Film-blown blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by compatibilization with poly(butylene-co-succinate-co-adipate) with a free radical initiator

Abstract

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a sustainable and biodegradable polymer that has potential for use in food packaging. However, its low melt strength makes it difficult to process using film-blowing techniques. To address this issue, 70% PHBV and 30% poly(butylene-co-succinate-co-adipate) (PBSA) were blended with dicumyl peroxide (DCP) as a compatibilizer. The resulting blend showed crosslinking and the presence of long-branched structures, as evidenced by Cole-Cole and van-Gurp-Palmen plots. The optimum formulation (30% PBSA and 0.1 phr DCP) improved the melt flow index, reducing it from 90 g/10 min (neat PHBV) to 22 g/10 min. This allowed for the successful small-scale production of blown PHBV/PBSA films. The thermal properties of PHBV, such as the glass transition and crystallinity index, remained unchanged with the addition of DCP. The films displayed a brittle behavior and a lower modulus compared to neat PHBV. However, they could be heat-sealed, and their mechanical properties remained stable during a six-month storage experiment under freezer conditions. Overall, the compatibilized PHBV/PBSA blend shows potential for use in the production of packaging films through film blowing.