Non-oriented poly(phenylene sulfide) fibers with different crystallinity were prepared by melt spinning and heat treating.Based on the measurement of density and sonic velocity

intrinsic horizontal sonic modulus of amorphous and crystalline phases of PPS fibers was determined to be 1.99 GPa and 4.40 GPa

respectively.Based on Samules's model and measured crystallinity and X-ray azimuth scanning

the Hermans orientation factor of amorphous phase of PPS fibers made at different drawing and heat-setting conditions was determined.The relationship between tenacity and processing conditions was discussed based on the above structure parameters.The work shows that the optimum stretching and setting temperature of PPS fiber is near 90℃ and 190℃ separately.The increasing of stretching and tense setting temperature is beneficial to the improvement of the fiber's crystallinity and is helpful to the promotion of fiber's tenacity within certain range.But the over rising of the processing temperature will be disadvantageous to fiber's amorphous orientation and thus reduce the tenacity.The increasing of stretching multiples will improve the amorphous orientation of the fiber and furthermore improve the tenacity of the fiber.