Non-isothermal melt-crystallization kinetics of poly(trimethylene terephthalate)

Non-isothermal melt-crystallization kinetics and subsequent melting behavior of poly(trimethylene terephthalate) (PTT) have been investigated by differential scanning calorimetry (DSC). The Avrami, Tobin and Ozawa equations were applied to describe the kinetics of the crystallization process. Both of the Avrami and Tobin crystallization rate parameters (i.e. K-A and K-T, respectively) were found to increase with increasing cooling rate. The Ozawa crystallization rate K-O was found to decrease with increasing temperature. The ability of PTT to crystallize from the melt under a unit cooling rate was determined by the Ziabicki's kinetic crystallizability index G(Z), which was found to be ca. 0.98. The effective energy barrier describing the non-isothermal melt-crystallization process DeltaE of PTT was estimated by the differential iso-conversional method of Friedman and was found to increase with an increase in the relative crystallinity. In its subsequent melting, PTT exhibited triple endothermic melting behavior when it was cooled at cooling rates lower than ca. 20 degreesC min(-1), while it exhibited double endothermic melting behavior when it was cooled at cooling rates greater than ca. 20 C min(-1). (C) 2004 Elsevier Ltd. All rights reserved.