4: Polymer Fibres
While there are a number of different polymeric fibres commonly in use the most popular of these are aramid fibres. Aramid fibre is a generic name for the aromatic polyamide fibre, which was first commercially produced by Du Pont in 1972 under the trade name Kevlar.
Aramid fibres are also expensive but are renowned for their high specific strength and stiffness. (strength/density, stiffness/density)
The two commercially available forms of aramid fibres are Kevlar 49 and Kevlar 29. Kevlar 49 is principally used in composites for aerospace, marine, and automotive applications. Kevlar 29 is used in applications for ballistic protection as well as ropes and cables.