Nonisothermal crystallization kinetics: poly(ethylene terephthalate)-poly(ethylene oxide) segmented copolymer and poly(ethylene oxide) homopolymer

The nonisothermal crystallization behavior of polyethylene oxide (PEO) in p oly(ethylene terephthalate)poly(ethylene oxide) (PETPEO) segmented copolyme r and PEO homopolymer has been studied by means of differential scanning ca lorimetry, as well as transmission electron microscope. The kinetics of PEO in copolymer and PEO homopolymer under nonisothermal crystallization condi tion has been analyzed by Ozawa equation. The results show that Ozawa equat ion only describes the crystallization behavior of PEO-6000 homopolymer suc cessfully, but fails to describe the whole crystallization process of PEO i n copolymer because the secondary crystallization in the later stage could not be neglected. Due to the constraint of PET segments imposed on the PEO segments, a distinct two stage of crystallization of PEO in copolymer has b een investigated by using Avrami equation modified by Jeziorny to deal with the nonisothermal crystallization data. In the case of PEO-6000 homopolyme r, good linear relation for the whole crystallization process is obtained o wing to the secondary crystallization does not occur under our experimental condition. (C) 2001 Elsevier Science Ltd. All rights reserved.