Reinforcing and Toughening Modification of poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/ethylene-vinyl Acetate Copolymer (PHBV/EVA) Blends Compatibilized by Benzoyl Peroxide

Due to the high brittleness of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), ethylene-vinyl acetate copolymer (EVA) was incorporated to prepare PHBV/EVA blends by melt blending, and the compatibility of the blends was improved by benzoyl peroxide (BPO). The research found that the addition of BPO triggered the production of free radicals in the PHBV and EVA polymers, followed by the recombination of the radicals to form the chemical cross-linking. The resultant PHBV/EVA/BPO blends showed improved mechanical properties and compatibility. At the optimal BPO content (0.5 phr), the elongation at break increased from 1.24% to 4.47%, the impact strength increased from 7.50 kJ/m2 to 17.75 kJ/m2, and the tensile toughness increased from 15.96 MJ/m3 to 70.00 MJ/m3. The gel content of the blends also reached the maximum value (13.88%) at 0.5 phr of BPO addition. This improvement was primarily attributed to interfacial adhesion between PHBV and EVA due to the chemical cross-linking, the hydrogen bonding interactions and the blends chain entanglements. Therefore, this research can improve the poor mechanical properties of PHBV and expand its potential application value.