 x 10-4 S/cm at RT in not-fully densified pellets. In this work we report on the fabrication of composite polymer-garnet ceramic particle electrolytes to produce flexible membranes that can be integrated with standard battery electrodes without the need for a separator. As a first step we incorporated the ceramic particles into polyethylene oxide polymers (PEO) to form flexible membranes. Early results are encouraging yielding ionic conductivity values 1.0 x 10-5 S/cm at RT. To increment the conductivity in the membranes, we are optimizing amongst other: the ceramic particle size distribution and weight load, the polymer molecular weight and chemical composition and the solvated Li-salt composition and content. Unhindered ion transport across interfaces between the composites and the battery electrode materials is paramount for battery performance. To this end, we are investigating the effect of interface morphology, its atomic composition and exploring novel electrode structures that facilitate ionic transport.

  11. Biodegradable modified Phba systems

    International Nuclear Information System (INIS)

    Aniscenko, L.; Dzenis, M.; Erkske, D.; Tupureina, V.; Savenkova, L.; Muizniece - Braslava, S.

    2004-01-01

    Compositions as well as production technology of ecologically sound biodegradable multicomponent polymer systems were developed. Our objective was to design some bio plastic based composites with required mechanical properties and biodegradability intended for use as biodegradable packaging. Significant characteristics required for food packaging such as barrier properties (water and oxygen permeability) and influence of γ-radiation on the structure and changes of main characteristics of some modified PHB matrices was evaluated. It was found that barrier properties were plasticizers chemical nature and sterilization with γ-radiation dependent and were comparable with corresponding values of typical polymeric packaging films. Low γ-radiation levels (25 kGy) can be recommended as an effective sterilization method of PHB based packaging materials. Purposely designed bio plastic packaging may provide an alternative to traditional synthetic packaging materials without reducing the comfort of the end-user due to specific qualities of PHB - biodegradability, Biocompatibility and hydrophobic nature

  12. Chemical microsensors based on polymer fiber composites

    Science.gov (United States)

    Kessick, Royal F.; Levit, Natalia; Tepper, Gary C.

    2005-05-01

    There is an urgent need for new chemical sensors for defense and security applications. In particular, sensors are required that can provide higher sensitivity and faster response in the field than existing baseline technologies. We have been developing a new solid-state chemical sensor technology based on microscale polymer composite fiber arrays. The fibers consist of an insulating polymer doped with conducting particles and are electrospun directly onto the surface of an interdigitated microelectrode. The concentration of the conducting particles within the fiber is controlled and is near the percolation threshold. Thus, the electrical resistance of the polymer fiber composite is very sensitive to volumetric changes produced in the polymer by vapor absorption. Preliminary results are presented on the fabrication and testing of the new microsensor. The objective is to take advantage of the very high surface to volume ratio, low thermal mass and linear geometry of the composite fibers to produce sensors exhibiting an extremely high vapor sensitivity and rapid response. The simplicity and low cost of a resistance-based chemical microsensor makes this sensing approach an attractive alternative to devices requiring RF electronics or time-of-flight analysis. Potential applications of this technology include battlespace awareness, homeland security, environmental surveillance, medical diagnostics and food process monitoring.

  13. Characterizing SWCNT Dispersion in Polymer Composites

    Science.gov (United States)

    Lillehei, Peter T.; Kim, Jae-Woo; Gibbons, Luke; Park, Cheol

    2007-01-01

    The new wave of single wall carbon nanotube (SWCNT) infused composites will yield structurally sound multifunctional nanomaterials. The SWCNT network requires thorough dispersion within the polymer matrix in order to maximize the benefits of the nanomaterial. However, before any nanomaterials can be used in aerospace applications a means of quality assurance and quality control must be certified. Quality control certification requires a means of quantification, however, the measurement protocol mandates a method of seeing the dispersion first. We describe here the new tools that we have developed and implemented to first be able to see carbon nanotubes in polymers and second to measure or quantify the dispersion of the nanotubes.

  14. Biodegradable Composites Based on Starch/EVOH/Glycerol Blends and Coconut Fibers

    Science.gov (United States)

    Unripe coconut fibers were used as fillers in a biodegradable polymer matrix of starch/Ethylene vinyl alcohol (EVOH)/glycerol. The effects of fiber content on the mechanical, thermal and structural properties were evaluated. The addition of coconut fiber into starch/EVOH/glycerol blends reduced the ...

  15. Antibacterial and anti-encrustation biodegradable polymer coating for urinary catheter.

    Science.gov (United States)

    Dayyoub, Eyas; Frant, Marion; Pinnapireddy, Shashank Reddy; Liefeith, Klaus; Bakowsky, Udo

    2017-10-05

    Bacterial biofilm and crystalline deposits are the common causes of failure of long-term indwelling urinary catheter. Bacteria colonise the catheter surface causing serious infections in the urinary tract and encrustations that can block the catheter and induce trauma in patients. In this study, the strategy used to resist bacterial adhesion and encrustation represents a combination of the antibacterial effects of norfloxacin and silver nanoparticles and the PLGA-based neutralisation of alkali products of urea hydrolysis gained through the degradation of the polymer in an aqueous milieu. Silver nanoparticles were coated with tetraether lipids (TEL) to avoid aggregation when dispersed in acetone and during the film formation. The polymer films loaded with the two antibacterial agents were applied on Polyurethane (PUR) and Silicon sheets. We demonstrated the antibacterial and anti-adhesion effectiveness of the coatings whereby commercially available biocompatible polymers PUR and Silicon were used as controls. Using artificial urine and an in vitro encrustation model, it was shown that the coatings resist the encrustation for at least 2 weeks. This combination of a biodegradable polymer and wide-range antibacterial agents represents a potentially attractive biocompatible coating for urinary catheters. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Electrical properties of biodegradable poly(ε-caprolactone): lithium thiocyanate complexed polymer electrolyte films

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, M. [Shenzhen Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Song, Shenhua, E-mail: shsonguk@aliyun.com [Shenzhen Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Gu, Kunming; Tang, Jiaoning [College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060 (China); Zhang, Zhongyi [Advanced Polymer and Composites (APC) Research Group, School of Engineering, University of Portsmouth, Portsmouth PO1 3DJ, Hampshire (United Kingdom)

    2015-05-15

    Graphical abstract: - Highlights: • The minimum T{sub m} and χ{sub c} values are observed in 15 wt% LiSCN complexed film. • The conductivity of PCL:LiSCN complexed films follows Johnscher's power law. • Conductivity and dielectric constant follows the same trend. • The charge carriers responsible for both conduction and relaxation are the same. - Abstract: Lithium ion conducting polymer electrolyte films based on biodegradable poly(ε-caprolactone) (PCL) complexed with lithium thiocyanate (LiSCN) salt were prepared by solution cast technique. Thermal and electrical properties of the polymer electrolyte films were studied using differential scanning calorimetry (DSC) and ac impedance spectroscopy. In order to investigate the ion conduction mechanism and relaxation behavior of complex polymer electrolyte films, the conductivity, dielectric constant, loss tangent and electric modulus were analyzed as a function of frequency and temperature. The variation of conductivity with frequency obeyed the Johnscher's power law. The dielectric constant exhibited a higher value at a lower frequency and increased with rising temperature due to the polar nature of host polymer. The activation energies for both dc conductivity and relaxation had the same value (∼0.87 eV), implying that the charge carriers responsible for both conduction and relaxation were the same.

  17. Electrical properties of biodegradable poly(ε-caprolactone): lithium thiocyanate complexed polymer electrolyte films

    International Nuclear Information System (INIS)

    Ravi, M.; Song, Shenhua; Gu, Kunming; Tang, Jiaoning; Zhang, Zhongyi

    2015-01-01

    Graphical abstract: - Highlights: • The minimum T m and χ c values are observed in 15 wt% LiSCN complexed film. • The conductivity of PCL:LiSCN complexed films follows Johnscher's power law. • Conductivity and dielectric constant follows the same trend. • The charge carriers responsible for both conduction and relaxation are the same. - Abstract: Lithium ion conducting polymer electrolyte films based on biodegradable poly(ε-caprolactone) (PCL) complexed with lithium thiocyanate (LiSCN) salt were prepared by solution cast technique. Thermal and electrical properties of the polymer electrolyte films were studied using differential scanning calorimetry (DSC) and ac impedance spectroscopy. In order to investigate the ion conduction mechanism and relaxation behavior of complex polymer electrolyte films, the conductivity, dielectric constant, loss tangent and electric modulus were analyzed as a function of frequency and temperature. The variation of conductivity with frequency obeyed the Johnscher's power law. The dielectric constant exhibited a higher value at a lower frequency and increased with rising temperature due to the polar nature of host polymer. The activation energies for both dc conductivity and relaxation had the same value (∼0.87 eV), implying that the charge carriers responsible for both conduction and relaxation were the same

  18. Polymer compositions, polymer films and methods and precursors for forming same

    Science.gov (United States)

    Klaehn, John R; Peterson, Eric S; Orme, Christopher J

    2013-09-24

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  19. Final five-year outcomes after implantation of biodegradable polymer-coated biolimus-eluting stents versus durable polymer-coated sirolimus-eluting stents

    DEFF Research Database (Denmark)

    Jakobsen, Lars; Christiansen, Evald H; Maeng, Michael

    2017-01-01

    AIMS: Our aim was to report the long-term safety and efficacy of the biodegradable polymer-coated biolimus- eluting Nobori stent compared to the durable polymer-coated sirolimus-eluting CYPHER stent. METHODS AND RESULTS: SORT OUT V randomised 2,468 patients 1:1 to the Nobori (n=1,229) versus...... also found to be similar in patients treated with the two study stents (Nobori 23/1,229 [1.9%] vs. CYPHER 18/1,239 [1.5%]; OR 1.31, 95% CI: 0.70-2.47; p=0.40), as were the other secondary endpoints. CONCLUSIONS: At five-year follow-up, the Nobori stent with a biodegradable polymer coating provided...... a similar safety and efficacy profile when compared to the durable polymer first-generation CYPHER stent....

  20. Mechanical Properties of Polymer Nano-composites

    Science.gov (United States)

    Srivastava, Iti

    Thermoset polymer composites are increasingly important in high-performance engineering industries due to their light-weight and high specific strength, finding cutting-edge applications such as aircraft fuselage material and automobile parts. Epoxy is the most widely employed thermoset polymer, but is brittle due to extensive cross-linking and notch sensitivity, necessitating mechanical property studies especially fracture toughness and fatigue resistance, to ameliorate the low crack resistance. Towards this end, various nano and micro fillers have been used with epoxy to form composite materials. Particularly for nano-fillers, the 1-100 nm scale dimensions lead to fascinating mechanical properties, oftentimes proving superior to the epoxy matrix. The chemical nature, topology, mechanical properties and geometry of the nano-fillers have a profound influence on nano-composite behavior and hence are studied in the context of enhancing properties and understanding reinforcement mechanisms in polymer matrix nano-composites. Using carbon nanotubes (CNTs) as polymer filler, uniquely results in both increased stiffness as well as toughness, leading to extensive research on their applications. Though CNTs-polymer nano-composites offer better mechanical properties, at high stress amplitude their fatigue resistance is lost. In this work covalent functionalization of CNTs has been found to have a profound impact on mechanical properties of the CNT-epoxy nano-composite. Amine treated CNTs were found to give rise to effective fatigue resistance throughout the whole range of stress intensity factor, in addition to significantly enhancing fracture toughness, ductility, Young's modulus and average hardness of the nano-composite by factors of 57%, 60%, 30% and 45% respectively over the matrix as a result of diminished localized cross-linking. Graphene, a one-atom-thick sheet of atoms is a carbon allotrope, which has garnered significant attention of the scientific community and is

  1. Junctions between metals and blends of conducting and biodegradable polymers (PLLA-PPy and PCL-PPy).

    Science.gov (United States)

    Boutry, C M; Müller, M; Hierold, C

    2012-08-01

    The junctions between newly developed biodegradable conducting polymers (polylactide-polypyrrole PLLA-PPy and polycaprolactone-polypyrrole PCL-PPy) and metal electrodes (Au, Au/Cu, Ag, Ag/Cu, Cu, Cr/Au/Cu, Pd/Au/Cu, Pt/Au/Cu) were studied. The objective was to determine the composite/metal combination having the lowest possible contact resistance and ohmic characteristics. In a first step, different surface treatments, adhesion and metal layers were tested in order to evaluate the contact resistance. Then the current-voltage (IV) characteristics were measured and both ohmic and rectifying behaviour were observed depending on the polymer/metal junctions investigated. The surface treatments studied included an argon sputtering step and a grinding of the polymer surface with the objective of improving the contact between the metal electrode and the polymer. It was found that the most favourable conditions resulted from a process flow without argon sputtering, without grinding for PLLA-PPy and with a slight grinding for PCL-PPy. Moreover the most favourable metal electrodes for PLLA-PPy were Pd/Au/Cu, while the best compromise for PCL-PPy was to use Au/Cu. For the rectifying polymer/metal junctions, the standard thermionic emission model modified with a series resistance was successfully applied to the measured current-voltage IV characteristics. The saturation current density J0, series resistance R, ideality diode factor n and barrier height φB were investigated. The Chot functions were computed for each rectifying junction and the corresponding threshold voltages were calculated. Finally the conductivity of both composites was evaluated as a function of temperature in the range of 30 °C to 80 °C. For PLLA-PPy a decrease of the resistivity was observed when the temperature was increasing, while no clearly recognisable pattern was identified for PCL-PPy in this temperature range. The electrical conductivity of the PLLA-PPy samples was found to follow the empirical

  2. Novel application of a Fe-Zn double-metal cyanide catalyst in the synthesis of biodegradable, hyperbranched polymers.

    Science.gov (United States)

    Sebastian, Joby; Srinivas, Darbha

    2011-10-07

    The use of Fe-Zn double-metal cyanide as a solid catalyst for synthesizing biodegradable, hyperbranched polymers from diacids and glycerol has been reported, for the first time, wherein acidity, micro-mesoporosity and hydrophobicity of the catalyst played an important role in controlling gelation. This journal is © The Royal Society of Chemistry 2011

  3. A Review on Recent Advances in Stabilizing Peptides/Proteins upon Fabrication in Hydrogels from Biodegradable Polymers

    OpenAIRE

    Faisal Raza; Hajra Zafar; Ying Zhu; Yuan Ren; Aftab -Ullah; Asif Ullah Khan; Xinyi He; Han Han; Md Aquib; Kofi Oti Boakye-Yiadom; Liang Ge

    2018-01-01

    Hydrogels evolved as an outstanding carrier material for local and controlled drug delivery that tend to overcome the shortcomings of old conventional dosage forms for small drugs (NSAIDS) and large peptides and proteins. The aqueous swellable and crosslinked polymeric network structure of hydrogels is composed of various natural, synthetic and semisynthetic biodegradable polymers. Hydrogels have remarkable properties of functionality, reversibility, sterilizability, and biocompatibility. All...

  4. Biodegradable polymer brush as nanocoupled interface for improving the durability of polymer coating on metal surface.

    Science.gov (United States)

    Bedair, Tarek M; Cho, Youngjin; Joung, Yoon Ki; Han, Dong Keun

    2014-10-01

    Metal-based drug-eluting stents (DESs) have severe drawbacks such as peeling-off and cracking of the coated polymer. To prevent the fracture of polymer-coated layer and improve the durability of DES, poly(l-lactide) (PLLA) brushes were synthesized onto cobalt-chromium (Co-Cr or CC) surface through atom transfer radical polymerization (ATRP) of 2-hydroxyethylmethacrylate (HEMA) followed by surface-initiated ring opening polymerization (SI-ROP) of l-lactide. The polymer brushes were then characterized by attenuated total reflection-Fourier transform infrared (ATR-FTIR), water contact angle, ellipsometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All of the unmodified and modified Co-Cr surfaces were coated with a matrix of poly(d,l-lactide) (PDLLA) and sirolimus (SRL). The in vitro drug release profile was measured for 70 days. The PLLA-modified Co-Cr showed a biphasic release pattern in the initial burst followed by a slow release. On the other hand, the unmodified Co-Cr showed fast drug release and detachment of the coated polymer layer due to the instability of the polymer layer on Co-Cr surface. In comparison, the PLLA-modified Co-Cr preserved a uniform coating without detachment even after 6 weeks of degradation test. The platelet morphology and low density of platelet adhered on the modified layer and the SRL-in-PDLLA coated Co-Cr surfaces demonstrated that these samples would be blood compatible. Therefore, the introduction of PLLA brush onto Co-Cr surface is proved to dramatically improve the durability of the coating layer, and it is a promising strategy to prevent the coating defects found in DESs. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. A life cycle framework to support materials selection for Ecodesign: A case study on biodegradable polymers

    International Nuclear Information System (INIS)

    Ribeiro, I.; Peças, P.; Henriques, E.

    2013-01-01

    Highlights: • Life cycle framework to support material selection in Ecodesign. • Early design stage estimates and sensitivity analyses based on process-based models. • Sensitivity analysis to product geometry, industrial context and EoL scenarios. • Cost and environmental performance comparison – BDP vs. fossil based polymers. • Best alternatives mapping integrating cost and environmental performances. - Abstract: Nowadays society compels designers to develop more sustainable products. Ecodesign directs product design towards the goal of reducing environmental impacts. Within Ecodesign, materials selection plays a major role on product cost and environmental performance throughout its life cycle. This paper proposes a comprehensive life cycle framework to support Ecodesign in material selection. Dealing with new materials and technologies in early design stages, process-based models are used to represent the whole life cycle and supply integrated data to assess material alternatives, considering cost and environmental dimensions. An integrated analysis is then proposed to support decision making by mapping the best alternative materials according to the importance given to upstream and downstream life phases and to the environmental impacts. The proposed framework is applied to compare the life cycle performance of injection moulded samples made of four commercial biodegradable polymers with different contents of Thermo Plasticized Starch and PolyLactic Acid and a common fossil based polymer, Polypropylene. Instead of labelling materials just as “green”, the need to fully capture all impacts in the whole life cycle was shown. The fossil based polymer is the best economic alternative, but polymers with higher content of Thermo Plasticized Starch have a better environmental performance. However, parts geometry and EoL scenarios play a major role on the life cycle performance of candidate materials. The selection decision is then supported by mapping

  6. Fiber reinforced polymer composites for bridge structures

    Directory of Open Access Journals (Sweden)

    Alexandra CANTORIU

    2013-12-01

    Full Text Available Rapid advances in construction materials technology have led to the emergence of new materials with special properties, aiming at safety, economy and functionality of bridges structures. A class of structural materials which was originally developed many years ago, but recently caught the attention of engineers involved in the construction of bridges is fiber reinforced polymer composites. This paper provides an overview of fiber reinforced polymer composites used in bridge structures including types, properties, applications and future trends. The results of this study have revealed that this class of materials presents outstanding properties such as high specific strength, high fatigue and environmental resistance, lightweight, stiffness, magnetic transparency, highly cost-effective, and quick assembly, but in the same time high initial costs, lack of data on long-term field performance, low fire resistance. Fiber reinforced polymer composites were widely used in construction of different bridge structures such as: deck and tower, I-beams, tendons, cable stands and proved to be materials for future in this field.

  7. Smooth Nanowire/Polymer Composite Transparent Electrodes

    KAUST Repository

    Gaynor, Whitney

    2011-04-29

    Smooth composite transparent electrodes are fabricated via lamination of silver nanowires into the polymer poly-(4,3-ethylene dioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS). The surface roughness is dramatically reduced compared to bare nanowires. High-efficiency P3HT:PCBM organic photovoltaic cells can be fabricated using these composites, reproducing the performance of cells on indium tin oxide (ITO) on glass and improving the performance of cells on ITO on plastic. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications.

    Science.gov (United States)

    Park, Jongsung; Kim, Ji-Kwan; Patil, Swati J; Park, Jun-Kyu; Park, SuA; Lee, Dong-Weon

    2016-06-02

    This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm² and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone) stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent.

  9. A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Jongsung Park

    2016-06-01

    Full Text Available This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm2 and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent.

  10. Microwave Measurements of Ferrite Polymer Composite Materials

    Directory of Open Access Journals (Sweden)

    Rastislav Dosoudil

    2004-01-01

    Full Text Available The article focuses on the microwave measurements performed on the nickel-zinc sintered ferrite with the chemical formula Ni0.3Zn0.7Fe2O4 produced by the ceramic technique and composite materials based on this ferrite and a non-magnetic polymer (polyvinyl chloride matrix. The prepared composite samples had the same particle size distribution 0-250um but different ferrite particle concentrations between 23 vol% and 80 vol%. The apparatus for measurement of the signal proportional to the absolute value of scattering parameter S11 (reflexion coefficient is described and the dependence of measured reflected signal on a bias magnetic field has been studied. By means of experiments, the resonances to be connected with the geometry of microwave experimental set-up were distinguished from ferromagnetic resonance arising in ferrite particles of composite structure. The role of local interaction fields of ferrite particles in composite material has been discussed.

  11. Implantable biodegradable polymers for IUdR radiosensitization of human glioma in vivo

    International Nuclear Information System (INIS)

    Williams, Jeffery; Dillehay, Larry; Tabassi, Kevin; Sipos, Eric; Brem, Henry

    1996-01-01

    Purpose: Halogenated pyrimidines are potentially useful for the radiosensitization of human malignant glioma. Therefore, we tested a synthetic, implantable biodegradable polymer for the controlled in vitro release of 5-iodo-2'-deoxyuridine (IUdR) and measured the resultant in vivo radiosensitization in nude mice bearing intracranial U251 human malignant glioma xenografts. Materials and Methods: In vitro: To measure release, increasing (10%, 30%, 50%) proportions of IUdR in synthetic [(poly(bis(p-carboxyphenoxy)-propane) (PCPP):sebacic acid (SA) (PCPP:SA ratio 20:80)] polymer discs were incubated in buffered physiologic saline solution. The supernatant fractions were periodically removed, replaced and assayed for IUdR. To test radiosensitization, U251 cells were incubated with or without 10 uM IUdR for 3 days followed by acute irradiation (0, 2.5, 5.0, or 10 Gy). In vivo: Polymer discs with 200 uCi of 125-IUdR were implanted intracranially in nude mice. Activity (cpm) was serially measured at specified times up to 311 hours after implantation via a collimated scintillation detector. To measure radiosensitization in vivo, mice had sequential intracranial inoculation of 2 x 10 5 U251 cells, implantation of polymer discs without (empty control) or with 50% IUdR, and radiation. We tested intensification and timing of radiation vs. timing of IUdR polymer implantation. When measured from the day of cellular inoculation, the days of implantation of empty (control) or 50% IUdR polymers and the subsequent schedules for radiation were: Expt. 1.) day 5 (5 Gy on days 7 and 8), Expt. 2.) days 4 or 7 (5 Gy on days 8 and 10), Expt. 3.) days 4 or 7 (2 Gy BID x 4 on days 7-10) and Expt. 4.) day 5 or 8 (2 Gy BID x 4 on days 8-11). Survival was measured. Results: In vitro: After 4 days the cumulative percentages of IUdR that were released were 43.7 ± 0.1, 70.0 ± 0.2, and 90.2 ± 0.2 (p 10 ) was -2.02 ± 0.02 or -3.68 ± 0.11 (p < 0.001), respectively. In vivo: The externally

  12. Durable polymer-aerogel based superhydrophobic coatings, a composite material

    Science.gov (United States)

    Kissel, David J; Brinker, Charles Jeffrey

    2014-03-04

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  13. Durable polymer-aerogel based superhydrophobic coatings: a composite material

    Science.gov (United States)

    Kissel, David J.; Brinker, Charles Jeffrey

    2016-02-02

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  14. Polymer/hemoglobin assemblies: biodegradable oxygen carriers for artificial red blood cells.

    Science.gov (United States)

    Li, Taihang; Jing, Xiabin; Huang, Yubin

    2011-07-07

    In routine clinical procedures, blood transfusion is now suffering from the defects of the blood products, like cross-matching, short storage time and virus infection. Various blood substitutes have been designed by researchers through continual efforts. With recent progress in nanotechnology, new types of artificial red blood cells with cellular structure are available. This article aims to describe some artificial red blood cells which encapsulate or conjugate hemoglobin molecules through various approaches, especially the nanoscale self-assembly technique, to mitigate the adverse effects of free hemoglobin molecules. These types of artificial red blood cell systems, which make use of biodegradable polymers as matrix materials, show advantages over the traditional types. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Dual growth factor delivery from bilayered, biodegradable hydrogel composites for spatially-guided osteochondral tissue repair

    NARCIS (Netherlands)

    Lu, S.; Lam, J.; Trachtenberg, J.E.; Lee, E.J.; Seyednejad, H.; van den Beucken, J.J.; Tabata, Y.; Wong, M.E.; Jansen, J.A.; Mikos, A.G.; Kasper, F.K.

    2014-01-01

    The present work investigated the use of biodegradable hydrogel composite scaffolds, based on the macromer oligo(poly(ethylene glycol) fumarate) (OPF), to deliver growth factors for the repair of osteochondral tissue in a rabbit model. In particular, bilayered OPF composites were used to mimic the

  16. Poly-γ-Glutamic Acid: Biodegradable Polymer for Potential Protection of Beneficial Viruses

    Directory of Open Access Journals (Sweden)

    Ibrahim R. Khalil

    2016-01-01

    Full Text Available Poly-γ-glutamic acid (γ-PGA is a naturally occurring polymer, which due to its biodegradable, non-toxic and non-immunogenic properties has been used successfully in the food, medical and wastewater industries. A major hurdle in bacteriophage application is the inability of phage to persist for extended periods in the environment due to their susceptibility to environmental factors such as temperature, sunlight, desiccation and irradiation. Thus, the aim of this study was to protect useful phage from the harmful effect of these environmental factors using the γ-PGA biodegradable polymer. In addition, the association between γ-PGA and phage was investigated. Formulated phage (with 1% γ-PGA and non-formulated phage were exposed to 50 °C. A clear difference was noticed as viability of non-formulated phage was reduced to 21% at log10 1.3 PFU/mL, while phage formulated with γ-PGA was 84% at log10 5.2 PFU/mL after 24 h of exposure. In addition, formulated phage remained viable at log10 2.5 PFU/mL even after 24 h of exposure at pH 3 solution. In contrast, non-formulated phages were totally inactivated after the same time of exposure. In addition, non-formulated phages when exposed to UV irradiation died within 10 min. In contrast also phages formulated with 1% γ-PGA had a viability of log10 4.1 PFU/mL at the same exposure time. Microscopy showed a clear interaction between γ-PGA and phages. In conclusion, the results suggest that γ-PGA has an unique protective effect on phage particles.

  17. Injectable and biodegradable temperature-responsive mixed polymer systems providing variable gel-forming pH regions.

    Science.gov (United States)

    Yoshida, Yasuyuki; Kawahara, Keisuke; Mitsumune, Shintaro; Kuzuya, Akinori; Ohya, Yuichi

    Aqueous solutions of biodegradable polymers exhibiting sol-to-gel transitions in response to external stimuli such as temperature and pH are expected to be used as injectable polymers (IPs) for biomedical applications. In this study, we prepared novel biodegradable temperature-responsive IP systems providing variable gel-forming pH regions. We synthesized PCGA-b-PEG-b-PCGA (tri-PCG) and attached carboxylic acid or primary amine groups on both termini, tri-PCG-COOH and tri-PCG-NH 2 , and investigated the temperature-responsive sol-to-gel transition behavior of the mixtures of these two copolymers at various pHs. We found that the gel-forming pH region of the mixed system could be easily controlled by simply changing the mixing ratios of these polymers.

  18. Effect of starch types on properties of biodegradable polymer based on thermoplastic starch process by injection molding technique

    Directory of Open Access Journals (Sweden)

    Yossathorn Tanetrungroj

    2015-04-01

    Full Text Available In this study effects of different starch types on the properties of biodegradable polymer based on thermoplastic starch (TPS were investigated. Different types of starch containing different contents of amylose and amylopectin were used, i.e. cassava starch, mungbean starch, and arrowroot starch. The TPS polymers were compounded and shaped using an internal mixer and an injection molding machine, respectively. It was found that the amount of amylose and amylopectin contents on native starch influence the properties of the TPS polymer. A high amylose starch of TPMS led to higher strength, hardness, degree of crystallization than the high amylopectin starch of TPCS. In addition, function group analysis by Fourier transforms infrared spectrophotometer, water absorption, and biodegradation by soil burial test were also examined.

  19. Synthesis of Biodegradable Polymer Micro- and Nanoparticles for Controlled Drug Delivery by Multiplexed Electrosprays

    Science.gov (United States)

    Almeria, Begona

    The goal of controlled drug delivery is to administer sustained amounts of a therapeutic agent over a prolonged period of time, improving the drug efficacy as compared to conventional, bolus doses that lead to variable concentrations of drug in blood. Although there are several systems capable to provide such a continuous-dose-based treatment, the use of biodegradable polymer micro- and, especially, nanoparticles offers multiple advantages with respect to other platforms. Their small size allows them to pass through physical barriers in the body and reach the site of treatment, allowing for a localized delivery, reducing side effects and toxicity. Polymer nanoparticles have lower clearance by the immune system, and are especially useful in intracellular delivery, delivery to the lymphatic system and the treatment of tumors, where the site of treatment is difficult to reach by larger particles. Conventional methods for biodegradable particle production rely predominately on batch, emulsion preparation methods and suffer from several shortcomings: low encapsulation efficiency (˜10% for hydrophilic drugs), difficulty to generate sufficiently small (dthe micro scale, and poor repeatability. We have developed an alternative process based on electrospray (ES) that offers distinct advantages and overcomes all of these limitations. We demonstrate this process with the Poly(DL-lactic-co-glycolic acid) (PLGA) system encapsulating agents such as Doxorubicin, Rhodamine B and Rhodamine B octadecyl ester prechlorate. We also employ this method for the generation of theranostic systems that combine their therapeutic mission with imaging capabilities to detect the biodistribution of particles inside the body. PLGA microparticles in different sizes, morphologies and compactness are generated using the electrospray-drying route. The size of the synthesized particles is primarily controlled by the delicate tuning of the solution physical properties and the ES operational parameters

  20. Phase stability and dynamics of entangled polymer-nanoparticle composites.

    KAUST Repository

    Mangal, Rahul

    2015-06-05

    Nanoparticle-polymer composites, or polymer-nanoparticle composites (PNCs), exhibit unusual mechanical and dynamical features when the particle size approaches the random coil dimensions of the host polymer. Here, we harness favourable enthalpic interactions between particle-tethered and free, host polymer chains to create model PNCs, in which spherical nanoparticles are uniformly dispersed in high molecular weight entangled polymers. Investigation of the mechanical properties of these model PNCs reveals that the nanoparticles have profound effects on the host polymer motions on all timescales. On short timescales, nanoparticles slow-down local dynamics of the host polymer segments and lower the glass transition temperature. On intermediate timescales, where polymer chain motion is typically constrained by entanglements with surrounding molecules, nanoparticles provide additional constraints, which lead to an early onset of entangled polymer dynamics. Finally, on long timescales, nanoparticles produce an apparent speeding up of relaxation of their polymer host.

  1. Modified glass fibre reinforced polymer composites

    Science.gov (United States)

    Cao, Yumei

    A high ratio of strength to density and relatively low-cost are some of the significant features of glass fibre reinforced polymer composites (GFRPCs) that made them one of the most rapidly developed materials in recent years. They are widely used as the material of construction in the areas of aerospace, marine and everyday life, such as airplane, helicopter, boat, canoe, fishing rod, racket, etc. Traditionally, researchers tried to raise the mechanical properties and keep a high strength/weight ratio using all or some of the following methods: increasing the volume fraction of the fibre; using different polymeric matrix material; or changing the curing conditions. In recent years, some new techniques and processing methods were developed to further improve the mechanical properties of glass fibre (GF) reinforced polymer composite. For example, by modifying the surface condition of the GF, both the interface strength between the GF and the polymer matrix and the shear strength of the final composite can be significantly increased. Also, by prestressing the fibre during the curing process of the composite, the tensile, flexural and the impact properties of the composite can be greatly improved. In this research project, a new method of preparing GFRPCs, which combined several traditional and modern techniques together, was developed. This new method includes modification of the surface of the GF with silica particles, application of different levels of prestressing on the GF during the curing process, and the change of the fibre volume fraction and curing conditions in different sets of experiments. The results of the new processing were tested by the three-point bend test, the short beam shear test and the impact test to determine the new set of properties so formed in the composite material. Scanning electronic microscopy (SEM) was used to study the fracture surface of the new materials after the mechanical tests were performed. By taking advantages of the

  2. Controlled drug release from a novel injectable biodegradable microsphere/scaffold composite based on poly(propylene fumarate).

    Science.gov (United States)

    Kempen, Diederik H R; Lu, Lichun; Kim, Choll; Zhu, Xun; Dhert, Wouter J A; Currier, Bradford L; Yaszemski, Michael J

    2006-04-01

    The ideal biomaterial for the repair of bone defects is expected to have good mechanical properties, be fabricated easily into a desired shape, support cell attachment, allow controlled release of bioactive factors to induce bone formation, and biodegrade into nontoxic products to permit natural bone formation and remodeling. The synthetic polymer poly(propylene fumarate) (PPF) holds great promise as such a biomaterial. In previous work we developed poly(DL-lactic-co-glycolic acid) (PLGA) and PPF microspheres for the controlled delivery of bioactive molecules. This study presents an approach to incorporate these microspheres into an injectable, porous PPF scaffold. Model drug Texas red dextran (TRD) was encapsulated into biodegradable PLGA and PPF microspheres at 2 microg/mg microsphere. Five porous composite formulations were fabricated via a gas foaming technique by combining the injectable PPF paste with the PLGA or PPF microspheres at 100 or 250 mg microsphere per composite formulation, or a control aqueous TRD solution (200 microg per composite). All scaffolds had an interconnected pore network with an average porosity of 64.8 +/- 3.6%. The presence of microspheres in the composite scaffolds was confirmed by scanning electron microscopy and confocal microscopy. The composite scaffolds exhibited a sustained release of the model drug for at least 28 days and had minimal burst release during the initial phase of release, as compared to drug release from microspheres alone. The compressive moduli of the scaffolds were between 2.4 and 26.2 MPa after fabrication, and between 14.9 and 62.8 MPa after 28 days in PBS. The scaffolds containing PPF microspheres exhibited a significantly higher initial compressive modulus than those containing PLGA microspheres. Increasing the amount of microspheres in the composites was found to significantly decrease the initial compressive modulus. The novel injectable PPF-based microsphere/scaffold composites developed in this study

  3. Magnetic polymer composite artificial bacterial flagella

    International Nuclear Information System (INIS)

    Peyer, K E; Siringil, E; Nelson, B J; Zhang, L

    2014-01-01

    Artificial bacterial flagella (ABFs) are magnetically actuated swimming microrobots inspired by Escherichia coli bacteria, which use a helical tail for propulsion. The ABFs presented are fabricated from a magnetic polymer composite (MPC) containing iron-oxide nanoparticles embedded in an SU-8 polymer that is shaped into a helix by direct laser writing. The paper discusses the swim performance of MPC ABFs fabricated with varying helicity angles. The locomotion model presented contains the fluidic drag of the microrobot, which is calculated based on the resistive force theory. The robot’s magnetization is approximated by an analytical model for a soft-magnetic ellipsoid. The helicity angle influences the fluidic and magnetic properties of the robot, and it is shown that weakly magnetized robots prefer a small helicity angle to achieve corkscrew-type motion. (paper)

  4. Characterization of Hybrid CNT Polymer Matrix Composites

    Science.gov (United States)

    Grimsley, Brian W.; Cano, Roberto J.; Kinney, Megan C.; Pressley, James; Sauti, Godfrey; Czabaj, Michael W.; Kim, Jae-Woo; Siochi, Emilie J.

    2015-01-01

    Carbon nanotubes (CNTs) have been studied extensively since their discovery and demonstrated at the nanoscale superior mechanical, electrical and thermal properties in comparison to micro and macro scale properties of conventional engineering materials. This combination of properties suggests their potential to enhance multi-functionality of composites in regions of primary structures on aerospace vehicles where lightweight materials with improved thermal and electrical conductivity are desirable. In this study, hybrid multifunctional polymer matrix composites were fabricated by interleaving layers of CNT sheets into Hexcel® IM7/8552 prepreg, a well-characterized toughened epoxy carbon fiber reinforced polymer (CFRP) composite. The resin content of these interleaved CNT sheets, as well as ply stacking location were varied to determine the effects on the electrical, thermal, and mechanical performance of the composites. The direct-current electrical conductivity of the hybrid CNT composites was characterized by in-line and Montgomery four-probe methods. For [0](sub 20) laminates containing a single layer of CNT sheet between each ply of IM7/8552, in-plane electrical conductivity of the hybrid laminate increased significantly, while in-plane thermal conductivity increased only slightly in comparison to the control IM7/8552 laminates. Photo-microscopy and short beam shear (SBS) strength tests were used to characterize the consolidation quality of the fabricated laminates. Hybrid panels fabricated without any pretreatment of the CNT sheets resulted in a SBS strength reduction of 70 percent. Aligning the tubes and pre-infusing the CNT sheets with resin significantly improved the SBS strength of the hybrid composite To determine the cause of this performance reduction, Mode I and Mode II fracture toughness of the CNT sheet to CFRP interface was characterized by double cantilever beam (DCB) and end notch flexure (ENF) testing, respectively. Results are compared to the

  5. Molecular Design and Evaluation of Biodegradable Polymers Using a Statistical Approach

    Science.gov (United States)

    Lewitus, Dan; Rios, Fabian; Rojas, Ramiro; Kohn, Joachim

    2013-01-01

    The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required. In this paper we describe how changes in the molecular architecture of a series of terpolymers allow for the design of polymers with varying glass transition temperatures and degradation rates. The effect of each component in the terpolymers is quantified via design of experiment (DoE) analysis. A linear relationship between terpolymer components and resulting Tg (ranging from 34 to 86 °C) was demonstrated. These findings were further supported with mass-per-flexible-bond (MPFB) analysis. The effect of terpolymer composition on the in vitro degradation of these polymers revealed molecular weight loss ranging from 20 to 60% within the first 24 hours. DoE modeling further illustrated the linear (but reciprocal) relationship between structure elements and degradation for these polymers. Thus, we describe a simple technique to provide insight into the structure property relationship of degradable polymers, specifically applied using a new family of tyrosine-derived polycarbonates, allowing for optimal design of materials for specific applications. PMID:23888354

  6. Molecular design and evaluation of biodegradable polymers using a statistical approach.

    Science.gov (United States)

    Lewitus, Dan Y; Rios, Fabian; Rojas, Ramiro; Kohn, Joachim

    2013-11-01

    The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required. In this paper we describe how changes in the molecular architecture of a series of terpolymers allow for the design of polymers with varying glass transition temperatures and degradation rates. The effect of each component in the terpolymers is quantified via design of experiment (DoE) analysis. A linear relationship between terpolymer components and resulting Tg (ranging from 34 to 86 °C) was demonstrated. These findings were further supported with mass-per-flexible-bond analysis. The effect of terpolymer composition on the in vitro degradation of these polymers revealed molecular weight loss ranging from 20 to 60 % within the first 24 h. DoE modeling further illustrated the linear (but reciprocal) relationship between structure elements and degradation for these polymers. Thus, we describe a simple technique to provide insight into the structure property relationship of degradable polymers, specifically applied using a new family of tyrosine-derived polycarbonates, allowing for optimal design of materials for specific applications.

  7. [The research of biodegradation of a composite material used in reconstructive and reparative surgery of maxillofacial area].

    Science.gov (United States)

    Malanchuk, V O; Astapenko, O O; Halatenko, N A; Rozhnova, R A

    2013-09-01

    Dates about the research of biodegradation of epoxy-polyurethane composite material used in reconstructive and reparative surgery of maxillofacial area are reflected in the article. Was founded: 1) notable biodegradation of species from epoxy-polyurethane composition in the term of observation up to 6 months was not founded. That testifies their preservation of physical and mechanical properties. 2) founded, that in species from epoxy-polyurethane composition, which contain levamisole, processes of biodegradation are faster then in species from pure epoxy-polyurethane composition and in species from epoxy-polyurethane composition with hydroxyapatite; 3) material from epoxy-polyurethane composition, which contains levamisole and hydroxyapatite, stays in biological environment in small quantity of petty fragments during the incubation in term of 2 years. So, it biodegrades practically totally. Authors suggest on the basis of achieved information, that the use of epoxy-polyurethane constructions that biodegrade, is pertinently in reconstructive maxillofacial surgery.

  8. Synthesis, characterization and biocompatibility of novel biodegradable cross-linked co-polymers based on poly(propylene oxide) diglycidylether and polyethylenimine.

    Science.gov (United States)

    Ding, Yunsheng; Wang, Jing; Wong, Cynthia S; Halley, Peter J; Guo, Qipeng

    2011-01-01

    Novel biodegradable cross-linked co-polymers were prepared from poly(propylene glycol) diglycidylether (PPGDGE) and poly(ethylene imine) (PEI). PPGDGE and PEI were mixed at ambient temperature with varying PEI concentrations of 10, 15, 18.5, 25, 30, 40 and 50 wt%; the homogenous PPGDGE/PEI mixtures obtained were cured at elevated temperatures, resulting in formation of PPG-PEI cross-linked co-polymers via ring-opening reaction of PPGDGE with PEI. The physicochemical and biological properties of these co-polymers were dependent on the PEI content and the extent of curing reaction. The glass transition temperature of PPG-PEI cross-linked co-polymers varied in the range from -14 to +42°C, while the co-polymers displayed composition-dependent mechanical behavior, from brittle to ductile with increasing PEI content from 18.5 wt% to 40 wt%. Chinese hamster ovary (CHO) cells were cultured on the PPG-PEI co-polymers; the MTT assay was used to measure cell viability and determine the cytotoxicity. The cell viability rate, relative to tissue-culture polystyrene (TCPS), increased from 49% to 125% with increasing PEI content from 18.5 wt% to 40 wt%. Although epoxy monomers usually exhibit cytotoxicity, the epoxy groups were exhausted via curing reaction in the fully cross-linked co-polymers. The PEI-cured PPG epoxy resin, i.e., PPG-PEI cross-linked co-polymers obtained in this study, showed excellent biocompatibility.

  9. Biodegradable polymer (PLGA) coatings featuring cinnamaldehyde and carvacrol mitigate biofilm formation.

    Science.gov (United States)

    Zodrow, Katherine R; Schiffman, Jessica D; Elimelech, Menachem

    2012-10-02

    Biofilm-associated infections are one of the leading causes of death in the United States. Although infections may be treated with antibiotics, the overuse of antibiotics has led to the spread of antibiotic resistance. Many natural antimicrobial compounds derived from edible plants are safe for human use and target bacteria nonspecifically. Therefore, they may impair biofilm formation with less evolutionary pressure on pathogens. Here, we explore the use of two natural antimicrobial compounds, cinnamaldehyde (CA, from cinnamon) and carvacrol (CARV, from oregano), for biofilm prevention. We have fabricated and characterized films that incorporate CA and CARV into the biodegradable, FDA-approved polymer poly(lactic-co-glycolic acid), PLGA. The addition of CA and CARV to PLGA films not only adds antimicrobial activity but also changes the surface properties of the films, making them more hydrophilic and therefore more resistant to bacterial attachment. An addition of 0.1% CA to a PLGA film significantly impairs biofilm development by Staphylococcus aureus, and 0.1% CARV in PLGA significantly decreases biofilm formation by both Escherichia coli and S. aureus. Pseudomonas aeruginosa, which is less susceptible to CA and CARV, was not affected by the addition of 0.1% CA or CARV to the PLGA coatings; however, P. aeruginosa biofilm was significantly reduced by 1.0% CA. These results indicate that both CA and CARV could potentially be used in low concentrations as natural additives in polymer coatings for indwelling devices to delay colonization by bacteria.

  10. Biodegradable poly lactone-family polymer and their applications in medical field

    International Nuclear Information System (INIS)

    Wang, S.; Bei, J.

    2005-01-01

    Poly lactone-family polymers such as poly lactide, poly glycolide and polycaprolactone are kind aliphatic polyester. Since they can degrade by hydrolysis reaction under all the ph condition and possess biocompatibility, biodegradability and other good properties, especially they included not peptide bond in their molecules, they are non-antigen and non-immunization, as well as have no-toxicity and no-stimulation. So they are interested biomaterials and very useful in medical field. However the properties of all of the homo-poly lactones can not be changed in a large range, the limited properties result in limited applications of these homo-poly lactones. Based on macromolecular design, a series of copolylactones such as poly(lactide-co-glycolide) (PLGA), poly(glycolide-co-lactide-co-caprolactone) tri- component copolymer (PGLC), tri- and multi-block poly lactide/poly(ethylene oxide) copolymer (TPLE and BPLE), as well as polycaprolactone/poly lactide/poly(ethylene oxide) copolymer (PCEL) et al were synthesized by copolymerization among various lactone monomers or lactone monomers with poly(ethylene glycol). These copolylactones have wide range of degradation life from several months to years and different mechanical properties. After plasma treatment the surface property of the copolylactones were improved further and cell affinity of the copolylactones was improved obviously. The applications of these poly lactone-family polymers in medical field for used as drug carrier in drug delivery system, and as cell scaffold in tissue engineering were discussed

  11. Arginine-based biodegradable ether-ester polymers with low cytotoxicity as potential gene carriers.

    Science.gov (United States)

    Memanishvili, Tamar; Zavradashvili, Nino; Kupatadze, Nino; Tugushi, David; Gverdtsiteli, Marekh; Torchilin, Vladimir P; Wandrey, Christine; Baldi, Lucia; Manoli, Sagar S; Katsarava, Ramaz

    2014-08-11

    The success of gene therapy depends on safe and effective gene carriers. Despite being widely used, synthetic vectors based on poly(ethylenimine) (PEI), poly(l-lysine) (PLL), or poly(l-arginine) (poly-Arg) are not yet fully satisfactory. Thus, both improvement of established carriers and creation of new synthetic vectors are necessary. A series of biodegradable arginine-based ether-ester polycations was developed, which consists of three main classes: amides, urethanes, and ureas. Compared to that of PEI, PLL, and poly-Arg, much lower cytotoxicity was achieved for the new cationic arginine-based ether-ester polymers. Even at polycation concentrations up to 2 mg/mL, no significant negative effect on cell viability was observed upon exposure of several cell lines (murine mammary carcinoma, human cervical adenocarcinoma, murine melanoma, and mouse fibroblast) to the new polymers. Interaction with plasmid DNA yielded compact and stable complexes. The results demonstrate the potential of arginine-based ether-ester polycations as nonviral carriers for gene therapy applications.

  12. Self-Rolled Porous Hollow Tubes Made up of Biodegradable Polymers.

    Science.gov (United States)

    Peng, Ling; Zhu, Jian; Agarwal, Seema

    2017-05-01

    A tubular highly porous scaffold of polylactide (PLA) and poly-ε-caprolactone (PCL) is fabricated by self-rolling of a 2D fibrous bilayer of PLA and PCL in water without use of any classical thermo-/pH-responsive polymers. The self-rolling and diameter of the tube are dependent upon the bilayer thickness and temperature. A 75 µm thick 2D bilayer (PLA = 25 µm; PCL = 50 µm) rolls to a hollow tube of diameter around 0.41 mm with multilayered wall at 40 °C within 5 min. The tubes keep their form and size in water at all temperatures once they are formed. The interesting properties of the hollow tubes, that is, permeation of gases through the walls and flow of water without leakage under tested conditions in combination with good mechanical stability, use of only biodegradable polymers, and easy and reproducible fabrication method, allow them to be promising candidates for future studies as scaffolds for tissue engineering. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Rapid prototyping of biodegradable microneedle arrays by integrating CO2 laser processing and polymer molding

    International Nuclear Information System (INIS)

    Tu, K T; Chung, C K

    2016-01-01

    An integrated technology of CO 2 laser processing and polymer molding has been demonstrated for the rapid prototyping of biodegradable poly-lactic-co-glycolic acid (PLGA) microneedle arrays. Rapid and low-cost CO 2 laser processing was used for the fabrication of a high-aspect-ratio microneedle master mold instead of conventional time-consuming and expensive photolithography and etching processes. It is crucial to use flexible polydimethylsiloxane (PDMS) to detach PLGA. However, the direct CO 2 laser-ablated PDMS could generate poor surfaces with bulges, scorches, re-solidification and shrinkage. Here, we have combined the polymethyl methacrylate (PMMA) ablation and two-step PDMS casting process to form a PDMS female microneedle mold to eliminate the problem of direct ablation. A self-assembled monolayer polyethylene glycol was coated to prevent stiction between the two PDMS layers during the peeling-off step in the PDMS-to-PDMS replication. Then the PLGA microneedle array was successfully released by bending the second-cast PDMS mold with flexibility and hydrophobic property. The depth of the polymer microneedles can range from hundreds of micrometers to millimeters. It is linked to the PMMA pattern profile and can be adjusted by CO 2 laser power and scanning speed. The proposed integration process is maskless, simple and low-cost for rapid prototyping with a reusable mold. (paper)

  14. Rapid prototyping of biodegradable microneedle arrays by integrating CO2 laser processing and polymer molding

    Science.gov (United States)

    Tu, K. T.; Chung, C. K.

    2016-06-01

    An integrated technology of CO2 laser processing and polymer molding has been demonstrated for the rapid prototyping of biodegradable poly-lactic-co-glycolic acid (PLGA) microneedle arrays. Rapid and low-cost CO2 laser processing was used for the fabrication of a high-aspect-ratio microneedle master mold instead of conventional time-consuming and expensive photolithography and etching processes. It is crucial to use flexible polydimethylsiloxane (PDMS) to detach PLGA. However, the direct CO2 laser-ablated PDMS could generate poor surfaces with bulges, scorches, re-solidification and shrinkage. Here, we have combined the polymethyl methacrylate (PMMA) ablation and two-step PDMS casting process to form a PDMS female microneedle mold to eliminate the problem of direct ablation. A self-assembled monolayer polyethylene glycol was coated to prevent stiction between the two PDMS layers during the peeling-off step in the PDMS-to-PDMS replication. Then the PLGA microneedle array was successfully released by bending the second-cast PDMS mold with flexibility and hydrophobic property. The depth of the polymer microneedles can range from hundreds of micrometers to millimeters. It is linked to the PMMA pattern profile and can be adjusted by CO2 laser power and scanning speed. The proposed integration process is maskless, simple and low-cost for rapid prototyping with a reusable mold.

  15. Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour

    Directory of Open Access Journals (Sweden)

    Ewa Oledzka

    2015-09-01

    Full Text Available The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched, and contained an active substance—bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA or hyperbranched 2,2-bis(hydroxymethylpropionic acid polyester-16-hydroxyl (bis-MPA initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol. The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites.

  16. Monitoring of the Enzymatically Catalyzed Degradation of Biodegradable Polymers by Means of Capacitive Field-Effect Sensors.

    Science.gov (United States)

    Schusser, Sebastian; Krischer, Maximilian; Bäcker, Matthias; Poghossian, Arshak; Wagner, Patrick; Schöning, Michael J

    2015-07-07

    Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(D,L-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers.

  17. Bone formation by three-dimensional stromal osteoblast culture in biodegradable polymer scaffolds

    Science.gov (United States)

    Ishaug, S. L.; Crane, G. M.; Miller, M. J.; Yasko, A. W.; Yaszemski, M. J.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    1997-01-01

    Bone formation was investigated in vitro by culturing stromal osteoblasts in three-dimensional (3-D), biodegradable poly(DL-lactic-co-glycolic acid) foams. Three polymer foam pore sizes, ranging from 150-300, 300-500, and 500-710 microns, and two different cell seeding densities, 6.83 x 10(5) cells/cm2 and 22.1 x 10(5) cells/cm2, were examined over a 56-day culture period. The polymer foams supported the proliferation of seeded osteoblasts as well as their differentiated function, as demonstrated by high alkaline phosphatase activity and deposition of a mineralized matrix by the cells. Cell number, alkaline phosphatase activity, and mineral deposition increased significantly over time for all the polymer foams. Osteoblast foam constructs created by seeding 6.83 x 10(5) cells/cm2 on foams with 300-500 microns pores resulted in a cell density of 4.63 x 10(5) cells/cm2 after 1 day in culture; they had alkaline phosphatase activities of 4.28 x 10(-7) and 2.91 x 10(-6) mumol/cell/min on Days 7 and 28, respectively; and they had a cell density that increased to 18.7 x 10(5) cells/cm2 by Day 56. For the same constructs, the mineralized matrix reached a maximum penetration depth of 240 microns from the top surface of the foam and a value of 0.083 mm for mineralized tissue volume per unit of cross sectional area. Seeding density was an important parameter for the constructs, but pore size over the range tested did not affect cell proliferation or function. This study suggests the feasibility of using poly(alpha-hydroxy ester) foams as scaffolding materials for the transplantation of autogenous osteoblasts to regenerate bone tissue.

  18. Methacrylated monosaccharides as the modifiers for carbochain polymers: Synthesis, mechanical/thermal properties and biodegradability of hybrids

    Science.gov (United States)

    Yakushev, P.; Bershtein, V.; Bukowska-Śluz, I.; Sobiesiak, M.; Gawdzik, B.

    2016-05-01

    Methacrylated derivatives of glucose (MGLU) and galactose (MGAL) were synthesized by the procedure described by Vogel, and their copolymers with methyl methacrylate (MMA) and MMA/N-vinyl pyrrolidone (MMA/NVP) (1:1) mixture were obtained with the aim to modify some properties of carbochain polymers, in particular to generate their biodegradability. These hybrids of synthetic and natural products, with 10, 20 or 30 wt. % modifiers, were characterized by DMA and TGA methods and in the biodegradation tests. Increasing Tg values by 20-30°C was registered in all cases whereas thermal stability was improved only for PMMA due to modification. On the contrary, only for hybrids based on hygroscopic MMA/NVP copolymer the essential biodegradability could be generated.

  19. Advanced bredigite-containing magnesium-matrix composites for biodegradable bone implant applications.

    Science.gov (United States)

    Dezfuli, Sina Naddaf; Huan, Zhiguang; Mol, Arjan; Leeflang, Sander; Chang, Jiang; Zhou, Jie

    2017-10-01

    The present research was aimed at developing magnesium-matrix composites that could allow effective control over their physiochemical and mechanical responses when in contact with physiological solutions. A biodegradable, bioactive ceramic - bredigite was chosen as the reinforcing phase in the composites, based on the hypothesis that the silicon- and magnesium-containing ceramic could protect magnesium from fast corrosion and at the same time stimulate cell proliferation. Methods to prepare composites with integrated microstructures - a prerequisite to achieve controlled biodegradation were developed. A systematic experimental approach was taken in order to elucidate the in vitro biodegradation mechanisms and kinetics of the composites. It was found that the composites with 20-40% homogenously dispersed bredigite particles, prepared from powders, could indeed significantly decrease the degradation rate of magnesium by up to 24 times. Slow degradation of the composites resulted in the retention of the mechanical integrity of the composites within the strength range of cortical bone after 12days of immersion in a cell culture medium. Cell attachment, cytotoxicity and bioactivity tests confirmed the stimulatory effects of bredigite embedded in the composites on the attachment, viability and differentiation of bone marrow stromal cells. Thus, the multiple benefits of adding bredigite to magnesium in enhancing degradation behavior, mechanical properties, biocompatibility and bioactivity were obtained. The results from this research showed the excellent potential of the bredigite-containing composites for bone implant applications, thus warranting further in vitro and in vivo research. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Nanotube/Polymer Composites: Materials Selection and Process Design

    National Research Council Canada - National Science Library

    Winey, Karen

    2004-01-01

    ...) define processing methods most appropriate for the materials identified. Our study of SWNT-polymer composites focuses on thermoplastics, because these materials can be readily drawn into fibers...

  1. Constitutive Behavior and Damage Characterization of High Temperature Polymer Composites

    National Research Council Canada - National Science Library

    Daniel, Isaac

    2001-01-01

    The objective of this investigation was to characterize the constitutive behavior, physical aging, damage mechanisms and damage development in high temperature polymer matrix composites under various...

  2. A review of electrohydrodynamic casting energy conversion polymer composites

    Directory of Open Access Journals (Sweden)

    Yong X. Gan

    2018-03-01

    Full Text Available This paper provides a brief review on manufacturing polymer composite materials through the nontraditional electrohydrodynamic (EHD casting approach. First, the EHD technology will be introduced. Then, typical functional polymer composite materials including thermoelectric and photoelectric energy conversion polymers and their composites will be presented. Specifically, how to make composite materials containing functional nanoparticles will be discussed. Converting polymeric fibers into partially carbonized fiber composites will also be shown. The latest research results of polymeric composite materials with energy conversion and sensing functions will be given.

  3. Accelerated Aging of Polymer Composite Bridge Materials

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Nancy Margaret; Blackwood, Larry Gene; Torres, Lucinda Laine; Rodriguez, Julio Gallardo; Yoder, Timothy Scott

    1999-03-01

    Accelerated aging research on samples of composite material and candidate ultraviolet (UV) protective coatings is determining the effects of six environmental factors on material durability. Candidate fastener materials are being evaluated to determine corrosion rates and crevice corrosion effects at load-bearing joints. This work supports field testing of a 30-ft long, 18-ft wide polymer matrix composite (PMC) bridge at the Idaho National Engineering and Environmental Laboratory (INEEL). Durability results and sensor data from tests with live loads provide information required for determining the cost/benefit measures to use in life-cycle planning, determining a maintenance strategy, establishing applicable inspection techniques, and establishing guidelines, standards, and acceptance criteria for PMC bridges for use in the transportation infrastructure.

  4. High barrier multilayer packaging by the coextrusion method: The effect of nanocomposites and biodegradable polymers on flexible film properties

    Science.gov (United States)

    Thellen, Christopher T.

    The objective of this research was to investigate the use of nanocomposite and multilayer co-extrusion technologies for the development of high gas barrier packaging that is more environmentally friendly than many current packaging system. Co-extruded bio-based and biodegradable polymers that could be composted in a municipal landfill were one direction that this research was aimed. Down-gauging of high performance barrier films using nanocomposite technology and co-extrusion was also investigated in order to reduce the amount of solid waste being generated by the packaging. Although the research is focused on military ration packaging, the technologies could easily be introduced into the commercial flexible packaging market. Multilayer packaging consisting of poly(m-xylylene adipamide) nanocomposite layers along with adhesive and tie layers was co-extruded using both laboratory and pilot-scale film extrusion equipment. Co-extrusion of biodegradable polyhydroxyalkanoates (PHA) along with polyvinyl alcohol (PVOH) and tie layers was also accomplished using similar co-extrusion technology. All multilayer films were characterized for gas barrier, mechanical, and thermal properties. The biodegradability of the PVOH and PHA materials in a marine environment was also investigated. The research has shown that co-extrusion of these materials is possible at a research and pilot level. The use of nanocomposite poly(m-xylylene adipamide) was effective in down-gauging the un-filled barrier film to thinner structures. Bio-based PHA/PVOH films required the use of a malefic anhydride grafted PHA tie layer to improve layer to layer adhesion in the structure to avoid delamination. The PHA polymer demonstrated a high rate of biodegradability/mineralization in the marine environment while the rate of biodegradation of the PVOH polymer was slower.

  5. Inorganic-whisker-reinforced polymer composites synthesis, properties and applications

    CERN Document Server

    Sun, Qiuju

    2015-01-01

    Inorganic-Whisker-Reinforced Polymer Composites: Synthesis, Properties and Applications gives a comprehensive presentation of inorganic microcrystalline fibers, or whiskers, a polymer composite filler. It covers whisker synthesis, surface modification, applications for reinforcing polymer-matrix composites, and analysis of resulting filled polymer composites. It focuses on calcium carbonate whiskers as a primary case study, introducing surface treatment methods for calcium carbonate whiskers and factors that influence them. Along with calcium carbonate, the book discusses potassium titanate and aluminum borate whiskers, which also comprise the new generation of inorganic whiskers. According to research results, composites filled by inorganic whiskers show improved strength, wear-resistance, thermal conductivity, and antistatic properties. It explains the importance of modifying polymer materials for use with inorganic whiskers and describes preparation and evaluation methods of polymers filled with inorganic ...

  6. Biodegradable and Multifunctional Polymer Micro-Tubes for Targeting Photothermal Therapy

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2014-07-01

    Full Text Available We describe an innovative form of polymer micro-tubes with diverse functions including biodegradation, magnetic manipulation, and photothermal effect that employs and activates photothermal therapy to target cancer cells. The micro-tube comprised soybean protein isolate, poly-l-glutamic acid, magnetite nanoparticles, plus gold nanoparticles. Through electrostatic force, these components, with opposite charges, formed pairs of layers in the pores of the template, various bilayers of soybean protein isolate and poly-l-glutamic acid served as the biodegradable building wall to each micro-tube. The layers of magnetite nanoparticle functionalized micro-tubes enabled the micro-tube manipulate to target the cancer cells by using an external magnetic field. The photo-thermal effect of the layer of gold nanoparticles on the outer surface of the micro-tubes, when under irradiation and when brought about by the near infrared radiation, elevated each sample’s temperature. In addition, and when under the exposure of the near infrared radiation, the elevated temperature of the suspension of the micro-tubes, likewise with a concentration of 0.2 mg/mL, and similarly with a power of 2 W and as well maintained for 10 min, elevated the temperature of the suspension beyond 42 °C. Such temperatures induced apoptosis of target cancer cells through the effect of photothermal therapy. The findings assert that structured micro-tubes have a promising application as a photothermal agent. From this assertion, the implications are that this multifunctional agent will significantly improve the methodology for cancer diagnosis and therapy.

  7. Boundary-condition analysis for physics-based modeling of ionic-polymer metal composite electroactive polymers

    Science.gov (United States)

    Bass, Patrick S.; Zhang, Lin; Cheng, Zhongyang

    2017-04-01

    Ionic-polymer metal composites (IPMCs) are a subset of ionic electroactive polymers (EAPs). They produce an actuation response based on the electrically induced flux of mobile ions through a parent-polymer matrix. This response is a result of the accumulation of cations and anions on opposing sides of the matrix and is directly related to the size disparity between the two types of ions. These factors impose a differential expansion across the matrix, which generates the macroscopic bending that is observed. It is well known that the motion of these EAPs is highly nonlinear and time dependent, making for a process that is difficult to model. A simplistic approach to modeling the physics behind this phenomenon and correlating that to experimental results is outlined, herein. This new methodology enables a comprehensive analysis of the boundary conditions (BCs) needed to be considered in order to accurately characterize the IPMC actuation response. The subsequent series of equations developed, which depict the ionic motion under these BCs, is presented. Empirical data for model analysis was acquired from IPMCs created using poly(ethylene oxide) (PEO), a well-known, biodegradable, solid-polymer electrolyte infused with lithium perchlorate, as the ionic salt. Experimental results fitted with this new model returned a favorable average adjusted-R2, goodness-of-fit, of 0.987, 0.994, and 0.992 when PEO films were tested under varying conditions, including: ionic concentration, applied voltage, and testing temperature, respectively.

  8. Mechanical Evaluation of Polymer Composite Hip Protectors

    Directory of Open Access Journals (Sweden)

    Jose Daniel Diniz Melo

    2010-01-01

    Full Text Available Hip fractures often result in serious health implications, particularly in the geriatric population, and have been related to long-term morbidity and death. In most cases, these fractures are caused by impact loads in the area of the greater trochanter, which are produced in a fall. This work is aimed at developing hip protectors using composite materials and evaluating their effectiveness in preventing hip fractures under high impact energy (120 J. The hip protectors were developed with an inner layer of energy absorbing soft material and an outer rigid shell of fiberglass-reinforced polymer composite. According to the experimental results, all tested configurations proved to be effective at reducing the impact load to below the average fracture threshold of proximal femur. Furthermore, an addition of Ethylene Vinyl Acetate (EVA to the impacted area of the composite shell proved to be beneficial to increase impact strength of the hip protectors. Thus, composite hip protectors proved to be a viable alternative for a mechanically efficient and cost-effective solution to prevent hip fractures.

  9. Microencapsulation of chemotherapeutics into monodisperse and tunable biodegradable polymers via electrified liquid jets: control of size, shape, and drug release.

    Science.gov (United States)

    Fattahi, Pouria; Borhan, Ali; Abidian, Mohammad Reza

    2013-09-06

    This paper describes microencapsulation of antitumor agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, Carmustine) into biodegradable polymer poly(lactic-co-glycolic) acid (PLGA) using an electrojetting technique. The resulting BCNU-loaded PLGA microcapsules have significantly higher drug encapsulation efficiency, more tunable drug loading capacity, and (3) narrower size distribution than those generated using other encapsulation methods. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Biodegradation of composites based on maltodextrin and wheat B-starch in compost

    Czech Academy of Sciences Publication Activity Database

    Růžek, L.; Růžková, M.; Koudela, M.; Bečková, L.; Bečka, D.; Kruliš, Zdeněk; Šárka, E.; Voříšek, K.; Ledvina, Š.; Šalounová, B.; Venyercsanová, J.

    2015-01-01

    Roč. 42, č. 4 (2015), s. 209-214 ISSN 0862-867X R&D Projects: GA ČR GA525/09/0607 Institutional support: RVO:61389013 Keywords : biodegradable plastics * acetylated maltodextrin * lettuce Subject RIV: JI - Composite Materials Impact factor: 0.436, year: 2015

  11. Biodegradable composites from polyester and sugar beet pulp with antimicrobial coating for food packaging

    Science.gov (United States)

    Totally biodegradable, double-layered antimicrobial composite Sheets were introduced for food packaging. The substrate layers of the sheets were prepared from poly (lactic acid) (PLA) and sugar beet pulp (SBP) or poly (butylene adipate-co-terephthalate (PBAT) and SBP by a twin-screw extruder. The ac...

  12. Synthesis and characterization of citrate-based fluorescent small molecules and biodegradable polymers.

    Science.gov (United States)

    Xie, Zhiwei; Kim, Jimin P; Cai, Qing; Zhang, Yi; Guo, Jinshan; Dhami, Ranjodh S; Li, Li; Kong, Bin; Su, Yixue; Schug, Kevin A; Yang, Jian

    2017-03-01

    Novel citric acid based photoluminescent dyes and biodegradable polymers are synthesized via a facile "one-pot" reaction. A comprehensive understanding of the fluorescence mechanisms of the resulting citric acid-based fluorophores is reported. Two distinct types of fluorophores are identified: a thiozolopyridine family with high quantum yield, long lifetime, and exceptional photostability, and a dioxopyridine family with relatively lower quantum yield, multiple lifetimes, and solvent-dependent band shifting behavior. Applications in molecular labeling and cell imaging were demonstrated. The above discoveries contribute to the field of fluorescence chemistry and have laid a solid foundation for further development of new fluorophores and materials that show promise in a diversity of fluorescence-based applications. Photoluminescent materials are pivotal for fluorescence based imaging, labeling and sensing applications. Understanding their fluorescence mechanism is challenging and imperative. We develop a new class of citric acid-derived fluorescent materials in forms of polymers and small molecular dyes by a one-step solvent free reaction. We discovered two different classes of citric acid-derived fluorophores. A two-ring thiozolopyridine structure demonstrates strong fluorescence and exceptional resistance to photo-bleaching. A one-ring dioxopyridine exhibits relative weak fluorescence but with intriguing excitation and solvent-dependent emission wavelength shifting. Our methodology of synthesizing citric acid-derived fluorophores and the understanding on their luminescence are instrumental to the design and production of a large number of new photoluminescent materials for biological and biomedical applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  13. Biodegradation behaviors and color change of composites based on type of bagasse pulp/polylactic acid

    OpenAIRE

    maryam allahdadi; sahab Hedjazi; mahdi jonoobi; Ali abdolkhani; laya Jamalirad

    2017-01-01

    In this research, appearance quality and decay resistance of polylactic acid (PLA) based green composites made from monoethanolamine (MEA) bagasse pulp, alkaline sulfite-anthraquinone (AS) bagasse pulp, bleached soda (B S) bagasse pulp, unbleached soda (UN S) bagasse pulp (UN S) bagasse pulp and raw bagasse fibers (B) were investigated. For the investigation of biodegradation behaviors, effect of the white rot fungi (Coriolus versicolor) on the neat PLA and composites with natural fibers duri...

  14. Mechanical properties of natural fibre reinforced polymer composites

    Indian Academy of Sciences (India)

    Wintec

    green composites involving Hibiscus sabdariffa fibre as a reinforcing material in urea–formaldehyde (UF) resin based polymer ... mixed Hibiscus sabdariffa fibre reinforced polymer composites such as tensile, compressive and wear proper- ties were ... in natural fibres and its applications in various fields. Natural fibres are ...

  15. Viscoelastic properties of polymer composites during processing

    Science.gov (United States)

    O'Brien, Daniel James

    Residual stresses that are induced during processing of polymer matrix composites lead to warpage of structural parts and can produce microcracks and other forms of damage. Process models that track the development of residual stresses in composites during processing have received growing attention in recent years. An accurate and easy to implement simulation will help lower the manufacturing cost by enabling engineers to predict and prevent the warpage in parts due to residual stress. The critical feature of a process model is the development of an accurate material model to predict mechanical properties throughout the entire manufacturing cycle. Material models are very complex since the matrix changes from a fluid to a viscoelastic solid at the end of cure. In this work several aspects of the curing, viscoelastic, and cure shrinkage behavior of an aerospace grade epoxy resin were characterized and modeled for the purpose of composites process modeling. Measurement of matrix viscoelastic properties during cure was accomplished through two experimental approaches, each suited to a particular range of cure states. To investigate the material behavior during later stages of cure after gelation, small beam specimens were tested in three-point bending. During early stages of curing, samples were examined by shearing the material between parallel plates in a rheometer. Specimens for each configuration were manufactured at several cure states and tested at a range of temperatures. These data were used to develop a material model to predict the relaxation modulus of the matrix at any time during cure. Additionally, moire interferometry was successfully applied to the measurement of the viscoelastic Poisson's ratio of the matrix through its entire glassy-to-rubbery transition. The matrix viscoelastic material models were then used to predict composite viscoelastic properties and correlated with experimental results. In addition, the viscoelastic shrinkage behavior of the

  16. Biodegradable shape-memory polymers exhibiting sharp thermal transitions and controlled drug release.

    Science.gov (United States)

    Nagahama, Koji; Ueda, Yuichi; Ouchi, Tatsuro; Ohya, Yuichi

    2009-07-13

    Biodegradable shape-memory polymer networks prepared by cross-linking star shape branched oligo(ε-caprolactone) (bOCL) with hexamethylene diisocyanate are introduced. The thermal and mechanical properties of these networks were investigated using differential scanning calorimetry and tensile testing, respectively, and the morphology of the phase structure was characterized by polarized optical microscopy. The shape-memory properties of the networks were quantified using thermomechanical tensile experiments and showed strain fixity rates R(f) higher than 97% and strain recovery rates R(r) as high as 100%. Of note, networks of OCL segments with a lower degree of polymerization (DP; 10) exhibited significantly improved temperature-sensitive shape recovery: 90% of the permanent shape was recovered upon heating to within a 2 °C range (37-39 °C). The networks exhibited complete shape recovery to the permanent shape within 10 s at 42 °C. Theophylline-loaded (10 and 20 wt %) shape-memory materials, prepared by cross-linking bOCL with hexamethylene diisocyanate in the presence of theophylline, are also described as a model for a controlled drug release device. The 10 wt % loaded material was sufficiently soft and flexible for complex shape transformation and also showed high R(f) (98%) and R(r) (99%). Sustained release of loaded theophylline was achieved over 1 month without initial burst-release in a phosphate buffer solution (PBS; pH 7.4) at 37 °C.

  17. Design, development and optimization of oral colon targeted drug delivery system of azathioprine using biodegradable polymers.

    Science.gov (United States)

    Nath, Bipul; Nath, L K

    2013-01-01

    The present study was aimed at designing a microflora triggered colon targeted drug delivery system (MCDDS) based on swellable polysaccharide, Sterculia gum in combination with biodegradable polymers with a view to specifically deliver azathioprine in the colonic region for the treatment of IBD with reduced systemic toxicity. The microflora degradation properties of Sterculia gum was investigated in rat caecal phosphate buffer medium. The polysaccharide tablet cores were coated to different film thicknesses with blends of Eudragit RLPO and chitosan and overcoated with Eudragit L00 to provide acid and intestinal resistance. Swelling and drug release studies were carried out in simulated gastric fluid, SGF (pH 1.2), simulated intestinal fluid, SIF (pH 6.8) and simulated colonic fluid, SCF (pH 7.4 under anaerobic environment), respectively. Drug release study in SCF revealed that swelling force of the Sterculia gum could concurrently drive the drug out of the polysaccharide core due to the rupture of the chitosan/Eudargit coating in microflora activated environment. The degradation of chitosan was the rate-limiting factor for drug release in the colon. Drug release from the MCDDS was directly proportional to the concentration of the pore former (chitosan), but inversely related to the Eudragit RLPO coating thickness.

  18. Comparison between biodegradable polymers from cassava starch and glycerol as additives to biogas production

    Directory of Open Access Journals (Sweden)

    Paulo André Cremonez

    2016-08-01

    Full Text Available In this study, we compared cassava starch-based biodegradable polymers (PBMs and glycerol (G as additives used to increase biogas production from the co-digestion of swine wastewater (ARS. We chose to work with an inoculum comprising 40% (v/v of the total volume of the reactor; this inoculum was obtained from a Canadian model digester for treating swine waste. In the anaerobic digestion process, batch reactors were used on a laboratory scale with a total volume of approximately 4 L and a working volume of 3.2 L. Three treatments were conducted to compare the efficiency of solid removal, the chemical oxygen demand (COD, and the production of biogas. The first treatment contained only swine waste; the second included the addition of glycerol at 1, 3, and 5% (w/v; and the third treatment included the addition of 1, 3, and 5% (w/v of PBM residue in relation to the swine wastewater. From the results, it can be concluded that higher yields were obtained for the treatment with 3% PBM and 1% glycerol. Most treatments showed high removal rates of total solids and total volatile solids. Reductions lower than 70% were obtained only for treatments with PBM and glycerol at a ratio of 5%.

  19. Biodegradation of naphthalenesulphonate polymers: the potential of a combined application of fungi and bacteria.

    Science.gov (United States)

    Gullotto, Antonella; Lubello, Claudio; Mannucci, Alberto; Gori, Riccardo; Munz, Giulio; Briganti, Fabrizio

    2015-01-01

    The potential of several fungi and their synergy with bacterial biomasses were evaluated as a solution for the removal of 2-naphthalensulphonic acid polymers (2-NSAPs) from petrochemical wastewater, characterized by a chemical oxygen demand (COD) greater than 9000 mg/L. The ability of fungi to grow on 2-NSAP mixtures was preliminarily investigated using a solid medium, and then the action of the selected strains, both in suspended and immobilized form, was evaluated in terms of degradation, depolymerization, sorption and an increase in biodegradability of 2-NSAP. Among the 25 fungi evaluated two, in particular, Bjerkandera adusta and Pleurotus ostreatus, have been found to significantly depolymerize 2-NSAP yielding to the corresponding monomer (2-naphthalenesulphonic acid, 2-NSA), which has been further degraded by a bacterial consortia selected in a wastewater treatment plant (WWTP). The fungal treatment alone was able to reduce the COD value up to 44%, while activated sludge removed only 9% of the initial COD. In addition, the combined treatment (fungi and bacteria) allowed an increase in the COD removal up to 62%.

  20. The effect of additives interaction on the miscibility and crystal structure of two immiscible biodegradable polymers

    Directory of Open Access Journals (Sweden)

    Ahmed Mohamed El-Hadi

    2014-01-01

    Full Text Available Poly lactic acid (PLLA is a promising biopolymer, obtained from polymerization of lactic acid that is derived from renewable resources through fermentation. The characteristic brittleness of PLLA is attributed to slow crystallization rates, which results in the formation of the large spherulites. Its glass temperature is relative high, above room temperature and close to 60 ºC, and therefore its applications are limited. The additives poly((R-3-hydroxybutyrate (PHB, poly(vinyl acetate (PVAc and tributyl citrate (TBC were used as compatibilizers in the biodegradable polymer blend of (PLLA/PPC. Results from DSC and POM analysis indicated that the blends of PLLA and PPC are immiscible. However, the blends with additives are miscible. TBC as plasticizer was added to PLLA to reduce its Tg. PVAc was used as compatibilizer to improve the miscibility between PLLA and PPC. FT-IR showed about 7 cm-1 shift in the C=O peak in miscible blends due to physical interactions. POM experiments together with the results of DSC and WAXD showed that PHB enhances the crystallization behavior of PLLA by acting as bio nuclei and the crystallization process can occur more quickly. Consequently an increase was observed in the peak intensity in WAXD.

  1. Controlled release of copper from an intrauterine device using a biodegradable polymer.

    Science.gov (United States)

    Ramakrishnan, Reshmi; B, Bharaniraja; Aprem, Abi Santhosh

    2015-12-01

    The adverse effects of copper intrauterine devices (IUDs) such as abnormal bleeding, pain and cramps may be due in part to the burst release of copper ions during the first few months of usage. This study focuses on controlling the initial burst release of copper ions. This study evaluated in vitro release rates of copper for a period of 1 year from standard CuT380 IUDs (n=6) and from CuT380 IUDs coated with poly(dl-lactide-co-glycolide) (PLGA) films (n=6). This study characterized the coated device for its morphological changes during degradation of film by scanning electron microscopy (SEM). CuT380 IUDs coated with PLGA film with a thickness of 0.10±0.02 mm showed a reduced initial copper release (40-80 mcg/day) compared with uncoated CuT380 IUDs (150-200 mcg/day). Statistically significant (p<.05) results were obtained at different time intervals during the overall study period of 1 year. SEM images showed degradation of coating. Coating a CuT380 IUD with biodegradable polymer reduced the initial copper release without affecting release at 1 year. Clinical trials are required to determine whether this could reduce side effects such as bleeding and pain associated with copper containing IUDs. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Pulsed laser deposition of polyhydroxybutyrate biodegradable polymer thin films using ArF excimer laser

    Science.gov (United States)

    Kecskemeti, G.; Smausz, T.; Kresz, N.; Tóth, Zs.; Hopp, B.; Chrisey, D.; Berkesi, O.

    2006-11-01

    We demonstrated the pulsed laser deposition (PLD) of high quality films of a biodegradable polymer, the polyhydroxybutyrate (PHB). Thin films of PHB were deposited on KBr substrates and fused silica plates using an ArF ( λ = 193 nm, FWHM = 30 ns) excimer laser with fluences between 0.05 and 1.5 J cm -2. FTIR spectroscopic measurements proved that at the appropriate fluence (0.05, 0.09 and 0.12 J cm -2), the films exhibited similar functional groups with no significant laser-produced modifications present. Optical microscopic images showed that the layers were contiguous with embedded micrometer-sized grains. Ellipsometric results determined the wavelength dependence ( λ ˜ 245-1000 nm) of the refractive index and absorption coefficient which were new information about the material and were not published in the scientific literature. We believe that our deposited PHB thin films would have more possible applications. For example to our supposal the thin layers would be applicable in laser induced forward transfer (LIFT) of biological materials using them as absorbing thin films.

  3. Pulsed laser deposition of polyhydroxybutyrate biodegradable polymer thin films using ArF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Kecskemeti, G. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: kega@physx.u-szeged.hu; Smausz, T. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: tomi@physx.u-szeged.hu; Kresz, N. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: knr@physx.u-szeged.hu; Toth, Zs. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: ztoth@physx.u-szeged.hu; Hopp, B. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: bhopp@physx.u-szeged.hu; Chrisey, D. [Naval Research Laboratory, Washington, DC 20375 (United States)]. E-mail: chrisey@ccf.nrl.navy.mil; Berkesi, O. [Department of Physical Chemistry, University of Szeged, H-6720 Szeged, Rerrich B. ter 1 (Hungary)]. E-mail: oberkesi@chem.u-szeged.hu

    2006-11-30

    We demonstrated the pulsed laser deposition (PLD) of high quality films of a biodegradable polymer, the polyhydroxybutyrate (PHB). Thin films of PHB were deposited on KBr substrates and fused silica plates using an ArF ({lambda} = 193 nm, FWHM = 30 ns) excimer laser with fluences between 0.05 and 1.5 J cm{sup -2}. FTIR spectroscopic measurements proved that at the appropriate fluence (0.05, 0.09 and 0.12 J cm{sup -2}), the films exhibited similar functional groups with no significant laser-produced modifications present. Optical microscopic images showed that the layers were contiguous with embedded micrometer-sized grains. Ellipsometric results determined the wavelength dependence ({lambda} {approx} 245-1000 nm) of the refractive index and absorption coefficient which were new information about the material and were not published in the scientific literature. We believe that our deposited PHB thin films would have more possible applications. For example to our supposal the thin layers would be applicable in laser induced forward transfer (LIFT) of biological materials using them as absorbing thin films.

  4. Drug release control in delivery system for biodegradable polymer drugs by γ-radiation

    International Nuclear Information System (INIS)

    Yoshioka, Sumie; Azo, Yukio; Kojima, Shigeo

    1997-01-01

    Characterizations of the drug release from microsphere and hydrogel preparation made from biodegradable polymers were investigated aiming at development of a drug delivery system which allows an optimum drug delivery and the identification of the factors which control its delivery. Poly-lactic acid microspheres containing 10% of progesterone were produced from poly DL-lactic acid and exposed to γ-ray at 5-1000 kGy. And its glass transition temperature (Tg) was determined by differential scanning calorimetry. The temperature was gradually lowered with an increase in the dose of radiation. Tg of the microsphere exposed at 1000 kGy was lower by 10degC compared with the untreated one, showing that Tg control is possible without changing the size distribution of microsphere. Then, the amount of progesterone released from microsphere was determined. The release rate of the drug linearly increased with a square root of radiation time. These results indicate that the control of drug release rate is possible through controling the microsphere's Tg by γ-ray radiation. (M.N.)

  5. A Comparative Study on Immobilization of Fructosyltransferase in Biodegradable Polymers by Electrospinning.

    Science.gov (United States)

    Gabrielczyk, Jakub; Duensing, Thilo; Buchholz, Stefanie; Schwinges, Alexander; Jördening, Hans-Joachim

    2018-01-24

    Commercial application of biocatalysts depends on the efficiency of the immobilization method and residual enzyme activity. Electrospinning offers a simple and versatile route to immobilize enzymes in submicron-sized fibers and thus improved mass transfer characteristics. Performance of encapsulation of fructosyltransferase from Bacillus subtilis by emulsion, suspension, and coaxial electrospinning was compared. We particularly focused on the effect of hydrophilic properties of a set of biodegradable polymers on support's activity. Bioactivity of electrospun support in aqueous medium increased in order of the matrix hydrophilicity. Additionally, the efficiency of electrospun fibers was compared with Sepabeads®, commercial epoxy-activated resins. In fibers, enzyme loading of 68.1 mg/g and specific enzyme activity of 5.5 U/mg was achieved compared to 49.5 mg/g and 2.2 U/mg on Sepabeads. Fructosyltransferase exhibited high sensitivity towards organic solvents and covalent attachment, respectively. Immobilization of native enzyme in coaxial fibers increased the specific activity to approx. 30 U/mg which corresponds to 24% of that of the free enzyme. Finally, operational stability of fiber supports was examined in a plug-flow reactor and 5% of initial substrate conversion remained after > 2000 cycles. The efficiency of core-shell immobilizates compared to one-dimensional fibers was both in batch and continuous reaction at least 4.4-fold higher.

  6. Polymer-SnO2 composite membranes

    DEFF Research Database (Denmark)

    Nørgaard, Casper Frydendal; Skou, Eivind Morten

    When designing sulfonic acid based ionomers, high ion exchange capacity (IEC) comes at the expense of the mechanical properties. With too high IEC, the membrane will excessively swell or even dissolve in water. Therefore a suitable compromise must be found between high charge carrier concentration...... and adequate mechanical properties. It has been demonstrated that this compromise can be found at higher IEC when the mechanical properties are improved by increasing crystallinity, increasing molecular weight, crosslinking or reinforcement of the membrane by dispersion of interacting particles therein....... This work utilizes the latter approach and makes use of particles of tin dioxide (SnO2). Polymer-SnO2 composite membranes were successfully prepared using an ion-exchange method. SnO2 was incorporated into membranes by ion-exchange in solutions of SnCl2 ∙ 2 H2O in methanol, followed by oxidation to SnO2...

  7. Biodegradable polymer nanocomposites based on natural nanotubes: effect of magnetically modified halloysite on the behaviour of polycaprolactone

    Czech Academy of Sciences Publication Activity Database

    Khunová, V.; Šafařík, Ivo; Škrátek, M.; Kelnar, Ivan; Tomanová, K.

    2016-01-01

    Roč. 51, č. 3 (2016), s. 435-444 ISSN 0009-8558 R&D Projects: GA ČR(CZ) GA13-15255S Institutional support: RVO:60077344 ; RVO:61389013 Keywords : magnetically modified HNTs * biodegradable poly mer nanocomposites * poly caprolactone Subject RIV: CD - Macromolecular Chemistry; JI - Composite Materials (UMCH-V) Impact factor: 1.052, year: 2016

  8. Processing and characterization of ceramic superconductor/polymer composites

    International Nuclear Information System (INIS)

    Kander, R.G.; Namboodri, S.L.

    1993-01-01

    One way to more easily process a brittle high-temperature ceramic superconductor into a useful structure is to combine it with a polymer to form a composite material. Processing of polymer-based composites into complex shapes is well established and relatively easy when compared with traditional ceramic processing unit operations. In addition, incorporating a ceramic superconductor into a polymer matrix can improve mechanical performance as compared with a monolithic ceramic. Finally, because ceramic superconductors are susceptible to attack by moisture, a polymer-based composite structure can also provide protection from deleterious environmental effects. This paper focuses on the processing and subsequent characterization of ceramic superconductor/polymer composites designed primarily for electromagnetic shielding and diamagnetic applications. YBa 2 Cu 3 O 7-x [YBCO] ceramic superconductor is combined with poly(methyl methacrylate) [PMMA] to form novel composite structures. Composite structures have been molded with both a discontinuous superconducting phase (i.e., ceramic particulate reinforced polymers) and with a continuous superconducting phase (i.e., polymer infiltrated porous ceramics). Characterization of these composite structures includes the determination of diamagnetic strength, electromagnetic shielding effectiveness, mechanical performance, and environmental resistance. The goal of this program is to produce a composite structure with increased mechanical integrity and environmental resistance at liquid nitrogen temperatures without compromising the electromagnetic shielding and diamagnetic properties of the superconducting phase. Composites structures of this type are potentially useful in numerous magnetic applications including electromagnetic shielding, magnetic sensors, energy storage, magnetic levitation, and motor windings

  9. Effects of reprocessing on nanoalumina polymer composites

    Science.gov (United States)

    Huang, Chunchia

    The life cycle of reprocessed polymer nanocomposites is a critical factor associated with their growing use, but the limited work on reprocessing of nanocomposites has focused solely on the effects of organoclays. This research investigated of the structure and property changes during reprocessing of polypropylene (PP) and polycarbonate (PC) nanocomposites with 3 wt. % nanoalumina. Neat PP and PC were used as controls. Reprocessing of the neat polymers and nanocomposites produced no indication of oxidation (in FTIR), no changes in the glass transition temperature of PC and the melting temperatures of PP, and no changes in thermal stability (as measured using thermogravimetric analysis). Significant decreases, however, occurred in the melt viscosity of the materials. The introduction of nanoalumina during twin screw extrusion also produced a significant decrease in the viscosity and a 10°C decrease in the glass transition temperature of the PC nanocomposite. Color changes did not correspond to the chain scission in PP and PC; neat PP and PP composite yellowed, neat PC turned brown, and the PC nanocomposite did not change color. Dispersion of the nanoalumina in both PP and PC improved with repeated reprocessing, the crystallinity in the PP/nanoalumina composites remained constant. The Young's moduli of both the PP and PP/A12O3 nanocomposite were similar, whereas the Young's modulus values of the PC/A1 2O3 nanocomposite was slighted lower than that of the neat PC. In contrast, the elongations at break of the PP/A12O3 and PC/A12O3 nanocomposites were, respectively, 50% and 16% of the values measured for the neat resins. All modulus and elongation at break values, however, remained constant over five reprocessing cycles. This behavior suggests that the major degradation mechanism during reprocessing of neat PP and PP nanocomposites was thermal-mechanical polymer chain scission and that the nanoalumina enhanced this degradation in the PC/nanoalumina. This additional

  10. Characterization of fabricated three dimensional scaffolds of bio ceramic-polymer composite via microstereolithography technique

    International Nuclear Information System (INIS)

    Marina Talib; Covington, J.A.; Bolarinwa, A.

    2013-01-01

    Full-text: Microstereolithography is a method used for rapid proto typing of polymeric and ceramic components. This technique converts a computer-aided design (CAD) to a three dimensional (3D) model, and enables layer per layer fabrication curing a liquid resin with UV-light or laser source. The aim of this project was to formulate photo curable polymer reinforced with synthesized calcium pyrophosphate (CPP), and to fabricate a 3D scaffolds with optimum mechanical properties for specific tissue engineering applications. The photo curable ceramic suspension was prepared with acrylate polyester, multifunctional acrylate monomer with the addition of 50-70 wt % of CPP, photo initiators and photo inhibitors. The 3D structure of disc (5 mm height x 4 mm diameter) was successfully fabricated using Envisiontec Perfactory3. They were then sintered at high temperature for polymer removal, to obtain a ceramic of the desired porosity. The density increased to more than 35 % and the dimensional shrinkage after sintering were 33 %. The discs were then subjected compressive measurement, biodegradation and bioactivity test. Morphology and CPP content of the sintered polymer was investigated with SEM and XRD, respectively. The addition of CPP coupled with high temperature sintering, had a significant effect on the compressive strength exhibited by the bio ceramic. The values are in the range of cancellous bone (2-4 MPa). In biodegradation and bioactivity test, the synthesized CPP induced the formation of apatite layer and its nucleation onto the composite surface. (author)

  11. Characterization of fabricated three dimensional scaffolds of bioceramic-polymer composite via microstereolithography technique

    Science.gov (United States)

    Talib, Marina; Covington, James A.; Bolarinwa, Aminat

    2014-02-01

    Microstereolithography is a method used for rapid prototyping of polymeric and ceramic components. This technique converts a computer-aided design (CAD) to a three dimensional (3D) model, and enables layer per layer fabrication curing a liquid resin with UV-light or laser source. The aim of this project was to formulate photocurable polymer reinforced with synthesized calcium pyrophosphate (CPP), and to fabricate a 3D scaffolds with optimum mechanical properties for specific tissue engineering applications. The photocurable ceramic suspension was prepared with acrylate polyester, multifunctional acrylate monomer with the addition of 50-70wt% of CPP, photoinitiators and photoinhibitors. The 3D structure of disc (5 mm height × 4 mm diameter) was successfully fabricated using Envisiontec Perfactory3® . They were then sintered at high temperature for polymer removal, to obtain a ceramic of the desired porosity. The density increased to more than 35% and the dimensional shrinkage after sintering were 33%. The discs were then subjected compressive measurement, biodegradation and bioactivity test. Morphology and CPP content of the sintered polymer was investigated with SEM and XRD, respectively. The addition of CPP coupled with high temperature sintering, had a significant effect on the compressive strength exhibited by the bioceramic. The values are in the range of cancellous bone (2-4 MPa). In biodegradation and bioactivity test, the synthesized CPP induced the formation of apatite layer and its nucleation onto the composite surface.

  12. Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  13. Mass spectrometry for the elucidation of the subtle molecular structure of biodegradable polymers and their degradation products.

    Science.gov (United States)

    Kowalczuk, Marek; Adamus, Grażyna

    2016-01-01

    Contemporary reports by Polish authors on the application of mass spectrometric methods for the elucidation of the subtle molecular structure of biodegradable polymers and their degradation products will be presented. Special emphasis will be given to natural aliphatic (co)polyesters (PHA) and their synthetic analogues, formed through anionic ring-opening polymerization (ROP) of β-substituted β-lactones. Moreover, the application of MS techniques for the evaluation of the structure of biodegradable polymers obtained in ionic and coordination polymerization of cyclic ethers and esters as well as products of step-growth polymerization, in which bifunctional or multifunctional monomers react to form oligomers and eventually long chain polymers, will be discussed. Furthermore, the application of modern MS techniques for the assessment of polymer degradation products, frequently bearing characteristic end groups that can be revealed and differentiated by MS, will be discussed within the context of specific degradation pathways. Finally, recent Polish accomplishments in the area of mass spectrometry will be outlined. © 2015 Wiley Periodicals, Inc.

  14. A Review on Potentiality of Nano Filler/Natural Fiber Filled Polymer Hybrid Composites

    Directory of Open Access Journals (Sweden)

    Naheed Saba

    2014-08-01

    Full Text Available The increasing demand for greener and biodegradable materials leading to the satisfaction of society requires a compelling towards the advancement of nano-materials science. The polymeric matrix materials with suitable and proper filler, better filler/matrix interaction together with advanced and new methods or approaches are able to develop polymeric composites which shows great prospective applications in constructions and buildings, automotive, aerospace and packaging industries. The biodegradability of the natural fibers is considered as the most important and interesting aspects of their utilization in polymeric materials. Nanocomposite shows considerable applications in different fields because of larger surface area, and greater aspect ratio, with fascinating properties. Being environmentally friendly, applications of nanocomposites offer new technology and business opportunities for several sectors, such as aerospace, automotive, electronics, and biotechnology industries. Hybrid bio-based composites that exploit the synergy between natural fibers in a nano-reinforced bio-based polymer can lead to improved properties along with maintaining environmental appeal. This review article intended to present information about diverse classes of natural fibers, nanofiller, cellulosic fiber based composite, nanocomposite, and natural fiber/nanofiller-based hybrid composite with specific concern to their applications. It will also provide summary of the emerging new aspects of nanotechnology for development of hybrid composites for the sustainable and greener environment.

  15. Biodegradable composites based on L-polylactide and jute fibres

    DEFF Research Database (Denmark)

    Plackett, David; Løgstrup Andersen, T.; Batsberg Pedersen, W.

    2003-01-01

    in the 180-220 degreesC range were significantly higher than those of polylactide alone. Composite samples failed in a brittle fashion under tensile load and showed little sign of fibre pull-out. Examination of composite fracture surfaces using electron microscopy showed voids occurring between the jute...

  16. Large Dielectric Constant Enhancement in MXene Percolative Polymer Composites

    KAUST Repository

    Tu, Shao Bo

    2018-04-06

    near the percolation limit of about 15.0 wt % MXene loading, which surpasses all previously reported composites made of carbon-based fillers in the same polymer. With up to 10 wt % MXene loading, the dielectric loss of the MXene/P(VDF-TrFE-CFE) composite indicates only an approximately 5-fold increase (from 0.06 to 0.35), while the dielectric constant increased by 25 times over the same composition range. Furthermore, the ratio of permittivity to loss factor of the MXene-polymer composite is superior to that of all previously reported fillers in this same polymer. The dielectric constant enhancement effect is demonstrated to exist in other polymers as well when loaded with MXene. We show that the dielectric constant enhancement is largely due to the charge accumulation caused by the formation of microscopic dipoles at the surfaces between the MXene sheets and the polymer matrix under an external applied electric field.

  17. A review on synthesis, properties and applications of natural polymer based carrageenan blends and composites.

    Science.gov (United States)

    Zia, Khalid Mahmood; Tabasum, Shazia; Nasif, Muhammad; Sultan, Neelam; Aslam, Nosheen; Noreen, Aqdas; Zuber, Mohammad

    2017-03-01

    Carrageenan is a natural polysaccharide extracted from edible red seaweeds of Rhodophycea class. It has been used as a viscosity increasing or gelling agent for prolonged and controlled drug release, food, pharmaceuticals and other industries. However, in spite of wide range of applications, carrageenan has some drawbacks and adverse effects on the biological systems, so its modifications with natural and synthetic polymers are carried out. This review article presents different sources and properties of carrageenans with special emphasis on natural polymer based carrageenan blends and composites and their applications in controlled drug delivery system, wound dressing and tissue engineering because of their biodegradability and biocompatibility, food industry as thickening/gelling materials, cosmeceuticals and making polyelectrolyte complexes. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Polymer composites on the aryl alicyclic polyimide base with another polymers

    International Nuclear Information System (INIS)

    Zhubanov, B.; Kudajkulova, S.; Musapirova, Z.

    2003-01-01

    Optimal conditions for synthesis of polymer composites on the base of aryl alicyclic polyimide (PI) with thermo stable polymers - polycarbonate (PC) and polysulfone (PS) - were selected. It was found 2 ways for obtain polymer-polymer composites: 1) mechanical mixing in m-cresol the polymers at different ratio of PI/PC and PI/PS equal to 90/10, 80/20,70/30; 2) reaction mixing of solution of PC or PS in m-cresol with monomers for syntheses of polyimide - tree cyclo decen tetra carbonic acid and oxydianiline. Physico-chemical properties and structure of the composites were studied by methods of UR-, X-ray-spectroscopy, optical microscopy and viscosimeter. X-ray phase spectroscopy possess to determine structure of polymers and their changes, phase transformations and conformation of macromolecules under different kinds of influence. It was shown that new modern materials with nano structure can be synthesised by suggested method

  19. Researches on the development of new composite materials complete / partially biodegradable using natural textile fibers of new vegetable origin and those recovered from textile waste

    Science.gov (United States)

    Todor, M. P.; Bulei, C.; Heput, T.; Kiss, I.

    2018-01-01

    The objective of the research is to develop new fully / partially biodegradable composite materials by using new natural fibers and those recovered from various wastes. Thus, the research aims to obtain some composites with matrix of various types of polymeric materials and the reinforcement phase of textile materials (of different natures, morphologies and composites) so that the resulting products to be (bio)degradable. The textile inserts used as raffle are ecological, non-toxic and biodegradable and they contain (divided or in combination) bast fibers (flax, hemp, jute) and other vegetable fibers (cotton, wool) as plain yarn or fabric, which can replace fibers of glass commonly used in polymeric composites. The main activities described in this article are carried out during the first phase of the research (phase I - initiation of research) and they are oriented towards the choice of types of textile inserts from which the composites will be obtained (the materials needed for the raffle), the choice of the types of polymers (the necessary materials for matrices) and choosing the variants of composites with different types and proportions of the constituent content (proposals and working variants) and choosing the right method for obtaining samples of composite materials (realization technology). The purpose of the research is to obtain composite materials with high structural, thermo-mechanical and / or tribological performances, according to ecological norms and international requirements in order to replace the existing classical materials, setting up current, innovative and high performance solutions, for applications in top areas such as automotive industry and not only.

  20. Ultra low density biodegradable shape memory polymer foams with tunable physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Singhal, Pooja; Wilson, Thomas S.; Cosgriff-Hernandez, Elizabeth; Maitland, Duncan J.

    2017-12-12

    Compositions and/or structures of degradable shape memory polymers (SMPs) ranging in form from neat/unfoamed to ultra low density materials of down to 0.005 g/cc density. These materials show controllable degradation rate, actuation temperature and breadth of transitions along with high modulus and excellent shape memory behavior. A method of m ly low density foams (up to 0.005 g/cc) via use of combined chemical and physical aking extreme blowing agents, where the physical blowing agents may be a single compound or mixtures of two or more compounds, and other related methods, including of using multiple co-blowing agents of successively higher boiling points in order to achieve a large range of densities for a fixed net chemical composition. Methods of optimization of the physical properties of the foams such as porosity, cell size and distribution, cell openness etc. of these materials, to further expand their uses and improve their performance.

  1. Biodegradable polymer for sealing porous PEO layer on pure magnesium: An in vitro degradation study

    Energy Technology Data Exchange (ETDEWEB)

    Alabbasi, Alyaa; Mehjabeen, Afrin [Biomaterials and Engineering Materials (BEM) Laboratory, James Cook University, Townsville 4811, Queensland (Australia); Kannan, M. Bobby, E-mail: bobby.mathan@jcu.edu.au [Biomaterials and Engineering Materials (BEM) Laboratory, James Cook University, Townsville 4811, Queensland (Australia); Ye, Qingsong [Discipline of Dentistry, James Cook University, Townsville 4811, Queensland (Australia); Blawert, Carsten [Magnesium Innovation Centre, Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht 21502 (Germany)

    2014-05-01

    Graphical abstract: - Highlights: • Poly(L-lactide) was used to seal the porous PEO layer on Mg. • The dual-layer coating improved the in vitro degradation resistance of Mg. • Localized degradation was inhibited in the dual-layer coated Mg. - Abstract: An attempt was made to seal the porous silicate-based plasma electrolytic oxidation (PEO) layer on pure magnesium (Mg) with a biodegradable polymer, poly(L-lactide) (PLLA), to delay the localized degradation of magnesium-based implants in body fluid for better in-service mechanical integrity. Firstly, a silicate-based PEO coating on pure magnesium was performed using a pulsed constant current method. In order to seal the pores in the PEO layer, PLLA was coated using a two-step spin coating method. The performance of the PEO–PLLA Mg was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The EIS results showed that the polarization resistance (R{sub p}) of the PEO–PLLA Mg was close to two orders of magnitude higher than that of the PEO Mg. While the corrosion current density (i{sub corr}) of the pure Mg was reduced by 65% with the PEO coating, the PEO–PLLA coating reduced the i{sub corr} by almost 100%. As expected, the R{sub p} of the PEO–PLLA Mg decreased with increase in exposure time. However, it was noted that the R{sub p} of the PEO–PLLA Mg even after 100 h was six times higher than that of the PEO Mg after 48 h exposure, and did not show any visible localized attack.

  2. Biodegradable polymer nanofiber membrane for the repair of cutaneous wounds in dogs - two case reports

    Directory of Open Access Journals (Sweden)

    Lívia Gomes Amaral

    2016-12-01

    Full Text Available The study of wound healing and its treatment is extremely important in veterinary medicine due to the high frequency of wounds and the difficulty in treating wounds by second intention. Thus, the objective of this study was to evaluate the use of a nanofiber membrane made of biodegradable polymers as a method of wound treatment in dogs. This study comprised two dogs with bite wounds. Debridement and cleaning was performed followed by the application of the membrane. In one dog, the wound was in the left proximal calcaneal region with clinical signs of infection, necrotic tissue, and muscle and the gastrocnemius tendon were exposed. The wound displayed rapid formation of granulation tissue which became excessive, so it was necessary to debride several times. However, with the suspension of the use of the membrane, formation of this tissue was not observed, and the wound evolved to epithelialization and fast contraction. In the second dog, there was a deep wound on the medial aspect of the proximal right hind limb, with clinical signs of infection, with muscle exposure. Once the membrane was placed, granulation tissue formed, and the membrane was used until the level of this tissue reached the skin. The wound underwent rapid epithelialization and contraction, without developing exuberant granulation tissue. Efficient wound repair was observed and the dogs exhibited greater comfort during application and use of the membrane. More studies should be conducted in dogs focusing on the application of this membrane until the appearance of healthy granulation tissue, as continued use seems to stimulate the formation of exuberant granulation tissue.

  3. Biodegradable polymer based theranostic agents for photoacoustic imaging and cancer therapy

    Science.gov (United States)

    Wang, Yan J.; Strohm, Eric M.; Kolios, Michael C.

    2016-03-01

    In this study, multifunctional theranostic agents for photoacoustic (PA), ultrasound (US), fluorescent imaging, and for therapeutic drug delivery were developed and tested. These agents consisted of a shell made from a biodegradable Poly(lactide-co-glycolic acid) (PLGA) polymer, loaded with perfluorohexane (PFH) liquid and gold nanoparticles (GNPs) in the core, and lipophilic carbocyanines fluorescent dye DiD and therapeutic drug Paclitaxel (PAC) in the shell. Their multifunctional capacity was investigated in an in vitro study. The PLGA/PFH/DiD-GNPs particles were synthesized by a double emulsion technique. The average PLGA particle diameter was 560 nm, with 50 nm diameter silica-coated gold nano-spheres in the shell. MCF7 human breast cancer cells were incubated with PLGA/PFH/DiDGNPs for 24 hours. Fluorescent and PA images were recorded using a fluorescent/PA microscope using a 1000 MHz transducer and a 532 nm pulsed laser. For the particle vaporization and drug delivery test, MCF7 cells were incubated with the PLGA/PFH-GNPs-PAC or PLGA/PFH-GNPs particles for 6, 12 and 24 hours. The effects of particle vaporization and drug delivery inside the cells were examined by irradiating the cells with a laser fluence of 100 mJ/cm2, and cell viability quantified using the MTT assay. The PA images of MCF7 cells containing PLGA/PFH/DiD-GNPs were spatially coincident with the fluorescent images, and confirmed particle uptake. After exposure to the PLGA/PFHGNP- PAC for 6, 12 and 24 hours, the cell survival rate was 43%, 38%, and 36% respectively compared with the control group, confirming drug delivery and release inside the cells. Upon vaporization, cell viability decreased to 20%. The particles show potential as imaging agents and drug delivery vehicles.

  4. Polymer blend compositions and methods of preparation

    Science.gov (United States)

    Naskar, Amit K.

    2016-09-27

    A polymer blend material comprising: (i) a first polymer containing hydrogen bond donating groups having at least one hydrogen atom bound to a heteroatom selected from oxygen, nitrogen, and sulfur, or an anionic version of said first polymer wherein at least a portion of hydrogen atoms bound to a heteroatom is absent and replaced with at least one electron pair; (ii) a second polymer containing hydrogen bond accepting groups selected from nitrile, halogen, and ether functional groups; and (iii) at least one modifying agent selected from carbon particles, ether-containing polymers, and Lewis acid compounds; wherein, if said second polymer contains ether functional groups, then said at least one modifying agent is selected from carbon particles and Lewis acid compounds. Methods for producing the polymer blend, molded forms thereof, and articles thereof, are also described.

  5. Three-dimensional culture of rat calvarial osteoblasts in porous biodegradable polymers

    Science.gov (United States)

    Ishaug-Riley, S. L.; Crane-Kruger, G. M.; Yaszemski, M. J.; Mikos, A. G.

    1998-01-01

    Neonatal rat calvarial osteoblasts were cultured in 90% porous, 75:25 poly(DL-lactic-co-glycolic acid) (PLGA) foam scaffolds for up to 56 days to examine the effects of the cell seeding density, scaffold pore size, and foam thickness on the proliferation and function of the cells in this three-dimensional environment. Osteoblasts were seeded at either 11.1 x 10(5) or 22.1 x 10(5) cells per cm2 onto PLGA scaffolds having pore sizes in the range of 150-300 or 500-710 microm with a thickness of either 1.9 or 3.2 mm. After 1 day in culture, 75.6 and 68.6% of the seeded cells attached and proliferated on the 1.9 mm thick scaffolds of 150-300 microm pore size for the low and high seeding densities, respectively. The number of osteoblasts continued to increase throughout the study and eventually leveled off near 56 days, as indicated by a quantitative DNA assay. Osteoblast/foam constructs with a low cell seeding density achieved comparable DNA content and alkaline phosphatase (ALPase) activity after 14 days, and mineralization results after 56 days to those with a high cell seeding density. A maximum penetration depth of osseous tissue of 220+/-40 microm was reached after 56 days in the osteoblast/foam constructs of 150-300 microm pore size initially seeded with a high cell density. For constructs of 500-710 microm pore size, the penetration depth was 190+/-40 microm under the same conditions. Scaffold pore size and thickness did not significantly affect the proliferation or function of osteoblasts as demonstrated by DNA content, ALPase activity, and mineralized tissue formation. These data show that comparable bone-like tissues can be engineered in vitro over a 56 day period using different rat calvarial osteoblast seeding densities onto biodegradable polymer scaffolds with pore sizes in the range of 150-710 microm. When compared with the results of a previous study where similar polymer scaffolds were seeded and cultured with marrow stromal cells, this study

  6. The impact of nanoclay on the crystal growth kinetics and morphology of biodegradable poly(ethylene succinate) composite

    CSIR Research Space (South Africa)

    Bandyopadhyay, J

    2012-07-01

    Full Text Available The impact of nanoclay on the isothermal crystal growth kinetics and morphology of biodegradable poly(ethylene succinate) (PES) is reported. A PES composite (PESNC) containing 5 wt% organically modified montmorillonite, was prepared via solvent...

  7. Solid polymer electrolyte composite membrane comprising laser micromachined porous support

    Science.gov (United States)

    Liu, Han [Waltham, MA; LaConti, Anthony B [Lynnfield, MA; Mittelsteadt, Cortney K [Natick, MA; McCallum, Thomas J [Ashland, MA

    2011-01-11

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 5 microns, are made by laser micromachining and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  8. New biodegradable air-entraining admixture based on LAS for cement-based composites

    International Nuclear Information System (INIS)

    Mendes, J.C.; Moro, T.K.; Dias, L.S.; Campos, P.A.M.; Silva, G.J.B.; Peixoto, R.A.F.; Cury, A.A.

    2016-01-01

    The active principle of Air Entraining Admixtures (AEA) are surfactants, analogously to washing up liquids. Washing up (or dishwashing) liquids are widely available products, relatively inexpensive, non-toxic and biodegradable, thus presenting smaller environmental impact. Therefore, the present work proposes the use of a biodegradable surfactant comprised in washing up liquids, Linear Alkylbenzene Sulfonate (LAS), as sustainable air entraining agent for cement-based composites. In this sense, a performance evaluation of the proposed AEA is carried out, by comparing the properties of mortars with proposed AEA, commercial AEA and ones without any admixture. Through the physical, mechanical and microstructural analysis, it was possible to determine the efficiency of the proposed AEA, as well as its optimum range of dosage. As a result, we seek to contribute to the technical development of cement-based composites in Brazil and in the world. (author)

  9. Carbon nanotube buckypaper reinforced polymer composites: a review

    Directory of Open Access Journals (Sweden)

    Bruno Ribeiro

    2017-09-01

    Full Text Available Abstract This review provides valuable information about the general characteristics, processing conditions and physical properties of carbon nanotube buckypaper (BP and its polymer composites. Vacuum filtration is the most common technique used for manufacturing BP, since the carbon nanotubes are dispersed in aqueous solution with the aid of surfactant. Previous works have reported that mechanical properties of BP prepared by vacuum filtration technique are relatively weak. On the other hand, the incorporation of polymer materials in those nanostructures revealed a significant improvement in their mechanical behavior, since the impregnation between matrix and BP is optimized. Electrical conductivity of BP/polymer composites can reach values as high as 2000 S/m, which are several orders of magnitude greater than traditional CNT/polymer composites. Also, BP can improve remarkably the thermal stability of polymer matrices, opening new perspectives to use this material in fire retardant applications.

  10. Electron beam curing of polymer matrix composites

    International Nuclear Information System (INIS)

    Janke, C.J.; Wheeler, D.; Saunders, C.

    1998-01-01

    The purpose of the CRADA was to conduct research and development activities to better understand and utilize the electron beam PMC curing technology. This technology will be used to replace or supplement existing PMC thermal curing processes in Department of Energy (DOE) Defense Programs (DP) projects and American aircraft and aerospace industries. This effort involved Lockheed Martin Energy Systems, Inc./Lockheed Martin Energy Research Corp. (Contractor), Sandia National Laboratories, and ten industrial Participants including four major aircraft and aerospace companies, three advanced materials companies, and three electron beam processing organizations. The technical objective of the CRADA was to synthesize and/or modify high performance, electron beam curable materials that meet specific end-use application requirements. There were six tasks in this CRADA including: Electron beam materials development; Electron beam database development; Economic analysis; Low-cost Electron Beam tooling development; Electron beam curing systems integration; and Demonstration articles/prototype structures development. The contractor managed, participated and integrated all the tasks, and optimized the project efforts through the coordination, exchange, and dissemination of information to the project participants. Members of the Contractor team were also the principal inventors on several electron beam related patents and a 1997 R and D 100 Award winner on Electron-Beam-Curable Cationic Epoxy Resins. The CRADA achieved a major breakthrough for the composites industry by having successfully developed high-performance electron beam curable cationic epoxy resins for use in composites, adhesives, tooling compounds, potting compounds, syntactic foams, etc. UCB Chemicals, the world's largest supplier of radiation-curable polymers, has acquired a license to produce and sell these resins worldwide

  11. Natural fiber-reinforced polymer composites

    International Nuclear Information System (INIS)

    Taj, S.; Khan, S.; Munawar, M.A.

    2007-01-01

    Natural fibers have been used to reinforce materials for over 3,000 years. More recently they have been employed in combination with plastics. Many types of natural fi fibers have been investigated for use in plastics including Flax, hemp, jute, straw, wood fiber, rice husks, wheat, barley, oats, rye, cane (sugar and bamboo), grass reeds, kenaf, ramie, oil palm empty fruit bunch, sisal, coir, water hyacinth, pennywort, kapok, paper-mulberry, raphia, banana fiber, pineapple leaf fiber and papyrus. Natural fibers have the advantage that they are renewable resources and have marketing appeal. The Asian markets have been using natural fibers for many years e.g., jute is a common reinforcement in India. Natural fibers are increasingly used in automotive and packaging materials. Pakistan is an agricultural country and it is the main stay of Pakistan's economy. Thousands of tons of different crops are produced but most of their wastes do not have any useful utilization. Agricultural wastes include wheat husk, rice husk, and their straw, hemp fiber and shells of various dry fruits. These agricultural wastes can be used to prepare fiber reinforced polymer composites for commercial use. This report examines the different types of fibers available and the current status of research. Many references to the latest work on properties, processing and application have been cited in this review. (author)

  12. Preparation and application of conducting polymer/Ag/clay composite nanoparticles formed by in situ UV-induced dispersion polymerization

    Science.gov (United States)

    Zang, Limin; Qiu, Jianhui; Yang, Chao; Sakai, Eiichi

    2016-02-01

    In this work, composite nanoparticles containing polypyrrole, silver and attapulgite (PPy/Ag/ATP) were prepared via UV-induced dispersion polymerization of pyrrole using ATP clay as a templet and silver nitrate as photoinitiator. The effects of ATP concentration on morphology, structure and electrical conductivity were studied. The obtained composite nanoparticles with an interesting beads-on-a-string morphology can be obtained in a short time (10 min), which indicates the preparation method is facile and feasible. To explore the potential applications of the prepared PPy/Ag/ATP composite nanoparticles, they were served as multifunctional filler and blended with poly(butylene succinate) (PBS) matrix to prepare biodegradable composite material. The distribution of fillers in polymer matrix and the interfacial interaction between fillers and PBS were confirmed by scanning electron microscope, elemental mapping and dynamic mechanical analysis. The well dispersed fillers in PBS matrix impart outstanding antibacterial property to the biodegradable composite material as well as enhanced storage modulus due to Ag nanoparticles and ATP clay. The biodegradable composite material also possesses modest surface resistivity (106 ~ 109 Ω/◻).

  13. Preparation and application of conducting polymer/Ag/clay composite nanoparticles formed by in situ UV-induced dispersion polymerization.

    Science.gov (United States)

    Zang, Limin; Qiu, Jianhui; Yang, Chao; Sakai, Eiichi

    2016-02-03

    In this work, composite nanoparticles containing polypyrrole, silver and attapulgite (PPy/Ag/ATP) were prepared via UV-induced dispersion polymerization of pyrrole using ATP clay as a templet and silver nitrate as photoinitiator. The effects of ATP concentration on morphology, structure and electrical conductivity were studied. The obtained composite nanoparticles with an interesting beads-on-a-string morphology can be obtained in a short time (10 min), which indicates the preparation method is facile and feasible. To explore the potential applications of the prepared PPy/Ag/ATP composite nanoparticles, they were served as multifunctional filler and blended with poly(butylene succinate) (PBS) matrix to prepare biodegradable composite material. The distribution of fillers in polymer matrix and the interfacial interaction between fillers and PBS were confirmed by scanning electron microscope, elemental mapping and dynamic mechanical analysis. The well dispersed fillers in PBS matrix impart outstanding antibacterial property to the biodegradable composite material as well as enhanced storage modulus due to Ag nanoparticles and ATP clay. The biodegradable composite material also possesses modest surface resistivity (10(6)~ 10(9) Ω/◻).

  14. A Review on Natural Fiber Reinforced Polymer Composite and Its Applications

    Directory of Open Access Journals (Sweden)

    Layth Mohammed

    2015-01-01

    Full Text Available Natural fibers are getting attention from researchers and academician to utilize in polymer composites due to their ecofriendly nature and sustainability. The aim of this review article is to provide a comprehensive review of the foremost appropriate as well as widely used natural fiber reinforced polymer composites (NFPCs and their applications. In addition, it presents summary of various surface treatments applied to natural fibers and their effect on NFPCs properties. The properties of NFPCs vary with fiber type and fiber source as well as fiber structure. The effects of various chemical treatments on the mechanical and thermal properties of natural fibers reinforcements thermosetting and thermoplastics composites were studied. A number of drawbacks of NFPCs like higher water absorption, inferior fire resistance, and lower mechanical properties limited its applications. Impacts of chemical treatment on the water absorption, tribology, viscoelastic behavior, relaxation behavior, energy absorption flames retardancy, and biodegradability properties of NFPCs were also highlighted. The applications of NFPCs in automobile and construction industry and other applications are demonstrated. It concluded that chemical treatment of the natural fiber improved adhesion between the fiber surface and the polymer matrix which ultimately enhanced physicomechanical and thermochemical properties of the NFPCs.

  15. Self-healing polymers and composites based on thermal activation

    Science.gov (United States)

    Wang, Ying; Bolanos, Ed; Wudl, Fred; Hahn, Thomas; Kwok, Nathan

    2007-04-01

    Structural polymer composites are susceptible to premature failure in the form of microcracks in the matrix. Although benign initially when they form, these matrix cracks tend to coalesce and lead in service to critical damage modes such as ply delamination. The matrix cracks are difficult to detect and almost impossible to repair because they form inside the composite laminate. Therefore, polymers with self-healing capability would provide a promising potential to minimize maintenance costs while extending the service lifetime of composite structures. In this paper we report on a group of polymers and their composites which exhibit mendable property upon heating. The failure and healing mechanisms of the polymers involve Diels-Alder (DA) and retro-Diels-Alder (RDA) reactions on the polymer back-bone chain, which are thermally reversible reactions requiring no catalyst. The polymers exhibited good healing property in bulk form. Composite panels were prepared by sandwiching the monomers between carbon fiber fabric layers and cured in autoclave. Microcracks were induced on the resin-rich surface of composite with Instron machine at room temperature by holding at 1% strain for 1 min. The healing ability of the composite was also demonstrated by the disappearance of microcracks after heating. In addition to the self-healing ability, the polymers and composites also exhibited shape memory property. These unique properties may provide the material multi-functional applications. Resistance heating of traditional composites and its applicability in self-healing composites is also studied to lay groundwork for a fully integrated self-healing composite.

  16. Flows in polymers, reinforced polymers and composites a multi-scale approach

    CERN Document Server

    Binetruy, Christophe; Keunings, Roland

    2015-01-01

    This book gives a detailed and practical introduction to complex flows of polymers and reinforced polymers as well as the flow of simple fluids in complex microstructures. Over the last decades, an increasing number of functional and structural parts, made so far with metals, has been progressively reengineered by replacing metallic materials by polymers, reinforced polymers and composites. The motivation for this substitution may be the weight reduction, the simpler, cheaper or faster forming process, or the ability to exploit additional functionalities. The present Brief surveys modern developments related to the multi-scale modeling and simulation of polymers, reinforced polymers, that involve a flowing microstructure and continuous fiber-reinforced composites, wherein the fluid flows inside a nearly stationary multi-scale microstructure. These developments concern both multi-scale modeling, defining bridges between the micro and macro scales - with special emphasis on the mesoscopic scale at which kinetic...

  17. Biodegradable multiblock polymers based on N-(2-hydroxypropyl)methacrylamide designed as drug carriers for tumor-targeted delivery

    Czech Academy of Sciences Publication Activity Database

    Mužíková, Gabriela; Pola, Robert; Laga, Richard; Pechar, Michal

    2016-01-01

    Roč. 217, č. 15 (2016), s. 1690-1703 ISSN 1022-1352 R&D Projects: GA ČR(CZ) GA14-12742S; GA ČR(CZ) GA16-17207S; GA MŠk(CZ) LO1507; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : biodegradable polymers * click chemistry * drug delivery systems Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.500, year: 2016

  18. Cytocompatibility of novel extracellular matrix protein analogs of biodegradable polyester polymers derived from α-hydroxy amino acids.

    Science.gov (United States)

    Lecht, Shimon; Cohen-Arazi, Naomi; Cohen, Gadi; Ettinger, Keren; Momic, Tatjana; Kolitz, Michal; Naamneh, Majdi; Katzhendler, Jehoshua; Domb, Abraham J; Lazarovici, Philip; Lelkes, Peter I

    2014-01-01

    One of the challenges in regenerative medicine is the development of novel biodegradable materials to build scaffolds that will support multiple cell types for tissue engineering. Here we describe the preparation, characterization, and cytocompatibility of homo- and hetero-polyesters of α-hydroxy amino acid derivatives with or without lactic acid conjugation. The polymers were prepared by a direct condensation method and characterized using gel permeation chromatography, (1)H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, optical activity, and solubility. The surface charge of the polymers was evaluated using zeta potential measurements. The polymers were coated onto glass cover slips followed by characterization using nano-surface profiler, thin film reflectometry, and atomic force microscopy (AFM). Their interaction with endothelial and neuronal cells was assessed using adhesion, proliferation, and differentiation assays. Of the characterized polymers, Poly-HOVal-LA, but not Poly-(D)HOPhe, significantly augmented nerve growth factor (NGF)-induced neuronal differentiation of the PC12 pheochromcytoma cells. In contrast, Poly-HOLeu increased by 20% the adhesion of endothelial cells, but did not affect PC12 cell differentiation. NGF-induced Erk1/2 phosphorylation in PC12 cells grown on the different polymers was similar to the effect observed for cells cultured on collagen type I. While no significant association could be established between charge and the differentiative/proliferative properties of the polymers, AFM analysis indicated augmentation of NGF-induced neuronal differentiation on smooth polymer surfaces. We conclude that overall selective cytocompatibility and bioactivity might render α-hydroxy amino acid polymers useful as extracellular matrix-mimicking materials for tissue engineering.

  19. Effective delivery of siRNA into cancer cells and tumors using well-defined biodegradable cationic star polymers.

    Science.gov (United States)

    Boyer, Cyrille; Teo, Joann; Phillips, Phoebe; Erlich, Rafael B; Sagnella, Sharon; Sharbeen, George; Dwarte, Tanya; Duong, Hien T T; Goldstein, David; Davis, Thomas P; Kavallaris, Maria; McCarroll, Joshua

    2013-06-03

    Cancer is one of the most common causes of death worldwide. Two types of cancer that have high mortality rates are pancreatic and lung cancer. Despite improvements in treatment strategies, resistance to chemotherapy and the presence of metastases are common. Therefore, novel therapies which target and silence genes involved in regulating these processes are required. Short-interfering RNA (siRNA) holds great promise as a therapeutic to silence disease-causing genes. However, siRNA requires a delivery vehicle to enter the cell to allow it to silence its target gene. Herein, we report on the design and synthesis of cationic star polymers as novel delivery vehicles for siRNA to silence genes in pancreatic and lung cancer cells. Dimethylaminoethyl methacrylate (DMAEMA) was polymerized via reversible addition-fragmentation transfer polymerization (RAFT) and then chain extended in the presence of both cross-linkers N,N-bis(acryloyl)cistamine and DMAEMA, yielding biodegradable well-defined star polymers. The star polymers were characterized by transmission electron microscopy, dynamic light scattering, ζ potential, and gel permeation chromatography. Importantly, the star polymers were able to self-assemble with siRNA and form small uniform nanoparticle complexes. Moreover, the ratios of star polymer required to complex siRNA were nontoxic in both pancreatic and lung cancer cells. Treatment with star polymer-siRNA complexes resulted in uptake of siRNA into both cell lines and a significant decrease in target gene mRNA and protein levels. In addition, delivery of clinically relevant amounts of siRNA complexed to the star polymer were able to silence target gene expression by 50% in an in vivo tumor setting. Collectively, these results provide the first evidence of well-defined small cationic star polymers to deliver active siRNA to both pancreatic and lung cancer cells and may be a valuable tool to inhibit key genes involved in promoting chemotherapy drug resistance and

  20. Fiberglass reinforced polymer composite bridge deck construction in Illinois

    Science.gov (United States)

    2002-09-01

    An experiment was conducted using a fiber reinforced polymer composite material for the bridge deck of a low volume bridge. The test location was on South Fayette Street over the Town Brook in Jacksonville, Illinois. This project included removal of ...

  1. Investigating accidents involving aircraft manufactured from polymer composite materials

    OpenAIRE

    Dunn, Leigh

    2013-01-01

    This thesis looks into the examination of polymer composite wreckage from the perspective of the aircraft accident investigator. It develops an understanding of the process of wreckage examination as well as identifying the potential for visual and macroscopic interpretation of polymer composite aircraft wreckage. The in-field examination of aircraft wreckage, and subsequent interpretations of material failures, can be a significant part of an aircraft accident investigation. ...

  2. Synthesis of biodegradable amphiphilic Y-shaped block co-polymers via ring-opening polymerization for drug delivery.

    Science.gov (United States)

    Jia, Lin; Yan, Lifeng; Li, Yang

    2011-01-01

    A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL-(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init-PCL-(OH)2). The init-PCL-(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by (1)H-, (13)C-, (31)P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init-PCL-(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, (1)H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.

  3. Full-scale performance of selected starch-based biodegradable polymers in sludge dewatering and recommendation for applications.

    Science.gov (United States)

    Zhou, Kuangxin; Stüber, Johan; Schubert, Rabea-Luisa; Kabbe, Christian; Barjenbruch, Matthias

    2018-01-01

    Agricultural reuse of dewatered sludge is a valid route for sludge valorization for small and mid-size wastewater treatment plants (WWTPs) due to the direct utilization of nutrients. A more stringent of German fertilizer ordinance requires the degradation of 20% of the synthetic additives like polymeric substance within two years, which came into force on 1 January 2017. This study assessed the use of starch-based polymers for full-scale dewatering of municipal sewage sludge. The laboratory-scale and pilot-scale trials paved the way for full-scale trials at three WWTPs in Germany. The general feasibility of applying starch-based 'green' polymers in full-scale centrifugation was demonstrated. Depending on the sludge type and the process used, the substitution potential was up to 70%. Substitution of 20-30% of the polyacrylamide (PAM)-based polymer was shown to achieve similar total solids (TS) of the dewatered sludge. Optimization of operational parameters as well as machinery set up in WWTPs is recommended in order to improve the shear stability force of sludge flocs and to achieve higher substitution potential. This study suggests that starch-based biodegradable polymers have great potential as alternatives to synthetic polymers in sludge dewatering.

  4. Development of biodegradable metaloxide/polymer nanocomposite films based on poly-ε-caprolactone and terephthalic acid.

    Science.gov (United States)

    Varaprasad, Kokkarachedu; Pariguana, Manuel; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Sadiku, Emmanuel Rotimi

    2017-01-01

    The present investigation describes the development of metal-oxide polymer nanocomposite films from biodegradable poly-ε-caprolactone, disposed poly(ethylene terephthalate) oil bottles monomer and zinc oxide-copper oxide nanoparticles. The terephthalic acid and zinc oxide-copper oxide nanoparticles were synthesized by using a temperature-dependent precipitation technique and double precipitation method, respectively. The terephthalic acid synthesized was confirmed by FTIR analysis and furthermore, it was characterized by thermal analysis. The as-prepared CuO-ZnO nanoparticles structure was confirmed by XRD analysis and its morphology was analyzed by SEM/EDS and TEM. Furthermore, the metal-oxide polymer nanocomposite films have excellent mechanical properties, with tensile strength and modulus better than pure films. The metal-oxide polymer nanocomposite films that were successfully developed show a relatively brighter colour when compared to CuO film. These new metal-oxide polymer nanocomposite films can replace many non-degradable plastics. The new metal-oxide polymer nanocomposite films developed are envisaged to be suitable for use in industrial and domestic packaging applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Synthesis, properties and applications of biodegradable polymers derived from diols and dicarboxylic acids: from polyesters to poly(ester amide)s.

    Science.gov (United States)

    Díaz, Angélica; Katsarava, Ramaz; Puiggalí, Jordi

    2014-04-25

    Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

  6. Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amide)s

    Science.gov (United States)

    Díaz, Angélica; Katsarava, Ramaz; Puiggalí, Jordi

    2014-01-01

    Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed. PMID:24776758

  7. METHOD FOR PROVIDING SHAPED BIODEGRADABLE AND ELASTOMERIC STRUCTURES OF (CO) POLYMERS OF 1,3-TRIMETHYLENE CARBONATE (TMC), SHAPED BIODEGRADABLE AND ELASTOMERIC STRUCTURES, AND THE USE OF THESE STRUCTURES

    NARCIS (Netherlands)

    Grijpma, D.W.; Pêgo, A.P.; Feijen, Jan

    2004-01-01

    The present invention relates to methods for providing shaped biodegradable and elastomeric structures of (co)polymers of 1,3­trimethylene carbonate (TMC) with improved (mechanical) properties which can be used for tissue or tissue component support, generation or regeneration. Such shaped

  8. TGF-beta1 release from biodegradable polymer microparticles: its effects on marrow stromal osteoblast function

    Science.gov (United States)

    Lu, L.; Yaszemski, M. J.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    2001-01-01

    BACKGROUND: Controlled release of transforming growth factor-beta1 (TGF-beta1) to a bone defect may be beneficial for the induction of a bone regeneration cascade. The objectives of this work were to assess the feasibility of using biodegradable polymer microparticles as carriers for controlled TGF-beta1 delivery and the effects of released TGF-beta1 on the proliferation and differentiation of marrow stromal cells in vitro. METHODS: Recombinant human TGF-beta1 was incorporated into microparticles of blends of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG). Fluorescein isothiocynate-labeled bovine serum albumin (FITC-BSA) was co-encapsulated as a porogen. The effects of PEG content (0, 1, or 5% by weight [wt%]) and buffer pH (3, 5, or 7.4) on the protein release kinetics and the degradation of PLGA were determined in vitro for as long as 28 days. Rat marrow stromal cells were seeded on a biodegradable poly(propylene fumarate) (PPF) substrate. The dose response and biological activity of released TGF-beta1 was determined after 3 days in culture. The effects of TGF-beta1 released from PLGA/PEG microparticles on marrow stromal cell proliferation and osteoblastic differentiation were assessed during a 21-day period. RESULTS: TGF-beta1 was encapsulated along with FITC-BSA into PLGA/PEG blend microparticles and released in a multiphasic fashion including an initial burst for as long as 28 days in vitro. Increasing the initial PEG content resulted in a decreased cumulative mass of released proteins. Aggregation of FITC-BSA occurred at lower buffer pH, which led to decreased release rates of both proteins. The degradation of PLGA was increased at higher PEG content and significantly accelerated at acidic pH conditions. Rat marrow stromal cells cultured on PPF substrates showed a dose response to TGF-beta1 released from the microparticles similar to that of added TGF-beta1, indicating that the activity of TGF-beta1 was retained during microparticle

  9. Thermally stimulated discharge conductivity in polymer composite ...

    Indian Academy of Sciences (India)

    Unknown

    Klason Carl and Kubat Josef 1975 J. Appl. Polym. Sci. 19 831. Ramadin Y, Ahmed M, Jawad S A and Zihlif A 1993 J. Polym. Mater. 10 251. Sangawar V S 1996 D.C. electrical conductivity study of poly- styrene and polymethyl methacrylate iodine doped thermo- electrets, Ph.D. Thesis, Amravati University, Amravati.

  10. Analysis of organometallics dispersed polymer composite irradiated ...

    Indian Academy of Sciences (India)

    about by ion beam in polymers underline that the physical modifications are limited to a few basic processes: gas evolution, cross linking and degradation. The chemical changes are more dramatic in polymers because of the macromolecular structure of these materials. The kind of changes, which predominate, depends on ...

  11. Biodegradable Kojic Acid-Based Polymers: Controlled Delivery of Bioactives for Melanogenesis Inhibition.

    Science.gov (United States)

    Faig, Jonathan J; Moretti, Alysha; Joseph, Laurie B; Zhang, Yingyue; Nova, Mary Joy; Smith, Kervin; Uhrich, Kathryn E

    2017-02-13

    Kojic acid (KA) is a naturally occurring fungal metabolite that is utilized as a skin-lightener and antibrowning agent owing to its potent tyrosinase inhibition activity. While efficacious, KA's inclination to undergo pH-mediated, thermal-, and photodegradation reduces its efficacy, necessitating stabilizing vehicles. To minimize degradation, poly(carbonate-esters) and polyesters comprised of KA and natural diacids were prepared via solution polymerization methods. In vitro hydrolytic degradation analyses revealed KA release was drastically influenced by polymer backbone composition (e.g., poly(carbonate-ester) vs polyester), linker molecule (aliphatic vs heteroatom-containing), and release conditions (physiological vs skin). Tyrosinase inhibition assays demonstrated that aliphatic KA dienols, the major degradation product under skin conditions, were more potent then KA itself. All dienols were found to be less toxic than KA at all tested concentrations. Additionally, the most lipophilic dienols were statistically more effective than KA at inhibiting melanin biosynthesis in cells. These KA-based polymer systems deliver KA analogues with improved efficacy and cytocompatible profiles, making them ideal candidates for sustained topical treatments in both medical and personal care products.

  12. Tethered Nanoparticle–Polymer Composites: Phase Stability and Curvature

    KAUST Repository

    Srivastava, Samanvaya

    2012-04-17

    Phase behavior of poly(ethylene glycol) (PEG) tethered silica nanoparticles dispersed in PEG hosts is investigated using small-angle X-ray scattering. Phase separation in dispersions of densely grafted nanoparticles is found to display strikingly different small-angle X-ray scattering signatures in comparison to phase-separated composites comprised of bare or sparsely grafted nanoparticles. A general diagram for the dispersion state and phase stability of polymer tethered nanoparticle-polymer composites incorporating results from this as well as various other contemporary studies is presented. We show that in the range of moderate to high grafting densities the dispersion state of nanoparticles in composites is largely insensitive to the grafting density of the tethered chains and chemistry of the polymer host. Instead, the ratio of the particle diameter to the size of the tethered chain and the ratio of the molecular weights of the host and tethered polymer chains (P/N) are shown to play a dominant role. Additionally, we find that well-functionalized nanoparticles form stable dispersions in their polymer host beyond the P/N limit that demarcates the wetting/dewetting transition in polymer brushes on flat substrates interacting with polymer melts. A general strategy for achieving uniform nanoparticle dispersion in polymers is proposed. © 2012 American Chemical Society.

  13. 3D Printing of Biocompatible Supramolecular Polymers and their Composites.

    Science.gov (United States)

    Hart, Lewis R; Li, Siwei; Sturgess, Craig; Wildman, Ricky; Jones, Julian R; Hayes, Wayne

    2016-02-10

    A series of polymers capable of self-assembling into infinite networks via supramolecular interactions have been designed, synthesized, and characterized for use in 3D printing applications. The biocompatible polymers and their composites with silica nanoparticles were successfully utilized to deposit both simple cubic structures, as well as a more complex twisted pyramidal feature. The polymers were found to be not toxic to a chondrogenic cell line, according to ISO 10993-5 and 10993-12 standard tests and the cells attached to the supramolecular polymers as demonstrated by confocal microscopy. Silica nanoparticles were then dispersed within the polymer matrix, yielding a composite material which was optimized for inkjet printing. The hybrid material showed promise in preliminary tests to facilitate the 3D deposition of a more complex structure.

  14. Low Density Polyethylene (LDPE blends based on Poly(3-Hydroxi-Butyrate (PHB and Guar Gum (GG biodegradable polymers

    Directory of Open Access Journals (Sweden)

    Marisa Cristina Guimarães Rocha

    2015-02-01

    Full Text Available LDPE blends based on PHB and GG biodegradable polymers were prepared by melt mixing in a twin screw extruder. The mechanical properties of the materials were evaluated. Preliminary information about the biodegradation behavior of the specimens was obtained by visual observation of samples removed from the simulated soil in 90 days. The results indicated that LDPE/PHB blends may be used for designing LDPE based materials with increased susceptibility to degradation, if elongation at break and impact properties are not determinant factors of their performance. LDPE based materials on GG present values of flexural and mechanical strength lower than those of LDPE/PHB blends. LDPE/PHB/GG blends exhibit unsatisfactory properties. Apparently, the effect of addition of GG to LDPE on the biodegradation behavior of LDPE/GG blends was less intense than the effect caused by addition of PHB to the blends. Similar observation has occurred with the partial replacement of GG by PHB in the ternary blends.

  15. Biocompatibility, osteointegration, osteoconduction, and biodegradation of a hydroxyapatite-polyhydroxybutyrate composite

    Directory of Open Access Journals (Sweden)

    Emily Correna Carlo Reis

    2010-08-01

    Full Text Available In this work, biocompatibility, osteointegration, osteoconductivity, and biodegradation of a hydroxyapatite polyhydroxybutyrate new composite were evaluated. The composite was implanted in rabbits' bone defects and clinical, radiographic, histological, and histomorphometric data of these animals were compared with those of unfilled defects on the days 8th, 45th, and 90th after surgery. No significant differences existed between the groups for the evaluated clinical parameters. Radiographs showed bone-composite direct contact. Bone formed within the defect, interface and inside the composite. Significant differences were found between the bone and connective tissues percentage within the defect at all dates and at the interface on the 45th day, bone tissue prevailing. Composite's biodegradation signs were evident: giant cells on the surface of composite fragments separated from the original block in the absence of inflammatory infiltrate. These data supported that such composite was biocompatible, biodegradable, osteoconductive and integrate to bone.A biocompatibilidade, osteointegração, osteocondução e biodegradação de um novo compósito de hidroxiapatita e polihidroxibutirato foram avaliados. O compósito foi implantado em defeitos ósseos em coelhos e dados clínicos, radiográficos, histológicos e histomorfométricos foram comparados aos de defeitos não preenchidos aos 8, 45 e 90 dias após a cirurgia. Não foram observadas diferenças significantes entre os grupos para os parâmetros clínicos avaliados. Contato direto entre osso e compósito foi observado nas radiografias. Tecido ósseo se formou dentro do defeito, interface e dentro do compósito. Foram observadas diferenças significativas entre a porcentagem dos tecidos ósseo e conjuntivo dentro do defeito em todas as datas de avaliação e na interface aos 45 dias, com predominância do tecido ósseo. Sinais de biodegradação foram observados: células gigantes na superf

  16. Endothelial Barrier Protein Expression in Biodegradable Polymer Sirolimus-Eluting Versus Durable Polymer Everolimus-Eluting Metallic Stents.

    Science.gov (United States)

    Mori, Hiroyoshi; Cheng, Qi; Lutter, Christoph; Smith, Samantha; Guo, Liang; Kutyna, Matthew; Torii, Sho; Harari, Emanuel; Acampado, Eduardo; Joner, Michael; Kolodgie, Frank D; Virmani, Renu; Finn, Aloke V

    2017-12-11

    This study sought to investigate endothelial coverage and barrier protein expression following stent implantation. Biodegradable polymer drug-eluting stents (BP-DES) have been purported to have biological advantages in vessel healing versus durable polymer DES (DP-DES), although clinical trial data suggest equipoise. Biodegradable polymer-sirolimus-eluting stents (BP-SES), durable polymer-everolimus-eluting stents (DP-EES), and bare-metal stents (BMS) were compared. In the rabbit model (28, 45, and 120 days), stented arteries underwent light microscopic analysis and immunostaining for the presence of vascular endothelium (VE)-cadherin, an endothelial barrier protein, and were subjected to confocal microscopy and scanning electron microscopy. A cell culture study in stented silicone tubes was performed to assess cell proliferation. Light microscopic assessments were similar between BP-SES and DP-EES. BMS showed nearly complete expression of VE-cadherin at 28 days, whereas both DES showed significantly less with results favoring BP-SES versus DP-EES (39% coverage in BP-SES, 22% in DP-EES, 95% in BMS). Endothelial cell morphologic patterns differed according to stent type with BMS showing a spindle-like shape, DP-EES a cobblestone pattern, and BP-SES a shape in between. VE-cadherin-negative areas showed greater surface monocytes regardless of type of stent. Cell proliferation was suppressed in both DES with numerically less suppression in BP-SES versus DP-EES. This is the first study to examine VE-cadherin expression after DES. All DES demonstrated deficient barrier expression relative to BMS with results favoring BP-SES versus DP-EES. These findings may have important implications for the development of neoatherosclerosis in different stent types. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  17. Biodegradable polymers by reactive blending trans-esterification of thermoplastic starch with poly (vinyl acetate) and poly (vinyl acetate-co-butyl acrylate)

    CSIR Research Space (South Africa)

    Vargha, V

    2005-04-01

    Full Text Available (vinyl alcohol- co-acetate) is expected. The internally plasticized PVAC, i.e. poly(vinyl acetate-co-butyl acrylate), would serve to decrease the glass transition temperature range of the resulting blend. Both polymers are sold as biodegradable by the supplier... stream_source_info vargha_2005.pdf.txt stream_content_type text/plain stream_size 37663 Content-Encoding ISO-8859-1 stream_name vargha_2005.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Biodegradable polymers...

  18. The application of radiothermoluminescence method to the analysis of polymers and polymer composites

    International Nuclear Information System (INIS)

    Nikol'skii, V.G.

    1982-01-01

    The basic results concerning the examination of copolymers, cross-linked polymers and polyblends structure, obtained by means of radiothermoluminescence method, are reviewed. The main emphasis is on the glow curve shape analysis that allows: a) to determine quantitatively the random copolymer composition; b) to reveal the existence of blocks in macromolecules; c) to examine the grafted copolymer distribution in polymer matrix; d) to estimate the degree of cross-linking both for individual polymers and heterogeneous polyblends; e) to study the mutual solubility of polymers. (author)

  19. Metallized Nanotube Polymer Composite (MNPC) and Methods for Making Same

    Science.gov (United States)

    Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Nazem, Negin (Inventor); Taylor, Larry (Inventor); Kang, Jin Ho (Inventor); Kim, Jae-Woo (Inventor); Sauti, Godfrey (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2017-01-01

    A novel method to develop highly conductive functional materials which can effectively shield various electromagnetic effects (EMEs) and harmful radiations. Metallized nanotube polymer composites (MNPC) are composed of a lightweight polymer matrix, superstrong nanotubes (NT), and functional nanoparticle inclusions. MNPC is prepared by supercritical fluid infusion of various metal precursors (Au, Pt, Fe, and Ni salts), incorporated simultaneously or sequentially, into a solid NT-polymer composite followed by thermal reduction. The infused metal precursor tends to diffuse toward the nanotube surface preferentially as well as the surfaces of the NT-polymer matrix, and is reduced to form nanometer-scale metal particles or metal coatings. The conductivity of the MNPC increases with the metallization, which provides better shielding capabilities against various EMEs and radiations by reflecting and absorbing EM waves more efficiently. Furthermore, the supercritical fluid infusion process aids to improve the toughness of the composite films significantly regardless of the existence of metal.

  20. Multifunctional Composites Obtained by Incorporating Nanocrystals into Decorated PVK Polymers

    Directory of Open Access Journals (Sweden)

    Haizhu Sun

    2007-01-01

    Full Text Available Poly(vinylcarbazole (PVK was decorated with surfactant group to achieve amphiphilic polymer with luminescent property. The composition and properties of the polymers were systematically investigated using FTIR, EA, TGA, UV-Vis, and PL characterizations. Different CdTe nanocrystals (NCs prepared in aqueous medium were directly transferred to organic phase using the PVK-based polymers. The quantum yield of NCs in the composites had been improved by 50% compared with their parent aqueous solution due to the short distance from carbazole moieties to NCs, which facilitated the Förster resonant energy transfer (FRET between them. Moreover, efficient electron transfer at the interface of NCs and polymers had been confirmed which also indicated the application in photovoltaic cell for such composites.

  1. Carbon nanotube polymer composition and devices

    Science.gov (United States)

    Liu, Gao [Oakland, CA; Johnson, Stephen [Richmond, CA; Kerr, John B [Oakland, CA; Minor, Andrew M [El Cerrito, CA; Mao, Samuel S [Castro Valley, CA

    2011-06-14

    A thin film device and compound having an anode, a cathode, and at least one light emitting layer between the anode and cathode, the at least one light emitting layer having at least one carbon nanotube and a conductive polymer.

  2. Pneumatically Powered Drilling of Carbon Fibre Composites Using Synthetic Biodegradable Lubricating Oil: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Corydon M. J. Morrell

    2018-01-01

    Full Text Available Carbon fibre composites are a key component of aircraft structures because of their enhanced material properties such as favourable strength to weight ratios when compared to metal alloys. During the assembly process of an aircraft, carbon fibre components are joined to other structures using rivets, bolts, and fasteners, and as part of the joining process, the components will need to be machined or drilled. Unlike metal alloys, composites are sensitive to heat and are vulnerable to internal structural damage from machining tools. They are also susceptible to a reduction in strength when fibres are exposed to moisture. In the machining process, carbon fibre composites may be drilled using oils to lubricate carbide machining tools. In this study, a description of the experimental apparatus is provided along with an investigation to determine the influence synthetic biodegradable lubricating oil has on drill rotational speed, drilling load, and drilling temperature when using a pneumatic drill to machine carbon fibre composite material.

  3. Polymer composites with plasmonic metal nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Dammer, Ondřej; Vlčková, B.; Podhájecká, Klára; Procházka, M.; Pfleger, Jiří

    2008-01-01

    Roč. 268, č. 1 (2008), s. 91-95 ISSN 1022-1360. [Microsymposium on Advanced Polymer Materials for Photonics and Electronics /47./. Prague, 15.07.2007-19.07.2007] R&D Projects: GA AV ČR IAA4050406 Institutional research plan: CEZ:AV0Z40500505 Keywords : metal nanoparticles * nanocomposites * .pi.-conjugated polymers Subject RIV: CD - Macromolecular Chemistry

  4. Disposal Options of Bamboo Fabric-Reinforced Poly(Lactic Acid Composites for Sustainable Packaging: Biodegradability and Recyclability

    Directory of Open Access Journals (Sweden)

    M.R. Nurul Fazita

    2015-08-01

    Full Text Available The present study was conducted to determine the recyclability and biodegradability of bamboo fabric-reinforced poly(lactic acid (BF-PLA composites for sustainable packaging. BF-PLA composite was recycled through the granulation, extrusion, pelletization and injection processes. Subsequently, mechanical properties (tensile, flexural and impact strength, thermal stability and the morphological appearance of recycled BF-PLA composites were determined and compared to BF-PLA composite (initial materials and virgin PLA. It was observed that the BF-PLA composites had the adequate mechanical rigidity and thermal stability to be recycled and reused. Moreover, the biodegradability of BF-PLA composite was evaluated in controlled and real composting conditions, and the rate of biodegradability of BF-PLA composites was compared to the virgin PLA. Morphological and thermal characteristics of the biodegradable BF-PLA and virgin PLA were obtained by using environment scanning electron microscopy (ESEM and differential scanning calorimetry (DSC, respectively. The first order decay rate was found to be 0.0278 and 0.0151 day−1 in a controlled composting condition and 0.0008 and 0.0009 day−1 in real composting conditions for virgin PLA and BF-PLA composite, respectively. Results indicate that the reinforcement of bamboo fabric in PLA matrix minimizes the degradation rate of BF-PLA composite. Thus, BF-PLA composite has the potential to be used in product packaging for providing sustainable packaging.

  5. A Mechanistic Model for Drug Release in PLGA Biodegradable Stent Coatings Coupled with Polymer Degradation and Erosion

    Science.gov (United States)

    Zhu, Xiaoxiang; Braatz, Richard D.

    2015-01-01

    Biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) coating for applications in drug-eluting stents has been receiving increasing interest as a result of its unique properties compared with biodurable polymers in delivering drug for reducing stents-related side effects. In this work, a mathematical model for describing the PLGA degradation and erosion and coupled drug release from PLGA stent coating is developed and validated. An analytical expression is derived for PLGA mass loss that predicts multiple experimental studies in the literature. An analytical model for the change of the number-average degree of polymerization (or molecular weight) is also derived. The drug transport model incorporates simultaneous drug diffusion through both the polymer solid and the liquid-filled pores in the coating, where an effective drug diffusivity model is derived taking into account factors including polymer molecular weight change, stent coating porosity change, and drug partitioning between solid and aqueous phases. The model is used to describe in vitro sirolimus release from PLGA stent coating, and demonstrates the significance of simultaneous sirolimus release via diffusion through both polymer solid and pore space. The proposed model is compared to existing drug transport models, and the impact of model parameters, limitations and possible extensions of the model are also discussed. PMID:25345656

  6. Theoretical study on modeling and prediction of optical rotation for biodegradable polymers containing α-amino acids using QSAR approaches.

    Science.gov (United States)

    Mallakpour, Shadpour; Hatami, Mehdi; Golmohammadi, Hassan

    2011-07-01

    The main purpose of the present study was modeling and prediction of the optical rotation ([M](D)) of some biodegradable polymers containing α-amino acids using quantitative structure-activity relationship (QSAR) approaches. In order to attain this goal, the optical rotation of a collection of 53 polymers was selected as a data set. The data set was randomly divided into three sections, training, test and external validation sets. By using dragon software, various descriptors were calculated for all molecules in the data set. The important descriptors were selected applying genetic algorithm-partial least squares (GA-PLS) method. Then an artificial neural network (ANN) was written with MATLAB 7 and used these descriptors as inputs and its output was optical rotation of desired polymers. Then, the constructed network was used for the prediction of ([M](D)) values of validation set. The squared correlation coefficient R² values of the ANN model for the training, test and validation sets were 0.998, 0.996 and 0.996 respectively. The results showed the ability of developed ANN to predict optical rotation of various polymers.

  7. Research regarding biodegradable properties of food polymeric products under microorganism activity

    Science.gov (United States)

    Opran, Constantin; Lazar, Veronica; Fierascu, Radu Claudiu; Ditu, Lia Mara

    2018-02-01

    Aim of this research is the structural analysis by comparison of the biodegradable properties of two polymeric products made by non-biodegradable polymeric material (polypropylene TIPPLEN H949 A) and biodegradable polymeric material (ECOVIO IS 1335), under microorganism activity in order to give the best solution for the manufacture of food packaging biodegradable products. It presents the results of experimental determinations on comparative analysis of tensile strength for the two types of polymers. The sample weight variations after fungal biodegradation activity revealed that, after 3 months, there are no significant changes in polymeric substratum for non-biodegradable polymeric. The microscopically analysis showed that the fungal filaments did not strongly adhered on the non-biodegradable polymeric material, instead, both filamentous fungi strains adhered and covered the surface of the biodegradable sample with germinated filamentous conidia. The spectral analysis of polymer composition revealed that non-biodegradable polymer polypropylene spectra are identical for control and for samples that were exposed to fungal activity, suggesting that this type of sample was not degraded by the fungi strains. Instead, for biodegradable polymer sample, it was observed significant structural changes across multiple absorption bands, suggesting enzyme activity manifested mainly by Aspergillus niger strain. Structural analysis of interdisciplinary research results, lead, to achieving optimal injection molded technology emphasizing technological parameters, in order to obtain food packaging biodegradable products.

  8. Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Composites

    Science.gov (United States)

    Kang, Jin Ho; Cano, Roberto J.; Ratcliffe, James G.; Luong, Hoa; Grimsley, Brian W.; Siochi, Emilie J.

    2016-01-01

    For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strengthand stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Despite several attempts to solve these issues with the addition of carbon nanotubes (CNT) into polymer matrices, and/or by interleaving CNT sheets between conventional carbon fiber (CF) composite layers, there are still interfacial problems that exist between CNTs (or CF) and the resin. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing (double cantilever beam and end-notched flexure test). Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated. Interleaving CNT sheets significantly improved the in-plane (axial and perpendicular direction of CF alignment) thermal conductivity of the hybrid composite laminates by 50 - 400%.

  9. Preparation and characterization of polymer composites based on ...

    Indian Academy of Sciences (India)

    Polymer composites based on charge-transfer complex of phenothiazine and iodine with polystyrene have been prepared in different weight ratios and characterized by FTIR, XRD, mechanical, microstructure and electrical properties (d.c. as well as a.c.). These composites show semiconducting behaviour as the ...

  10. Preparation and characterization of polymer composites based on ...

    Indian Academy of Sciences (India)

    Unknown

    2003-11-29

    Nov 29, 2003 ... Abstract. Polymer composites based on charge-transfer complex of phenothiazine and iodine with polystyrene have been prepared in different weight ratios and characterized by FTIR, XRD, mechanical, microstructure and electrical properties (d.c. as well as a.c.). These composites show semiconducting ...

  11. Early vascular healing with rapid breakdown biodegradable polymer sirolimus-eluting versus durable polymer everolimus-eluting stents assessed by optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Tomohisa, E-mail: tomohisa@dhm.mhn.de [Deutsches Herzzentrum, Technische Universität, München (Germany); Byrne, Robert A. [Deutsches Herzzentrum, Technische Universität, München (Germany); Schuster, Tibor [Institut für Medizinische Statistik und Epidemiologie, München (Germany); Cuni, Rezarta [Deutsches Herzzentrum, Technische Universität, München (Germany); Kitabata, Hironori [Wakayama Medical University, Wakayama (Japan); Tiroch, Klaus [Deutsches Herzzentrum, Technische Universität, München (Germany); Dirninger, Alfred; Gratze, Franz; Kaspar, Klaus; Zenker, Gerald [Landeskrankenhaus Bruck/Mur (Austria); Joner, Michael; Schömig, Albert; Kastrati, Adnan [Deutsches Herzzentrum, Technische Universität, München (Germany)

    2013-03-15

    Background: Differences in early arterial healing patterns after stent implantation between biodegradable and durable polymer based new generation drug-eluting stents are not well understood. The aim of this study was to compare the healing patterns of a novel rapid breakdown (≤ 8 weeks) biodegradable polymer sirolimus-eluting stent (BP-SES) with a durable polymer everolimus-eluting stent (EES) using intravascular optical coherence tomography (OCT) at 4 months. Methods: A total of 20 patients were randomly assigned to stenting with BP-SES (n = 11) or EES (n = 9). Overall intravascular imaging was available for 15 (75%) patients. The primary endpoint was the difference in rate of uncovered struts between BP-SES and EES. To account for strut-level clustering, the results in both treatment groups were compared using a generalized linear mixed model approach. Results: Regarding the primary endpoint, BP-SES as compared to EES showed similar rates of uncovered struts (37 [6.8%] versus 167 [17.5%], odds ratio (OR) 0.45 (95% CI 0.09-2.24), p = 0.33). There were no malapposed struts in BP-SES group and 14 malapposed struts in EES group (p = 0.97). No difference in percent neointimal volume (14.1 ± 8.2% vs. 11.4 ± 6.4%, p = 0.56) was observed. Conclusions: Although rapid-breakdown BP-SES as compared to EES showed signs of improved early tissue coverage, after adjustment for strut-level clustering these differences were not statistically significant. No differences in ability to suppress neointimal hyperplasia after stent implantation between 2 stents were observed.

  12. Standard Guide for Testing Polymer Matrix Composite Materials

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This guide summarizes the application of ASTM standard test methods (and other supporting standards) to continuous-fiber reinforced polymer matrix composite materials. The most commonly used or most applicable ASTM standards are included, emphasizing use of standards of Committee D30 on Composite Materials. 1.2 This guide does not cover all possible standards that could apply to polymer matrix composites and restricts discussion to the documented scope. Commonly used but non-standard industry extensions of test method scopes, such as application of static test methods to fatigue testing, are not discussed. A more complete summary of general composite testing standards, including non-ASTM test methods, is included in the Composite Materials Handbook (MIL-HDBK-17). Additional specific recommendations for testing textile (fabric, braided) composites are contained in Guide D6856. 1.3 This guide does not specify a system of measurement; the systems specified within each of the referenced standards shall appl...

  13. Compositions, methods, and systems comprising fluorous-soluble polymers

    Science.gov (United States)

    Swager, Timothy M.; Lim, Jeewoo; Takeda, Yohei

    2015-10-13

    The present invention generally relates to compositions, methods, and systems comprising polymers that are fluorous-soluble and/or organize at interfaces between a fluorous phase and a non-fluorous phase. In some embodiments, emulsions or films are provided comprising a polymer. The polymers, emulsions, and films can be used in many applications, including for determining, treating, and/or imaging a condition and/or disease in a subject. The polymer may also be incorporated into various optoelectronic device such as photovoltaic cells, organic light-emitting diodes, organic field effect transistors, or the like. In some embodiments, the polymers comprise pi-conjugated backbones, and in some cases, are highly emissive.

  14. Preparation of wood-polymer composites using radiation

    International Nuclear Information System (INIS)

    Ajji, Z.

    2003-11-01

    Wood-polymer composites (WPC) have been prepared of pinewood with different monomers using Gamma radiation: acrylamide, butyl acrylate, butyl methacrylate, styrene, acrylonitrile, and polyester. The polymer loading was determined as a function of monomer concentration and absorbed dose. The data show that polymer loading increases by increasing the monomer concentration. In two cases, BMA and polyester, the polymer loading decreases at high concentrations. This can be explained by the increase of the viscosity. Thus the diffusion of the compound into bulk would be slower. The absorbed dose seems to play a positive role in enhancing the polymer loading by increasing the dose. The mechanical properties, tensile and compression strength, have been improved in the most cases for all monomer concentrations or absorbed doses. Using polyester there was no improvement in the mechanical properties, and using acrylamide the improvement was at high monomer concentration.(author)

  15. Thermal, Morphological, and Biodegradability Properties of Bioplastic Fertilizer Composites Made of Oil Palm Biomass, Fertilizer, and Poly(hydroxybutyrate-co-valerate

    Directory of Open Access Journals (Sweden)

    A. S. Harmaen

    2016-01-01

    Full Text Available Slow-release bioplastic fertilizer (BpF composites were developed by processing oil palm empty fruit bunch (EFB, fertilizer, and poly(hydroxybutyrate-co-valerate (PHBv using extrusion techniques with controlled formulation and temperature. The temperature was kept at 150°C for 3 to 5 min during processing using twin-screw extruder. The PHBv lost weight gradually with the increasing temperature and its thermal degradation occurred initially at 263.4°C and reached the maximum at 300.7°C. Scanning electron microscope (SEM images showed that the bonding of all composites created small gaps between matrices polymer and fiber because the hydrophilic characteristic of EFB fibers weakened the interfacial bonding. PHBv/EFB/NPKC2 showed faster biodegradation over PHBv/NPKC1 and PHBv/NPKC2, which was 99.35% compared to 68.66% and 90.28%, respectively.

  16. Structural studies of thermally stable, combustion-resistant polymer composites

    OpenAIRE

    Smith, G.N.; Hallett, J.E.; Joseph, P.; Tretsiakova-McNally, S.; Zhang, T.; Blum, F.D.; Eastoe, J.

    2017-01-01

    Composites of the industrially important polymer, poly(methyl methacrylate) (PMMA), were prepared by free-radical polymerization of MMA with varying amounts (1–30 wt. %) of sodium dioctylsulfosuccinate (Aerosol OT or AOT) surfactant added to the reaction mixture. The composites with AOT incorporated show enhanced resistance to thermal degradation compared to pure PMMA homopolymer, and micro-cone combustion calorimetry measurements also show that the composites are combustion-resistant. The ph...

  17. Nano-structured polymer composites and process for preparing same

    Science.gov (United States)

    Hillmyer, Marc; Chen, Liang

    2013-04-16

    A process for preparing a polymer composite that includes reacting (a) a multi-functional monomer and (b) a block copolymer comprising (i) a first block and (ii) a second block that includes a functional group capable of reacting with the multi-functional monomer, to form a crosslinked, nano-structured, bi-continuous composite. The composite includes a continuous matrix phase and a second continuous phase comprising the first block of the block copolymer.

  18. Developing tricalcium phosphate/polyhydroxybutyrate composite as a new biodegradable material for clinical applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, M.; Weng, J.; Ni, J.; Goh, C.H.; Wang, C.X. [Nanyang Technological Univ. (Singapore). School of Mechanical and Production Engineering

    2001-07-01

    Two biodegradable materials, namely, tricalcium phosphate (TCP) and polyhydroxybutyrate (PHB), were used to produce a new composite material for tissue replacement/regeneration. Commercially available TCP and PHB were used, with both materials being in the form of fine powders. They were characterised prior to composite production. TCP/PHB composite containing up to 30vol% of TCP was produced. Manufacture of the composite consisted of compounding, milling, drying and compression moulding. During the manufacturing process, the temperature and time for maintaining PHB in the molten state were carefully controlled as PHB is very heat-sensitive. Thermogravimetric analysis (TGA) of the composite indicated that intended compositions for the composite had been achieved. Examinations using a scanning electron microscope (SEM) revealed that TCP particles were well distributed in compounded and compression moulded materials. Differential scanning calorimetry (DSC) analysis showed that an increase in the TCP content resulted in decreases in both the melting temperature and the crystallinity of PHB. An ascending trend of microhardness was observed for TCP/PHB with an increase in the TCP volume percentage. Dynamic mechanical analysis (DMA) showed that the storage modulus increased from 2.76 GPa for the unfilled PHB to 4.80 GPa for the composite containing 20vol% of TCP. (orig.)

  19. Conductive polymer composites with carbonic fillers: Shear induced electrical behaviour

    Czech Academy of Sciences Publication Activity Database

    Starý, Zdeněk; Krückel, J.

    2018-01-01

    Roč. 139, 14 March (2018), s. 52-59 ISSN 0032-3861 R&D Projects: GA ČR(CZ) GA17-05654S; GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : polymer-matrix composites * carbon fibres * electrical properties Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 3.684, year: 2016

  20. MANUFACTURING BIODEGRADABLE COMPOSITE MATERIALS BASED ON POLYETHYLENE AND FUNCTIONALIZED BY ALCOHOLYSIS OF ETHYLENE-VINYL ACETATE COPOLYMER

    Directory of Open Access Journals (Sweden)

    Aleksandr A. Shabarin

    2016-06-01

    Full Text Available Introduction. The continuous growth of production and consumption of plastic packaging creates a serious problem of disposal of package. This problem has ecological character, because the contents of the landfills decompose for decades, emit toxic com¬pounds and pollute the environment. The work is devoted to obtaining and investigation mechanical and rheological properties of biodegradable composite materials based on polyethylene and starch. Materials and Methods. In this work the author used polyethylene grade HDPE 273- 83 (GOST 16338-85, Sevilen brand 12206-007 (TU 6-05-1636-97 and potato starch (GOST 53876-2010 as a filler. Functionalization of sevilen was carried in the 30 % ethanol solution KOH at a temperature 80 °C during 3 hours. Compounding components was carried out at the laboratory of the two rotary mixer HAAKE PolyLab Rheomix 600 OS with rotors Banbury. Formation of plates for elastic strength and rheological studies were carried out on a hydraulic press Gibitre. Elastic and strength tests were carried out on the tensile machine the UAI-7000 M. Rheology tests were carried out on the rheometer Haake MARS III. The humidity filler (starch authors determined by the thermogravimetric method on the analyzer of moisture “Evlas-2M”. Results. It is shown, that the filler should not contain more than 7% moisture. Functionalization of ethylene with vinyl acetate copolymer (sevilen has performed by the method of alkaline alcoholysis. By the method of IC – spectroscopy the authors confirmed the presence of hydroxyl groups in the polymer. Using as a compatibilizer functionalized by the method of alcoholises has greatly ( significantly improved physical, mechanical and rheological properties of composite materials. Optimal content of sevilen (F in the compound according to the results of experiments amount 10 %. Discussion and Conclusions. Using of functionalized by the method of alcoholysis ethy-lene-vinyl acetate copolymer as a

  1. Biocompatible, biodegradable polymer-based, lighter than or light as water scaffolds for tissue engineering and methods for preparation and use thereof

    Science.gov (United States)

    Laurencin, Cato T. (Inventor); Pollack, Solomon R. (Inventor); Levine, Elliot (Inventor); Botchwey, Edward (Inventor); Lu, Helen H. (Inventor); Khan, Mohammed Yusuf (Inventor)

    2012-01-01

    Scaffolds for tissue engineering prepared from biocompatible, biodegradable polymer-based, lighter than or light as water microcarriers and designed for cell culturing in vitro in a rotating bioreactor are provided. Methods for preparation and use of these scaffolds as tissue engineering devices are also provided.

  2. Challenges and opportunities in using Life Cycle Assessment and Cradle to Cradle® for biodegradable bio-based polymers: a review

    DEFF Research Database (Denmark)

    Niero, Monia; Manat, Renil; Møller, Birger Lindberg

    2015-01-01

    Both Life Cycle Assessment (LCA) and Cradle to Cradle® (C2C) approaches can provide operative insightsin the design of biodegradable bio-based polymers. Some of the challenges shared by both LCA and C2Cthat need further investigation are the use of lab scale data versus primary data from establis...

  3. Uranium-containing plastisol compositions and polymers based on them

    International Nuclear Information System (INIS)

    Katkova, M.A.; Leonov, M.R.; Severina, T.V.; Selivestrov, V.N.; Kozina, I.Z.

    1992-01-01

    Uranium-containing polyvinylchloride plastisol compositions are prepared, from which flexible polymer dielectric films with uranium trioxide content up to 80 % are produced. It is shown that uranium trioxide is an active filler of PVC plastisols, the influence of which on the properties of the polymers produced is diverse and complex. Thus, extreme dependence of strength characteristics of uranium-containing polymers on filling degree is ascertained. Introduction of uranium oxide increases considerably the rate of thermal decomposition and changes sharply absorption characteristics of X radiation

  4. Polymer-Nanoparticle Composites: From Synthesis to Modern Applications

    Directory of Open Access Journals (Sweden)

    Thomas Hanemann

    2010-05-01

    Full Text Available The addition of inorganic spherical nanoparticles to polymers allows the modification of the polymers physical properties as well as the implementation of new features in the polymer matrix. This review article covers considerations on special features of inorganic nanoparticles, the most important synthesis methods for ceramic nanoparticles and nanocomposites, nanoparticle surface modification, and composite formation, including drawbacks. Classical nanocomposite properties, as thermomechanical, dielectric, conductive, magnetic, as well as optical properties, will be summarized. Finally, typical existing and potential applications will be shown with the focus on new and innovative applications, like in energy storage systems.

  5. Compositions for directed alignment of conjugated polymers

    Science.gov (United States)

    Kim, Jinsang; Kim, Bong-Gi; Jeong, Eun Jeong

    2016-04-19

    Conjugated polymers (CPs) achieve directed alignment along an applied flow field and a dichroic ratio of as high as 16.67 in emission from well-aligned thin films and fully realized anisotropic optoelectronic properties of CPs in field-effect transistor (FET).

  6. Light weight polymer matrix composite material

    Science.gov (United States)

    Bowles, Kenneth J. (Inventor); Lowell, Carl E. (Inventor)

    1991-01-01

    A graphite fiber reinforced polymer matrix is layed up, cured, and thermally aged at about 750.degree. F. in the presence of an inert gas. The heat treatment improves the structural integrity and alters the electrical conductivity of the materials. In the preferred embodiment PMR-15 polyimides and Celion-6000 graphite fibers are used.

  7. Electrospinning of polymer-aerogel composite fibres

    DEFF Research Database (Denmark)

    Christiansen, Lasse; Fojan, Peter

    En poster om produktion af polymer-aerogel kompositfibre ved hjælp af elektrospinning. Fiberne er produceret fra en opløsning af aerogel og polyethylene oxide i vand, som er elektrospundet gennem en enkeltnålsprocess....

  8. Performance and environmental impact of biodegradable polymers as agricultural mulching films.

    Science.gov (United States)

    Touchaleaume, François; Martin-Closas, Lluís; Angellier-Coussy, Hélène; Chevillard, Anne; Cesar, Guy; Gontard, Nathalie; Gastaldi, Emmanuelle

    2016-02-01

    In the aim of resolving environmental key issues such as irreversible soil pollution by non-biodegradable and non-recoverable polyethylene (PE) fragments, a full-scale field experiment was set up to evaluate the suitability of four biodegradable materials based on poly(butylene adipate-co-terephtalate) (PBAT) to be used as sustainable alternatives to PE for mulching application in vineyard. Initial ultimate tensile properties, functional properties during field ageing (water vapour permeability and radiometric properties), biodegradability and agronomical performance of the mulched vines (wood production and fruiting yield) were studied. In spite of their early loss of physical integrity that occurred only five months after vine planting, the four materials satisfied all the requested functional properties and led to agronomic performance as high as polyethylene. In the light of the obtained results, the mulching material lifespan was questioned in the case of long-term perennial crop such as grapevine. Taking into account their mulching efficiency and biodegradability, the four PBAT-based studied materials are proven to constitute suitable alternatives to the excessively resistant PE material. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Fabrication of an Electrically-Resistive, Varistor-Polymer Composite

    Directory of Open Access Journals (Sweden)

    Sanaz A. Mohammadi

    2012-11-01

    Full Text Available This study focuses on the fabrication and electrical characterization of a polymer composite based on nano-sized varistor powder. The polymer composite was fabricated by the melt-blending method. The developed nano-composite was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, field emission scanning electron microscopy (FeSEM, and energy-dispersive X-ray spectroscopy (EDAX. The XRD pattern revealed the crystallinity of the composite. The XRD study also showed the presence of secondary phases due to the substitution of zinc by other cations, such as bismuth and manganese. The TEM picture of the sample revealed the distribution of the spherical, nano-sized, filler particles throughout the matrix, which were in the 10–50 nm range with an average of approximately 11 nm. The presence of a bismuth-rich phase and a ZnO matrix phase in the ZnO-based varistor powder was confirmed by FeSEM images and EDX spectra. From the current-voltage curves, the non-linear coefficient of the varistor polymer composite with 70 wt% of nano filler was 3.57, and its electrical resistivity after the onset point was 861 KΩ. The non-linear coefficient was 1.11 in the sample with 100 wt% polymer content. Thus, it was concluded that the composites established a better electrical non-linearity at higher filler amounts due to the nano-metric structure and closer particle linkages.

  10. Sustained clinical safety and efficacy of a biodegradable-polymer coated sirolimus-eluting stent in "real-world" practice: three-year outcomes of the CREATE (Multi-Center Registry of EXCEL Biodegradable Polymer Drug Eluting Stents) study.

    Science.gov (United States)

    Han, Yaling; Jing, Quanmin; Li, Yi; Yang, Lixia; Liu, Huiliang; Shang, Xiaoming; Jiang, Tiemin; Li, Zhanquan; Zhang, Hua; Yan, Gaoliang

    2012-02-01

    The CREATE is a post-marketing surveillance multicenter registry that demonstrated satisfactory angiographic and clinical (at 18 months) outcomes of a biodegradable polymer based sirolimus-eluting stent (EXCEL, JW Medical System, Weihai, China) for the treatment of patients in routine clinical practice. To evaluate the three-year clinical safety and efficacy outcomes in patients enrolled in the CREATE study. A total of 2077 all comers have been enrolled in the CREATE study at 59 centers from four countries. Recommended antiplatelet regimen was clopidogrel and aspirin for six months followed by chronic aspirin therapy. The prespecified primary outcome was the rate of major adverse cardiac events (MACE) at 12, 18, and 36 months. Clinical follow-up was completed in 2025 (97.5%) patients at three years. The average duration of clopidogrel treatment was 199.8 ± 52.7 days and 80.5% of discharged patients discontinued clopidogrel at six months. The cumulative rate of MACE was 4.5% and the rate of stent thrombosis was 1.53% at three years. At six months to three years, prolonged clopidogrel therapy (>6 months) was not beneficial in reducing cumulative hazards of MACE (3.4% vs. 3.1%, log rank P = 0.725) or stent thrombosis (1.5% vs. 0.6%, log rank P = 0.053). This study demonstrates sustained three-year clinical safety and efficacy of biodegradable polymer-based sirolimus-eluting stents when used with six months of dual antiplatelet therapy in a "real-world" setting. Copyright © 2011 Wiley Periodicals, Inc.

  11. Bioactivity of freeze-dried platelet-rich plasma in an adsorbed form on a biodegradable polymer material.

    Science.gov (United States)

    Nakajima, Yu; Kawase, Tomoyuki; Kobayashi, Mito; Okuda, Kazuhiro; Wolff, Larry F; Yoshie, Hiromasa

    2012-01-01

    Owing to the necessity for the immediate preparation from patients' blood, autologous platelet-rich plasma (PRP) limits its clinical applicability. To address this concern and respond to emergency care and other unpredictable uses, we have developed a freeze-dried PRP in an adsorbed form on a biodegradable polymer material (Polyglactin 910). On the polymer filaments of PRP mesh, which was prepared by coating the polymer mesh with human fresh PRP and subsequent freeze-drying, platelets were incorporated, and related growth factors were preserved at high levels. This new PRP mesh preparation significantly and reproducibly stimulated the proliferation of human periodontal ligament cells in vitro and neovascularization in a chorioallantoic membrane assay. A full-thickness skin defect model in a diabetic mouse demonstrated the PRP mesh, although prepared from human blood, substantially facilitated angiogenesis, granulation tissue formation, and re-epithelialization without inducing severe inflammation in vivo. These data demonstrate that our new PRP mesh preparation functions as a bioactive material to facilitate tissue repair/regeneration. Therefore, we suggest that this bioactive material, composed of allogeneic PRP, could be clinically used as a promising alternative in emergency care or at times when autologous PRP is not prepared immediately before application.

  12. Biodegradation study of enzymatically catalyzed interpenetrating polymer network: Evaluation of agrochemical release and impact on soil fertility

    Directory of Open Access Journals (Sweden)

    Saruchi

    2016-03-01

    Full Text Available A novel interpenetrating polymer network (IPN has been synthesized through enzymatic initiation using lipase as initiator, glutaraldehyde as cross-linker, acrylic acid as primary monomer and acrylamide as secondary monomer. Biodegradability of synthesized interpenetrating polymer network was studied through soil burial and composting methods. Synthesized hydrogel was completely degraded within 70 days using composting method, while it was 86.03% degraded within 77 days using soil burial method. This was confirmed by Fourier transform Infrared spectroscopy (FTIR and Scanning electron microscopy (SEM techniques. Synthesized interpenetrating polymer network hydrogel was used as a device for controlled release of urea and also act as water releasing device. Their impact on soil fertility and plant growth was also studied. The initial diffusion coefficient has a greater value than the later diffusion coefficient indicating a higher fertilizer release rate during the early stage. Fertilizer release kinetic was also studied which showed Non-Fickian diffusion behavior, as the rate of fertilizer release was comparable to the relaxation time of the synthesized matrix. Synthesized IPN enhance the water uptake capacity up to 6.2% and 7.2% in sandy loam and clay soil, respectively.

  13. Thermal Protective Coating for High Temperature Polymer Composites

    Science.gov (United States)

    Barron, Andrew R.

    1999-01-01

    The central theme of this research is the application of carboxylate-alumoxane nanoparticles as precursors to thermally protective coatings for high temperature polymer composites. In addition, we will investigate the application of carboxylate-alumoxane nanoparticle as a component to polymer composites. The objective of this research was the high temperature protection of polymer composites via novel chemistry. The significance of this research is the development of a low cost and highly flexible synthetic methodology, with a compatible processing technique, for the fabrication of high temperature polymer composites. We proposed to accomplish this broad goal through the use of a class of ceramic precursor material, alumoxanes. Alumoxanes are nano-particles with a boehmite-like structure and an organic periphery. The technical goals of this program are to prepare and evaluate water soluble carboxylate-alumoxane for the preparation of ceramic coatings on polymer substrates. Our proposed approach is attractive since proof of concept has been demonstrated under the NRA 96-LeRC-1 Technology for Advanced High Temperature Gas Turbine Engines, HITEMP Program. For example, carbon and Kevlar(tm) fibers and matting have been successfully coated with ceramic thermally protective layers.

  14. Biodegradation behaviors and color change of composites based on type of bagasse pulp/polylactic acid

    Directory of Open Access Journals (Sweden)

    maryam allahdadi

    2017-05-01

    Full Text Available In this research, appearance quality and decay resistance of polylactic acid (PLA based green composites made from monoethanolamine (MEA bagasse pulp, alkaline sulfite-anthraquinone (AS bagasse pulp, bleached soda (B S bagasse pulp, unbleached soda (UN S bagasse pulp (UN S bagasse pulp and raw bagasse fibers (B were investigated. For the investigation of biodegradation behaviors, effect of the white rot fungi (Coriolus versicolor on the neat PLA and composites with natural fibers during 30 and 60 days were studied. It is found that when the bagasse fibers were incorporated into composites matrix, percentage weight reduction and stiffness of samples have been increased. Also, the rate of loss mentioned of the composites made from bagasse pulp fibers were superior to the relevant raw bagase fibers. This can be explained by the removal of non-cellulosic components such as lignin and hemicelluloses from the fibers by pulping process. Also, the results indicates the inferior of surface qualities of fabricated composites regarding to neat PLA. Depending on the fiber type, different reductions of the surface qualities were attained. However, the degree of color change of the composites with any type of bagasse pulp fibers were lower compared with composite with raw bagasse fiber. Finally, as compared with the raw bagasse fibers, bagasse pulp fibers have better reinforcing capability.

  15. Method for producing nanowire-polymer composite electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Qibing; Yu, Zhibin

    2017-11-21

    A method for producing flexible, nanoparticle-polymer composite electrodes is described. Conductive nanoparticles, preferably metal nanowires or nanotubes, are deposited on a smooth surface of a platform to produce a porous conductive layer. A second application of conductive nanoparticles or a mixture of nanoparticles can also be deposited to form a porous conductive layer. The conductive layer is then coated with at least one coating of monomers that is polymerized to form a conductive layer-polymer composite film. Optionally, a protective coating can be applied to the top of the composite film. In one embodiment, the monomer coating includes light transducing particles to reduce the total internal reflection of light through the composite film or pigments that absorb light at one wavelength and re-emit light at a longer wavelength. The resulting composite film has an active side that is smooth with surface height variations of 100 nm or less.

  16. Sustained Drug Release on Temperature-responsive Polymer Hybrid Nanoporous Silica Composites

    International Nuclear Information System (INIS)

    Chang, Jeong Ho; Kim, Kyung Ja; Shin, Young Kook

    2004-01-01

    This work describes the potential bio-application of hierarchically ordered nanoporous materials for the smart drug delivery system that involves a self-assembly process at the molecular level based upon thermo-responsive polymers. Thermosensitive polymer hybrid nano-porous materials were developed based on tailoring network of PNIPAm for smart drug release, and showed a sustained positive thermoresponsive drug release profile in which the overall release amount was controlled by change of the pore channel size. The use of biodegradable/thermo-responsive polymers in hierarchically ordered nanoporous structure can be useful for smart drug delivery applications. The discovery of ordered nanoporous materials using a surfactant-templated approach has opend a new era in the synthesis of ordered nanoscale materials. Many investigations have been explored on the preparation of nanoporous materials with novel chemical composition, on the fundamental understanding of the reaction processes, and on the potential applications such as catalysis, and separation technology expected to open up further application possibilities. Interest in the structure of the pore network is necessarily concomitant with the formation of different structures including a hexagonal, cubic, and lamellar structure

  17. Nanoporous materials modified with biodegradable polymers as models for drug delivery applications

    DEFF Research Database (Denmark)

    Gruber, Mathias F; Schulte, Lars; Ndoni, Sokol

    2013-01-01

    Polymers play a central role in the development of carriers for diagnostic and therapeutic agents. Especially the use of either degradable polymers or porous materials to encapsulate drug compounds in order to obtain steady drug release profiles has received much attention. We present here a proof...... of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model. Rhodamine 6G (R6G) mixed with Poly(l-Lactic Acid) (PLLA) were confined within the 14nm pores of a NP with gyroid morphology...

  18. Large energy absorption in Ni-Mn-Ga/polymer composites

    International Nuclear Information System (INIS)

    Feuchtwanger, Jorge; Richard, Marc L.; Tang, Yun J.; Berkowitz, Ami E.; O'Handley, Robert C.; Allen, Samuel M.

    2005-01-01

    Ferromagnetic shape memory alloys can respond to a magnetic field or applied stress by the motion of twin boundaries and hence they show large hysteresis or energy loss. Ni-Mn-Ga particles made by spark erosion have been dispersed and oriented in a polymer matrix to form pseudo 3:1 composites which are studied under applied stress. Loss ratios have been determined from the stress-strain data. The loss ratios of the composites range from 63% to 67% compared to only about 17% for the pure, unfilled polymer samples

  19. Nanophosphor composite scintillators comprising a polymer matrix

    Science.gov (United States)

    Muenchausen, Ross Edward; Mckigney, Edward Allen; Gilbertson, Robert David

    2010-11-16

    An improved nanophosphor composite comprises surface modified nanophosphor particles in a solid matrix. The nanophosphor particle surface is modified with an organic ligand, or by covalently bonding a polymeric or polymeric precursor material. The surface modified nanophosphor particle is essentially charge neutral, thereby preventing agglomeration of the nanophosphor particles during formation of the composite material. The improved nanophosphor composite may be used in any conventional scintillator application, including in a radiation detector.

  20. Surface-enrichment with hydroxyapatite nanoparticles in stereolithography-fabricated composite polymer scaffolds promotes bone repair.

    Science.gov (United States)

    Guillaume, O; Geven, M A; Sprecher, C M; Stadelmann, V A; Grijpma, D W; Tang, T T; Qin, L; Lai, Y; Alini, M; de Bruijn, J D; Yuan, H; Richards, R G; Eglin, D

    2017-05-01

    Fabrication of composite scaffolds using stereolithography (SLA) for bone tissue engineering has shown great promises. However, in order to trigger effective bone formation and implant integration, exogenous growth factors are commonly combined to scaffold materials. In this study, we fabricated biodegradable composite scaffolds using SLA and endowed them with osteopromotive properties in the absence of biologics. First we prepared photo-crosslinkable poly(trimethylene carbonate) (PTMC) resins containing 20 and 40wt% of hydroxyapatite (HA) nanoparticles and fabricated scaffolds with controlled macro-architecture. Then, we conducted experiments to investigate how the incorporation of HA in photo-crosslinked PTMC matrices improved human bone marrow stem cells osteogenic differentiation in vitro and kinetic of bone healing in vivo. We observed that bone regeneration was significantly improved using composite scaffolds containing as low as 20wt% of HA, along with difference in terms of osteogenesis and degree of implant osseointegration. Further investigations revealed that SLA process was responsible for the formation of a rich microscale layer of HA corralling scaffolds. To summarize, this work is of substantial importance as it shows how the fabrication of hierarchical biomaterials via surface-enrichment of functional HA nanoparticles in composite polymer stereolithographic structures could impact in vitro and in vivo osteogenesis. This study reports for the first time the enhance osteopromotion of composite biomaterials, with controlled macro-architecture and microscale distribution of hydroxyapatite particles, manufactured by stereolithography. In this process, the hydroxyapatite particles are not only embedded into an erodible polymer matrix, as reported so far in the literature, but concentrated at the surface of the structures. This leads to robust in vivo bone formation at low concentration of hydroxyapatite. The reported 3D self-corralling composite

  1. Effect of chemical heterogeneity of biodegradable polymers on surface energy: A static contact angle analysis of polyester model films.

    Science.gov (United States)

    Belibel, R; Avramoglou, T; Garcia, A; Barbaud, C; Mora, L

    2016-02-01

    Biodegradable and bioassimilable poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) derivatives were synthesized and characterized in order to develop a new coating for coronary endoprosthesis enabling the reduction of restenosis. The PDMMLA was chemically modified to form different custom groups in its side chain. Three side groups were chosen: the hexyl group for its hydrophobic nature, the carboxylic acid and alcohol groups for their acid and neutral hydrophilic character, respectively. The sessile drop method was applied to characterize the wettability of biodegradable polymer film coatings. Surface energy and components were calculated. The van Oss approach helped reach not only the dispersive and polar acid-base components of surface energy but also acid and basic components. Surface topography was quantified by atomic force microscopy (AFM) and subnanometer average values of roughness (Ra) were obtained for all the analyzed surfaces. Thus, roughness was considered to have a negligible effect on wettability measurements. In contrast, heterogeneous surfaces had to be corrected by the Cassie-Baxter equation for copolymers (10/90, 20/80 and 30/70). The impact of this correction was quantified for all the wettability parameters. Very high relative corrections (%) were found, reaching 100% for energies and 30% for contact angles. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Enzyme-polymer composites with high biocatalytic activity and stability

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jungbae; Kosto, Timothy J.; Manimala, Joseph C.; Nauman, E B.; Dordick, Jonathan S.

    2004-08-22

    We have applied vacuum-spraying and electrospinning to incorporate an enzyme into a polymer matrix, creating a novel and highly active biocatalytic composite. As a unique technical approach, enzymes were co-dissolved in toluene with polymers, and the solvent was then rapidly removed by injecting the mixture into a vacuum chamber or by electrospinning. Subsequent crosslinking of the enzyme with glutaraldehyde resulted in stable entrapped enzyme within the polymeric matrices. For example, an amorphous composite of alpha-chymotrypsin and polyethylene showed no significant loss of enzymatic activity in aqueous buffer for one month. Nanofibers of alpha-chymotrypsin and polystyrene also showed no decrease in activity for more than two weeks. The normalized activity of amorphous composite in organic solvents was 3-13 times higher than that of native alpha-chymotrypsin. The activity of nanofibers was 5-7 times higher than that of amorphous composite in aqueous buffer solution. The composites of alpha-chymotrypsin and polymers demonstrate the feasibility of obtaining a wide variety of active and stable biocatalytic materials with many combinations of enzymes and polymers.

  3. Biodegradable and compostable alternatives to conventional plastics.

    Science.gov (United States)

    Song, J H; Murphy, R J; Narayan, R; Davies, G B H

    2009-07-27

    Packaging waste forms a significant part of municipal solid waste and has caused increasing environmental concerns, resulting in a strengthening of various regulations aimed at reducing the amounts generated. Among other materials, a wide range of oil-based polymers is currently used in packaging applications. These are virtually all non-biodegradable, and some are difficult to recycle or reuse due to being complex composites having varying levels of contamination. Recently, significant progress has been made in the development of biodegradable plastics, largely from renewable natural resources, to produce biodegradable materials with similar functionality to that of oil-based polymers. The expansion in these bio-based materials has several potential benefits for greenhouse gas balances and other environmental impacts over whole life cycles and in the use of renewable, rather than finite resources. It is intended that use of biodegradable materials will contribute to sustainability and reduction in the environmental impact associated with disposal of oil-based polymers. The diversity of biodegradable materials and their varying properties makes it difficult to make simple, generic assessments such as biodegradable products are all 'good' or petrochemical-based products are all 'bad'. This paper discusses the potential impacts of biodegradable packaging materials and their waste management, particularly via composting. It presents the key issues that inform judgements of the benefits these materials have in relation to conventional, petrochemical-based counterparts. Specific examples are given from new research on biodegradability in simulated 'home' composting systems. It is the view of the authors that biodegradable packaging materials are most suitable for single-use disposable applications where the post-consumer waste can be locally composted.

  4. Biodegradable and compostable alternatives to conventional plastics

    Science.gov (United States)

    Song, J. H.; Murphy, R. J.; Narayan, R.; Davies, G. B. H.

    2009-01-01

    Packaging waste forms a significant part of municipal solid waste and has caused increasing environmental concerns, resulting in a strengthening of various regulations aimed at reducing the amounts generated. Among other materials, a wide range of oil-based polymers is currently used in packaging applications. These are virtually all non-biodegradable, and some are difficult to recycle or reuse due to being complex composites having varying levels of contamination. Recently, significant progress has been made in the development of biodegradable plastics, largely from renewable natural resources, to produce biodegradable materials with similar functionality to that of oil-based polymers. The expansion in these bio-based materials has several potential benefits for greenhouse gas balances and other environmental impacts over whole life cycles and in the use of renewable, rather than finite resources. It is intended that use of biodegradable materials will contribute to sustainability and reduction in the environmental impact associated with disposal of oil-based polymers. The diversity of biodegradable materials and their varying properties makes it difficult to make simple, generic assessments such as biodegradable products are all ‘good’ or petrochemical-based products are all ‘bad’. This paper discusses the potential impacts of biodegradable packaging materials and their waste management, particularly via composting. It presents the key issues that inform judgements of the benefits these materials have in relation to conventional, petrochemical-based counterparts. Specific examples are given from new research on biodegradability in simulated ‘home’ composting systems. It is the view of the authors that biodegradable packaging materials are most suitable for single-use disposable applications where the post-consumer waste can be locally composted. PMID:19528060

  5. Late clinical outcomes after implantation of drug-eluting stents coated with biodegradable polymers: 3-year follow-up of the PAINT randomised trial.

    Science.gov (United States)

    Lemos, Pedro A; Moulin, Bruno; Perin, Marco A; Oliveira, Ludmilla A R R; Arruda, J Airton; Lima, Valter C; Lima, Antonio A G; Caramori, Paulo R A; Medeiros, Cesar R; Barbosa, Mauricio R; Brito, Fabio S; Ribeiro, Expedito E

    2012-05-15

    The long-term clinical performance of drug-eluting stents (DES) coated with biodegradable polymers is poorly known. A total of 274 coronary patients were randomly allocated to paclitaxel-eluting stents, sirolimus-eluting stents, or bare metal stents (2:2:1 ratio). The two DES used the same biodegradable polymers and were identical except for the drug. At three years, the pooled DES population had similar rates of cardiac death or myocardial infarction (9.0% vs. 7.1; p=0.6), but lower risk of repeat interventions (10.0% vs. 29.9%; pbiodegradable-polymer coated DES releasing either paclitaxel or sirolimus were effective in reducing the 3-year rate of re-interventions.

  6. Solid polymer electrolyte composite membrane comprising plasma etched porous support

    Science.gov (United States)

    Liu, Han; LaConti, Anthony B.

    2010-10-05

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  7. Synthesis and characterization of polymers based on citric acid and glycerol: Its application in non-biodegradable polymers

    Directory of Open Access Journals (Sweden)

    Jaime Alfredo Mariano-Torres

    2015-01-01

    Full Text Available El notable incremento mundial en el consumo de plásticos y su l argo tiempo de residencia en el ambiente muestran la gran neces idad de productos con caracterís ticas biodegradables. En este proyecto fueron desarrollados polímeros biodegradables a base del ácido cítrico y del glicerol. La síntesis de esto s se lleva a cabo a diferentes condiciones de concentración y a temperatura constante. Se des arrollaron mediante un proceso económicamente viable. Se caracterizaron p or medio de las siguientes técnicas: Numero ácido, espectroscop ia infrarroja FTIR, índice de refracc ión, viscosidad, análisis de impacto, ensayo de tensión, dure za, calorimetría, el % de Humed ad (método de la estufa con recirculación de aire, determinación de densi dad, además de pruebas cualitativas para corroborar su biodegra dabilidad. Los polímeros elaborados fueron mezclados con una formulación de PVC grado médico, obteniendo un polímero hibrido y se pudo observar que modifica sus propiedades mecánicas.

  8. Characterization of chitosan composites with synthetic polymers and inorganic additives.

    Science.gov (United States)

    Lewandowska, Katarzyna

    2015-11-01

    In the present study, the results from thermogravimetric analysis (TGA), contact angle measurements, tensile tests, scanning electron microscopy (SEM) and atomic force microscopy (AFM) of polymer composites containing chitosan (Ch) and montmorillonite (MMT) with and without poly(vinyl alcohol) (PVA) are presented. Measurements of the contact angles for diiodomethane (D) and glycerol (G) on the surfaces of chitosan films, Ch/MMT and Ch/PVA/MMT, were made and surface free energies were calculated. It was found that the wettability of the chitosan/MMT or Ch/PVA/MMT composite films decreased relative to the wettability of chitosan. The microstructure of unmodified polymers and their composites, as observed by SEM and AFM, showed particles that are relatively well dispersed in the polymer matrix. The TGA thermograms and mass loss percentages at different decomposition temperatures showed that the thermal stability of the binary composite slightly decreases upon the addition of PVA. The film mechanical properties such as tensile strength, Young's modulus and tensile strain at break depend on the composition and varied non-uniformly. Both composites possessed a tensile strength and Young's modulus of 27.6-94.3MPa and 1.5-3.5GPa, respectively. The addition of PVA to the composite led to a reduction in tensile strength by approximately 40%. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Mechanical and thermal properties of promising polymer composites for food packaging applications

    Science.gov (United States)

    Abdellah Ali, S. F.

    2016-07-01

    Blending starches with biodegradable polycaprolactone (PCL) was used as a route to make processable thermoplastics. When developing biodegradable polymer composites it is important to use high concentrations of starch for legislative and cost reasons. The addition of starch has a significant effect on all physical properties including toughness, elongation at break and the rheological behaviour of the melt. To enhance the physical properties, we used cellulose acetate propionate (CAP) as a cellulose derivative with high amylase starch and PCL blends. It is suggested that the PCL/starch/CAP blends are partially miscible. It was found that the yield tensile strengths of most PCL/Starch/CAP blends were higher than that of pure PCL itself. There was a big difference between glass transition temperature values of PCL/Starch/CAP blends and the pure PCL glass transition temperature which indicates that no phase separation occurs. Addition of CAP to starch and PCL blends improved the mechanical and thermal properties even at high content of starch.

  10. Analysis Models for Polymer Composites Across Different Length Scales

    Science.gov (United States)

    Camanho, Pedro P.; Arteiro, Albertino

    This chapter presents the analysis models, developed at different length scales, for the prediction of inelastic deformation and fracture of polymer composite materials reinforced by unidirectional fibers. Three different length scales are covered. Micro-mechanical models are used to understand in detail the effects of the constituents on the response of the composite material, and to support the development of analysis models based on homogenized representations of composite materials. Meso-mechanical models are used to predict the strength of composite structural components under general loading conditions. Finally, macro-mechanical models based on Finite Fracture Mechanics, which enable fast strength predictions of simple structural details, are discussed.

  11. 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.

  12. Damage-induced hydrolyses modelling of biodegradable polymers for tendons and ligaments repair.

    Science.gov (United States)

    Vieira, André C; Guedes, Rui M; Tita, Volnei

    2015-09-18

    The use of biodegradable synthetic grafts to repair injured ligaments may overcome the disadvantages of other solutions. Apart from biological compatibility, these devices shall also be functionally compatible and temporarily displayed, during the healing process, adequate mechanical support. Laxity of these devices is an important concern. This can cause failure since it may result in joint instability. Laxity results from a progressive accumulation of plastic strain during the cyclic loading. The functional compatibility of a biodegradable synthetic graft and, therefore, the global mechanical properties of the scaffold during degradation, can be optimised using computer-aiding and numerical tools. Therefore, in this work, the ability of numerical tools to predict the mechanical behaviour of the device during its degradation is discussed. Computational approaches based on elastoplastic and viscoplastic constitutive models are also presented. These models enable to simulate the plastic strain accumulation. These computational approaches, where the material model parameters depend on the hydrolytic degradation damage, are calibrated using experimental data measured from biodegradable suture fibres at different degradation steps. Due to durability requirements the selected materials are polydioxone (PDO) and polylactic acid and poly-caprolactone blend (PLA-PCL). Computational approaches investigated are able to predict well the experimental results for both materials, in full strain range until rupture and for different degradation steps. These approaches can be further used in more complex fibrous structures, to predict its global mechanical behaviour during degradation process. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Conductive polymer/metal composites for interconnect of flexible devices

    Science.gov (United States)

    Kawakita, Jin; Hashimoto Shinoda, Yasuo; Shuto, Takanori; Chikyow, Toyohiro

    2015-06-01

    An interconnect of flexible and foldable devices based on advanced electronics requires high electrical conductivity, flexibility, adhesiveness on a plastic substrate, and efficient productivity. In this study, we investigated the applicability of a conductive polymer/metal composite to the interconnect of flexible devices. By combining an inkjet process and a photochemical reaction, micropatterns of a polypyrrole/silver composite were formed on flexible plastic substrates with an average linewidth of approximately 70 µm within 10 min. The conductivity of the composite was improved to 6.0 × 102 Ω-1·cm-1. From these results, it is expected that the conducting polymer/metal composite can be applied to the microwiring of flexible electronic devices.

  14. Properties of Polymer Composites Used in High-Voltage Applications

    Directory of Open Access Journals (Sweden)

    Ilona Pleşa

    2016-04-01

    Full Text Available The present review article represents a comprehensive study on polymer micro/nanocomposites that are used in high-voltage applications. Particular focus is on the structure-property relationship of composite materials used in power engineering, by exploiting fundamental theory as well as numerical/analytical models and the influence of material design on electrical, mechanical and thermal properties. In addition to describing the scientific development of micro/nanocomposites electrical features desired in power engineering, the study is mainly focused on the electrical properties of insulating materials, particularly cross-linked polyethylene (XLPE and epoxy resins, unfilled and filled with different types of filler. Polymer micro/nanocomposites based on XLPE and epoxy resins are usually used as insulating systems for high-voltage applications, such as: cables, generators, motors, cast resin dry-type transformers, etc. Furthermore, this paper includes ample discussions regarding the advantages and disadvantages resulting in the electrical, mechanical and thermal properties by the addition of micro- and nanofillers into the base polymer. The study goals are to determine the impact of filler size, type and distribution of the particles into the polymer matrix on the electrical, mechanical and thermal properties of the polymer micro/nanocomposites compared to the neat polymer and traditionally materials used as insulation systems in high-voltage engineering. Properties such as electrical conductivity, relative permittivity, dielectric losses, partial discharges, erosion resistance, space charge behavior, electric breakdown, tracking and electrical tree resistance, thermal conductivity, tensile strength and modulus, elongation at break of micro- and nanocomposites based on epoxy resin and XLPE are analyzed. Finally, it was concluded that the use of polymer micro/nanocomposites in electrical engineering is very promising and further research work

  15. Gamma and electron beam curing of polymers and composites

    International Nuclear Information System (INIS)

    Saunders, C.B.; Dickson, L.W.; Singh, A.

    1987-01-01

    Radiation polymerization has helped us understand polymer chemistry, and is also playing an increasing role in the field of practical applications. Radiation curing has a present market share of about 5% of the total market for curing of polymers and composites and the annual growth rate of the radiation curing market is ≥20% per year. Advantages of radiation curing over thermal or chemical curing methods include: improved control of the curing rate, reduced curing times, curing at ambient temperatures, curing without the need for chemical initiators, and complete (100%) curing with minimal toxic chemical emissions. Radiation treatment may also be used to effect crosslinking and grafting of polymer and composite materials. The major advantage in these cases is the ability to process products in their final shape. Cable insulation, automotive and aircraft components, and improved construction materials are some of the current and near-future industrial applications of radiation curing and crosslinking. 19 refs

  16. Comparison of 3 biodegradable polymer and durable polymer-based drug-eluting stents in all-comers (BIO-RESORT): Rationale and study design of the randomized TWENTE III multicenter trial

    NARCIS (Netherlands)

    Lam, Ming Kai; Sen, Hanim; Sen, Hanim; Tandjung, K.; Tandjung, K.; van Houwelingen, K. Gert; de Vries, Arie G.; Danse, Peter W.; Schotborgh, Carl E.; Scholte, Martijn; Löwik, Marije M.; Linssen, Gerard C.M.; IJzerman, Maarten Joost; van der Palen, Jacobus Adrianus Maria; Doggen, Catharina Jacoba Maria; von Birgelen, Clemens

    2014-01-01

    Aim To evaluate the safety and efficacy of 2 novel drug-eluting stents (DES) with biodegradable polymer-based coatings versus a durable coating DES. Methods and Results BIO-RESORT is an investigator-initiated, prospective, patient-blinded, randomized multicenter trial in 3540 Dutch all-comers with

  17. Self healing in polymers and polymer composites. Concepts, realization and outlook: A review

    Directory of Open Access Journals (Sweden)

    2008-04-01

    Full Text Available Formation of microcracks is a critical problem in polymers and polymer composites during their service in structural applications. Development and coalescence of microcracks would bring about catastrophic failure of the materials and then reduce their lifetimes. Therefore, early sensing, diagnosis and repair of microcracks become necessary for removing the latent perils. In this context, the materials possessing self-healing function are ideal for long-term operation. Self-repairing polymers and polymer composites have attracted increasing research interests. Attempts have been made to develop solutions in this field. The present article reviews state-of-art of the achievements on the topic. According to the ways of healing, the smart materials are classified into two categories: (i intrinsic self-healing ones that are able to heal cracks by the polymers themselves, and (ii extrinsic in which healing agent has to be pre-embedded. The advances in this field show that selection and optimization of proper repair mechanisms are prerequisites for high healing efficiency. It is a challenging job to either invent new polymers with inherent crack repair capability or integrate existing materials with novel healing system.

  18. Effects of mechanical properties of polymer on ceramic-polymer composite thick films fabricated by aerosol deposition

    OpenAIRE

    Kwon, Oh-Yun; Na, Hyun-Jun; Kim, Hyung-Jun; Lee, Dong-Won; Nam, Song-Min

    2012-01-01

    Two types of ceramic-polymer composite thick films were deposited on Cu substrates by an aerosol deposition process, and their properties were investigated to fabricate optimized ceramic-based polymer composite thick films for application onto integrated substrates with the advantage of plasticity. When polymers with different mechanical properties, such as polyimide (PI) and poly(methyl methacrylate) (PMMA), are used as starting powders together with α-Al2O3 powder, two types of composite fi...

  19. Advanced moisture modeling of polymer composites.

    Science.gov (United States)

    2014-04-01

    Long term moisture exposure has been shown to affect the mechanical performance of polymeric composite structures. This reduction : in mechanical performance must be considered during product design in order to ensure long term structure survival. In...

  20. Solution electrospinning of particle-polymer composite fibres

    DEFF Research Database (Denmark)

    Christiansen, Lasse; Fojan, Peter

    2016-01-01

    into scaffolds. The formation of a particle/polymer composite results in improved mechanical stability, without compromising the porosity. In the presented study, aerogel and poly(ethylene oxide) are mixed into a solution, and spun to thin fibres. Thereby a porous membrane, on the micro- and nano...

  1. Polymer--calcium phosphate cement composites for bone substitutes.

    Science.gov (United States)

    Mickiewicz, Rafal A; Mayes, Anne M; Knaack, David

    2002-09-15

    The use of self-setting calcium phosphate cements (CPCs) as bioresorbable bone-replacement implant materials presently is limited to non-load-bearing applications because of their low compressive strength relative to natural bone. The present study investigated the possibility of strengthening a commercially available CPC, alpha-BSM, by incorporating various water-soluble polymers into the cement paste during setting. Several polyelectrolytes, poly(ethylene oxide), and the protein bovine serum albumin (BSA) were added in solution to the cement paste to create calcium phosphate-polymer composites. Composites formulated with the polycations poly(ethylenimine) and poly(allylamine hydrochloride) exhibited compressive strengths up to six times greater than that of pure alpha-BSM material, with a maximum value reached at intermediate polymer content and for the highest molecular weight studied. Composites containing BSA developed compressive strengths twice that of the original cement at protein concentrations of 13-25% by weight. In each case, XRD studies correlate the improvement in compressive strength with reduced crystallite dimensions, as evidenced by a broadening of the (0,0,2) reflection. This suggests that polycation or BSA adsorption inhibits crystal growth and possibly leads to a larger crystal aspect ratio. SEM results indicate a denser, more interdigitated microstructure. The increased strength was attributed to the polymer's capacity to bridge between multiple crystallites (thus forming a more cohesive composite) and to absorb energy through plastic flow. Copyright 2002 Wiley Periodicals, Inc.

  2. Effects Of Solvent Composition And Polymer Concentration On Poly ...

    African Journals Online (AJOL)

    Its solution in Phenol: 1,2-dichlorobenzene solvent mixtures of 35%: 65%, 50%: 50%, 65%: 35% by weight was degraded at 143± 2oC. The effects of solvent composition and polymer concentration on poly (ethylene terephthalate) degradation in solution were investigated by dilute solution viscometric method using 0.460, ...

  3. Polymer-based composites for RFI/EMI/ applications

    Science.gov (United States)

    Williams, Neil; Varadan, Vijay K.; Varadan, Vasundara V.

    1990-10-01

    A conductive polymer composite of 2.4 mm thickness has been measured at a frequency range of 100 MHz to 18 GHz. This sample was measured for its EMI and EMC characteristics for use in electromagnetic shielding applications. It was shown that this thin sample achieved high transmission loss over a broad frequency range.

  4. Tribological performance of polymer composites used in electrical ...

    Indian Academy of Sciences (India)

    GFR) polymer composite. Wear test was carried out at 10, 20 and 30 N applied load values and 0·5 m/s sliding speed and at ambient temperature and humidity. Different combinations of rubbing surfaces were examined and friction coefficient and ...

  5. Mechanical properties of natural fibre reinforced polymer composites

    Indian Academy of Sciences (India)

    In the present communication, a study on the synthesis and mechanical properties of new series of green composites involving Hibiscus sabdariffa fibre as a reinforcing material in urea–formaldehyde (UF) resin based polymer matrix has been reported. Static mechanical properties of randomly oriented intimately mixed ...

  6. Tribological performance of polymer composites used in electrical ...

    Indian Academy of Sciences (India)

    Sliding wear performance of 20% mica-filled polyamide 6 (PA6 + 20% mica) and 20% short glass fibrereinforced polysulphone (PSU + 20 GFR) polymer composites used in electrical applications were investigated using a pin-on-disc wear test apparatus. Two different disc materials were used in this study. These are AISI ...

  7. Mechanics of Carbon Nanotubes and their Polymer Composites

    Science.gov (United States)

    Wei, Chenyu; Cho, K. J.; Srivastava, Deepak; Tang, Harry (Technical Monitor)

    2002-01-01

    Contents include the folloving: carbon nanotube (CNT): structures, application of carbon nanotubes, simulation method, Elastic properties of carbon nanotubes, yield strain of CNT, yielding under tensile stress, yielding: strain-rate and temperature dependence, yield strain under tension, yielding at realistic conditions, nano fibers, polymer CNT composite, force field, density dependency on temperature, diffusion coefficients, young modulus, and conclusions.

  8. Tribological performance of polymer composites used in electrical ...

    Indian Academy of Sciences (India)

    These are AISI 316 L stainless steel and 30% glass fibre-reinforced polyphenylenesulphide (PPS + 30%GFR) polymer composite. Wear test was carried out at 10, 20 and 30 N applied load values and 0.5 m/s sliding speed and at ambient temperature and humidity. Different combinations of rubbing surfaces were examined ...

  9. Machining of Machine Elements Made of Polymer Composite Materials

    Science.gov (United States)

    Baurova, N. I.; Makarov, K. A.

    2017-12-01

    The machining of the machine elements that are made of polymer composite materials (PCMs) or are repaired using them is considered. Turning, milling, and drilling are shown to be most widely used among all methods of cutting PCMs. Cutting conditions for the machining of PCMs are presented. The factors that most strongly affect the roughness parameters and the accuracy of cutting PCMs are considered.

  10. Corn gluten meal as a biodegradable matrix material in wood fibre reinforced composites

    Energy Technology Data Exchange (ETDEWEB)

    Beg, M.D.H. [Department of Materials and Process Engineering, University of Waikato, Private Bag 3105, Hamilton (New Zealand); Pickering, K.L. [Department of Materials and Process Engineering, University of Waikato, Private Bag 3105, Hamilton (New Zealand)]. E-mail: klp@waikato.ac.nz; Weal, S.J. [Department of Materials and Process Engineering, University of Waikato, Private Bag 3105, Hamilton (New Zealand)

    2005-12-05

    This study was undertaken to investigate corn gluten meal (CGM) as a biodegradable matrix material for wood fibre reinforced composites. CGM was used alone, as well as hybridized with polypropylene, and reinforced with radiata pine (Pinus Radiata) fibre using a twin-screw extruder followed by injection moulding. Tensile testing, scanning electron microscopy and differential scanning calorimetry were carried out to assess the composites. For composites from CGM and wood fibres, extrusion was carried out with the aid of the following plasticizers: octanoic acid, glycerol, polyethylene glycol and water. Windows of processability for the different plasticizers were obtained for all plasticizers. These were found to lie between 20 and 50 wt.% of plasticizer with a maximum of approximately 20% wood fibre reinforcement. The best mechanical properties were obtained with a matrix containing 10 wt.% octanoic acid and 30 wt.% water, which gave a tensile strength and Young's modulus of 18.7 MPa and 4 GPa, respectively. Hybrid matrix composites were compounded with a maleated polypropylene coupling agent and benzoyl peroxide as a cross-linking agent. The highest tensile strength and Young's modulus obtained from hybrid matrix composites were 36.9 MPa and 5.8 GPa with 50 wt.% fibre.

  11. Extrudable polymer-polymer composites based on ultra-high molecular weight polyethylene

    Science.gov (United States)

    Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Buslovich, D. G.; Dontsov, Yu. V.

    2017-12-01

    Mechanical and tribotechnical characteristics of polymer-polymeric composites of UHMWPE are studied with the aim of developing extrudable, wear-resistant, self-lubricant polymer mixtures for Additive Manufacturing (AM). The motivation of the study is their further application as feedstocks for 3D printing. Blends of UHMWPE with graft- and block copolymers of low-density polyethylene (HDPE-g-VTMS, HDPE-g-SMA, HDPE-b-EVA), polypropylene (PP), block copolymers of polypropylene and polyamide with linear low density polyethylene (PP-b-LLDPE, PA-b-LLDPE), as well as cross-linked polyethylene (PEX-b), are examined. The choice of compatible polymer components for an ultra- high molecular weight matrix for increasing processability (extrudability) is motivated by the search for commercially available and efficient additives aimed at developing wear-resistant extrudable polymer composites for additive manufacturing. The extrudability, mechanical properties and wear resistance of UHMWPE-based polymer-polymeric composites under sliding friction with different velocities and loads are studied.

  12. Study of dielectric properties of biodegradable composites using (Poly)lactic acid and Luffa fiber

    Science.gov (United States)

    Parida, Chhatrapati; Patra, Subhasree; Mohanta, Kamal lochan; Dash, Sarat kumar; Parashar, S. K. S.

    2017-05-01

    Composites were made from bio degradable polymer (poly)lactic acid and lignocellulosic materials derived from natural fibers of luffa cylindrica using injection moulding technique. Before reinforcement in the poymer, the fibers were subjected to chemical treatments like alkali treatment, bleaching and acid hydrolysis. Frequency dependence of dielectric parameters like dielectric constant, di electric loss and ac conductivity of the composites were investigated in the frequency range from 1000Hz to 1MHz. The effect of wt of fiber in the composites on the above mentioned dielectric parameters were also evaluated. The experimental results show that the values of dielectric constant, ac conductivity and loss factor increase with increase in wt of fiber in the polymer matrix. However when fibers exposed to alkali treatment, bleaching and acid hydrolysis were incorporated in to the matrix, the composites showed inferior dielectric response compared to composites having fibers exposed to alkali treatment and bleaching only. It was also found that dielectric constant and dielectric loss factor of all the composite samples decreased with increase in frequency of the applied field. However, the ac conductivity of all the samples is found to increase with increase in frequency.

  13. Polymer derived ceramic composites as environmental barrier coatings on steel

    Science.gov (United States)

    Torrey, Jessica D.

    Polymer derived ceramics have shown promise as a novel way to process low-dimensional ceramics such as fibers and coatings. They offer advantages over traditional ceramic processing routes including lower pyrolysis temperatures and the ability to employ polymeric processing techniques. The main drawback to preceramic polymers is that they undergo a shrinkage during pyrolysis that can be greater than 50-volume%. One way to overcome this shrinkage is to add filler particles, usually elemental or binary metals, which will expand upon reaction with the pyrolysis atmosphere, thereby compensating for the shrinkage of the polymer. The aim of this study is to develop a polymer derived ceramic composite coating on steel as a barrier to oxidation and carburization, while concurrently gaining insight as to the fundamental mechanisms for compositional and microstructural evolution within the system. A systematic approach to selecting the preceramic polymer and expansion agents was taken. Six commercially available poly(silsesquioxane) polymers and a polysiloxane were studied. Several metals and an intermetallic were considered as potential expansion agents. The most desirable polymer/expansion agent combination was achieved with poly(hydridomethylsiloxane) as the matrix and titanium disilicide as the filler. Processing parameters have been optimized and a relationship derived to predict final coating thickness based on slurry viscosity and dip coating withdrawal speed. Microstructural analysis reveals an amorphous composite coating of oxidized filler particles in a silica matrix. A diffusion layer is visible at the coating-steel interface, indicating good bonding. The optimized coatings are ˜18mum thick, have some residual porosity and a density of 2.57g/cm3. A systematic study of the phase transformations and microstructural changes in the coating and its components during pyrolysis in air is also presented. The system evolves from a polymer filled with a binary metal at

  14. Nanoporous materials modified with biodegradable polymers as models for drug delivery applications

    DEFF Research Database (Denmark)

    Gruber, Mathias F; Schulte, Lars; Ndoni, Sokol

    2013-01-01

    Polymers play a central role in the development of carriers for diagnostic and therapeutic agents. Especially the use of either degradable polymers or porous materials to encapsulate drug compounds in order to obtain steady drug release profiles has received much attention. We present here a proof...... of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model. Rhodamine 6G (R6G) mixed with Poly(l-Lactic Acid) (PLLA) were confined within the 14nm pores of a NP with gyroid morphology...... the hydrolysis of PLLA. The obtained release profiles demonstrate that the degradation of PLLA in nanoporous confinement is significantly slower than the degradation of unconfined PLLA. The release of R6G encapsulated in PLLA becomes correspondingly slower, while the initial burst release virtually disappears...

  15. Preparation of Cellulose Nanofibrils from Bamboo Pulp by Mechanical Defibrillation for Their Applications in Biodegradable Composites.

    Science.gov (United States)

    Guimarães, Mario; Botaro, Vagner Roberto; Novack, Kátia Monteiro; Neto, Wilson Pires Flauzino; Mendes, Lourival Marin; Tonoli, Gustavo H D

    2015-09-01

    There is a growing interest in cellulose nanofibrils from renewable sources for various industrial applications. However, there is a lack of information on cellulose arising from bamboo pulps. Nanofibrils from refined bamboo pulps, including bleached, unbleached, and unrefined/unbleached, were obtained by mechanical defibrillation for use in biodegradable composites. The influence of industrial processes, such as pulping and refining of unbleached pulps, as well as of alkali pretreatments and bleaching of refined pulps, on the chemical composition of the samples was analyzed. Morphological, structural, thermal, optical and viscometric properties were investigated as a function of the number of passages of refined/bleached suspensions through a defibrillator. For the unbleached suspensions, the effects of refining and bleaching on the properties of nanofibrils were evaluated, fixing the number of passages through the defibrillator. Microscopic studies demonstrated that nanoscale cellulose fibers were obtained from both pulps, with a higher yield for the refined/bleached and refined/unbleached pulp, at the expense of the unbleached/unrefined pulps. The study showed that, in addition to the effectiveness of the pre-treatments, there was an increase in the production efficiency of nanofibrils, as well as in the transparency of the bleached suspensions, while viscosity, thermal stability and crystallinity had reduced levels as the number of passages through the defibrillator increased, showing a gradual improvement in the transition from the micro- to the nano-scale. The present study contributed to the different methods that are available for the production of bamboo cellulose nanofibrils, which can be used in the production of biodegradable composites for various applications.

  16. Biodegradation Resistance and Bioactivity of Hydroxyapatite Enhanced Mg-Zn Composites via Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Cijun Shuai

    2017-03-01

    Full Text Available Mg-Zn alloys have attracted great attention as implant biomaterials due to their biodegradability and biomechanical compatibility. However, their clinical application was limited due to the too rapid degradation. In the study, hydroxyapatite (HA was incorporated into Mg-Zn alloy via selective laser melting. Results showed that the degradation rate slowed down due to the decrease of grain size and the formation of protective layer of bone-like apatite. Moreover, the grain size continually decreased with increasing HA content, which was attributed to the heterogeneous nucleation and increased number of nucleation particles in the process of solidification. At the same time, the amount of bone-like apatite increased because HA could provide favorable areas for apatite nucleation. Besides, HA also enhanced the hardness due to the fine grain strengthening and second phase strengthening. However, some pores occurred owing to the agglomerate of HA when its content was excessive, which decreased the biodegradation resistance. These results demonstrated that the Mg-Zn/HA composites were potential implant biomaterials.

  17. Biodegradation Resistance and Bioactivity of Hydroxyapatite Enhanced Mg-Zn Composites via Selective Laser Melting.

    Science.gov (United States)

    Shuai, Cijun; Zhou, Yuanzhuo; Yang, Youwen; Feng, Pei; Liu, Long; He, Chongxian; Zhao, Mingchun; Yang, Sheng; Gao, Chengde; Wu, Ping

    2017-03-17

    Mg-Zn alloys have attracted great attention as implant biomaterials due to their biodegradability and biomechanical compatibility. However, their clinical application was limited due to the too rapid degradation. In the study, hydroxyapatite (HA) was incorporated into Mg-Zn alloy via selective laser melting. Results showed that the degradation rate slowed down due to the decrease of grain size and the formation of protective layer of bone-like apatite. Moreover, the grain size continually decreased with increasing HA content, which was attributed to the heterogeneous nucleation and increased number of nucleation particles in the process of solidification. At the same time, the amount of bone-like apatite increased because HA could provide favorable areas for apatite nucleation. Besides, HA also enhanced the hardness due to the fine grain strengthening and second phase strengthening. However, some pores occurred owing to the agglomerate of HA when its content was excessive, which decreased the biodegradation resistance. These results demonstrated that the Mg-Zn/HA composites were potential implant biomaterials.

  18. Porous polymer networks and ion-exchange media and metal-polymer composites made therefrom

    Science.gov (United States)

    Kanatzidis, Mercouri G.; Katsoulidis, Alexandros

    2016-10-18

    Porous polymeric networks and composite materials comprising metal nanoparticles distributed in the polymeric networks are provided. Also provided are methods for using the polymeric networks and the composite materials in liquid- and vapor-phase waste remediation applications. The porous polymeric networks, are highly porous, three-dimensional structures characterized by high surface areas. The polymeric networks comprise polymers polymerized from aldehydes and phenolic molecules.

  19. Properties of Plant Fiber Yarn Polymer Composites

    DEFF Research Database (Denmark)

    Madsen, Bo

    2004-01-01

    . The thesis presents experimental investigations and modelling of the properties of aligned plant fibre composites based on textile hemp yarn and thermoplastic matrices. The textile hemp yarn has been characterised. It is high in cellulose and with fibres well separated from each other; i.e. only few fibres...... are situated in bundles. The twisting angle is low; i.e. about 15 o for the outermost fibres in the yarn. The moisture sorption capacity of the yarn fibres is much lower than that of raw hemp fibres. Stiffness and strength of the fibres as calculated from composite data are in the ranges 50-65 GPa and 530......-650 MPa respectively. These properties show that textile hemp yarn is well suited as composite reinforcement. The relationship between fibre volume fraction and porosity has been studied. A model has been developed that predicts porosity from experimentally determined parameters such as fibre lumen...

  20. Gender difference on five-year outcomes of EXCEL biodegradable polymer-coated sirolimus-eluting stents implantation: results from the CREATE study.

    Science.gov (United States)

    Zhang, Lei; Qiao, Bing; Han, Ya-Ling; Li, Yi; Xu, Kai; Zhang, Quan-Yu; Yang, Li-Xia; Liu, Hui-Liang; Xu, Bo; Gao, Run-Lin

    2013-03-01

    The gender difference on long-term outcome in unselected patients after percutaneous coronary intervention (PCI) has not yet been fully investigated. This study aimed to evaluate the gender difference on five-year outcomes following EXCEL biodegradable polymer-coated sirolimus-eluting stenting in patients with coronary disease. A total of 2077 "all comers", consisting of 1528 (73.6%) men and 549 (26.4%) women, who were exclusively treated with EXCEL coronary stents were enrolled in the prospective CREATE study at 59 centers from four countries. After propensity score matching, the baseline characteristics of the two groups were well matched. Recommended antiplatelet regimen was clopidogrel and aspirin for six months followed by chronic aspirin therapy. The primary outcome that was the rate of major adverse cardiac events (MACE), defined as a composite of cardiac mortality, non-fatal myocardial infarction (MI) and target lesion revascularization (TLR), and stent thrombosis (ST) at five years were compared between the two gender groups. In the two groups, women had higher proportions of clinical risk factors, such as being elderly, diabetes mellitus, hypertension and hyperlipidemia, compared to men. Besides, the mean target vessel number per patient was higher and the mean reference vessel diameter smaller for women. Men had higher risks of cardiac death (3.7% vs. 1.6%, P = 0.021) and MACE (8.4% vs. 4.7%, P = 0.004) at five years compared with women. However, the cumulative hazards of non-fatal MI and TLR were similar between men and women. The incidence of Academic Research Consortium (ARC) definite or probable stent thrombosis was similar between the two groups (1.3% vs. 1.0%, P = 0.639). Prolonged clopidogrel therapy (>6 months) did not reduce the cumulative hazards of ST from six months to five years in both men (χ(2) = 0.098, log rank P = 0.754) and women (χ(2) = 2.043, log rank P = 0.153) patients. Women had a lower MACE and cardiac death rate than men after

  1. Mechanical, thermal, and fire properties of biodegradable polylactide/boehmite alumina composites

    CSIR Research Space (South Africa)

    Das, K

    2013-05-01

    Full Text Available -Smith‡ †Department of Applied Chemistry, University of Johannesburg, Doornforntein 2028, Johannesburg, South Africa ‡DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001, South Africa §Polymer... and Composites, Materials Science and Manufacturing, Council for Scientific and Industrial Research, Port Elizabeth 6000, South Africa Abstract Boehmite alumina (BAl) was investigated in terms of its use as an filler to improve the inherent properties...

  2. Electrochemical properties of polypyrrole/polyfuran polymer composite electrode

    International Nuclear Information System (INIS)

    Cha, Seong Keuck

    1998-01-01

    Poly pyrrole polymer(ppy) has an excellent electrical conductivity and can be easily polymerized on anode to give various morphology according to doped anion on electroactive sites. To improve the properties of brittleness, ageing and hydrophobicity, poly furan polymer(pfu) having a high initiation potential was anodically implanted in this porous ppy film matrix to get the Pt/ppy/pfu(x)type of polymer campsite electrode. Cyclic voltammetry and electrochemical impedance methods were used to these electrode, where PF 6 - , BF 4 - , and ClO 4 - ions were employed as dopants. The composition of the pfu(x) at the electrode was changed from 0 to 1.10, but the range was useful only at 0.1 to 0.2 as the redox electrode. The polymer composite electrode doped with PF 6 - was better in charge transfer resistance by a factor of 40 times and in double layer capacitance by a factor of 20 times than others. The charge transfer in the polymer film of the electrode was influenced on frequency change and equivalent circuit of this electrode had Warburg impedance including mass transfer

  3. Photoluminescent and biodegradable polycitrate-polyethylene glycol-polyethyleneimine polymers as highly biocompatible and efficient vectors for bioimaging-guided siRNA and miRNA delivery.

    Science.gov (United States)

    Wang, Min; Guo, Yi; Yu, Meng; Ma, Peter X; Mao, Cong; Lei, Bo

    2017-05-01

    Development of biodegradable and biocompatible non-viral vectors with intrinsical multifunctional properties such as bioimaging ability for highly efficient nucleic acids delivery still remains a challenge. Here, a biodegradable poly (1,8-octanedio-citric acid)-co-polyethylene glycol grafted with polyethyleneimine (PEI) (POCG-PEI) polymers with the photoluminescent capacity were synthesized for nucleic acids delivery (siRNA and miRNA). POCG-PEI polymers can efficiently bind various nucleic acids, protect them against enzymatic degradation and release the genes in the presence of polyanionic heparin. POCG-PEI also showed a significantly low cytotoxicity, enhanced cellular uptake and high transfection efficiency of nucleic acids, as compared to commercial transfection agents, lipofectamine 2000 (Lipo) and polyethylenimine (PEI 25K). POCG-PEI polymers demonstrate an excellent photostability, which allows for imaging the cells and real-time tracking the nucleic acids delivery. The photoluminescent property, low cytotoxicity, biodegradation, good gene binding and protection ability and high genes delivery efficiency make POCG-PEI highly competitive as a non-virus vector for genes delivery and real-time bioimaging applications. Our results may be also an important step for designing biodegradable biomaterials with multifunctional properties towards bioimaging-guided genes therapeutic applications. Here, a biodegradable poly (1,8-octanedio-citric acid)-co-polyethylene glycol grafted with polyethyleneimine (PEI) (POCG-PEI) polymers with controlled photoluminescent capacity were synthesized for nucleic acids delivery (siRNA and miRNA). POCG-PEI polymers can efficiently bind various nucleic acids, protect them against enzymatic degradation and release the genes in the presence of polyanionic heparin. POCG-PEI also showed a significantly low cytotoxicity, enhanced cellular uptake and high transfection efficiency of nucleic acids, as compared to commercial transfection agents

  4. Composite Polymer Electrolytes: Nanoparticles Affect Structure and Properties

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2016-11-01

    Full Text Available Composite polymer electrolytes (CPEs can significantly improve the performance in electrochemical devices such as lithium-ion batteries. This review summarizes property/performance relationships in the case where nanoparticles are introduced to polymer electrolytes. It is the aim of this review to provide a knowledge network that elucidates the role of nano-additives in the CPEs. Central to the discussion is the impact on the CPE performance of properties such as crystalline/amorphous structure, dielectric behavior, and interactions within the CPE. The amorphous domains of semi-crystalline polymer facilitate the ion transport, while an enhanced mobility of polymer chains contributes to high ionic conductivity. Dielectric properties reflect the relaxation behavior of polymer chains as an important factor in ion conduction. Further, the dielectric constant (ε determines the capability of the polymer to dissolve salt. The atom/ion/nanoparticle interactions within CPEs suggest ways to enhance the CPE conductivity by generating more free lithium ions. Certain properties can be improved simultaneously by nanoparticle addition in order to optimize the overall performance of the electrolyte. The effects of nano-additives on thermal and mechanical properties of CPEs are also presented in order to evaluate the electrolyte competence for lithium-ion battery applications.

  5. Sensing and Energy Harvesting Novel Polymer Composites

    NARCIS (Netherlands)

    Zwaag, S. van der; Ende, D.A. van der; Groen, W.A.

    2014-01-01

    This chapter describes the development and properties of novel functional composite materials consisting of aligned piezo-ceramic particles or fibers in a polymeric matrix, which can be fully integrated in thermoset or thermoplastic products. The materials have a low potential for applications

  6. Characterization of piezoelectric polymer composites for MEMS ...

    Indian Academy of Sciences (India)

    Abstract. Composite piezoelectric ceramics are important materials for transducer applications in medical diag- nostic devices and MEMS devices. In micrometer scale the material properties of piezopolymers or piezoceramics do not coincide with that of bulk materials. The present work is aimed at simulating the material ...

  7. Additive Manufacturing of Ultem Polymers and Composites

    Science.gov (United States)

    Chuang, Kathy C.; Grady, Joseph E.; Draper, Robert D.; Shin, Euy-Sik E.; Patterson, Clark; Santelle, Thomas D.

    2015-01-01

    The objective of this project was to conduct additive manufacturing to produce aircraft engine components by Fused Deposition Modeling (FDM), using commercially available polyetherimdes Ultem 9085 and experimental Ultem 1000 filled with 10 chopped carbon fiber. A property comparison between FDM-printed and injection molded coupons for Ultem 9085, Ultem 1000 resin and the fiber-filled composite Ultem 1000 was carried out. Furthermore, an acoustic liner was printed from Ultem 9085 simulating conventional honeycomb structured liners and tested in a wind tunnel. Composite compressor inlet guide vanes were also printed using fiber-filled Ultem 1000 filaments and tested in a cascade rig. The fiber-filled Ultem 1000 filaments and composite vanes were characterized by scanning electron microscope (SEM) and acid digestion to determine the porosity of FDM-printed articles which ranged from 25-31. Coupons of Ultem 9085, experimental Ultem 1000 composites and XH6050 resin were tested at room temperature and 400F to evaluate their corresponding mechanical properties.

  8. Nanomodified polymer composites: Thermophysical and physico-mechanical properties

    Science.gov (United States)

    Shchegolkov, Alexander; Shchegolkov, Alexey; Dyachkova, Tatyana; Borovskikh, Pavel

    2017-11-01

    The paper presents the results of investigation of thermophysical and physicomechanical properties of polymer-based composites modified with paraffin and carbon nanotubes (CNTs) mixture. Thermal conductivity of composites based on polyethylene, fluoroplastic, polyvinyl chloride (PVC) is 0.48, 0.42 and 0.36 W/(m.°C), respectively, compared to thermal conductivity of pure paraffin - 0.25 W/(m.°C). It has been revealed that for materials heat capacity the polymer matrix determines the position of the maximum point on temperature dependence having extreme nature. Temperature changes in composites volume do not exceed 3% from the initial state to the phase transition, that allows them to be used in a combination with other materials.

  9. Improvement of acoustical characteristics : wideband bamboo based polymer composite

    Science.gov (United States)

    Farid, M.; Purniawan, A.; Rasyida, A.; Ramadhani, M.; Komariyah, S.

    2017-07-01

    Environmental friendly and comfortable materials are desirable for applications in the automobile interior. The objective of this research was to examine and develop bamboo based polymer composites applied to the sound absorption materials of automobile door panels. Morphological analysis of the polyurethane/bamboo powder composite materials was carried out using scanning electron microscope to reveal the microscopic material behavior and followed by the FTIR and TGA testing. The finding demonstrated that this acoustical polymer composite materials provided a potential wideband sound absorption material. The range of frequency can be controlled between 500 and 4000 Hz with an average of sound absorption coefficient around 0.411 and it met to the door panels criteria.

  10. Biodegradable nanofibers-reinforced microfibrous composite scaffolds for bone tissue engineering.

    Science.gov (United States)

    Martins, Albino; Pinho, Elisabete D; Correlo, Vítor M; Faria, Susana; Marques, Alexandra P; Reis, Rui L; Neves, Nuno M

    2010-12-01

    Native bone extracellular matrix (ECM) is a complex hierarchical fibrous composite structure, resulting from the assembling of collagen fibrils at several length scales, ranging from the macro to the nanoscale. The combination of nanofibers within microfibers after conventional reinforcement methodologies seems to be a feasible solution to the rational design of highly functional synthetic ECM substitutes. The present work aims at the development of bone ECM inspired structures, conjugating electrospun chitosan (Cht) nanofibers within biodegradable polymeric microfibers [poly(butylene succinate)-PBS and PBS/Cht], assembled in a fiber mesh structure. The nanofibers-reinforced composite fiber mesh scaffolds were seeded with human bone marrow mesenchymal stem cells (hBMSCs) and cultured under osteogenic differentiation conditions. These nanofibers-reinforced composite scaffolds sustained ECM deposition and mineralization, mainly in the PBS/Cht-based fiber meshes, as depicted by the increased amount of calcium phosphates produced by the osteogenic differentiated hBMSCs. The osteogenic genotype of the cultured hBMSCs was confirmed by the expression of osteoblastic genes, namely Alkaline Phosphatase, Osteopontin, Bone Sialoprotein and Osteocalcin, and the transcription factors Runx2 and Osterix, all involved in different stages of the osteogenesis. These data represent the first report on the biological functionality of nanofibers-reinforced composite scaffolds, envisaging the applicability of the developed structures for bone tissue engineering.

  11. Thermoresistive mechanisms of carbon nanotube/polymer composites

    Science.gov (United States)

    Cen-Puc, M.; Oliva-Avilés, A. I.; Avilés, F.

    2018-01-01

    The mechanisms governing thermoresistivity of carbon nanotube (CNT)/polymer composites are theoretically and experimentally investigated. Two modeling approaches are proposed to this aim considering a broad range of CNT concentrations (0.5-50 wt%). In the first model, thermal expansion of the polymer composite is predicted using a finite element model; the resulting CNT-to-CNT separation distance feeds a classical tunneling model to predict the dependence of the electrical resistance with temperature. The second approach uses the general effective medium considering the dilution of the CNT volume fraction due to the thermal expansion of the polymer. Both models predict that the electrical resistance increases with increased temperature (i.e. a positive temperature coefficient of resistance, TCR) for all investigated CNT concentrations, with higher TCRs for lower CNT concentrations. Comparison between modeling outcomes and experimental data suggests that polymer thermal expansion (and tunneling) play a dominant role for low CNT concentrations (≤ 10 wt%) heated above room temperature. On the other hand, for composites at high CNT concentrations (50 wt%) or for freezing temperatures (-110 °C), a negative TCR was experimentally obtained, suggesting that for those conditions the CNT intrinsic thermoresistivity and the electronic conduction between CNTs by thermal activation may play a paramount role.

  12. RF electromagnetic wave absorbing properties of ferrite polymer composite materials

    International Nuclear Information System (INIS)

    Dosoudil, Rastislav; Usakova, Marianna; Franek, Jaroslav; Slama, Jozef; Olah, Vladimir

    2006-01-01

    The frequency dispersion of complex initial (relative) permeability (μ * =μ ' -jμ ' ') and the electromagnetic wave absorbing properties of composite materials based on NiZn sintered ferrite and a polyvinylchloride (PVC) polymer matrix have been studied in frequency range from 1MHz to 1GHz. The complex permeability of the composites was found to increase as the ferrite content increased, and was characterized by frequency dispersion localized above 50MHz. The variation of return loss (RL) of single-layer RF absorbers using the prepared composite materials has been investigated as a function of frequency, ferrite content and the thickness of the absorbers

  13. Tridimensional ionic polymer metal composites: optimization of the manufacturing techniques

    International Nuclear Information System (INIS)

    Bonomo, C; Brunetto, P; Fortuna, L; Graziani, S; Bottino, M; Di Pasquale, G; Pollicino, A

    2010-01-01

    Ionic polymer metal composites (IPMCs) belong to electroactive polymers (EAPs) and have been suggested for various applications due to their light weight and to the fact that they react mechanically when stimulated by an electrical signal and vice versa. Thick IPMCs (3D-IPMCs) have been fabricated by hot pressing several Nafion ® 117 films. Additional post-processes (more cycles of Pt electroless plating and dispersing agents) have been applied to improve the 3D-IPMC performance. The electromechanical response of 3D-IPMCs has been examined by applying electrical signals and measuring the displacement and blocking force produced

  14. Dispersion and alignment of carbon nanotubes in polymer based composites

    Science.gov (United States)

    Camponeschi, Erin Lynn

    This research is intended to create usable carbon nanotube polymer based composites for structural applications by effectively aligning and dispersing the carbon nanotubes in a polymer matrix. The motivation for this research is to create very lightweight, high strength materials that will surpass their predecessors: carbon fibers. The final product then can be used in applications across the industries. This research determined the effect of three different surface-active agents and two different aligning methods on the structural features and mechanical properties of the polymer-based composite. The three types of surface-active agents used in this research are a surfactant and two different block copolymers. From this research, it will be determined how different surface-active agents adequately disperse the carbon nanotube, and the effects the dispersing agent have on a final dispersed product. In addition, the dispersing agent effects on the alignment of the carbon nanotubes and the final product can be compared. The two alignment techniques used in this research were alignment via shear flow and tethering iron oxide particles to the carbon nanotubes to induce alignment in a magnetic field. The method of shear aligning carbon nanotubes is very simplistic in theory, but actual application becomes much more challenging. This research illustrates the effects on shear alignment in a viscous polymer flow and then applies those theories to polymers. This work then compares the different alignment techniques to determine the overall increase of properties and the effective carbon nanotube alignment. This research provides a framework for the creation of dispersed and aligned composites that can be expanded upon and improved to further develop the carbon nanotubes as possible replacement fillers for composite materials.

  15. Novel meloxicam releasing electrospun polymer/ceramic reinforced biodegradable membranes for periodontal regeneration applications

    International Nuclear Information System (INIS)

    Yar, Muhammad; Farooq, Ariba; Shahzadi, Lubna; Khan, Abdul Samad; Mahmood, Nasir; Rauf, Abdul; Chaudhry, Aqif Anwar; Rehman, Ihtesham ur

    2016-01-01

    Periodontal disease is associated with the destruction of periodontal tissues, along with other disorders/problems including inflammation of tissues and severe pain. This paper reports the synthesis of meloxicam (MX) immobilized biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) based electrospun (e-spun) fibers and films. Electrospinning was employed to produce drug loaded fibrous mats, whereas films were generated by solvent casting method. In-vitro drug release from materials containing varying concentrations of MX revealed that the scaffolds containing higher amount of drug showed comparatively faster release. During initial first few hours fast release was noted from membranes and films; however after around 5 h sustained release was achieved. The hydrogels showed good swelling property, which is highly desired for soft tissue engineered implants. To investigate the biocompatibility of our synthesized materials, VERO cells (epithelial cells) were selected and cell culture results showed that these all materials were non-cytotoxic and also these cells were very well proliferated on these synthesized scaffolds. These properties along with the anti-inflammatory potential of our fabricated materials suggest their effective utilization in periodontital treatments. - Highlights: • NSAIDs releasing scaffolds for periodontal regeneration applications • Meloxicam immobilized biodegradable nanocomposite electrospun membranes and films • Good swelling properties • Controlled drug release • VERO cells were very well proliferated and synthesized materials were found to be non-cytotoxic.

  16. Novel meloxicam releasing electrospun polymer/ceramic reinforced biodegradable membranes for periodontal regeneration applications

    Energy Technology Data Exchange (ETDEWEB)

    Yar, Muhammad, E-mail: drmyar@ciitlahore.edu.pk [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Farooq, Ariba [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Shahzadi, Lubna; Khan, Abdul Samad [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Mahmood, Nasir [Department of Allied Health Sciences and Chemical Pathology, Department of Human Genetics and Molecular Biology, University of Health Sciences, Lahore (Pakistan); Rauf, Abdul [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Chaudhry, Aqif Anwar [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Rehman, Ihtesham ur [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Materials Science and Engineering, The Kroto Research Institute, The University of Sheffield, North Campus, Broad Lane, Sheffield S3 7HQ (United Kingdom)

    2016-07-01

    Periodontal disease is associated with the destruction of periodontal tissues, along with other disorders/problems including inflammation of tissues and severe pain. This paper reports the synthesis of meloxicam (MX) immobilized biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) based electrospun (e-spun) fibers and films. Electrospinning was employed to produce drug loaded fibrous mats, whereas films were generated by solvent casting method. In-vitro drug release from materials containing varying concentrations of MX revealed that the scaffolds containing higher amount of drug showed comparatively faster release. During initial first few hours fast release was noted from membranes and films; however after around 5 h sustained release was achieved. The hydrogels showed good swelling property, which is highly desired for soft tissue engineered implants. To investigate the biocompatibility of our synthesized materials, VERO cells (epithelial cells) were selected and cell culture results showed that these all materials were non-cytotoxic and also these cells were very well proliferated on these synthesized scaffolds. These properties along with the anti-inflammatory potential of our fabricated materials suggest their effective utilization in periodontital treatments. - Highlights: • NSAIDs releasing scaffolds for periodontal regeneration applications • Meloxicam immobilized biodegradable nanocomposite electrospun membranes and films • Good swelling properties • Controlled drug release • VERO cells were very well proliferated and synthesized materials were found to be non-cytotoxic.

  17. Effects of Temperature on Dynamic Properties of a Biodegradable Polymer Made from Corn Starch

    Science.gov (United States)

    Nishida, Masahiro; Ito, Noriomi; Kawase, Hiroyuki; Tanaka, Koichi

    The effect of strain rate on compressive properties of starch-based biodegradable plastics (Nihon Cornstarch Co., CPR-M2) was examined. Dynamic stress-strain curves of starch-based biodegradable plastics were measured over a wide range of strain rates from 10-5 s-1 to 104 s-1, using a quasi-static compression testing machine and a split Hopkinson pressure bar (SHPB) system. The strain rate slightly affected Young's modulus and considerably increased 7% flow stress. Empirical equation for 7% flow stress was derived for the strain rates from 10-5 s-1 to 104 s-1. In addition, the effect of temperature on Young's modulus and flow stress was also examined in a range from 4°C to 63°C. A master curve of 7% flow stress, reduced to 24°C, was made. The values of activation energies related to the α and β relaxation processes were respectively estimated from the master curve of 7% flow stress and from the best fit of equations based on Ree-Eyring theory and Bauwens' treatment. Temperature measurement of specimens was also made using thermocouples during dynamic compression.

  18. A Biodegradable Thermoset Polymer Made by Esterification of Citric Acid and Glycerol

    Science.gov (United States)

    Halpern, Jeffrey M.; Urbanski, Richard; Weinstock, Allison K.; Iwig, David F.; Mathers, Robert T.; von Recum, Horst

    2014-01-01

    A new biomaterial, a degradable thermoset polymer, was made from simple, economical, biocompatable monomers without the need for a catalyst. Glycerol and citric acid, non-toxic and renewable reagents, were crosslinked by a melt polymerization reaction at temperatures from 90-150°C. Consistent with a condensation reaction, water was determined to be the primary byproduct. The amount of crosslinking was controlled by the reaction conditions, including temperature, reaction time, and ratio between glycerol and citric acid. Also, the amount of crosslinking was inversely proportional to the rate of degradation. As a proof-of-principle for drug delivery applications, gentamicin, an antibiotic, was incorporated into the polymer with preliminary evaluations of antimicrobial activity. The polymers incorporating gentamicin had significantly better bacteria clearing of Staphylococcus aureus compared to non-gentamicin gels for up to nine days. PMID:23737239

  19. Enhancement of the optical properties of a new radiochromic dosimeter based on aliphatic-aromatic biodegradable polymers

    Energy Technology Data Exchange (ETDEWEB)

    Schimitberger, Thiago, E-mail: tschimitberger@ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Escola de Engenharia. Departamento de Engenharia Nuclear; Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    The development of a dosimeter that is of low cost, easy to process without dependence on expensive complex instruments and environment friendly is a challenging in irradiation quality control. Recently, an aliphatic-aromatic biodegradable polymer has been proposed as radiochromic dosimeter. The dosimeter is based on biodegradable poly(butylene adipate-co-terephthalate) copolymers (PBAT). In order to improve the photoluminescence (PL) properties of PBAT, increasing its range of applicability (50 kGy to 1000 kGy), this work investigates the influence of solution concentration in the dose response. Films with thickness of c.a. 80 μm were produce by wirebar coating, a simple deposition method for preparing large areas of organic films at low cost. The irradiation of samples was performed at room temperature using a Co-60 source at dose rate of 20 kGy/h. The films were exposed to doses ranging from 501 kGy to 1000 kGy. A 405 nm LED light source was used to excite the films. The USB2000 spectrometer made by Ocean Optics was used to collect the emission spectra of the luminescent films. The photoluminescent intensity captured by the spectrometer present linear radiation dose dependence. The maximum PL for the film sample made from a 0.05 g.mL{sup -1} solution is 1.5 (a.u.) while it is about 3.5 (a.u.) for a film sample made from a 0.2 mg.mL{sup -1} solution, when irradiated with 1000 kGy. These results indicate that PBAT films have great potential to be used as a high gamma dose radiochromic dosimeter over a wide dose range, expanding its applicability for different radiations process. (author)

  20. Control of enzymatic degradation of biodegradable polymers by treatment with biosurfactants, mannosylerythritol lipids, derived from Pseudozyma spp. yeast strains.

    Science.gov (United States)

    Fukuoka, Tokuma; Shinozaki, Yukiko; Tsuchiya, Wataru; Suzuki, Ken; Watanabe, Takashi; Yamazaki, Toshimasa; Kitamoto, Dai; Kitamoto, Hiroko

    2016-02-01

    Cutinase-like esterase from the yeasts Pseudozyma antarctica (PaE) shows strong degradation activity in an agricultural biodegradable plastic (BP) model of mulch films composed of poly(butylene succinate-co-adipate) (PBSA). P. antarctica is known to abundantly produce a glycolipid biosurfactant, mannosylerythritol lipid (MEL). Here, the effects of MEL on PaE-catalyzed degradation of BPs were investigated. Based on PBSA dispersion solution, the degradation of PBSA particles by PaE was inhibited in the presence of MEL. MEL behavior on BP substrates was monitored by surface plasmon resonance (SPR) using a sensor chip coated with polymer films. The positive SPR signal shift indicated that MEL readily adsorbed and spread onto the surface of a BP film. The amount of BP degradation by PaE was monitored based on the negative SPR signal shift and was decreased 1.7-fold by MEL pretreatment. Furthermore, the shape of PBSA mulch films in PaE-containing solution was maintained with MEL pretreatment, whereas untreated films were almost completely degraded and dissolved. These results suggest that MEL covering the surface of BP film inhibits adsorption of PaE and PaE-catalyzed degradation of BPs. We applied the above results to control the microbial degradation of BP mulch films. MEL pretreatment significantly inhibited BP mulch film degradation by both PaE solution and BP-degradable microorganism. Moreover, the degradation of these films was recovered after removal of the coated MEL by ethanol treatment. These results demonstrate that the biodegradation of BP films can be readily and reversibly controlled by a physical approach using MEL.

  1. Honeycomb structural composite polymer network of gelatin and functional cellulose ester for controlled release of omeprazole.

    Science.gov (United States)

    Zhuang, Chen; Shi, Chengmei; Tao, Furong; Cui, Yuezhi

    2017-12-01

    The functionalized cellulose ester MCN was firstly synthesized and used to cross-link gelatin by amidation between -NH 2 in gelatin and active ester groups in MCN to form a composite polymer network Gel-MCN, which was confirmed by Van Slyke method, FTIR, XRD and TGA-DTG spectra. The model drug omeprazole was loaded in Gel-MCN composites mainly by electrostatic interaction and hydrogen bonds, which were certified by FTIR, XRD and TGA-DSC. Thermal stability, anti-biodegradability, mechanical property and surface hydrophobicity of the composites with different cross-linking extents and drug loading were systematically investigated. SEM images demonstrated the honeycomb structural cells of cross-linked gelatin networks and this ensured drug entrapment. The drug release mechanism was dominated by a combined effect of diffusion and degradation, and the release rate decreased with cross-linking degree increased. The developed drug delivery system had profound significance in improving pesticide effect and bioavailability of drugs. Copyright © 2017. Published by Elsevier B.V.

  2. Polímeros biodegradáveis - uma solução parcial para diminuir a quantidade dos resíduos plásticos Biodegradable polymers - a partial way for decreasing the amount of plastic waste

    Directory of Open Access Journals (Sweden)

    Sandra Mara Martins Franchetti

    2006-07-01

    Full Text Available The large use of plastics has generated a waste deposit problem. Today plastic wastes represent 20% in volume of the total waste in the municipal landfills. To solve the disposal problem of plastics methods have been employed such as incineration, recycling, landfill disposal, biodegradation and the use of biodegradable polymers. Incineration of plastic wastes provokes pollution due to the production of poisonous gases. Recycling is important to reduce final costs of plastic materials, but is not enough in face of the amount of discarded plastic. In landfills plastic wastes remain undegraded for a long time, causing space and pollution problems. Biodegradation is a feasible method to treat some plastics, but intensive research is necessary to find conditions for the action of microorganisms. All of these methods are important and the practical application of each one depends on the type and amount of the plastic wastes and the environmental conditions. Therefore, a great deal of research has focused on developing biodegradable plastics and its application because it is an important way for minimizing the effect of the large volume of plastic waste discarded in the world.

  3. Nanostructures on spin-coated polymer films controlled by solvent composition and polymer molecular weight

    Energy Technology Data Exchange (ETDEWEB)

    Dario, Aline F.; Macia, Henrique B.; Petri, Denise F.S., E-mail: dfsp@iq.usp.br

    2012-12-01

    In this study we systematically investigated how the solvent composition used for polymer dissolution affects the porous structures of spin-coated polymers films. Cellulose acetate butyrate (CAB) and poly(methyl methacrylate) with low (PMMA-L) and high (PMMA-H) molecular weights were dissolved in mixtures of acetone (AC) and ethyl acetate (EA) at constant polymer concentration of 10 g/L The films were spin-coated at a relative air humidity of 55 {+-} 5%, their thickness and index of refraction were determined by means of ellipsometry and their morphology was analyzed by atomic force microscopy. The dimensions and frequency of nanocavities on polymer films increased with the acetone content ({phi}{sub AC}) in the solvent mixture and decreased with increasing polymer molecular weight. Consequently, as the void content increased in the films, their apparent thicknesses increased and their indices of refraction decreased, creating low-cost anti-reflection surface. The void depth was larger for PMMA-L than for CAB. This effect was attributed to different activities of EA and AC in CAB or PMMA-L solution, the larger mobility of chains and the lower polarity of PMMA-L in comparison to CAB. - Highlights: Black-Right-Pointing-Pointer Nanostructures in spin-coated polymer films depend on the solvent vapor pressure. Black-Right-Pointing-Pointer Anti-reflection polymer films are produced at high solvent vapor pressure. Black-Right-Pointing-Pointer Only shallow cavities are obtained in films of polymers with high molecular weight.

  4. Smart conducting polymer composites having zero temperature coefficient of resistance

    Science.gov (United States)

    Chu, Kunmo; Lee, Sung-Chul; Lee, Sangeui; Kim, Dongearn; Moon, Changyoul; Park, Sung-Hoon

    2014-12-01

    Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compounds; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either a negative (NTC) or a positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we developed a hybrid conducting zero-TCR composite having self-heating properties for thermal stability and reliable temperature control. The bi-layer composites consisted of a carbon nanotube (CNT)-based layer having an NTC of resistance and a carbon black (CB)-based layer having a PTC of resistance which was in direct contact with electrodes to stabilize the electrical resistance change during electric Joule heating. The composite showed nearly constant resistance values with less than 2% deviation of the normalized resistance until 200 °C. The CB layer worked both as a buffer and as a distributor layer against the current flow from an applied voltage. This behavior, which was confirmed both experimentally and theoretically, has been rarely reported for polymer-based composite systems.Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compounds; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either a negative (NTC) or a positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we developed a hybrid conducting zero-TCR composite having self

  5. Nanoporous materials modified with biodegradable polymers as models for drug delivery applications.

    Science.gov (United States)

    Gruber, Mathias F; Schulte, Lars; Ndoni, Sokol

    2013-04-01

    Polymers play a central role in the development of carriers for diagnostic and therapeutic agents. Especially the use of either degradable polymers or porous materials to encapsulate drug compounds in order to obtain steady drug release profiles has received much attention. We present here a proof of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model. Rhodamine 6G (R6G) mixed with Poly(L-Lactic Acid) (PLLA) were confined within the 14 nm pores of a NP with gyroid morphology derived from a diblock copolymer precursor. Glass transition, crystallization and melting of free and confined PLLA were monitored by differential scanning calorimetry. Release profiles for R6G were measured in methanol-water solvents at pH 13, which works as an accelerated release test by speeding up the hydrolysis of PLLA. The obtained release profiles demonstrate that the degradation of PLLA in nanoporous confinement is significantly slower than the degradation of unconfined PLLA. The release of R6G encapsulated in PLLA becomes correspondingly slower, while the initial burst release virtually disappears. These findings suggest that the presented proof of principle constitutes a promising basis for the development of novel implantable drug delivery systems. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Tissue ingrowth and degradation of two biodegradable porous polymers with different porosities and pore sizes.

    NARCIS (Netherlands)

    Tienen, T. van; Heijkants, R.G.J.C.; Buma, P.; Groot, J.H. de; Pennings, A.J.; Veth, R.P.H.

    2002-01-01

    Commonly, spontaneous repair of lesions in the avascular zone of the knee meniscus does not occur. By implanting a porous polymer scaffold in a knee meniscus defect, the lesion is connected with the abundantly vascularized knee capsule and healing can be realized. Ingrowth of fibrovascular tissue

  7. Tissue ingrowth polymers and degradation of two biodegradable porous with different porosities and pore sizes

    NARCIS (Netherlands)

    van Tienen, TG; Heijkants, RGJC; Buma, P; de Groot, JH; Pennings, AJ; Veth, RPH

    Commonly, spontaneous repair of lesions in the avascular zone of the knee meniscus does not occur. By implanting a porous polymer scaffold in a knee meniscus defect, the lesion is connected with the abundantly vascularized knee capsule and heating can be realized. Ingrowth of fibrovascular tissue

  8. Self-healing polymer cement composites for geothermal wellbore applications

    Science.gov (United States)

    Rod, K. A.; Fernandez, C.; Childers, I.; Koech, P.; Um, W.; Roosendaal, T.; Nguyen, M.; Huerta, N. J.; Chun, J.; Glezakou, V. A.

    2017-12-01

    Cement is vital for controlling leaks from wellbores employed in oil, gas, and geothermal operations by sealing the annulus between the wellbore casing and geologic formation. Wellbore cement failure due to physical and chemical stresses is common and can result in significant environmental consequences and ultimately significant financial costs due to remediation efforts. To date numerous alternative cement blends have been proposed for the oil and gas industry. Most of these possess poor mechanical properties, or are not designed to work in high temperature environments. This research investigates novel polymer-cement composites which could function at most geothermal temperatures. Thermal stability and mechanical strength of the polymer is attributed to the formation of a number of chemical interactions between the polymer and cement matrix including covalent bonds, hydrogen bonding, and van der Waals interactions. It has been demonstrated that the bonding between cement and casing is more predictable when polymer is added to cement and can even improve healing of adhesion break when subjected to stresses such as thermal shock. Fractures have also been healed, effectively reducing permeability with fractures up to 0.3-0.5mm apertures, which is two orders of magnitude larger than typical wellbore fractures. Additionally, tomography analysis was used to determine internal structure of the cement polymer composite and imaging reveals that polymers fill fractures in the cement and between the cement and casing. By plugging fractures that occur in wellbore cement, reducing permeability of fractures, both environmental safety and economics of subsurface operations will be improved for geothermal energy and oil and gas production.

  9. Thermosetting Polymer-Matrix Composites for Strucutral Repair Applications

    Energy Technology Data Exchange (ETDEWEB)

    Goertzen, William Kirby [Iowa State Univ., Ames, IA (United States)

    2007-12-01

    Several classes of thermosetting polymer matrix composites were evaluated for use in structural repair applications. Initial work involved the characterization and evaluation of woven carbon fiber/epoxy matrix composites for structural pipeline repair. Cyanate ester resins were evaluated as a replacement for epoxy in composites for high-temperature pipe repair applications, and as the basis for adhesives for resin infusion repair of high-temperature composite materials. Carbon fiber/cyanate ester matrix composites and fumed silica/cyanate ester nanocomposites were evaluated for their thermal, mechanical, viscoelastic, and rheological properties as they relate to their structure, chemistry, and processing characteristics. The bisphenol E cyanate ester under investigation possesses a high glass transition temperature, excellent mechanical properties, and unique ambient temperature processability. The incorporate of fumed silica served to enhance the mechanical and rheological properties of the polymer and reduce thermal expansion without sacrificing glass transition or drastically altering curing kinetics. Characterization of the composites included dynamic mechanical analysis, thermomechanical analysis, differential scanning calorimetry, thermogravimetric analysis, rheological and rheokinetic evaluation, and transmission electron microscopy.

  10. Thermosetting polymer-matrix composites for structural repair applications

    Science.gov (United States)

    Goertzen, William Kirby

    2007-12-01

    Several classes of thermosetting polymer matrix composites were evaluated for use in structural repair applications. Initial work involved the characterization and evaluation of woven carbon fiber/epoxy matrix composites for structural pipeline repair. Cyanate ester resins were evaluated as a replacement for epoxy in composites for high-temperature pipe repair applications, and as the basis for adhesives for resin infusion repair of high-temperature composite materials. Carbon fiber/cyanate ester matrix composites and fumed silica/cyanate ester nanocomposites were evaluated for their thermal, mechanical, viscoelastic, and rheological properties as they relate to their structure, chemistry, and processing characteristics. The bisphenol E cyanate ester under investigation possesses a high glass transition temperature, excellent mechanical properties, and unique ambient temperature processability. The incorporation of fumed silica served to enhance the mechanical and rheological properties of the polymer and reduce thermal expansion without sacrificing glass transition or drastically altering curing kinetics. Characterization of the composites included dynamic mechanical analysis, thermomechanical analysis, differential scanning calorimetry, thermogravimetric analysis, rheological and rheokinetic evaluation, and transmission electron microscopy.

  11. New generation fiber reinforced polymer composites incorporating carbon nanotubes

    Science.gov (United States)

    Soliman, Eslam

    The last five decades observed an increasing use of fiber reinforced polymer (FRP) composites as alternative construction materials for aerospace and infrastructure. The high specific strength of FRP attracted its use as non-corrosive reinforcement. However, FRP materials were characterized with a relatively low ductility and low shear strength compared with steel reinforcement. On the other hand, carbon nanotubes (CNTs) have been introduced in the last decade as a material with minimal defect that is capable of increasing the mechanical properties of polymer matrices. This dissertation reports experimental investigations on the use of multi-walled carbon nanotubes (MWCNTs) to produce a new generation of FRP composites. The experiments showed significant improvements in the flexure properties of the nanocomposite when functionalized MWCNTs were used. In addition, MWCNTs were used to produce FRP composites in order to examine static, dynamic, and creep behavior. The MWCNTs improved the off-axis tension, off-axis flexure, FRP lap shear joint responses. In addition, they reduced the creep of FRP-concrete interface, enhanced the fracture toughness, and altered the impact resistance significantly. In general, the MWCNTs are found to affect the behaviour of the FRP composites when matrix failure dominates the behaviour. The improvement in the mechanical response with the addition of low contents of MWCNTs would benefit many industrial and military applications such as strengthening structures using FRP composites, composite pipelines, aircrafts, and armoured vehicles.

  12. Conducting polymer/carbon nanocoil composite electrodes for efficient supercapacitors

    KAUST Repository

    Baby, Rakhi Raghavan

    2012-01-01

    Herein, we report for the first time, conducting polymer (polyaniline (PANI) and polypyrrole (PPY)) coated carbon nanocoils (CNCs) as efficient binder-free electrode materials for supercapacitors. CNCs act as a perfect backbone for the uniform distribution of the conducting polymers in the composites. In two electrode configuration, the samples exhibited high specific capacitance with the values reaching up to 360 and 202 F g -1 for PANI/CNCs and PPY/CNCs respectively. The values obtained for specific capacitance and maximum storage energy per unit mass of the composites were found to be comparable to one of the best reported values for polymer coated multi-walled carbon nanotubes. In addition, the fabricated PANI/CNC based supercapacitors exhibited a high value of 44.61 Wh kg -1 for maximum storage energy per unit mass. Although the devices exhibit an initial capacitance loss due to the instability of the polymer, the specific capacitance stabilizes at a fixed value after 500 charge-discharge cycles. © 2012 The Royal Society of Chemistry.

  13. Nanocellulose in Polymer Composites and Biomedical: Research and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yuan [ORNL; Tekinalp, Halil L [ORNL; Peter, William H [ORNL; Eberle, Cliff [ORNL; Naskar, Amit K [ORNL; Ozcan, Soydan [ORNL

    2014-01-01

    Nanocellulose materials are nano-sized cellulose fibers or crystals that are produced by bacteria or derived from plants. These materials exhibit exceptional strength characteristics, light weight, transparency, and excellent biocompatibility. Compared to some other nanomaterials, nanocellulose is renewable and less expensive to produce. As such, a wide range of applications for nanocellulose has been envisioned. Most extensively studied areas include polymer composites and biomedical applications. Cellulose nanofibrils and nanocrystals have been used to reinforce both thermoplastic and thermoset polymers. Given the hydrophilic nature of these materials, the interfacial properties with most polymers are often poor. Various surface modification procedures have thus been adopted to improve the interaction between polymer matrix and cellulose nanofibrils or nanocrystals. In addition, the applications of nanocellulose as biomaterials have been explored including wound dressing, tissue repair, and medical implants. Nanocellulose materials for wound healing and periodontal tissue recovery have become commercially available, demonstrating the great potential of nanocellulose as a new generation of biomaterials. In this review, we highlight the applications of nanocellulose as reinforcing fillers for composites and the effect of surface modification on the mechanical properties as well as the application as biomaterials.

  14. High strength, biodegradable and cytocompatible alpha tricalcium phosphate-iron composites for temporal reduction of bone fractures.

    Science.gov (United States)

    Montufar, E B; Casas-Luna, M; Horynová, M; Tkachenko, S; Fohlerová, Z; Diaz-de-la-Torre, S; Dvořák, K; Čelko, L; Kaiser, J

    2018-04-01

    In this work alpha tricalcium phosphate (α-TCP)/iron (Fe) composites were developed as a new family of biodegradable, load-bearing and cytocompatible materials. The composites with composition from pure ceramic to pure metallic samples were consolidated by pulsed electric current assisted sintering to minimise processing time and temperature while improving their mechanical performance. The mechanical strength of the composites was increased and controlled with the Fe content, passing from brittle to ductile failure. In particular, the addition of 25 vol% of Fe produced a ceramic matrix composite with elastic modulus much closer to cortical bone than that of titanium or biodegradable magnesium alloys and specific compressive strength above that of stainless steel, chromium-cobalt alloys and pure titanium, currently used in clinic for internal fracture fixation. All the composites studied exhibited higher degradation rate than their individual components, presenting values around 200 μm/year, but also their compressive strength did not show a significant reduction in the period required for bone fracture consolidation. Composites showed preferential degradation of α-TCP areas rather than β-TCP areas, suggesting that α-TCP can produce composites with higher degradation rate. The composites were cytocompatible both in indirect and direct contact with bone cells. Osteoblast-like cells attached and spread on the surface of the composites, presenting proliferation rate similar to cells on tissue culture-grade polystyrene and they showed alkaline phosphatase activity. Therefore, this new family of composites is a potential alternative to produce implants for temporal reduction of bone fractures. Biodegradable alpha-tricalcium phosphate/iron (α-TCP/Fe) composites are promising candidates for the fabrication of temporal osteosynthesis devices. Similar to biodegradable metals, these composites can avoid implant removal after bone fracture healing, particularly in

  15. Cryogenic performance of single polymer polypropylene composites

    Science.gov (United States)

    Atli-Veltin, Bilim

    2018-03-01

    The main objective of the experimental study detailed in this paper is to investigate the performance of fully recyclable, lightweight, low-cost, thermoplastic Polypropylene (PP) composite tapes at low temperatures. Coupons made of [±45] and [0/90] laminates are subjected to tensile and 3-point bending tests at room temperature as well as at -196 °C. In addition to that, cryogenic low velocity impact tests at 268 J and 777 J impact energies are performed on tubular structures. The results are indicating that the laminates made of PP tapes have sufficient ductility for cryogenic applications. Low velocity impact tests showed that the viscoelastic behavior of the material is preserved, even at such low temperatures and more than 72% of impact energy is absorbed by the material.

  16. Study on the structure of pitch-polymer compositions by fluorescence microscope

    OpenAIRE

    Makomaski, Grzegorz

    2014-01-01

    In this work, the results of studies on the evaluation of colloidal structure of coal-tar pitch compositions with selected waste polymers by fluorescence microscope. For pitch-polymer compositions containing 10?50?wt% waste polymer, softening point, coking value and content of components insoluble in toluene and quinoline were carried out. The results indicate that pitch-polymer compositions can be treated as microheterogeneous systems, colloidal and biphase, generally exhibiting uniform disp...

  17. Polymer-Cement Composites Containing Waste Perlite Powder

    Directory of Open Access Journals (Sweden)

    Paweł Łukowski

    2016-10-01

    Full Text Available Polymer-cement composites (PCCs are materials in which the polymer and mineral binder create an interpenetrating network and co-operate, significantly improving the performance of the material. On the other hand, the need for the utilization of waste materials is a demand of sustainable construction. Various mineral powders, such as fly ash or blast-furnace slag, are successfully used for the production of cement and concrete. This paper deals with the use of perlite powder, which is a burdensome waste from the process of thermal expansion of the raw perlite, as a component of PCCs. The results of the testing of the mechanical properties of the composite and some microscopic observations are presented, indicating that there is a possibility to rationally and efficiently utilize waste perlite powder as a component of the PCC. This would lead to creating a new type of building material that successfully meets the requirements of sustainable construction.

  18. A novel use of bio-based natural fibers, polymers, and rubbers for composite materials

    Science.gov (United States)

    Modi, Sunny Jitendra

    The composites, materials, and packaging industries are searching for alternative materials to attain environmental sustainability. Bio-plastics are highly desired and current microbially-derived bio-plastics, such as PHA (poly-(hydroxy alkanoate)), PHB (poly-(hydroxybutyrate)), and PHBV (poly-(beta-hydroxy butyrate-co-valerate)) could be engineered to have similar properties to conventional thermoplastics. Poly-(hydroxybutyrate) (PHB) is a bio-degradable aliphatic polyester that is produced by a wide range of microorganisms. Basic PHB has relatively high glass transition and melting temperatures. To improve flexibility for potential packaging applications, PHB is synthesized with various co-polymers such as Poly-(3-hydroxyvalerate) (HV) to decrease the glass and melting temperatures and, since there is improved melt stability at lower processing temperatures, broaden the processing window. However, previous work has shown that this polymer is too brittle, temperature-sensitive, and hydrophilic to meet packaging material physical requirements. Therefore, the proposed work focuses on addressing the needs for bio-derived and bio-degradable materials by creating a range of composite materials using natural fibers as reinforcement agents in bio-polymers and bio- plastic-rubber matrices. The new materials should possess properties lacking in PHBV and broaden the processing capabilities, elasticity, and improve the mechanical properties. The first approach was to create novel composites using poly-(beta-hydroxy butyrate-co-valerate) (PHBV) combined with fibers from invasive plants such as common reed (Phragmites australis), reed canary grass (Phalaris arundinacea), and water celery ( Vallisneria americana). The composites were manufactured using traditional processing techniques of extrusion compounding followed by injection molding of ASTM type I parts. The effects of each bio-fiber at 2, 5, and 10% loading on the mechanical, morphological, rheological, and thermal

  19. Non-destructive inspection of polymer composite products

    Science.gov (United States)

    Anoshkin, A. N.; Sal’nikov, A. F.; Osokin, V. M.; Tretyakov, A. A.; Luzin, G. S.; Potrakhov, N. N.; Bessonov, V. B.

    2018-02-01

    The paper considers the main types of defects encountered in products made of polymer composite materials for aviation use. The analysis of existing methods of nondestructive testing is carried out, features of their application are considered taking into account design features, geometrical parameters and internal structure of objects of inspection. The advantages and disadvantages of the considered methods of nondestructive testing used in industrial production are shown.

  20. Electron Beam Curing of Polymer Matrix Composites - CRADA Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Janke, C. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Dave [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Norris, Robert E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    1997-05-01

    The major cost driver in manufacturing polymer matrix composite (PMC) parts and structures, and one of the elements having the greatest effect on their quality and performance, is the standard thermal cure process. Thermal curing of PMCs requires long cure times and high energy consumption, creates residual thermal stresses in the part, produces volatile toxic by-products, and requires expensive tooling that is tolerant of the high cure temperatures.

  1. A second-generation ionic liquid matrix-assisted laser desorption/ionization matrix for effective mass spectrometric analysis of biodegradable polymers.

    Science.gov (United States)

    Berthod, Alain; Crank, Jeffrey A; Rundlett, Kimber L; Armstrong, Daniel W

    2009-11-01

    A second generation ionic liquid matrix (ILM), N,N-diisopropylethylammonium alpha-cyano-4-hydroxycinnamate (DEA-CHCA), was developed for the characterization of polar biodegradable polymers. It is compared with five solid matrices typically used for the characterization of these polymers and one other new ILM. It is shown that use of the ILM, DEA-CHCA, allows maximum signal with minimum laser intensity which minimizes polymer degradation. In these conditions, the DEA-CHCA ILM is able to assist in the ionization of analytes in an efficient but soft manner. These qualities produce spectra that allow an accurate and sensitive determination of the number average molecular weights, weight average m.w., and polydispersity index of labile polar polymers. With such polymers, many solid matrices produce spectra showing extensive polymer degradation leading to the underestimation of molecular weights. The distribution of intact analyte peaks obtained with the ILM DEA-CHCA allows for identification of the fine structure of complex copolymers. ILMs were much less susceptible to effects of extraction delay times on molecular weight determination than were solid matrices. The liquid nature of the matrix is an important reason for the outstanding results obtained for labile analyte polymers. No comparable results could be obtained with any known solid matrices or other ILMs. In many cases, the manufacturers' listed molecular weights and polydispersity measurements for biodegradable polymers are determined by size-exclusion chromatography and the data obtained by that method may differ considerably from the high-precision matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) results presented here. Copyright 2009 John Wiley & Sons, Ltd.

  2. Development of modified release gliclazide biological macromolecules using natural biodegradable polymers.

    Science.gov (United States)

    Prajapati, Vipulkumar D; Mashru, Krupa H; Solanki, Himanshu K; Jani, Girish K

    2013-04-01

    Modified release biological macromolecules (beads) of gliclazide using sodium alginate combined with either gellan gum or pectin in different ratios were prepared by Ionotropic gelation method. Biological macromolecules were evaluated for different physico-chemical parameters. Increase in polymers proportion showed difficulty in production of biological macromolecules due to high viscosity of dispersion. As the polymer concentration increases, the swelling and entrapment efficiency of drug increased. Compared to all other batches and commercial modified release gliclazide tablet, formulated biological macromolecules of sodium alginate with pectin (2:1 ratio) and with gellan gum (6:0.75 ratio) exhibited spherical shape, biphasic in vitro release profile and initial high drug release followed by moderate release up to 12 h as matrix diffusion kinetics and Higuchi model as well as Korsmeyer model. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. [Biodegradable synthetic polymers for the design of implantable medical devices: the ligamentoplasty case].

    Science.gov (United States)

    Garric, Xavier; Nottelet, Benjamin; Pinese, Coline; Leroy, Adrien; Coudane, Jean

    2017-01-01

    The sector of implantable medical devices is a growing sector of health products especially dynamic in the field of research. To improve the management of patients and to meet clinical requirements, researchers are developing new types of medical devices. They use different families of biomaterials presenting various chemical and physical characteristics in order for providing clinicians with health products optimized for biomedical applications. In this article, we aim to show how, starting from a family of biomaterials (degradable polymers), it is possible to design an implantable medical device for the therapeutic management of the failure of anterior cruciate ligament. The main steps leading to the design of a total ligament reinforcement are detailed. They range from the synthesis and characterization of degradable polymer to the shaping of the knitted implant, through the assessment of the study of the impact of sterilization on mechanical properties and checking cytocompatibility. © 2017 médecine/sciences – Inserm.

  4. Effects of mechanical properties of polymer on ceramic-polymer composite thick films fabricated by aerosol deposition

    Science.gov (United States)

    Kwon, Oh-Yun; Na, Hyun-Jun; Kim, Hyung-Jun; Lee, Dong-Won; Nam, Song-Min

    2012-05-01

    Two types of ceramic-polymer composite thick films were deposited on Cu substrates by an aerosol deposition process, and their properties were investigated to fabricate optimized ceramic-based polymer composite thick films for application onto integrated substrates with the advantage of plasticity. When polymers with different mechanical properties, such as polyimide (PI) and poly(methyl methacrylate) (PMMA), are used as starting powders together with α-Al2O3 powder, two types of composite films are formed with different characteristics - surface morphologies, deposition rates, and crystallite size of α-Al2O3. Through the results of micro-Vickers hardness testing, it was confirmed that the mechanical properties of the polymer itself are associated with the performances of the ceramic-polymer composite films. To support and explain these results, the microstructures of the two types of polymer powders were observed after planetary milling and an additional modeling test was carried out. As a result, we could conclude that the PMMA powder is distorted by the impact of the Al2O3 powder, so that the resulting Al2O3-PMMA composite film had a very small amount of PMMA and a low deposition rate. In contrast, when using PI powder, the Al2O3-PI composite film had a high deposition rate due to the cracking of PI particles. Consequently, it was revealed that the mechanical properties of polymers have a considerable effect on the properties of the resulting ceramic-polymer composite thick films.

  5. Magnetoimpedance of cobalt-based amorphous ribbons/polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Semirov, A.V., E-mail: semirov@mail.ru [Irkutsk State University, Irkutsk (Russian Federation); Derevyanko, M.S.; Bukreev, D.A.; Moiseev, A.A.; Kudryavtsev, V.O. [Irkutsk State University, Irkutsk (Russian Federation); Safronov, A.P. [Ural Federal University, Yekaterinburg (Russian Federation)

    2016-10-01

    The combined influence of the temperature, the elastic tensile stress and the external magnetic field on the total impedance and impedance components were studied for rapidly quenched amorphous Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16} ribbons. Both as-cast amorphous ribbons and Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16}/polymer amorphous ribbon based composites were considered. Following polymer coverings were studied: modified rubber solution in o-xylene, solution of butyl methacrylate and methacrylic acid copolymer in isopropanol and solution of polymethylphenylsiloxane resin in toluene. All selected composites showed very good adhesion of the coverings and allowed to provide temperature measurements from 163 K up to 383 K under the applied deforming tensile force up to 30 N. The dependence of the modulus of the impedance and its components on the external magnetic field was influenced by the elastic tensile stresses and was affected by the temperature of the samples. It was shown that maximal sensitivity of the impedance and its components to the external magnetic field was observed at minimal temperature and maximal deforming force depended on the frequency of an alternating current. - Highlights: • Impedance and its components of amorphous Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16} ribbons were studied. • MI sensitivity to the magnetic field depends on a temperature and a deforming force. • Polymer covering can affect the functional properties of the composite.

  6. Application of atmospheric pressure plasma in polymer and composite adhesion

    Science.gov (United States)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  7. Effect of cross-linked biodegradable polymers on sustained release of sodium diclofenac-loaded microspheres

    Directory of Open Access Journals (Sweden)

    Avik Kumar Saha

    2013-12-01

    Full Text Available The objective of this study was to formulate an oral sustained release delivery system of sodium diclofenac(DS based on sodium alginate (SA as a hydrophilic carrier in combination with chitosan (CH and sodium carboxymethyl cellulose (SCMC as drug release modifiers to overcome the drug-related adverse effects and to improve bioavailability. Microspheres of DS were prepared using an easy method of ionotropic gelation. The prepared beads were evaluated for mean particle size, entrapment efficiency, swelling capacity, erosion and in-vitro drug release. They were also subjected to various studies such as Fourier Transform Infra-Red Spectroscopy (FTIR for drug polymer compatibility, Scanning Electron Microscopy for surface morphology, X-ray Powder Diffraction Analysis (XRD and Differential Scanning Calorimetric Analysis (DSC to determine the physical state of the drug in the beads. The addition of SCMC during the preparation of polymeric beads resulted in lower drug loading and prolonged release of the DS. The release profile of batches F5 and F6 showed a maximum drug release of 96.97 ± 0.356% after 8 h, in which drug polymer ratio was decreased. The microspheres of sodium diclofenac with the polymers were formulated successfully. Analysis of the release profiles showed that the data corresponds to the diffusion-controlled mechanism as suggested by Higuchi.

  8. An atomic finite element model for biodegradable polymers. Part 1. Formulation of the finite elements.

    Science.gov (United States)

    Gleadall, Andrew; Pan, Jingzhe; Ding, Lifeng; Kruft, Marc-Anton; Curcó, David

    2015-11-01

    Molecular dynamics (MD) simulations are widely used to analyse materials at the atomic scale. However, MD has high computational demands, which may inhibit its use for simulations of structures involving large numbers of atoms such as amorphous polymer structures. An atomic-scale finite element method (AFEM) is presented in this study with significantly lower computational demands than MD. Due to the reduced computational demands, AFEM is suitable for the analysis of Young's modulus of amorphous polymer structures. This is of particular interest when studying the degradation of bioresorbable polymers, which is the topic of an accompanying paper. AFEM is derived from the inter-atomic potential energy functions of an MD force field. The nonlinear MD functions were adapted to enable static linear analysis. Finite element formulations were derived to represent interatomic potential energy functions between two, three and four atoms. Validation of the AFEM was conducted through its application to atomic structures for crystalline and amorphous poly(lactide). Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Peculiarities of Shape Recovery in Polymer Composites with Compacting Filler

    Directory of Open Access Journals (Sweden)

    V. A. Beloshenko

    2011-01-01

    Full Text Available Peculiarities of the shape memory effect development in composites based on the epoxy polymer and various fillers, such as thermoexpanded graphite, aerosils, metallized graphite, and basalt flakes, have been investigated. It has been determined that straining followed by the shape recovery of composites is accompanied by changes in their volume. Extent and character of the changes depend on the ability of fillers to compaction under pressure, deformation scheme, adsorption ability of the filler. It is shown that the combined deformation consisting of compression and stretching of specimens in different sequence gives structural states for which the longitudinal strain-transverse strain ratio can take zero, positive, or negative values.

  10. A healable, semitransparent silver nanowire-polymer composite conductor.

    Science.gov (United States)

    Gong, Chaokun; Liang, Jiajie; Hu, Wei; Niu, Xiaofan; Ma, Sungwon; Hahn, H Thomas; Pei, Qibing

    2013-08-14

    A quick recovery: A semitransparent composite conductor comprising a layer of silver nanowire percolation network inlaid in the surface layer of a Diels-Alder-based healable polymer film is fabricated. The composite is flexible and highly conductive, and is capable of both structural and electrical healing via heating. Cut samples that completely lose their conductivity can recover 97% of it within 5 minutes of heating at 110 °C. The cutting and healing can be repeated at the same location for multiple cycles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Wood-Polymer composites obtained by gamma irradiation

    Science.gov (United States)

    Gago, J.; López, A.; Santiago, J.; Acevedo, M.; Rodríguez, J.

    2007-10-01

    In this work we impregnate three Peruvian woods (Calycophy spruceanum Be, Aniba amazonica Meiz and Hura crepitans L) with styrene-polyester resin and methyl methacrylate. The polymerization of the system was promoted by gamma radiation and the experimental optimal condition was obtained with styrene-polyester 1:1 and 15 kGy. The obtained composites show reduced water absorption and better mechanical properties compared to the original wood. The structure of the wood-polymer composites was studied by light microscopy. Water absorption and hardness were also obtained.

  12. Wood-Polymer composites obtained by gamma irradiation

    International Nuclear Information System (INIS)

    Gago, J.; Lopez, A.; Rodriguez, J.; Santiago, J.; Acevedo, M.

    2007-01-01

    In this work we impregnate three Peruvian woods (Calycophy spruceanum Be, Aniba amazonica Meiz and Hura crepitans L) with styrene-polyester resin and methyl methacrylate. The polymerization of the system was promoted by gamma radiation and the experimental optimal condition was obtained with styrene-polyester 1:1 and 15 kGy. The obtained composites show reduced water absorption and better mechanical properties compared to the original wood. The structure of the wood-polymer composites was studied by light microscopy. Water absorption and hardness were also obtained

  13. First-in-man randomised comparison of the BuMA Supreme biodegradable polymer sirolimus-eluting stent versus a durable polymer zotarolimus-eluting coronary stent: the PIONEER trial.

    Science.gov (United States)

    von Birgelen, Clemens; Asano, Taku; Amoroso, Giovanni; Aminian, Adel; Brugaletta, Salvatore; Vrolix, Mathias; Hernandez-Antolín, Rosana; van de Harst, Pim; Iñiguez, Andres; Janssens, Luc; Smits, Pieter C; Wykrzykowska, Joanna J; Ribeiro, Vasco Gama; Pereira, Hélder; da Silva, Pedro Canas; Piek, Jan J; Onuma, Yoshinobu; Serruys, Patrick W; Sabaté, Manel

    2018-04-20

    A second iteration of a sirolimus-eluting stent (SES) that has a biodegradable PLGA polymer coating with an electrografting base layer on a thin-strut (80 µm) cobalt-chromium platform (BuMA Supreme; SINOMED, Tianjin, China) has been developed. This first-in-man trial aimed to assess the efficacy and safety of the novel device. This randomised, multicentre, single-blinded, non-inferiority trial compared the BuMA Supreme SES versus a contemporary durable polymer zotarolimus-eluting stent (ZES) in terms of angiographic in-stent late lumen loss (LLL) at nine-month follow-up as the primary endpoint. A total of 170 patients were randomly allocated to treatment with either SES (n=83) or ZES (n=87). At nine-month angiographic follow-up, in-stent LLL was 0.29±0.33 mm in the SES group and 0.14±0.37 mm in the ZES group (pnon-inferiority=0.45). The in-stent percent diameter stenosis and the binary restenosis rate of the two treatment arms were similar (19.2±12.0% vs. 16.1±12.6%, p=0.09, and 3.3% vs. 4.4%, p=1.00, respectively). At 12-month clinical follow-up, there was no difference between treatment arms with regard to the device-oriented composite clinical endpoint (4.9% vs. 5.7%; p=0.72). The PIONEER trial did not meet its primary endpoint in terms of in-stent LLL at nine-month follow-up. However, this result did not translate into any increase in restenosis rate or impairment in 12-month clinical outcomes.

  14. A propensity score-matched comparison of biodegradable polymer vs second-generation durable polymer drug-eluting stents in a real-world population.

    Science.gov (United States)

    Zhao, Ying Jiao; Teng, Monica; Khoo, Ai Leng; Ananthakrishna, Rajiv; Yeo, Tiong Cheng; Lim, Boon Peng; Loh, Joshua P; Chan, Mark Y

    2018-04-01

    The safety and efficacy of BP-DES compared to second-generation DP-DES remain unclear in the real-world setting. We compared the clinical outcomes of biodegradable polymer drug-eluting stents (BP-DES) with second-generation durable polymer drug-eluting stents (DP-DES) in an all-comer percutaneous coronary intervention (PCI) registry. The study included a cohort of 1065 patients treated with either BP-DES or DP-DES from January 2009 through October 2015. Propensity score matching was performed to account for potential confounders and produced 497 matched pairs of patients. The primary endpoint was target lesion failure (TLF) at one-year follow-up. The rates of TLF were comparable between BP-DES and DP-DES (8.7% vs 9.1%, P = .823) at 1 year. The rates of stent thrombosis at 30 days (0.4% vs 0.4%, P = 1.00) and 1 year (0.8% vs 0.8%, P = 1.00) did not differ between BP-DES and DP-DES. There were no significant differences in other clinical outcomes including target vessel failure (8.9% vs 9.5%, P = .741), in-stent restenosis (1.8% vs 1.0%, P = .282), and cardiac death (6.4% vs 7.4%, P = .533) at 1 year. Multivariate cox regression analysis showed that the risk of TLF at one-year did not differ significantly between BP-DES and DP-DES (hazard ratio 0.94, P = .763). Efficacy and safety of BP-DES were not better than DP-DES at one-year follow-up. © 2018 John Wiley & Sons Ltd.

  15. Biodegradable polymer stents vs second generation drug eluting stents: A meta-analysis and systematic review of randomized controlled trials.

    Science.gov (United States)

    Pandya, Bhavi; Gaddam, Sainath; Raza, Muhammad; Asti, Deepak; Nalluri, Nikhil; Vazzana, Thomas; Kandov, Ruben; Lafferty, James

    2016-02-26

    To evaluate the premise, that biodegradable polymer drug eluting stents (BD-DES) could improve clinical outcomes compared to second generation permanent polymer drug eluting stents (PP-DES), we pooled the data from all the available randomized control trials (RCT) comparing the clinical performance of both these stents. A systematic literature search of PubMed, Cochrane, Google scholar databases, EMBASE, MEDLINE and SCOPUS was performed during time period of January 2001 to April 2015 for RCT and comparing safety and efficacy of BD-DES vs second generation PP-DES. The primary outcomes of interest were definite stent thrombosis, target lesion revascularization, myocardial infarction, cardiac deaths and total deaths during the study period. A total of 11 RCT's with a total of 12644 patients were included in the meta-analysis, with 6598 patients in BD-DES vs 6046 patients in second generation PP-DES. The mean follow up period was 16 mo. Pooled analysis showed non-inferiority of BD-DES, comparing events of stent thrombosis (OR = 1.42, 95%CI: 0.79-2.52, P = 0.24), target lesion revascularization (OR = 0.99, 95%CI: 0.84-1.17, P = 0.92), myocardial infarction (OR = 1.06, 95%CI: 0.86-1.29, P = 0.92), cardiac deaths (OR = 1.07, 95%CI 0.82-1.41, P = 0.94) and total deaths (OR = 0.96, 95%CI: 0.80-1.17, P = 0.71). BD-DES, when compared to second generation PP-DES, showed no significant advantage and the outcomes were comparable between both the groups.

  16. A Review on Recent Advances in Stabilizing Peptides/Proteins upon Fabrication in Hydrogels from Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Faisal Raza

    2018-01-01

    Full Text Available Hydrogels evolved as an outstanding carrier material for local and controlled drug delivery that tend to overcome the shortcomings of old conventional dosage forms for small drugs (NSAIDS and large peptides and proteins. The aqueous swellable and crosslinked polymeric network structure of hydrogels is composed of various natural, synthetic and semisynthetic biodegradable polymers. Hydrogels have remarkable properties of functionality, reversibility, sterilizability, and biocompatibility. All these dynamic properties of hydrogels have increased the interest in their use as a carrier for peptides and proteins to be released slowly in a sustained manner. Peptide and proteins are remarkable therapeutic agents in today’s world that allow the treatment of severe, chronic and life-threatening diseases, such as diabetes, rheumatoid arthritis, hepatitis. Despite few limitations, hydrogels provide fine tuning of proteins and peptides delivery with enormous impact in clinical medicine. Novels drug delivery systems composed of smart peptides and molecules have the ability to drive self-assembly and form hydrogels at physiological pH. These hydrogels are significantly important for biological and medical fields. The primary objective of this article is to review current issues concerned with the therapeutic peptides and proteins and impact of remarkable properties of hydrogels on these therapeutic agents. Different routes for pharmaceutical peptides and proteins and superiority over other drugs candidates are presented. Recent advances based on various approaches like self-assembly of peptides and small molecules to form novel hydrogels are also discussed. The article will also review the literature concerning the classification of hydrogels on a different basis, polymers used, “release mechanisms” their physical and chemical characteristics and diverse applications.

  17. Hybrid Titanium/Biodegradable Polymer Implants with an Hierarchical Pore Structure as a Means to Control Selective Cell Movement

    Science.gov (United States)

    Vrana, Nihal Engin; Dupret, Agnès; Coraux, Christelle; Vautier, Dominique; Debry, Christian; Lavalle, Philippe

    2011-01-01

    In order to improve implant success rate, it is important to enhance their responsiveness to the prevailing conditions following implantation. Uncontrolled movement of inflammatory cells and fibroblasts is one of these in vivo problems and the porosity properties of the implant have a strong effect on these. Here, we describe a hybrid system composed of a macroporous titanium structure filled with a microporous biodegradable polymer. This polymer matrix has a distinct porosity gradient to accommodate different cell types (fibroblasts and epithelial cells). The main clinical application of this system will be the prevention of restenosis due to excessive fibroblast migration and proliferation in the case of tracheal implants. Methodology/Principal Findings A microbead-based titanium template was filled with a porous Poly (L-lactic acid) (PLLA) body by freeze-extraction method. A distinct porosity difference was obtained between the inner and outer surfaces of the implant as characterized by image analysis and Mercury porosimetry (9.8±2.2 µm vs. 36.7±11.4 µm, p≤0.05). On top, a thin PLLA film was added to optimize the growth of epithelial cells, which was confirmed by using human respiratory epithelial cells. To check the control of fibroblast movement, PKH26 labeled fibroblasts were seeded onto Titanium and Titanium/PLLA implants. The cell movement was quantified by confocal microscopy: in one week cells moved deeper in Ti samples compared to Ti/PLLA. Conclusions In vitro experiments showed that this new implant is effective for guiding different kind of cells it will contact upon implantation. Overall, this system would enable spatial and temporal control over cell migration by a gradient ranging from macroporosity to nanoporosity within a tracheal implant. Moreover, mechanical properties will be dependent mainly on the titanium frame. This will make it possible to create a polymeric environment which is suitable for cells without the need to meet mechanical

  18. A Review on Recent Advances in Stabilizing Peptides/Proteins upon Fabrication in Hydrogels from Biodegradable Polymers.

    Science.gov (United States)

    Raza, Faisal; Zafar, Hajra; Zhu, Ying; Ren, Yuan; -Ullah, Aftab; Khan, Asif Ullah; He, Xinyi; Han, Han; Aquib, Md; Boakye-Yiadom, Kofi Oti; Ge, Liang

    2018-01-18

    Hydrogels evolved as an outstanding carrier material for local and controlled drug delivery that tend to overcome the shortcomings of old conventional dosage forms for small drugs (NSAIDS) and large peptides and proteins. The aqueous swellable and crosslinked polymeric network structure of hydrogels is composed of various natural, synthetic and semisynthetic biodegradable polymers. Hydrogels have remarkable properties of functionality, reversibility, sterilizability, and biocompatibility. All these dynamic properties of hydrogels have increased the interest in their use as a carrier for peptides and proteins to be released slowly in a sustained manner. Peptide and proteins are remarkable therapeutic agents in today's world that allow the treatment of severe, chronic and life-threatening diseases, such as diabetes, rheumatoid arthritis, hepatitis. Despite few limitations, hydrogels provide fine tuning of proteins and peptides delivery with enormous impact in clinical medicine. Novels drug delivery systems composed of smart peptides and molecules have the ability to drive self-assembly and form hydrogels at physiological pH. These hydrogels are significantly important for biological and medical fields. The primary objective of this article is to review current issues concerned with the therapeutic peptides and proteins and impact of remarkable properties of hydrogels on these therapeutic agents. Different routes for pharmaceutical peptides and proteins and superiority over other drugs candidates are presented. Recent advances based on various approaches like self-assembly of peptides and small molecules to form novel hydrogels are also discussed. The article will also review the literature concerning the classification of hydrogels on a different basis, polymers used, "release mechanisms" their physical and chemical characteristics and diverse applications.

  19. Inorganic Polymer Matrix Composite Strength Related to Interface Condition

    Directory of Open Access Journals (Sweden)

    John Bridge

    2009-12-01

    Full Text Available Resin transfer molding of an inorganic polymer binder was successfully demonstrated in the preparation of ceramic fiber reinforced engine exhaust valves. Unfortunately, in the preliminary processing trials, the resulting composite valves were too brittle for in-engine evaluation. To address this limited toughness, the effectiveness of a modified fiber-matrix interface is investigated through the use of carbon as a model material fiber coating. After sequential heat treatments composites molded from uncoated and carbon coated fibers are compared using room temperature 3-point bend testing. Carbon coated Nextel fiber reinforced geopolymer composites demonstrated a 50% improvement in strength, versus that of the uncoated fiber reinforced composites, after the 250 °C postcure.

  20. Synthesis, characterization and antibacterial activity of biodegradable starch/PVA composite films reinforced with cellulosic fibre.

    Science.gov (United States)

    Priya, Bhanu; Gupta, Vinod Kumar; Pathania, Deepak; Singha, Amar Singh

    2014-08-30

    Cellulosic fibres reinforced composite blend films of starch/poly(vinyl alcohol) (PVA) were prepared by using citric acid as plasticizer and glutaraldehyde as the cross-linker. The mechanical properties of cellulosic fibres reinforced composite blend were compared with starch/PVA crossed linked blend films. The increase in the tensile strength, elongation percentage, degree of swelling and biodegradability of blend films was evaluated as compared to starch/PVA crosslinked blend films. The value of different evaluated parameters such as citric acid, glutaraldehyde and reinforced fibre to starch/PVA (5:5) was found to be 25 wt.%, 0.100 wt.% and 20 wt.%, respectively. The blend films were characterized using Fourier transform-infrared spectrophotometry (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA/DTA/DTG). Scanning electron microscopy illustrated a good adhesion between starch/PVA blend and fibres. The blend films were also explored for antimicrobial activities against pathogenic bacteria like Staphylococcus aureus and Escherichia coli. The results confirmed that the blended films may be used as exceptional material for food packaging. Copyright © 2014 Elsevier Ltd. All rights reserved.