Toughened Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/Epoxidized Natural Rubber Blends Fabricated by Dynamic Vulcanization and Interfacial Compatibilization

Biodegradable polymers, particularly Polyhydroxyalkanoates (PHAs) and their derivatives, have garnered increasing attention across diverse industries owing to their distinct advantages such as bio-based sourcing, biocompatibility, and impressive biodegradability performance. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is one of the most attractive members of PHAs with a great potential to replace conventional non-biodegradable polymers. However, one critical drawback restricting PHBV usage is its thermal instability, which could bring about a narrow processing window, especially for conventional melt processing methods such as injection molding. Moreover, the high crystallinity and slow nucleation rate make PHBV brittle, leading to poor mechanical performance. This study incorporated epoxidized natural rubbers (ENR-25 and ENR-50) into PHBV through a melt blending process to enhance PHBV toughness and flexibility. Incorporation of 5wt% polybutadiene grafted maleic anhydride (PB-g-MA) as a compatibilizer notably enhances mechanical properties. Furthermore, the study introduces the concept of thermoplastic vulcanizate (TPV) through melt blending using dynamic vulcanization (DV) to enhance mechanical properties, particularly the toughness of the 70/30 PHBV/ENR blends, identified as the optimal blending ratio based on prior research. The resulting blend vulcanizate (PHBV/ENRv) exhibits toughness values of 63.0 ± 14.8 J m^− 1 and 24.4 ± 2.8 J m^− 1 for blends with ENRv-25 and ENRv-50, respectively. These findings hold promise for advancing the design and development of biodegradable polymer blend systems, with a focus on enhancing processability and mechanical performance.

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