Organic Fibre: Kevlar

The generic name of this group of fibres is poly-aramid. However, these fibres are more known in commercial form as Kevlar & Nomex (Dupont), Technora ( Teijin), Twaron (Akzo). These fibres are processed from the solution of polycondensation of diamines and diacid halides at low temperature by taking advantage of the mesophase order like ex-pitch carbon fibres. The followings are the characteristics of Kevlar fibre:

• They have strong covalent bond in the axial direction and weak hydrogen bond in the transverse direction.
• Density 1440 Kg/m³ , Tensile Strength (2.8 Gpa), Modulus ( 65-125 Gpa)
• Negative Coefficient of thermal expansion due to kinks
• UV sensitive - degrades
• Kevlar - rubber reinforcement, K-29 - ropes, cables etc., K-49 aerospace & automotive applications