Effect of thermal aging on crystallization behaviors and dynamic mechanical properties of glass fiber reinforced polyphenylene sulfide (PPS/GF) composites

In this study, the main purpose is to systematically evaluate isothermal and non-isothermal crystallization behavior of short glass fiber-reinforced polyphenylene sulfide polymer composites (PPS/GF) by a wide range of commonly applied models and also to preciously discuss the crystallization evolution and dynamic mechanical properties together with the consideration of thermal aging effects. Some interesting progress concerning this study can be concluded as follows: the Avrami model was used to examine the isothermal crystallization behavior of PPS/GF and the Avrami plot results exhibit that the isothermal crystallization contains primary and second crystallization process. In terms of non-isothermal crystallization, the Jeriorny model and Mo model could describe the mechanism of nucleation and crystal growth of PPS/GF material under study. Also, the activation energy of non-isothermal crystallization is calculated (-58.78 kJ/mol) by Kissinger method. Another important aspect is that thermal aging has an obvious effect on crystallization behaviors of PPS under study. The degree of crystallinity increases from 44% (virgin sample) to 56% after 96 h of aging at 200 degrees C. After a long period of oxidation up to 1080 h at 200 degrees C, the crystallinity degree decreases to 36.6% due to thermo-oxidation effect. DMA results imply that thermal aging may lead to more crosslinking reactions and result into more restriction of molecule mobility in PPS composite materials.