ACETAL, POLYACETAL POLY-OXYMETHYLENE POM

Acetal, (Polyacetal) Poly-oxymethylene (POM) Acetal is a polymer obtained through an addition reaction of formaldehyde — (CH2—0) . It excels in mechanical performance and is regarded as a prominent engineering polymer. It appeared in 1959 with the commercial name Delrin . A short time later a useful copolymer was also developed with a cyclic ether like ethylene oxide. The monomer formaldehyde is a gas produced mostly by oxidizing methanol, and it is very useful in thermoset polymers like phenol, urea and melamine-formaldehydes. For high purity it is initially converted to trioxane or paraformaldehyde. The polymerization is carried out by ionic mechanism, wherein the monomer is dispersed in an inert liquid (heptane). The molecular weights reach 20,000 to 110,000. 

If the stracture of acetal is compared to that of polyethylene, it is apparent that by replacing the methylene group (CH2) with an oxygen atom, a compact stracture is reached leading to high crystallinity (about 80%) and melting 

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