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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Thermoplastic

A polymer made of separate chains with no covalent cross-links, so it softens when heated and can be melted and remoulded many times. Most everyday plastics, and all the recyclable ones, are thermoplastics.

Thermoplastic versus thermosetLeft: in a thermoplastic the chains are separate and held only by intermolecular forces, so on heating they slide past each other and the plastic can be remelted. Right: in a thermoset, covalent crosslinks join the chains into one network, so it does not melt when heated.thermoplasticseparate chainsremelts on heatingthermosetcrosslinked (red bars)does not remelt

Left: separate chains (thermoplastic). Right: cross-linked chains (thermoset).

Example

Used PET bottles can be melted and spun into polyester fibre for fleece clothing.

See alsoThermosetCross-linkingPolymer