Research On Affecting Factors Of Crystallinity And Mechanical Properties Of Polyphenylene Sulfide(PPS)

Thermoplastic composites have developed rapidly in the aerospace industry and are widely used in recent years.Polyphenylene sulfide(PPS)is a semi-crystalline thermoplastic material,and the degree of crystallinity is critical to the stiffness and mechanical properties of thermoplastic polymers.Therefore,as an advanced thermoplastic composite matrix,it is of great significance to study the factors affecting the crystallinity of PPS for preparing PPS products and fibers with excellent performancePPS and Carbon Fiber/Polyphenylene Sulfide(CF/PPS)were used as the research objects in paper.Crystallinity and crystallization behavior of PPS resin were investigated by differential scanning calorimetry(DSC)and thermal gravity analysis(TGA).The effects of melting time,melting temperatures,heat treatment time and heat treatment temperatures on the crystallinity of PPS resin.The results show that the crystallinity of PPS resin decreased with the increase of melting time in the range of 10min~30 min.The maximum crystallinity is 54.3% and the minimum is 48.7%.The thermal weight loss rate of PPS resin decreased with the increase of melting time,the weight loss rate reduced from 51.9% to 49.1%,the crystallization peak shifts to the low temperature direction,the peak width increased,and the peak intensity decreased.In the range of melting temperature from 300 °C to 360 °C,the crystallinity of PPS resin increased first and then decreased with the increase of the melting temperature,and the crystallinity of PPS reaches the highest at 320 °C,it is 44.6%,and the lowest at 360 °C,it is 23.3%.When the heat treatment temperature is constant,the crystallinity increased first and then decreased with the increase of heat treatment time;When the heat treatment time is constant,the crystallinity increased first,then stabilized and then decreased with the increase of heat treatment temperature.The heat treatment temperature of 150 °C,and the heat treatment time of 2h,get the highest relative crystallinity of PPS is 65.4%.The mechanical properties and micromorphology of CF/PPS laminates with different crystallinity were studied.Research the effect of crystallinity on the mechanical properties of the composites.The experimental results show that the mechanical properties of CF/PPS increased with the increase of crystallinity.The performance was gradually improved.Under the condition of heat treatment temperature of 150°C and heat treatment time of 2h,the mechanical properties of CF/PPS were the best.The tensile strength,flexural strength and modulus are 718.2 MPa,746.7 MPa and 15.7 GPa respectively.The tensile strength was increased by 15.3% and the bending strength was increased by 4% compared to the original composite sample without heat treatment.