Perfluorinated rubber Tetrapropyl fluoride rubber Neoprene rubber Ethylene-propylene rubber Chlorol rubber Butyl rubber Nitrile butadiene rubber Vinyl acrylic rubber Polyurethane rubber Fluorine rubber Hydrogenated nitrile butadiene rubber Fluorosilicone rubber Silicone rubber PTFE RPTFE German yellow nylon PEEK PCTFE POM
POM is a thermoplastic crystalline polymer with the scientific name polyoxymethylene. The structural formula is CH-O, before 1942, formaldehyde polymerization is mostly obtained by the polymerization degree is not high, easily subject to thermal depolymerization of polyoxymethylene glycol HO CH O H, which = 8 ~ 100 for paraformaldehyde; more than 100 for - paraformaldehyde, around 1955, the United States DuPont company from formaldehyde polymerization to get formaldehyde homopolymer, namely homopolymer. The United States Celanese company from the triple formaldehyde, made with a small amount of dioxopentacyclic or ethylene oxide copolymer, that is, the copolymer formaldehyde, the trade name Celcon.
Paraformaldehyde is easily crystallised, with a degree of crystallinity of 70%; this can be increased by annealing at high temperatures. Homopolymer formaldehyde has a melting temperature of 181°C and a density of 1.425 g/cm . The melting point of homopolymeric formaldehyde is around 170°C. The glass transition temperature of homopolymeric formaldehyde is -60°C. The glass transition temperature of homopolymeric formaldehyde is -60°C. Phenolic compounds are the best solvents for paraformaldehyde. The study of the melting index shows that homopolymeric formaldehyde has a narrow molecular weight distribution. Co-polyformaldehyde is stable to chemical reagents except strong acids, oxidising agents and phenols, while homopolymeric formaldehyde is also unstable to concentrated ammonia. Stabilised paraformaldehyde can be heated to 230°C without significant decomposition. Paraformaldehyde can be compressed, injected, extruded, blow moulded and other methods, processing temperature of 170 ~ 200 ℃; also available machine tool processing, but also welding. The products are light, hard, rigid and elastic, dimensionally stable, with a low coefficient of friction, low water absorption, good insulation properties and resistant to organic solvents; they can be used in a wide range of temperatures -50 to 105°C and humidity; they remain unchanged under the action of various solvents and chemical reagents, as well as under heavy loads and long cyclic stresses.
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