No abstract

a b s t r a c tA method is addressed to prepare poly(hydroxybutyrate)/poly(ethylene-co-vinyl acetate)/starch (PHB/EVA/starch) blends with fine dispersion of starch, i.e. by an in situ compatibilization in the presence of maleic anhydride (MA) and peroxide. The starch particle size is reduced from hundreds-m to sub-m after the compatibilization accompanied by an improvement in interfacial adhesion. Meanwhile, starch-in-EVA-type morphology is observed in the blends. The EVA and starch gradually changed into a (partially) co-continuous phase with increasing MA content. Consequently, toughness of the blends was improved as evidenced by an increase in elongation at break and tensile-fracture energy (work). Cavitation, fibrillation and matrix yielding are regarded as the toughening mechanism for the compatibilized blends. In addition, the T g of the EVA phase is dependent on its phase morphology in the blends while the thermal behavior of the PHB was only slightly affected by the compatibilization.

Partially crosslinked poly(β‐hydroxybutyrate‐co‐β‐hydroxyvalerate)/poly(butylene succinate) (PHBV/PBS) and poly(β‐hydroxybutyrate)/poly(butylene succinate) (PHB/PBS) blends were prepared by melt compounding with dicumyl peroxide. The effect of partial crosslinking on crystallization of the PHBV/PBS and PHB/PBS blends was investigated systematically. Differential scanning calorimetry results showed that the overall crystallization rates of both PHBV and PBS in their blends were enhanced considerably by the partial crosslinking. Similar results were also detected in the PHB/PBS blends. The polarized optical microscope observation displayed that the nuclei density of PHBV was increased while the spherulitic morphology did not change much. Conversely, the PBS spherulites turned into cloud‐like morphology after the partial crosslinking which is a result of the decrease in spherulite size, the reduction in interspherulite distance and the interconnection of fine PBS domains. Wide angle X‐ray diffraction patterns confirmed the enhancement in crystallization of the PHBV/PBS blends after the partial crosslinking without modification on crystalline forms of the PHBV and PBS components. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41020.