Crystallization/Melting Kinetics and Morphological Analysis of Polyphenylene Sulfide

Crystallization and melting kinetics of polyphenylene sulfide (PPS) are determined using fast scanning calorimetry. The temperature dependence of half-time crystallization of isothermally melt-crystallized PPS shows a downward convex curve with a minimum at 160 degrees C. The minimum crystallization half-time is about 3 s. The analysis of heating rate dependence of the melting temperature reveals a zero-entropy-production melting temperature of the sample. The microstructure of the sample, which is prepared by fast scanning calorimetry, is investigated by small-angle X-ray scattering and polarizing optical microscopy. The crystallinity and lamellar thickness of the sample annealed for 400 s decrease with decreasing crystallization temperature. The size of spherulites becomes small as the isothermal temperature is decreased. Transcrystalline morphology is observed near the surface between the sample and nitrogen gas at a crystallization temperature of 120 degrees C. The thickness of the transcrystalline layer disappears as the isothermal temperature is increased.