PS | Specific Performance

(1) General Performance

PS is a colorless and transparent pellet. It emits heavy smoke and smells of turpentine when it burns. It can be stretched when blown out; the product is hard, like glass, and it will make a metal-like sound when it falls or is knocked; it can be broken but not bent, when broken, there is a clamshell silver light. The water absorption rate of PS is 0.05%, which is slightly higher than that of PE, but it has little effect on the strength and dimensional stability of the product.

(2) Optical Properties

Good transparency is the biggest feature of PS. Its light transmittance can reach 88%~92%. Like PC and PMMA, it belongs to the most excellent transparent plastic varieties, collectively referred as the three major transparent plastics. The refractive index of PS is 1.59~1.60, but due to the existence of benzene ring, its birefringence is relatively large, so it cannot be used in high-end optical instruments.

(3) Mechanical Properties

PS is hard and brittle, has no elongation, and breaks when stretched to near the yield point. The tensile strength and bending strength of PS are the highest among general-purpose thermoplastics, and its tensile strength can reach 60MPa; but the impact strength is very small, and it is difficult to be used as an engineering plastic. PS has poor wear resistance and average creep resistance. The mechanical properties of PS are greatly affected by temperature.

(4) Thermal Properties

The heat resistance of PS is not good, and the heat distortion temperature is only 70~90℃, so it can only be used in the range of 60~80℃ for long time. The low temperature resistance of PS is not good, and the embrittlement temperature is -30℃. The thermal conductivity of PS is low, generally it is 0.04~0.13W/(m·K); the linear expansion coefficient is relatively large, generally is (6~8)×10^-5K^-1, which is very different from metal, so the product is not easy with metal inserts.

(5) Electrical Properties

PS has excellent electrical insulation and is not affected by temperature and humidity; the dielectric loss tangent is small, and it can withstand appropriate corona discharge; it has good arc resistance and is suitable for high-frequency insulating materials.

(6) Environmental Performance

PS has good chemical stability and can resist general acids, alkalis, salts, mineral oils and lower alcohols, etc., but can be corroded by many hydrocarbons, ketones and higher fatty acids, etc. It can melt in aromatic hydrocarbon（such as Benzene, methylbenzene, ethylbenzene, and styrene, etc.), chlorinated hydrocarbons (such as carbon tetrachloride, chloroform, methylene chloride and chlorobenzene) and esters, etc. The weather resistance of PS is not good, and its light resistance and oxidation resistance are poor, so it is not suitable for long-term outdoor use; but PS has good radiation resistance.