Thermoplastic
A polymer that softens on heating and hardens again on cooling, reversibly and repeatedly.
Unit
°C
In depth
Thermoplastics consist of separate chains held together only by weak intermolecular forces, which heat overcomes without breaking any covalent bonds. This makes them mouldable, weldable and, importantly, recyclable by melting and reforming.
Examples in the real world
Polythene, polypropene, PVC and PET; the entire injection moulding industry depends on them.