Thermoplastic Vulcanizates (TPE-V or TPV) are blends of PP with crosslinked rubber, oil and filler produced under a process developed in the late seventies called dynamic vulcanization as opposite to thermoset rubber where the crosslinking reaction is done in a static way after the rubber compound has been processed. The production of such compounds requires a high shear process where a thermoplastic polymer and a suitable rubber are first intimately mixed before adding the curatives for the crosslinking reaction. The morphology of the resulting blend is a continuous phase of thermoplastic with crosslinked particles of rubber finely dispersed; the smaller the particle size, the better the properties.

TPE-V based on PP and EPDM are well known and have been successfully commercialized to replace crosslinked EPDM, polychloroprene (CR) or chlorosulphonated polyethylene (CSM) rubbers.

PP based TPV containing nitrile, butyl or natural rubbers have also been developed and recently TPE-V based on high temperature thermoplastic and oil resistant rubbers have been introduced as alternative to expensive acrylate or hydrogenated nitrile rubbers.

TPE-V (PP) Major Properties
Soft touch
High temperature compression set
Resistance to oil and grease
Long term stress relaxation
Fatigue resistance
Non slip
Easy to color

Table 1: TPE-V (PP) Major Properties

As a rule, the compatibility between the thermoplastic and the rubber has to be good enough to allow acceptable interfacial adhesion and mechanical properties. In case the two polymers are incompatible, the addition of a compatibilizer is mandatory.

TPE-V are probably the TPE that have the closest properties to thermoset rubber. They have been successfully introduced as rubber replacement in window profile extrusion, automotive weatherseals and suspension bellows. They are used instead of TPE-S as soft touch materials when oil resistance is needed in power tools applications for example.

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