Question

why the nylon fabric is only used for making of bullet proof jackets ?

Answer 1

Nylon was used in the Bullet proof jackets till 1970's because of its strength and toughness. But now they are made of nylon fibre known as 'Kevlar'. It has high tensile strength-to-weight ratio and is 5 times stronger than steel. These fibres work together to share the force required to stop bullets.
Nylon resists mildew and bacterial growth as compared to other fibres, making it an excellent choice for outdoor use when it's exposed to dirt, grime and water. Kevlar fiber is much lighter, carbon fibre is next and the e glass is the heaviest. Also, Kevlar has a high strength-to-weight ratio while carbon fibers and e glass have a lower strength-to-weight ratio. Kevlar is also more resistant to fatigue and abrasion of the three fibres.