Which polymer is most commonly used to manufacture refrigerator components (liners, trays) and small electronic housings such as radio or transistor parts?

Introduction / Context:
Selection of plastics for appliance components balances stiffness, processability, surface finish, and cost. Refrigerator liners, trays, and many consumer electronics housings historically use polystyrene (including high-impact polystyrene, HIPS) because it offers good rigidity, ease of thermoforming/injection molding, and acceptable aesthetics.

Given Data / Assumptions:

• Refrigerator components often require thermoformability, dimensional stability, and food-contact compliance.
• Transistor or small electronic housings require moldability and surface finish.
• We consider widely used commodity solutions rather than specialty engineering upgrades.

Concept / Approach:
Polystyrene’s glassy nature at room temperature yields stiffness and dimensional stability, while its melt flow suits complex molds and thermoformed shapes. HIPS adds rubber impact modifiers to improve toughness. Alternatives exist (e.g., ABS or PP in some modern designs), but polystyrene remains a canonical answer for legacy exam questions about refrigerator liners and small electronic casings.

Step-by-Step Solution:
Evaluate needs: easy forming, adequate rigidity, low cost.Match to polymer properties: PS/HIPS fits well.Select polystyrene as the best-known material for this application.

Verification / Alternative check:
Industrial practice and product datasheets cite HIPS for refrigerator liners and PS or ABS for small appliance housings; exam conventions typically list polystyrene.

Why Other Options Are Wrong:
Polypropylene: good for hinges and containers but can suffer from stiffness/finish limits in this traditional context.Unsaturated polyester: thermoset matrix used with fibres, not typical for liners.Polyurethane: commonly used as insulation foam in refrigerators, not for liners or housings.Polycarbonate: excellent but costlier and over-specified for many such parts.

Common Pitfalls:
Confusing PU foam (insulation) with liner material; liners are commonly PS/HIPS.

Final Answer:
Polystyrene (PS, including HIPS grades)