Effect of tackifier compatibility and blend viscoelasticity on peel strength behavior of vulcanized EPDM rubber co-cured with unvulcanized rubber

Peel adhesion behavior of unvulcanized EPDM containing different tackifiers co-cured with vulcanized EPDM surfaces has been investigated and is reported in this paper. This work has great technical significance, as it involves adhesion studies on vulcanized rubber surfaces especially using a rubber like EPDM that has poor adhesion. Two different resins namely hydrocarbon (HC) and coumaroneindene (CI) have been used as tackifiers in this study. Wide range of concentrations of the tackifiers starting from 2 to 32 wt% with respect to EPDM has been investigated. The joint between vulcanized EPDM and tackifier modified unvulcanized EPDM has been prepared through co-curing method. The 180° peel test shows that HC modified EPDM exhibits better joint strength than the CI blended samples. These results have been explained with the help of “single side interdiffusion” concept inherited from viscoelastic studies and surface characterization of the unvulcanized rubber–resin blends. The peel strength of vulcanized EPDM co-cured with tackifier containing unvulcanized EPDM depends not only on compatibility but also on viscoelstic properties. A maximum of 138% improvement in peel strength value has been observed for HC containing system, while CI containing systems show only 27% improvement.