kevalar(composite)

PROPERTIES

FORMULAE

USES

BASIC INFORMATION

High tensile strength at low weight

Low elongation to break

High modulus(Structural Rigidity)

High Chemical Resistance

High Cut Resistance

Flame Resistant, Self extinguishing

Has tensile strength of about 3620 MPa.

A relative density of 1.44

5 times stronger than steel

Although it has high melting point, it can be easily moulded

It has high heat stability

It is slightly stronger at low temperatures

After some hours the strength progressively reduces further

PREPARATION

Kevlar is synthesized in solution from the monomers 1,4-phenylene-diamine (para-phenylenediamine) and terephthaloyl chloride in acondensation reaction yielding hydrochloric acid as a byproduct. The result has liquid-crystalline behavior, and mechanical drawing orients the polymer chains in the fiber's direction. Hexamethylphosphoramide (HMPA) was the solvent initially used for the polymerization, but for safety reasons, DuPont replaced it by a solution of N-methyl-pyrrolidoneand calcium chloride

Formulae

It has the Iupac name poly(imino-p-phenyleneimino=terephthaloyl)

Its molecular formula is [-CO-C6H4-CO-NH-C6H4-NH-]n

It is made up of the monomers 4-phenylene-diamine(para-phenylenediamine) and terephthaloyl chloride

USES Honey comb core technology

In Aerospace Used for weight reduction& increase fuel efficiency

In Marine Light weight & high impact and fatigue resistsnce

Liquid body armour Silicon particles suspended in polyethylene glycol

Enclosed between different kevlar sheets

Light weight Helmet Reduction in 15% back face deformation

Advanced vehicle armour Reliable and durable ballastic protection

Inherent fire & flame resistance

Automotive industry Tyres

Belts

Brake pads

gaskets

Optical cables Provide crush resistance

Load bearing capacity

Heat resistant gloves Cut resistant

High strength