Thermosetting materials exhibit which of the following structural and behavioural features after cure?

Introduction / Context:Thermosets like phenolics, epoxies, and melamines cure into networks. Recognising this architecture helps explain their heat, solvent, and mechanical responses.

Given Data / Assumptions:

• Network formation restricts chain mobility.
• Crosslinked polymers do not melt upon reheating and are typically insoluble.
• Elastomeric behaviour is formulation-dependent and not universal for thermosets.

Concept / Approach:The key identifier of a thermoset is a three-dimensional crosslinked network after cure. This structure underlies heat resistance and chemical resistance, in contrast to thermoplastics which soften with heat.

Step-by-Step Solution:Link “thermoset” to “crosslinked network.”Eliminate claims of easy softening/solubility.Select “Are cross-linked molecules.”

Verification / Alternative check:Thermal analysis lacks melting endotherm for cured thermosets; instead, decomposition dominates at high temperatures.

Why Other Options Are Wrong:Soften and reshape: thermoplastic trait.Solvent soluble: networks generally only swell.Always elastomeric: many thermosets are rigid structural materials.

Common Pitfalls:Confusing uncured resin behaviour with cured network behaviour.

Final Answer:Are cross-linked molecules