Applications of phenolic thermosets: non-sulphonated hard bakelites are generally NOT used for which of the following products?

Introduction / Context:
Bakelite is the common name for phenol–formaldehyde thermoset resins. Non-sulphonated, hard grades are valued for heat resistance, dimensional stability, and electrical insulation. However, ion-exchange resins require specific functional groups to perform reversible ion substitution in water-treatment applications.

Given Data / Assumptions:

• Non-sulphonated phenolic (hard bakelite) has no ion-exchange functional groups.
• Typical bakelite uses: electrical components, handles, knobs, combs, and decorative laminates.
• Ion-exchange resins must carry acidic or basic ionisable groups (e.g., sulfonic or amine groups).

Concept / Approach:
Ion-exchange relies on fixed charged sites attached to an insoluble matrix. Non-sulphonated phenolic networks are neutral and lack sulfonic (–SO3H) or quaternary ammonium sites. Therefore, they are unsuitable as ion exchange media without chemical modification. In contrast, moulded goods and laminates benefit from bakelite’s hardness and heat resistance.

Step-by-Step Solution:
Identify the application that mandates ionic functional groups: ion-exchange resins.Match material chemistry: non-sulphonated phenolic lacks such groups.Conclude: it is not used for ion-exchange resins, whereas it is common for moulded articles and laminates.

Verification / Alternative check:
Commercial ion-exchange resins are typically sulfonated polystyrene–divinylbenzene (strong acid), phenolic resins only after sulfonation (specialty), or amine-functional resins (anion exchangers).

Why Other Options Are Wrong:
Fountain pen barrels, formica-type tops, and combs: common uses of hard phenolic thermosets.

Common Pitfalls:
Assuming any thermoset works for ion exchange; overlooking the essential role of functional groups.

Final Answer:
Ion-exchange resins