The goal of this study was to investigate the synthesis and the resulting thermal, rheological, and mechanical properties of polyamide 6/11 copolymers (PA 6/11) as a function of their composition and to further investigate their usability as matrix polymers for wood-plastic composites (WPC). A significant composition dependency of the melting temperature was found due to the hindered crystallization of the PA 6/11 copolymers with increasing content of the minor component. In result, the lowest melting temperature of the copolymers was measured at 120 8 C for 40 wt % of E-caprolactam (PA 6/11-40/60) by DSC analysis. Due to its low melting point and feasible mechanical properties, a copolyamide with 70 wt % of E -caprolactam (PA 6/11-70/30) was chosen as matrix material for the processing of WPC. Incorporation of 30 wt % of wood fibers into PA 6/11-70/30 caused a significant increase in tensile modulus and a decrease in tensile strength and strain at break. However, the processed WPC still showed an exceptional ductility with a strain at break of 15 to 20%
Linear polyurethane elastomers based on polymer polyols were synthesized by the one-shot technique. The hard-segment content of the polyurethanes, the chain length of the base polyether, and the styrene/acrylonitrile content and/or the ratio of the polymer polyols were varied. The mechanical properties and the results of the dynamic mechanical analysis are discussed and compared with those of equivalent crosslinked polyurethane elastomers.
ZUSAMMENFASSUNG:Lineare Polyurethan-Elastomere auf Basis von Polymerpolyolen wurden nach dem one-shot-Verfahren hergestellt. Der Hartsegmentgehalt der Polyurethane, die Kettenlange des Basispolyethers sowie das StyroVAcrylnitril-Verhaltnis und der Gesamtgehalt an Polymerpolyol wurden variiert. Die mechanischen Eigenschaften und die Ergebnisse der dynamisch-mechanischen Analyse werden diskutiert und mit denen von entsprechenden vernetzten Polyurethan-Elastomeren verglichen.
In this study mechanical properties and biocompatibility (In Vitro) of a new bone cement were investigated. A new platform technology named COOL is a variable composite of dissolved, chemically modified PMMA and different bioceramics. COOL cures at body temperature via a classical cementation reaction. Compressive strengths ranging from 3.6 ± 0.8 to 62.8 ± 1.3 MPa and bending strengths ranging from 9.9 ± 2.4 to 26.4 ± 3.0 MPa were achieved with different COOL formulations. Porosity varied between 31 and 43%. Varying the components of each formulation mechanical properties and porosity could be adjusted. In Vitro biocompatibility studies with primary human osteoblasts (pHOB) in direct contact with different COOL formulations, did not reveal any signs of toxicity. In contrast to Refobacin ® R, cells incubated with COOL showed similar density, viability and ALP activity compared to control, if specimen were added immediately to the cell monolayer after preparation. In conclusion, COOL has promising mechanical properties in combination with high biocompatibility In Vitro and combines different advantages of both CPCs and PMMA cements by avoiding some of the respective shortcomings.
Non-polar hydrophobic poly(isobutylene)glycol (PIBG) was substituted for poly(tetramethylene ether)glycol (PTMEG) in poly(ether urethanes) based on 4,4'-methylenebis-(phenylisocyanate) (MDI) and 1,4-butanediol (BD) as chain extender. Two series of polyurethanes differing in their soft segment length, polymer composition, and hard segment content were studied by dynamic mechanical analysis (DMA) and static, as well as dynamic, contact angle measurements. The thrombogenicity of these polymers was characterized by studying the adhesion and activation of platelets using ELISA for GMP 140 and fluorescence microscopy. It was found by DMA that in PIBG-containing polyurethanes (PUE) exist soft domains containing hard segments, strictly separated hard segment domains, and hard segments partially mixed with soft segments. Contact angle measurements revealed that 25% PIBG or even less, are sufficient for a remarkable enrichment of these non-polar soft segments on the polymer surface. The platelet adhesion/activation on these materials was demonstrated to increase with the rise in hard segment content, as well as with an enhancement of the PIBG content. However, comparison of PIBG-containing PUE with medical applied polypropylene and pellethane expressed that PUE with PIBG content equal or less 25% have excellent haemocompatibility.
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