Polyvinyl acetate (PVAc): identify the application that PVAc is never used for in standard industrial practice.

Introduction / Context:
Polyvinyl acetate (PVAc) is a widely used polymer noted for its excellent adhesion to porous substrates and film-forming capability. However, its thermal and mechanical profile constrains certain applications. The question seeks the use case that PVAc does not serve in typical materials engineering practice.

Given Data / Assumptions:

• PVAc softens at relatively low temperatures and hydrolyses to PVOH under alkaline conditions.
• Common PVAc forms include emulsions/latices for adhesives and coatings.
• We consider mainstream industrial practice, not niche laboratory curiosities.

Concept / Approach:
PVAc is a mainstay for adhesives (wood glues, packaging), paper and textile binders, and as a precursor to polyvinyl alcohol (via hydrolysis). It is not a fibre-forming polymer for apparel or technical fibres due to its low melting/softening point, thermal instability during drawing, and moisture sensitivity. PVAc moulding is limited, but blends and copolymers can be formed into certain shaped goods; the “never used” option classically highlighted in exams is “fibres.”

Step-by-Step Solution:

Verification / Alternative check:
Industry data sheets emphasise PVAc in adhesives/coatings; fibre technology texts do not list PVAc as a commercial fibre polymer.

Why Other Options Are Wrong:

• Adhesives/paper sizing: core applications of PVAc.
• Moulded articles: niche but possible in blends; not “never.”

Common Pitfalls:
Confusing PVAc with vinyl acetate copolymers such as EVA, which have broader thermoplastic uses.

Final Answer:
Fibres