Polyformaldehyde

Polyformaldehyde, also known as polyoxymethylene (POM) or acetal, is a high-performance engineering thermoplastic. It is a linear polymer with the repeating unit [-CH2-O-]. POM is characterized by its high stiffness, strength, hardness, and excellent dimensional stability. It also exhibits low friction, good wear resistance, and good chemical resistance to many solvents and fuels.

The synthesis of polyformaldehyde typically involves the ring-opening polymerization of formaldehyde or the polymerization of trioxane, a cyclic trimer of formaldehyde. Two main types of POM exist: homopolymers and copolymers. Homopolymers, derived primarily from purified formaldehyde, offer higher stiffness and strength but have a lower melting point and are more susceptible to thermal degradation. Copolymers, produced by incorporating small amounts of comonomers like ethylene oxide, have improved thermal stability, broader processing windows, and better resistance to hot water and alkaline solutions, though at a slight reduction in mechanical properties.

Polyformaldehyde is widely used in industries such as automotive, electronics, consumer goods, and manufacturing. Its applications include gears, bearings, conveyor belts, automotive fuel systems, electrical insulators, and components for appliances and toys. Its properties make it a suitable replacement for metals in many applications due to its lighter weight and ease of molding. POM is processed using standard thermoplastic techniques like injection molding, extrusion, and blow molding. It can also be machined.