Primary and secondary crystallization of fast-cooled poly(vinylidene fluoride) studied by Flash DSC, wide-angle X-ray diffraction and Fourier transform infrared spectroscopy

摘要

Industrial processing of polymeric materials normally involves fast cooling. We employed a commercial chip calorimeter (Flash DSC) to investigate the crystallization and annealing behaviors of poly(vinylidene fluoride) (PVDF) under fast cooling towards low temperatures. The corresponding polymorphic crystalline phases were identified by wide-angle X-ray diffraction and Fourier transform infrared spectroscopy. The results demonstrated that a cooling process faster than -500 K s(-1) results in major thick -phase crystallites at high temperatures; in addition, subsequent isothermal annealing at low temperatures slowly generates minor thin -phase crystallites rich with trans conformation. Our observations facilitate a better understanding of structural optimization during PVDF processing for its ferroelectric and piezoresponse performance in versatile applications. (c) 2016 Society of Chemical Industry