Question

Give the preparations, properties and uses of Kevlar. 

Answer 1

 It is an aromatic polyamide with benzene rings linked to the amide group, -CO NH- group.
1.PREPARATION.
It is prepared by polycondensation between aromatic dichloride like terephthalic acid dichloride (terephthaloyl chloride) and aromatic diamines like 1,4-phenylene diamine {1,4-diamine benzene).
2.PROPERTIES.
• It is exceptionally strong, 5 times stronger than steel and 10 times stronger than aluminium.
• It has high heat stability and flexibility.
• It has resistance against almost all the solvents except some powerful acids.
• It does not lose its strength at -196°C.

3.USES.
• It is used in aerospace and aircraft industries.
• It is used for the preparation pf car parts such as tyres, brakes, clutch, lining etc.
• Used for the preparation of ropes ,cables, helmets etc.