Blends of chlorobutyl rubber (CIIR) with two grades of ethylene-propylene diene
monomer rubber (EPDM) were prepared and the effect of blend ratio on the cure
characteristics, hot air ageing resistance, steam ageing resistance, and mechanical
properties were evaluated. The blend of CIIR with EPDM grade 301 T showed
additive behavior and the blend with the other grade of EPDM (NDR 4640)
showed synergistic behavior.