pom: that is, polyformaldehyde, polyformaldehyde scientific name polyoxide polyformaldehyde (referred to as pom), also known as steel, special steel. It is formaldehyde and other raw materials polymerization obtained. pom-h (paraformaldehyde homopolymer), pom-k (paraformaldehyde copolymer) is a high-density, high crystallinity thermoplastic engineering plastics. It has good physical, mechanical and chemical properties, especially excellent friction resistance. Characteristics: 1, pom has a very low coefficient of friction and very good geometric stability, especially suitable for making gears and bearings. 2, pom has high temperature resistance properties, so it is also used for piping devices (piping valves, pump shells), lawn equipment, etc.. 3, pom is a tough and elastic material, even at low temperatures still has good creep resistance, geometric stability and impact resistance. 4, pom's high degree of crystallization leads to it has a fairly high shrinkage rate, can be as high as 2% ~ 3.5%. For a variety of different reinforced materials have different shrinkage rates. 5, pom is a crystalline plastic, melting point is obvious, once it reaches the melting point, the viscosity of the melt drops rapidly. Specific gravity 1.43, melting point 175 degrees Celsius, stretch strength (yield) 70mpa, elongation (yield) 15%, (break) 15%, impact strength (without notch) 108kj/square meter, (with notch) 7.6kj/square meter.