Crystallization Behavior and Crystal Polymorphism of Partially Miscible Blends of Poly(vinylidene fluoride) /Poly(ethylene oxide)

Effects of liquid-liquid phase separation (LLPS) on overall crystallization behavior and polymorphism of partially miscible blends of poly(vinylidene fluoride)/poly(ethylene oxide) (PVDF/PEO) were systematically investigated over the whole composition range. Due to substantial difference in the melting points of PVDF and PEO, their melting (Tm), crystallization (Tc) and equilibrium melting temperatures (Tm eq) and also, degree of crystallization (Xc) were measured separately in the blends. The results showed that the crystallization behavior and kinetics are strongly affected by the miscibility state of the blends in the melt state. For those with high content of PEO, the occurrence of phase separation and presence of the preexisting PVDF crystals resulted in higher degree of crystallization in PEO component (Interface assisted crystallization). Wide-angle X-ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FTIR) were also utilized to investigate the crystallization polymorphism of PVDF and PEO in the blends