Polymorphic Crystallization and Phase Transition of Poly(butylene adipate) in Its Miscible Crystalline/Crystalline Blend with Poly(vinylidene fluoride)

The effects of poly(vinylidene fluoride) (PVDF) component on the crystallization kinetics, crystalline structure, phase transition, and morphology of polymorphic poly(butylene adipate) (PBA) in their miscible PVDF/PBA binary blends have been investigated. The polymorphism of PBA can be regulated upon blending with PVDF. The incorporated PVDF faciliates the formation of PBA alpha-crystal, which is probably attributed to the thermodynamic and kinetic contributions. From the crystallization kinetics, it was found that a small amount of PVDF acts as a nucleating agent and can accelerate the crystallization of PBA, while a large amount of PVDF hinders the crystallization of PBA due to the confinement effect. In addition, the addition of PVDF greatly accelerates the beta- to alpha-form phase transition of PBA upon annealing the PBA beta-form at higher tmeperataure (48 degrees C). However, the large amount of PVDF decelerates the phase transition to a certain extent. The possible reasons for these phenomena were also proposed.