Glyptal-type alkyd resins (phthalic anhydride + glycerol): which of the following is NOT a typical application?

Introduction / Context:
Glyptal is a classic alkyd resin widely used in coatings. While alkyds can modify flexibility and adhesion in films (and can be blended with plasticisers), they are not used as primary fibre-forming polymers like PET, nylon, or acrylics.

Given Data / Assumptions:

• Composition: phthalic anhydride + glycerol (plus fatty acids/oils).
• Applications: enamels, varnishes, primers, and as modifiers/plasticisers in coatings.
• Industrial fibre spinning demands polymers tailored for melt/solution spinning and drawing.

Concept / Approach:
Coatings require film formation and adhesion; alkyds excel as binders and film-formers. Fibre making requires high-molecular-weight polymers with melt stability and crystallisation behavior compatible with spinning—criteria alkyds do not satisfy.

Step-by-Step Solution:
Map each option to known alkyd uses.Identify the outlier: fibre making.Select 'Fibre making (as a fibre-forming polymer)' as not typical.

Verification / Alternative check:
Standards and product literature list alkyds as binders; there is no commercial fibre segment based on alkyd resins.

Why Other Options Are Wrong:
Automotive/aircraft finishes, plasticiser roles in coatings, and film-forming binders are all legitimate alkyd applications.

Common Pitfalls:
Interpreting 'plasticiser' as a standalone commodity; here, alkyds act in concert with or as part of film systems to impart flexibility and adhesion.

Final Answer:
Fibre making (as a fibre-forming polymer)