Thermoplastic elastomer

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Thermoplastic elastomers (TPE), sometimes referred to as thermoplastic rubbers, are a class of copolymers which consist of materials with both thermoplastic and elastomeric properties. While most elastomers are thermosets, thermoplastics are in contrast relatively easy to use in manufacturing, for example, by injection molding. Thermoplastic elastomers show both advantages typical of rubbery materials and plastic materials.

The principal difference between thermoset elastomers and thermoplastic elastomers is the type of crosslinking bond in their structures. Infact, crosslinking is a critical structural factor which contributes to impart high elastic properties. The crosslink in thermoset polymers is a covalent bond created during the vulcanization process. On the other hand the crosslink in thermoplastic elastomer polymers is a weaker dipole or hydrogen bond.

TPE materials have the potential to be recyclable since they can be molded, extruded and reused like plastics, but they have typical elastic properties of rubbers which are not recyclable owing to their thermosetting characteristics.

A family of TPE materials are the ThermoPlastic Vulcanizates or TPV for short. TPV are biphasic materials composed by a plastic phase and a rubbery phase which is crosslinked. The rubbery phase is crosslinked by chemical covalent bonds. The morphology of these materials can be described as a continuos phase of plastic, which contributes to mechanical properties and is responsible for the property of being recyclable, and a dispersed phase of covalently crosslinked rubber which is responsible for elastic properties. Generally TPV can show good mechanic-elastic properties at temperatures up to 110 °C.