Kevlar is an aromatic polyamide. The chemical composition of Kevlar is poly para-phenyleneterephthalamide, Aramids belong to the family of nylons, such as nylon 6,6, do not have very good structural properties, so the para-aramid distinction is important. The aramid ring gives Kevlar thermal stability,
while the para structure gives it high strength and modulus. Like nylons, Kevlar filaments are made by extruding the precursor through a spinneret.
The Kevlar precursor is very stable both chemically and thermally. Today, there are three grades of Kevlar available: Kevlar 29, Kevlar 49, and Kevlar 149.

Kevlar® brand fiber is an innovative technology from DuPont that combines high strength with light weight to help dramatically improve the performance of a variety of consumer and industrial products.