Question

Which characteristic differentiates thermosetting polymers from thermoplastic polymers?

• A. Thermosetting polymers can be reshaped with heat
• B. Thermoplastic polymers are primarily used in adhesives
• C. Thermosetting polymers are cross-linked and do not melt upon heating
• D. Thermoplastic polymers have higher tensile strength

Hint:

Thermoplastics vs. Thermosets. Thermoplastics: Linear/branched chains, soften on heating, reshapeable. Thermosets: Cross-linked network structure, cure irreversibly, do not melt or reshape on heating, degrade at high T.

Answer 1

The Correct Option is C

The fundamental difference between thermoplastic and thermosetting polymers lies in their molecular structure and behavior upon heating: - Thermoplastics: Consist of linear or branched polymer chains held together by relatively weak intermolecular forces.
Upon heating, they soften and can be repeatedly reshaped (molded) and solidify upon cooling.
- Thermosetting polymers (Thermosets): Initially consist of monomers or prepolymers that undergo irreversible chemical reactions (curing) upon heating or addition of a catalyst, forming extensive covalent cross-links between chains.
This creates a rigid, infusible 3D network structure.
Once cured, thermosets cannot be remelted or reshaped by heating; further heating leads to degradation rather than melting.
Option (3) correctly describes thermosets as being cross-linked and not melting upon heating.
Option (1) describes thermoplastics.
Option (2) is incorrect application generalization.
Option (4) is not universally true; properties vary widely.