TPVs are a special category of TPEs made out of a dispersed phase of a soft partly or fully vulcanized elastomer forming microscopic droplets in a continuous phase of a hard thermoplastic (see figure 'Rubber-particles-dispersed-in-TPV' showing the vulcanized rubber particles encapsulated by the free macromolecules of the thermoplastic phase). This one allows the processing in accordance with the thermoplastic techniques. The rubber particles, dynamically vulcanized, have diameters in the order of 1-2 microns and provide elasticity.
TPVs lead to a combination of interesting properties:
1. Elasticity in a limited range of temperatures.
2. Ease of thermoplastic processing without curing and, often without a mixing step.
Among the TPVs, several subcategories can be arbitrarily distinguished:
1. PP/EPDM-VD made out of a dynamically vulcanized EPDM dispersed in a polypropylene (PP) continuous phase: Good elasticity and thermal resistance. The most consumed.
2. PP/RR made out of a recycled rubber dispersed in a PP continuous phase: Low cost, environment-friendly, fair elasticity.