Polycaprolactone based biodegradable polyurethanes |
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Authors: | Shu Hui Wang Luiziana F Silva Juliana Kloss Marilda Munaro Gabriel Pinto de Souza M Alice Wada J Gregório C Gomez S Zawadzki L Akcelrud |
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Institution: | 1. Departmento de Engenharia Metalúrgica e de Materiais, Escola Politécnica da Universidade de São Paulo, 05508-900 SP, Brazil;2. Agrupamento de Biotecnologia do Instituto de Pesquisa Tecnológica, São Paulo, 05508-901 SP, Brazil;3. Departmento de Química da Universidade Federal do Paraná, 81531-990 PR, Brazil;4. Instituto Tecnológico para o Desenvolvimento, LACTEC, Centro Politécnico, 81531-990 PR, Brazil |
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Abstract: | Two series of segmented polyurethanes were prepared with systematic variation in soft and hard segment length. The soft segment was constituted by polycaprolactone (PCL) blocks of molecular masses 530 or 2000 and the hard segment (HS) by urethane blocks, in a concentration that varied from 12% to 44% in weight of the whole polyurethane. Morphological analyses indicated that the amount of crystallinity of copolymers was strongly dependent on the PCL molar mass and hard segment content. The copolymers with longer PCL soft segments (Mn=2000) were semicrystalline, but those with shorter PCL segment (Mn=530) were unable to crystallize. The primary factor affectingthe biodegradability of copolymers as evaluated by Sturm tests was the extent of the phase separation, and that the segmental blending of the less biodegradable polyurethane (HS) blocks with PCL in the amorphous phase had a critical unfavorable consequence, which may be attributed to the size of the accessible area by microorganisms. |
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Keywords: | biodegradable block copolymers morphology polyesters polyurethanes |
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