Reinforcing and toughening modification of bio-based and biodegradable PHBV/BEPE blends with benzoyl peroxide by micro-crosslinking.

To improve the shortcomings of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), such as brittleness, large grain size and high crystallinity, a kind of bio-based engineering polyester elastomer (BEPE) was incorporated into PHBV by melting blending method with benzoyl peroxide (BPO) as the initiator. With the addition of BPO, the interfacial adhesion between PHBV and BEPE was improved, and BPO hindered the crystallization and reduced the crystallinity of PHBV/BEPE blends. At the same time, the gel content, the dynamic complex viscosity and dynamic elastic modulus of blends were increased significantly in low-frequency region with 0.7-phr BPO. Compared to that of neat PHBV, the elongation at break and impact strength of PHBV/BEPE/BPO (0.7 phr) blends were increased by 373.6 and 158.7%, respectively. Compared to that of PHBV/BEPE blends, the elongation at break and impact strength of the PHBV/BEPE/BPO (0.7 phr) blends were increased by 44.3 and 122.7%, respectively. The above phenomena were resulted from the formation of chemical micro-crosslinking between PHBV and BEPE. The main mechanism can be explained, PHBV and BEPE polymer radicals were generated by BPO initiator, and then, PHBV and BEPE polymer radicals recombined to form carbon–carbon crosslinking. [ABSTRACT FROM AUTHOR]