Preparation, thermal properties, and morphology of graft copolymers in reactive blends of PHBV and PPC

Abstract Chemical modification of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) with glycidyl methacrylate (GMA) monomer, followed by reactively blending with end‐capped poly(propylene carbonate) (PPC) (50 wt%) was carried out during melt processing with dicumyl peroxide (DCP) initiation. The two kinds of graft copolymers of PHBV‐g‐GMA and PHBV‐g‐PPC were extracted with Soxhlet's apparatus, respectively. These grafting reaction mechanisms were proposed and the presence of grafting copolymers was confirmed by weight analysis, FTIR and NMR. The methyne carbon of GMA is confirmed to attach to quaternary carbon of the PHBV backbone. The epoxy groups in the copolymer of PHBV‐g‐GMA were capable to react with the carboxyl groups of end‐capped PPC, resulting in the formation of PHBV‐g‐PPC copolymer in situ. Their thermal properties and morphology were also characterized by DSC, WAXD, POM, and AFM. It revealed that after GMA grafting, the degradation of PHBV decreased and the nucleation of PHBV improved. The crystallinity degree, spherulites dimension and phase segregation between the two macromolecules decreased after PHBV grafted with PPC. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers