Nylon is a polymer, composed of repetitive units of diamines and dicarboxylic acids that contain different numbers of carbon atoms. Most contemporary nylon is made from petrochemical monomers (the chemical building blocks making up polymers), combined to form a long chain through a condensation polymerisation reaction. The resulting mixture can be cooled and the filaments stretched into an elastic thread.
Fiber forming polymers are tough, opaque, solids that become viscous and transparent when heated. Filaments can be obtained by pulling threads like taffy from the molten polymer, and, when cooled, stretched to several times their original length. Also known as polyamide, the resulting nylon polymer has a variety of pharmaceutical and industrial applications, with a global market of more than 6.6 million tons per year. Currently, nylon production goes hand-in-hand with petroleum production, but scientists have had promising results replacing well-established petrochemical polymers with bio-polyamides from amino acids.