POLYETHYLENE (hereinafter PEX) – This is a thermoplastic polymer is white.
In industry, it is obtained by polymerization of ethylene under high pressure (PP low density) and low or medium pressure (PEX high density). Structure and properties of PP are determined by way of its receipt. The mean molecular mass of the most popular brands of 30-800 thousand, the degree of crystallization and density at 20 ° C are respectively 50% and 0,918-0,930 g/cm3 for PEX. Low Density and 75-90%, and 0,955-0,968 g / cm 3 for PEX . high density. With the increase in density increases the hardness, modulus of elasticity in bending, yield strength, chemical resistance. PEX combines high tensile strength (10-45 Mn/m2, or 100-450 kgf/cm2) with elasticity (elongation at break of 500-1000%).
He has good electrical properties (eg, dielectric loss tangent of 2 × 10-4-4 × 10-4 at temperatures from -120 to 120 ° C and a frequency of 10-50 kHz). Resistant to the action of alkalis any concentrations of organic acids, concentrated hydrochloric and hydrofluoric acids; destroyed by nitric acid, chlorine, fluorine and above 80 ° C soluble in aliphatic and aromatic hydrocarbons and their halogen; relatively resistant to radioactive radiation is harmless; range of operating temperatures from -80 ¸ -120 to 60 ¸ 100 ° C. VP – one of the cheapest polymers, combining valuable properties with the ability to be processed by all known for high-performance thermoplastic methods (see Plastics). That is why in the world production of plastics polymerization PEX occupies the first place (see Polyolefins).
From PEX manufactures films, pipes (including waste water and corrosive liquids, pipelines), profiled products, insulation for wire and cable, containers (bottles, cans, tanks), galvanic baths, sanitary ware, fiber, etc., are widely used in various branches of engineering, agriculture and households. The most popular PEX low density. Many technical significance as products of chlorination and chlor sulfirization of PEX.
