Miscibility, crystallization, rheological and mechanical properties of biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/poly(vinyl acetate) blends

•Binary blends of P34HB and PVAc were prepared.•P34HB and PVAc are miscible.•The addition of PVAc reduced the crystallization rate of P34HB in the blends.•The blends showed an improvement in the rheological and mechanical properties. Herein, biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) was mixed with amorphous poly(vinyl acetate) (PVAc) to prepare a binary blend system by melt compounding. The miscibility, thermal behavior, isothermal crystallization behaviors, and mechanical and rheological properties of P34HB/PVAc blends were investigated. Only one glass transition temperature of the blends indicated that P34HB and PVAc were miscible. The introduction of PVAc suppressed the cold crystallization of the blends and reduced the degree of crystallinity. The study of isothermal crystallization behaviors revealed that the addition of amorphous PVAc reduced the crystallization rate of blends, but did not change the crystallization mechanism. In addition, the blends showed a remarkable improvement in the rheological properties compared with those of neat P34HB. The most intriguing result was a greatly increased elongation at break, coupled with an only slightly reduced modulus and strength for blends.