Nonisothermal Crystallization Kinetics of Poly (Phenylene Sulphide) in Composites with a Liquid Crystalline Polymer

The article deals with the melting and nonisothermal crystallization behavior of neat poly (phenylene sulphide) (PPS) and its composites with a thermotropic liquid crystalline polymer (TLCP) Vectra A950, prepared by melt mixing and probed by differential scanning calorimetry. The various macrokinetic models namely, the Ozawa, the modified Avrami, the Tobin, and the Mo models were applied to describe the crystallization kinetics under nonisothermal conditions. The kinetic crystallizabilty of PPS/TLCP composites calculated using the approach of Ziabicki varies depending on these two composite composition-induced effects. Similarly Mo model predicts that to obtain a higher degree of crystallizabilty for PPS/TLCP composites, a higher cooling rate should be used. The effective energy barrier based on the differential isoconversional method of Friedman is found to be an increasing function of relative degree of melt conversion. The effect is explained in terms of nucleation theory proposed by Wunderlich to crystallization of polymers. The Lauritzen-Hoffman parameters are estimated using G = 1/t(0.5) effective activation energy equation proposed by Vyazovkin and Sbirrazzuoli. The K-g values estimated from latter equations are more comparable with values obtained using isothermal crystallization data than 1/t(0.5) method. Furthermore, the kinetic analysis using this equation shows a regime transition from regime II to regime III for 100/00, 90/10, 80/20 PPS/TLCP composites, basically attributed to reduced mobility of PPS chains in composites. This regime II to III transition is accompanied by a morphological transition from defective spherulitic sheaf-like structures to ordered sheaf-like structures. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1070-1100, 2010