The Polyoxymethylene, with the CAS registry number 9002-81-7, is also known as Formaldehyde, homopolymer. This chemical's molecular formula is (CH₂O)n and molecular weight is variable. Its classification code is TSCA Flag XU [Exempt from reporting under the Inventory Update Rule]. Polyoxymethylene is characterized by its high strength, hardness and rigidity to -40°C. It is intrinsically opaque white, due to its high crystalline composition, but it is available in all colors. Polyoxymethylene is a tough material with a very low coefficient of friction. It is used for manufacturing various structures in automobiles, agricultural machinery, instruments, daily products and building materials, ect. It has limited resistance to strong acids and oxidizing agents. The copolymers and some of the homopolymers are resistant to the action of weak bases. They are used for cams, gears, bearings, springs, sprockets, and other mechanical parts, as well as for electrical parts, housings, and hardware.

Preparation: polyoxymethylene homopolymer is made by reaction of the aqueous formaldehyde with an alcohol to create a hemiformal, dehydration of the hemiformal/water mixture and release of the formaldehyde by heating the hemiformal. The formaldehyde is then polymerized by anionic catalysis and the resulting polymer stabilized by reaction with acetic anhydride. Polyoxymethylene copolymer, formaldehyde is generally converted to trioxane. This is done by acid catalysis followed by purificaiton of the trioxane by distillation and/or extraction to remove water and other active hydrogen containing impurities.