Enthalpy relaxation of poly(phenylene sulfide) fibers.

Abstract

Poly (phenylene sulfide) (PPS) fiber (158 denier) was prepared by the melt spinning and thermal properties, such as phase transition temperatures, heat of transitions, were investigated by differential scanning calorimetry (DSC). In the DSC melting curve of the as-spun PPS fiber, the glass transition, cold crystallization and melting were observed. In order to investigate the enthalpy relaxation, PPS fibers were treated at a temperature lower than glass transition. The excess enthalpy was calculated from DSC curves of the annealed samples. Assuming the total excess enthalpy, ΔH0 of quenched sample could be calculated by the equation, ΔH0=ΔCp(Tg-Ta), where ΔCp is the heat capacity difference between the liquid state and the glassy state at the glass transition temperature (Tg) and Ta is the annealing temperature. From the change of the excess enthalpy with the annealing time, the relaxation time was obtained. It was found that the relaxation rate of PPS fiber was the highest among the reported values of other engineering plastics.