Synergistic Effect of Gamma Radiation and Peroxide on Dynamic Vulcanization of Thermoplastic Vulcanizes Based on (Devulcanized Rubber)/Polypropylene

Devulcanized rubber (DR) with highly crystalline polypropylene (PP) was used to prepare thermoplastic vulcanizates on the basis of DR/PP (75/25) blends. Influences of the curing systems, dicumyl peroxide (DCP) and gamma radiation, were investigated by Xray diffraction and scanning electron microscopy techniques. The mechanical and thermal behaviors of the composites in different proportions were studied. We found that the elastic modulus and tensile strength of the thermoplastic vulcanizates exhibited higher values than unvulcanized material. This finding may be attributed to an improvement in DR dispersion as well as interaction networks between the PP matrix and DR in the presence of DCP and the formation of more stable linkages. Peroxide caused a degradation of the PP molecules. A higher level of DCP was used in the peroxide-vulcanized system and caused greater influence on properties. The mechanical and thermal properties of the unirradiated and irradiated composites were evaluated. (C) 2014 Society of Plastics Engineers