Aug 30 2001
Acetal Polyoxymethylene - POM is made in both copolymer and homopolymer forms, which do not differ considerably. Both are tough, hard, stiff polymers with good appearance (can give high surface gloss) and excellent abrasion resistance.
Generally, these polymers are highly opaque and crystalline and their natural color is white, but they are frequently used colored. They have poor resistance to UV and generally to alkalis and acids.
The homopolymer has somewhat better mechanical properties but slightly worse thermo-oxidative stability than the copolymer. Only the copolymer is suited for continuous use with hot water.
Advantages
Highly crystalline, more creep resistant than Nylon. Excellent abrasion resistance. Good resistance to solvents (except phenols). Low smoke emission. High gloss surfaces. Lower moisture absorption than Nylons.
Disadvantages
Poor resistance to acids/alkalies (particularly homoploymer). Burns easily, (not available with flame retardants). Limited processing temperature range. Poor UV resistance. High mould shrinkage.
Applications
Applications are wide-ranging including gears, bearings, conveyor belt tracks, fan blades, pen cases, lock mechanisms, aerosol valves, snap fittings, and many other engineering components such as spring levers, nuts, screws, video/audio cassette components, disposable lighters, switches, jug kettles, appliance casings, and plumbing fittings.
Source : Abstracted from Plascams
For more information on Plascams please visit The Rubber and Plastics Research Association