Polymer identification in fibres: polycaprolactam is commercially known as which nylon grade in fibre and engineering plastic applications?

Introduction / Context:
Many examination questions ask you to map a chemical name to its widely used trade or generic polymer name. Polycaprolactam is one such case, intimately tied to the nylon family. Understanding these equivalences helps engineers choose the correct resin or fibre for performance, processing temperature, and chemical resistance.

Given Data / Assumptions:

• Polycaprolactam is the chemical name given.
• Answer options include well-known polymer families used in textiles and packaging.
• We assume standard naming conventions in polymer science.

Concept / Approach:
Polycaprolactam is formed by ring-opening polymerisation of caprolactam to yield a linear polyamide. Within industry, this material is known as nylon 6 (also written as PA6). By contrast, nylon 6,6 is produced by condensation of hexamethylene diamine and adipic acid, orlon is polyacrylonitrile, and saran typically refers to polyvinylidene chloride or its copolymers.

Step-by-Step Solution:
Identify monomer → caprolactam.Polymerisation route → ring-opening to polycaprolactam.Industrial name mapping → polycaprolactam = nylon 6 (PA6).Eliminate lookalikes → nylon 6,6 (different monomer pair), orlon (PAN), saran (PVDC).

Verification / Alternative check:
Materials handbooks, fibre standards, and resin datasheets consistently list polycaprolactam as nylon 6. Typical melt temperature, crystallinity range, and moisture uptake values cross-reference between PA6 and polycaprolactam literature.

Why Other Options Are Wrong:
Orlon: polyacrylonitrile, not a polyamide.Nylon 6,6: condensation of two monomers; not polycaprolactam.Saran: PVDC, used for barrier films.

Common Pitfalls:
Confusing nylon 6 with nylon 6,6 because of similar names; ignoring that “6,6” indicates two six-carbon monomers, whereas nylon 6 comes from a single lactam.

Final Answer:
Nylon 6