acetaal

Acetaal, in chemistry, is the Dutch term most often used for the acetal functional group and for a family of thermoplastic polymers derived from it. As a functional group, an acetal consists of a carbon atom bonded to two alkoxy groups (OR units) and two other carbon substituents. Acetals are typically formed by the reaction of an aldehyde or a ketone with an alcohol in the presence of an acid catalyst, a process called acetalization. They are hydrolyzed back to the original carbonyl compound and alcohols under acidic conditions.

In Dutch chemical usage, acetaal is also commonly used to refer to polyacetals, especially polyoxymethylene (POM). POM is a crystalline, engineering thermoplastic known for its high stiffness and strength, low coefficient of friction, and good dimensional stability. It offers excellent wear resistance and chemical resistance to fuels and many solvents, making it suitable for precision mechanical parts. POM is somewhat sensitive to heat and moisture can influence dimensions, so processing and storage conditions are important. It is generally considered chemically resistant, though strong oxidizing agents and certain concentrated acids can attack the polymer.

Production and processing of POM typically involve polymerizing formaldehyde or cyclizing and polymerizing trioxane, often with catalysts that promote cationic polymerization. Commercial grades are supplied as homopolymers or copolymers with comonomers that improve processability and reduce end-group effects. Common processing methods include extrusion and injection molding, which yield parts such as gears, bushings, bearings, fittings, and other precision components used in automotive, electronics, and consumer product applications.

Safety and environmental considerations for acetal polymers are similar to other engineering plastics: they are generally stable but should be handled according to standard polymer safety guidelines and disposed of through appropriate recycling streams where available.