Effects of Crystallization Temperature of Poly(vinyliclene fluoride) on Crystal Modification and Phase Transition of Poly(butylene adipate)in Their Blends: A Novel Approach for Polymorphic Control

摘要

Effects of the isothermal crystallization temperatures of poly(vinyIidene fluoride), T_(UCMOVDF), on polymorphic crystalline structure, phase transition, fractional crystallization, and enzymatic degradation of poly(butylene adipate) (PBA) in crystalline/crystalline blends have been investigated. The crystal modifications of PBA can be regulated by T_(UCMOVDF). Lower T_(UCMOVDF) (e.g., 80 °C) facilitates the formation of PBA a crystals in both the isothermal and nonisothermal melt crystallizations and also favors the β-to-α phase transition of PBA upon annealing at elevated temperatures. This might be attributable to the decreased equilibrium melting temperature of PBA when _(UCMOVDF) is decreased. Higher T_(UCMOVDF) is favorable for the fractional crystallization of PBA, which tends to segregate in the interlamellar regions of thePVDF matrix under these conditions. PBA shows faster enzymatic degradation in the blends with a lower _(UCMOVDF) than those with a higher T_(UCMOVDF), attributable to the preferential formation of α crystals at a lower _(UCMOVDF). This study provides a new method to control the crystal modification and physical properties of polymorphic polymers in their blend systems.