Influence of various stabilizers on ageing of dicumyl Peroxide-cured polypropylene/ethylene-propylene-diene thermoplastic vulcanizates

Stabilizers are used to prevent the degradation of polymers and thereby, to effectively extend their useful lifetime. However, the application of stabilizers in combination with a peroxide-cure system needs special care, because the main function of these materials is to deactivate the radicals formed after the decomposition of a peroxide, resulting in a reduced crosslinking efficiency of the peroxide. In this investigation, the changes of the physical properties after ageing, of dicumyl peroxide (DCP)/triallyl cyanurate (TAC)-cured thermoplastic vulcanizates (TPVs) at a fixed polypropylene (PP)/EPDM ratio as well as at varied blend ratios in presence of various structurally different stabilizers are described. TMQ performs the best amongst all the stabilizers. However, it discolours the TPV-end products. Combinations of Irganox 1076 + Irgafos 168 and Chimassorb 944 LD + Irgastab FS 042 turn out to be the best stabilizer packages, since they fulfil all the basic criteria required of a good stabilizer: little interaction with the peroxide cure, good stabilization against ageing and no discolouration of the TPV.