Question

Which of the following polymer is an example of fibre
A Bakelite
B Buna $-S$
C Nylon $-66$
D PVC

Answer 1

Hint: Fibres are defined as thread-like structures which are generally thin, long, and flexible. Animals and plants are the major sources of fibres. Fibres are of two types, natural (silk and wool) and man-made (ropes and cloth). Fibres are made up of polymers (cellulose, collagen, and silk, then from polymer fibres yarn is generated and from it, many fabrics are made. Cotton is fibres made from a natural polymer, cellulose.

Complete Step by Step Solution:
Bakelite is a thermosetting polymer (hard plastic) and once bakelite is set into any shape with some radiation or heat, it can not be deformed easily upon further heating. This is not like fibres which are quite long, thinner than a strand of hair, and are not hard. Today, bakelite is generally not used as it cannot be recycled due to its resistivity toward change which is not the case with fibre that can be recycled.

Buna- $S$ is a synthetic polymer, styrene and butadiene are its monomers. Buna- $S$ is not fibre but it is an elastomer, having a weak van der Waals force of attraction. Due to the weak van der Waals force of attraction present in Burma-S, it tends to stretch whereas fibre, thread like, has a strong force of attraction.

Nylon-66 (polyamide) is a type of nylon and it is a synthetic polymer. Nylon-66 is generally used as textile fibre and is also known as fibre #66. Nylon-66 fibre is used as brushes, fishing lines, string, clothing, and many more. Whereas PVC is not an example of fibre but a plastic polymer. PVC makes the environment hazardous whereas fibres are nature friendly.
Thus, the correct option is $\mathrm{C}$

Note: Nylon-66 is made up of hexamethylene diamine and adipic acid through polycondensation reaction, both contain 6 carbon atoms per molecule. This is the reason why we call it nylon-66. Nylon- 66 which are synthetic fibres are fire resistant but once they are forced to catch fire, they can be hazardous.