His research resulted in the invention of a number of new polyamides. Dicarboxylic acids are also used in the preparation of copolymers such as polyamides and polyesters. Nylon belongs to a class of polymers called polyamides. They are used to make specialty polyamides. Among these, PVC, polyamides (PA) and acetates are commonly welded with this technology. Bolton instructed Carothers to work on polyamides. Annual demand for polyamides in Europe amounts to a million tonnes. Modern fishing nets are usually made of artificial polyamides like nylon. Polyamides and IntermediatesBASF manufactures polyamide precursors and polyamide. Polyesters, polyamides, and isocyanates are derived via acid-base catalysis. The resulting polyamides are known as proteins or polypeptides. Many polymers are synthesized via step-growth polymerization and include polyesters, polyamides, and polyurethanes. Fibres like polyamides, polyacrylics and polyacetates can be bleached using reductive bleaching technology. Examples of naturally occurring polyamides are proteins, such as wool and silk. Diamines are used as monomers to prepare polyamides, polyimides, and polyureas.