Question

Which one from the following is the fibre forming polymer?

• A. Polyisoprene
• B. Polyamides
• C. Polyethers
• D. Polysulfides

Hint:

Nylon, a polyamide, is one of the most important synthetic fibres.

Answer 1

The Correct Option is B

Step 1: Understanding fibre-forming polymers.
Fibre-forming polymers are polymers that possess high tensile strength, elasticity, and the ability to be drawn into fibres. They usually have strong intermolecular forces like hydrogen bonding.
Step 2: Structural requirement.
Polyamides contain amide linkages (–CONH–) that enable hydrogen bonding between polymer chains, providing strength and fibre-forming capability.
Step 3: Analysis of options.
(A) Polyisoprene: Mainly used in rubber, not fibre formation.
(B) Polyamides: Correct — Nylon is a polyamide and a well-known fibre.
(C) Polyethers: Generally flexible polymers, not fibre-forming.
(D) Polysulfides: Used as elastomers and sealants.
Step 4: Conclusion.
Polyamides are fibre-forming polymers, therefore option (B) is correct.

Answer 2

A good fibre-forming polymer needs strong intermolecular attraction between chains (so the fibre has tensile strength) plus the ability for chains to align when drawn. Checking each option against this requirement clarifies the answer.

1. Polyisoprene: This is the polymer of natural or synthetic rubber, valued for its flexibility and elastic recoil rather than tensile strength or fibre-forming ability, it is used to make elastic products, not fibres.
2. Polyamides: Polyamides contain amide (–CONH–) linkages along the backbone, and these groups form strong hydrogen bonds between neighbouring chains. When drawn (stretched), the chains align and pack closely, and the resulting network of hydrogen bonds gives the fibre high tensile strength, exactly the property needed to spin a polymer into usable textile or industrial fibre (as in nylon).
3. Polyethers: These generally have flexible C-O-C backbones without strong inter-chain hydrogen bonding, giving soft, rubbery or waxy materials rather than strong, drawable fibres.
4. Polysulfides: These are mainly used as elastomers and sealants, valued for chemical resistance and flexibility, not for the high strength and drawability required of textile fibres.

Only the amide linkage's hydrogen bonding gives polyamides the tensile strength needed to be drawn into strong fibres.

Therefore, the correct answer is Polyamides.