- 2068 Baisakh · 3+1+1 marks
Classification of plastics with examples
Short answer
Thermoplastics soften when heated and harden on cooling, e.g., PVC (pipes) and polyethylene (tanks). Thermosetting plastics set permanently on heating and cannot be remolded, e.g., bakelite (electrical switches) and epoxy resin (adhesives, concrete repair).
Distinguish between two major classifications of plastics. Name two popular plastics of each type and indicate their uses.
Plastics are classified into two major groups based on how they behave on heating: thermoplastics and thermosetting plastics.
| Point | Thermoplastics | Thermosetting plastics |
|---|---|---|
| Behaviour | Soften on heating, harden on cooling, repeatable | Set permanently on heating; cannot be softened again |
| Structure | Linear chains | Cross-linked network |
| Properties | Soft, flexible, recyclable | Hard, rigid, heat resistant |
Popular plastics and uses
Thermoplastics
- PVC: pipes, conduits, flooring, window frames.
- Polyethylene: water tanks, DPC sheets, geomembranes.
Thermosetting plastics
- Bakelite (phenol formaldehyde): electrical switches, sockets, handles, laminates.
- Epoxy resin: adhesives, floor coatings, concrete repair, FRP.
✓ Answer checked by Claude Opus 5.5 (high effort)
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