Interplay between amorphous and crystalline domains in semicrystalline polymers by simultaneous SAXS, WAXS and Dielectric Spectroscopy

This work presents an experimental study on the interplay between structure and dynamics during isothermal cold crystallization of a copolymer based on poly(ethylene terephthalate) and poly(ethylene isophthalate) of poly(trimethylene terephthalate). Simultaneous X-ray scattering and dielectric spectroscopy measurements revealed that, during cold crystallization, crystalline lamellae tend form lamellar stacks during primary crystallization. A significant amount of rigid amorphous phase is formed during cold crystallization, and its location is assigned to the intralamellar stacks amorphous regions. The formation of the rigid amorphous phase during cold crystallization is less effective for. The mobile amorphous phase, giving rise to the dielectric α relaxation in the semicrystalline system is mainly located out of the stacks. The segmental dynamics of the amorphous phase is restricted by the growing crystals during secondary crystallization, but to a lesser extent than in the case of the homopolymer PET..