Electron-induced reactive processing of thermoplastic vulcanizate based on polypropylene and ethylene propylene diene terpolymer rubber

Thermoplastic vulcanizate (TPV) was prepared by in situ cross-linking of the rubber phase by high-energy electrons during melt mixing with a thermoplastic. The electron accelerator was directly coupled with the mixing device to cross-link the rubber phase in situ. The effect of the electron energy and absorbed dose per rotation on the properties and morphology of the TPV was studied. An absorbed dose of 100 kGy and a dose per rotation of 90 kGy per rotation resulted in a TPV with the best set of mechanical properties, as confirmed by morphological analysis too. The effect of different blend ratios was also studied, and it was found that a 50:50 blend ratio produced TPV with superior mechanical properties compared with 30:70 blends, as confirmed by the morphological analysis. A mechanism for the observed improvement in mechanical properties was proposed, based on the viscosity ratio of the blend components and the blend ratio. Finally, the effect of the premixing time of the blend components on the mechanical properties and morphology before the electron-induced reactive processing (EIReP) was studied. A premixing time of 14 min was required to achieve the optimum dispersion of the rubber phase in the thermoplastic phase before in situ cross-linking. Polymer Journal (2012) 44, 439-448; doi:10.1038/pj.2012.3; published online 14 March 2012