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PMMA Polymer (pmma + polymer)
Selected AbstractsChlorhexidine release and antibacterial properties of chlorhexidine-incorporated polymethyl methacrylate-based resin cementJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2010N. Hiraishi Abstract This study evaluated chlorhexidine release from experimental, chlorhexidine-incorporated polymethyl methacrylate (PMMA)-based resin cements prepared from Super-Bond C&B (Sun Medical) and examined the antimicrobial activity against Streptococcus mutans and Enterococcus faecalis. Chlorhexidine diacetate was added into PMMA polymer to obtain chlorhexidine concentration of 0.0, 1.0, 2.0, 3.0, and 4.0 wt %. Chlorhexidine-incorporated, cured resin disks were immersed in distilled water at 37°C for 5 weeks, and the chlorhexidine release was analyzed by high-performance liquid chromatography. The antibacterial effect of freshly mixed resin cements was examined using the agar diffusion test. For the direct contact test, the wells (n = 6) of microtiter plates were coated with cements. The coated wells were aged up to 3 weeks prior to the placement of bacterial suspensions directly on cured cements. The 3.0 and 4.0% chlorhexidine-incorporated cement exhibited chlorhexidine release for 5 weeks; however, more than 98% of chlorhexidine was retained in resin matrix. No release was detected from the 1.0 and 2.0% incorporated cement at 1 week and 2 weeks, respectively. The agar diffusion test failed to detect antibacterial effects against Enterococcus faecalis, whereas the direct contact test revealed the antibacterial effect of 3.0 and 4.0% incorporated cements against each microbe for 2 weeks. The 3.0 and 4.0% chlorhexidine-incorporated resin cement possessed prolonged chlorhexidine release and antibacterial properties for 2 weeks. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010 [source] Production of leather-like composites using short leather fibers.POLYMER COMPOSITES, Issue 6 2002Leather-like composites were prepared by addition of chemically modified short leather fibers (SLF) into a plasticized polyvinyl chloride (pPVC) matrix. The fibers were subjected to chemical modification by emulsion polymerization to achieve good interfacial adhesion between SLF and the pPVC matrix. The SLF with chemical modification were obtained from three different reaction conditions where these SLF have different percentages of grafted and deposited PMMA polymer onto the fiber surface. The incorporation of the SLF into the thermoplastic matrix was carried out using a torque-rheometer and the composites obtained were molded by compression. Tensile and tear mechanical tests were performed on composite samples, and the morphology of the fractured surfaces was analyzed using scanning electron microscopy (SEM). The results show that the incorporation by grafting of polymethyl metacrylate (PMMA) onto the fibers produced a significant improvement of their interfacial adhesion to pPVC, promoting the compatibilization between the fiber surface and matrix. The findings are discussed and interpreted in terms of enhanced adhesion at phase boundaries. Overall, the results confirm that it is possible to produce modified leather composites based on a pPVC matrix, which exhibit relatively high tensile strength, tear resistance and flexibility. These composites are very suitable candidate materials for applications in the footwear industry. [source] Hexafluoroisopropanol as size exclusion chromatography mobile phase for Polyamide 6JOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2004Raniero Mendichi Abstract The present study deals with the use of hexafluoroisopropanol (HFIP) as size exclusion chromatography (SEC) mobile phase for polyamide 6 (PA6). Contradictory conclusions relating to the use of HFIP as SEC mobile phase for polyamides are found in the literature. By using a multi-detector SEC apparatus equipped with on-line viscometer and multi-angle light scattering we have studied the chromatographic artifacts and the validity of the universal calibration (UC) in HFIP for different PA6 samples (hydrolytic and anionic, monofunctional or bifunctional activator). Appropriate SEC columns and optimized experimental conditions allow most of the chromatographic artifacts to be avoided, even in neat HFIP. The use of a salt in the mobile phase, namely 0.01 M tetraethylammonium nitrate (TEAN), slightly increases the elution volume for both PA6 and PMMA polymers. Under the right conditions, the UC substantially holds for PA6. The validity of the UC is not linked to the presence of TEAN in the mobile phase. With some PA6 samples, namely those anionically synthesized using a bifunctional activator, aggregation becomes a problem and the molar mass in neat HFIP is overestimated. Addition of TEAN prevents any aggregation of the above anionically synthesized PA6. In contrast, the use of a different salt, namely potassium trifluoroacetate, increases the extent of aggregation. [source] Methylation of acidic moieties in poly(methyl methacrylate-co-methacrylic acid) copolymers for end-group characterization by tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2010Rémi Giordanengo The complete structural characterization of a copolymer composed of methacrylic acid (MAA) and methyl methacrylate (MMA) units was achieved using tandem mass spectrometry. In a first step, collision-induced dissociation (CID) of sodiated MAA-MMA co-oligomers allowed us to determine the co-monomeric composition, the random nature of the copolymer and the sum of the end-group masses. However, dissociation reactions of MAA-based molecules mainly involve the acidic pendant groups, precluding individual characterization of the end groups. Therefore, methylation of all the acrylic acid moieties was performed to transform the MAA-MMA copolymer into a PMMA homopolymer, for which CID mainly proceeds via backbone cleavages. Using trimethylsilyldiazomethane as a derivatization agent, this methylation reaction was shown to be complete without affecting the end groups. Using fragmentation rules established for PMMA polymers together with accurate mass measurements of the product ions and knowledge of reagents used for the studied copolymer synthesis, a structure could be proposed for both end groups and it was found to be consistent with signals obtained in nuclear magnetic resonance spectra. Copyright © 2010 John Wiley & Sons, Ltd. [source] | |||||||||||||