APPLICATION OF ZONE-DRAWING AND ZONE-ANNEALING METHOD TO POLY(P-PHENYLENE SULFIDE) FIBERS

A zone-drawing and zone-annealing treatment was applied to poly(p-phen ylene sulfide) fibers in order to improve their mechanical properties. The zone-drawing (ZD) was carried out at a drawing temperature of 90 degrees C under an applied tension of 5.5 MPa, and the zone-annealing (ZA) was carried out at an annealing temperature of 220 degrees C unde r 138.0 MPa. The differential scanning calorimetry (DSC) thermogram of the ZD fiber had a broad exothermic transition (T-c = 110 degrees C) attributed to cold-crystallization and a melting endotherm peaking at 286 degrees C. The T-c of the ZD fiber was lower than that (T-c = 128 degrees C) of the undrawn fiber. In the temperature dependence of stor age modulus (E') for the ZD fiber, the E' values decreased with increa sing temperature, but increased slightly in the temperature range of 9 0-100 degrees C, and decreased again. The slight increase in E' was at tributable to the additional increase in the crosslink density of the network, which was caused by strain-induced crystallization during mea surement. The resulting ZA fiber had a draw ratio of 6.0, a degree of crystallinity of 38%, a tensile modulus of 8 GPa, and a tensile streng th of 0.7 GPa. (C) 1998 John Wiley & Sons, Inc.