- 2067 Chaitra · 2+3 marks
Thermosetting vs thermoplastics; polymers for ropes, utensils
Short answer
Thermoplastics soften on heating and can be remoulded; thermosets form permanent cross‑links. Nylon 6,6 (ropes/socks) is made by condensing hexamethylenediamine and adipic acid. Teflon (PTFE) for non‑stick utensils is produced by addition polymerisation of tetrafluoroethylene.
Differentiate thermosetting and thermoplastics polymers. Write the name and the preparation of the organic polymers that are used for (i) Preparing ropes and socks (ii) Preparing non stick cooking utensils.
Thermosetting vs thermoplastic polymers
| Point | Thermoplastic | Thermosetting |
|---|---|---|
| Structure | Linear or slightly branched chains | Cross-linked 3-D network |
| Effect of heat | Softens on heating, hardens on cooling (reversible) | Sets permanently on heating; does not soften again |
| Moulding | Can be remoulded and recycled | Cannot be remoulded |
| Solubility | Soluble in some organic solvents | Insoluble and infusible |
| Mechanical nature | Soft, flexible, less strong | Hard, rigid, strong, brittle |
| Examples | Polyethylene, PVC, nylon, polystyrene | Bakelite, epoxy resin, melamine–formaldehyde |
(i) Polymer for ropes and socks: Nylon 6,6
Nylon 6,6 is a polyamide made by condensation polymerisation of hexamethylenediamine (6 carbons) and adipic acid (6 carbons) at about 250 °C under pressure:
n H₂N(CH₂)₆NH₂ + n HOOC(CH₂)₄COOH → [–NH(CH₂)₆NH–CO(CH₂)₄CO–]ₙ + 2n H₂O
The repeating unit has the amide (–CONH–) link. (Nylon 6 is made from caprolactam by ring-opening polymerisation.)
(ii) Polymer for non-stick cooking utensils: Teflon (PTFE)
Teflon (PTFE, polytetrafluoroethylene) is made by free-radical addition polymerisation of tetrafluoroethylene (TFE) using a persulphate initiator under pressure:
n CF₂=CF₂ → [–CF₂–CF₂–]ₙ
TFE itself is obtained by heating chlorodifluoromethane (CHClF₂) at 600–800 °C.
PTFE coating is non-stick because of the very low surface energy of the C–F bonds.
✓ Answer checked by Claude Opus 5.5 (high effort)
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