Terylene identification:\n“Terylene” is a trade name used historically in fibres. Which statement best describes it?

Introduction / Context:
Trade names often map to standard polymer families. Terylene (UK) and Dacron (USA) became synonymous with polyethylene terephthalate (PET) fibres, the dominant polyester fibre in apparel and industrial applications. Recognising these equivalences prevents confusion in technical reading and procurement.

Given Data / Assumptions:

• Terylene and Dacron are historical brand names for PET fibre.
• PET is a polyester formed by condensation of terephthalic acid (or DMT) with ethylene glycol.

Concept / Approach:
The accurate description is that Terylene equals Dacron in generic chemistry and both refer to the polyester family. Hence, the correct choice is “Both (a) & (b).”

Step-by-Step Solution:

Verification / Alternative check:
Fibre dictionaries and historical marketing document that Terylene (ICI) and Dacron (DuPont) were PET brands.

Why Other Options Are Wrong:

• Each alone is incomplete; “Neither” is false; polyamide is incorrect.

Common Pitfalls:
Confusing polyester (PET) with polyamide (nylon) because both can be melt-spun and drawn.

Final Answer:
Both (a) & (b)