PPS is a white, highly crystalline polymer with a density of 1.34. Its excellent mechanical properties, tensile strength and flexural strength are better than PA, PC, PBT, etc., has extremely high rigidity and creep resistance, but its brittleness is large, notched impact strength is lower, lower than PA, PC, PBT Higher than POM. After adding glass fiber reinforcement, its mechanical properties are better. PPS is an inert substance and non-toxic.
Because PPS is a crystalline polymer, the highest crystallinity can reach 65%. Its crystallization temperature is 127 ° C, its melting point is 286 ° C, and its heat distortion temperature is 260 ° C. It decomposes in the air at 430-460 ° C. PA, PBT, POM and other engineering plastics, the long-term use temperature is the highest in thermoplastics, up to 220-240 ℃. PPS still has good thermal insulation and flame retardancy. Its critical oxygen index is equivalent to that of PVC, which can reach 47%. PPS can reach UL94-V0 level without adding flame retardant.
The molecular structure of PPS is symmetrical, non-polar, and low in water absorption, so its electrical insulation is very good. Compared with other engineering plastics, its dielectric constant is small, and its arc resistance is equivalent to thermosetting plastics. At high temperature, high humidity, frequency conversion, etc. Under the conditions, PPS can also maintain excellent electrical insulation. By adding conductive fillers, conductive PPS composites can be prepared for antistatic and electromagnetic shielding.
Because PPS has high crystallinity, it has excellent chemical resistance. It is insoluble in any organic solvents below 200 ° C. In addition to strong oxidizing acids, it can withstand the attack of various acids, alkalis and salts. After long-term soaking with various chemicals, it still maintains high strength, second only to polytetrafluoroethylene. PPS also has good weather resistance and radiation resistance.
1) Water absorption
The water absorption of PPS is low, only 0.02%.
PPS Machining Material has good fluidity, and can process thin-walled products. Its fluidity varies according to the type and specifications of PPS. Linear PPS has higher fluidity than branched and crosslinked PPS. As the temperature increases, the fluidity of the material increases, but If the temperature is too high or the material stays in the barrel for too long, the material will be partially cross-linked, resulting in reduced flow.
PPS is a crystalline polymer, and its crystallinity varies with the cooling temperature and rate during molding. The faster the cooling rate, the lower its crystallinity. And the degree of crystallinity has a greater impact on its strength, heat resistance, weather resistance, and dimensional stability. With the increase of crystallinity, the thermal transition temperature of the product increases, rigidity, surface smoothness, surface hard shrinkage, etc. increase, and dimensional stability also increases.
4) Thermal stability
PPS will undergo partial oxidative cross-linking reaction for a long time at high temperature, which will reduce the fluidity of the material, darken the color, and affect the quality and performance of the product. In addition, PPS has strong adhesion to metal, and it is necessary to prevent the material from solidifying in the barrel.