Describe the differences between thermosoftening and thermosetting polymers in terms of their structure and behaviour when heated.

Cambridge International IGCSE Chemistry (0620) — 11.8 Polymers · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Thermosoftening polymers have no cross‑links between chains, so when heated they soften or melt and can be reshaped.
Thermosetting polymers contain cross‑links between chains; when heated they do not soften or melt and cannot be reshaped.

Examiner tips

Use the terms ‘cross‑links’ and ‘soften/melt’ explicitly. Show the contrast: no cross‑links vs. cross‑links, soften vs. no soften. Keep each point short and to the point to hit all four marks.

Common mistakes

Confusing ‘softening’ with ‘melting’ – both are acceptable but must be linked to cross‑linking. Forgetting to mention the inability to reshape thermosets. Using vague words like ‘hard’ or ‘soft’ without explaining cross‑linking.

Mark scheme (4 marks)

Thermosoftening polymers have no cross-links between polymer chains
Thermosetting polymers have cross-links between polymer chains
Thermosoftening polymers soften / melt when heated and can be reshaped
Thermosetting polymers do not soften / melt when heated and cannot be reshaped

Key terms in this question

thermosetting polymer