CRYSTALLIZATION OF FIBER-REINFORCED POLY(PHENYLENE SULFIDE) COMPOSITES .1. EXPERIMENTAL STUDIES OF CRYSTALLIZATION RATES AND MORPHOLOGY

The isothermal crystallization from the melt of unreinforced poly(phenylene sulfide) (PPS) and of model carbon, aramid, and glass-fiber-reinforced PPS composites was studied by differential scanning calorimetry and optical microscopy. Crystallization was studied as a function of temperature, and the fiber contents in the composites were varied over a wide range. The results indicate that the influence of fibers on PPS crystallization is not only fiber specific, but also strongly dependent on the surface treatment (size). In general, fiber-reinforced systems crystallized faster than unreinforced (PPS), and the degree of crystallinity was less under comparable crystallization conditions. It was also observed that the rate of crystallization was enhanced in those systems which exhibited transcrystallinity in thin PPS film/single fiber composites as compared to those systems which did not exhibit transcrystallinity. Furthermore, the degree of crystallinity showed a nonlinear crystallization temperature dependence for those systems that exhibited transcrystallinity.