Crystallization Study of Glassy PET/PEN Blends by Means of Real Time X-ray Scattering

摘要

The crystallization of several blends of poly(ethylene terephthalate) (PET) and poly(ethylene 2,6 naphthalene dicarboxylate) (PEN) has been investigated by wide angle- (WAXS) and small angle X-ray scattering (SAXS) using synchrotron radiation. The role of transesterification reactions, giving rise to a fully amorphous non-crystallizable material (copolyester) is brought up. For the blends rich in PET, crystallization temperatures (T_c) of 105 and 117 deg C were used. Forblends rich in PEN, crystallization was performed at T_c=150 and 165 deg C, respectively. The time variation of the degree of crystallinity was fitted into an Avrami equation considering the induction time prior to tehbeginning of crystallization. The Avrami parameters, the half times of crystallization, as well as the nanostructure development (SAXS invariant and long period) for the blends, are discussed in relationto blend composition and are compared to the parameters observed for the homopolymers PET and PEN.