There are some plastics that when moulded once cannot be softened by heating. These are called:
Show answer & explanation
Correct answer: D
Explanation
The correct option is option 4 i.e. thermosetting polymers.
| Thermosetting polymers | A thermosetting polymer, resin, or plastic, often called a thermoset, is a polymer that is irreversibly hardened by curing of a soft solid or viscous liquid prepolymer or resin. |
| Curing is induced by heat or suitable radiation and may be promoted by high pressure, or mixing with a catalyst. | |
| They are used when resistance to heat is important (eg kettles, plugs, laptop chargers etc). |