Blends of poly(3-hydroxybutyrate)/4,4 '-thiodiphenol and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/4,4 '-thiodiphenol: Specific interaction and properties

The specific interaction between poly(3-hydroxybutyrate) [P(3HB)] and 4,4'- thiodiphenol (TDP) and between poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and TDP was investigated by Fourier transform infrared (FTIR) spect roscopy. Interassociated hydrogen bonds were found between the polyester ch ains and the TDP molecules in the binary blends. The fractions of associate d carbonyl groups, F-b's, in the blends first increased and then decreased as the TDP content increased. The thermal and dynamic mechanical properties of P(3HB)-TDP and PHBV-TDP blends were investigated by differential scanni ng calorimetry and dynamic mechanical thermal analysis, respectively. Therm al analysis revealed that the P(3HB)-TDP blends possessed eutectic phase be havior. Furthermore, it was found that the thermal and dynamic mechanical p roperties of P(3HB) and PHBV were greatly modified through blending with TD P. Environmental degradability in river water was evaluated by a biochemica l oxygen demand tester, and it was clarified that TDP lowered the degradati on rate of P(3HB). The results suggest that TDP is effective in modifying t he physical properties as well as the biodegradability of polyesters. (C) 2 000 John Wiley & Sons, Inc.