Crystallization and Thermal Properties of Biodegradable Polyurethanes Based on Poly[(R)-3-hydroxybutyrate] and Their Composites with Chitin Whiskers

A series of biodegradable polyurethanes (PUs) were synthesized from hydroxylated bacterial poly[(R)-3-hydroxybutyrate], P[(R)-HB]-diol, as crystallizable hard segment and hydroxyl-terminated synthetic poly[(R, S)-3-hydroxybutyrate), P[(R, S)-HB]-diol, as an amorphous soft segment, using 1,6-hexamethylene diisocyanate, as non-toxic connecting agent. The P[(R)-HB] content was varied from 30 to 70 wt %. The resulting copolymers were characterized by FT-IR, 1 H-NMR, DSC, and TGA. The DSC data revealed that the melting of P[(R)-HB] segment increases with increasing its own content in the PUs. The cold and melt crystallization are enhanced with increasing P[(R)-HB] content. The TGA data revealed that the thermal decomposition mainly occurred via a single degradation step and the thermal stability slightly increased with increasing P[(R)-HB] content. The non-isothermal crystallization behavior of PU sample containing 40 wt % PHB with and without a-Chitin whiskers was studied using DSC, and their kinetics data were investigated via the Avrami, Ozawa, and Z.S. Mo methods, respectively. Crystallization activation energy was estimated using Kissinger's method. (C) 2014 Wiley Periodicals, Inc.