Isothermal crystallization kinetics of PEO in poly(ethylene terephthalate)-poly(ethylene oxide) segmented copolymers. I. Effect of the soft-block length

Abstract

The isothermal crystallization kinetics of poly(ethylene oxide) (PEO) block in two poly(ethylene terephthalate) (PET)–PEO segmented copolymers was studied with differential scanning calorimetry. The Avrami equation failed to describe the overall crystallization process, but a modified Avrami equation, the Q equation, did. The crystallizability of the PET block and the different lengths of the PEO block exerted strong influences on the crystallization process, the crystallinity, and the final morphology of the PEO block. The mechanism of nucleation and the growth dimension of the PEO block were different because of the crystallizability of the PET block and the compositional heterogeneity. The crystallization of the PEO block was physically constrained by the microstructure of the PET crystalline phase, which resulted in a lower crystallization rate. However, this influence became weak with the increase in the soft-block length. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3230–3238, 2000