Polyester fibres and naming: Which of the following is not a polyester fibre? (Assume Terylene and Dacron are trade names for PET polyester.)

Introduction / Context:
Many fibre names are trade names or family names. Distinguishing polyester fibres from other synthetic fibres helps in fabric selection, dyeing behavior, and end-use performance (wrinkle resistance, moisture uptake, melting behavior).

Given Data / Assumptions:

• Terylene and Dacron are well-known trade names for PET polyester fibres.
• PET (polyethylene terephthalate) is the archetypal polyester fibre.
• Nylon denotes a polyamide, not a polyester.

Concept / Approach:
Polyester fibres contain ester linkages in the backbone, e.g., PET from ethylene glycol and terephthalic acid. Polyamides (nylons) contain amide linkages (–CONH–) formed from diamines and diacids. Therefore, nylon is chemically distinct and not a polyester. Clarifying names avoids confusion caused by branding and common usage.

Step-by-Step Solution:

Verification / Alternative check:
Textile references list polyester (PET) separately from polyamide (nylon) families, with different dye classes, moisture regain, and melting points.

Why Other Options Are Wrong:

• Terylene, Dacron, and PET all denote the same polyester chemistry (PET) used broadly in textiles.

Common Pitfalls:
Confusing trade names with polymer families; assuming all synthetics are interchangeable despite different chemical backbones.

Final Answer:
Nylon