Effect of Different Types of Peroxides on Properties of Vulcanized EPDM plus PP Blends

Mechanical and tribological behavior of several dynamic vulcanizate blends of polypropylene (PP) with ethylene-propylene-diene rubber (EPDM) was examined and compared with those of uncrosslinked blends. Vulcanization was performed using two types of organic peroxides combined with (meth) acrylate coagent. The effect of different types and concentrations of peroxides as crosslinking agents on the properties of the resulting materials were investigated. Dicumyl peroxide (DCP) provides higher reactivity and exhibits nearly the same crosslinking efficiency for both 60/40 and 50/50 blends; almost fully crosslinked samples are obtained if the compound contains 1.0 or 2.0 wt% DCP. These results correlate to the gel content and mechanical properties of our materials. Variation of PP + elastomer ratio does not have a significant influence on friction. From 60/40 group of composites, lower friction values were obtained for samples cured with 0.5 wt% benzoyl peroxide (BP) and 1.0 wt% DCP. The tribological properties of the samples with higher amount of DCP show rubbery rather than a toughened thermoplastic behavior. Wear of the composites decreases with the increasing concentration of the curing agent. Compared to BP, the samples cured with DCP display lower wear. POLYM. COMPOS., 31: 1678-1691, 2010. (C) 2010 Society of Plastics Engineers