acrylic fibre

Synthetic fibre often used as a substitute for wool. It was first developed in the mid-1940s but was not produced in large quantities until the 1950s. Strong and warm, acrylic fibre is often used for sweaters and tracksuits and as linings for boots and gloves, as well as in furnishing fabrics and carpets. It is manufactured as a filament, then cut into short staple lengths similar to wool hairs, and spun into yarn. Modacrylic is a modified acrylic yarn.

Acrylic is formed by polymerizing acrylonitrile to give the polymer [CH2CH(CN)]n, where n is about 2,000. Most commercial acrylics contain about 10% of other constituents to enhance their properties, in particular to make them more easily dyeable. If the proportion of additives exceeds 15%, the fibre is known as modacrylic, some of the modacrylics being highly flame-resistant. The fibres are made either by a dry spinning process, by dissolving in a solvent such as dimethyl acetamide, or by a wet spinning process. The fibres are strong, absorb very little water, and are resistant to most chemicals likely to be encountered in normal use. The fibres become plastic (or flexible) in very hot water or steam, so that care is required in handling fabrics to prevent excessive stretching. If heated under the correct conditions, the fibres char and form carbon fibres.