Epoxidised natural rubber as adhesion promoter in natural rubber based compounds

Natural rubber (NR) is the most preferred raw material for both tyre and non-tyre applications, which require good adhesion performance. It has a naturally sticky character to provide green tack. However, it has limitations to improve adhesion further due to its relatively low reactivity. In this study, epoxidised natural rubber (ENR) has been evaluated as an adhesion promoter for NR based model tyre compounds. ENR based adhesive compounds were prepared by blending NR with ENR in various ratios. Rheological, physical, and mechanical properties of NR/ENR compounds were studied. Sufficient cure rate and cure extent were achieved for elevated curing temperatures. The adhesion performance was measured with the T-peel adhesion test. In addition, thermodynamic work of adhesion (TWA) was calculated by using the surface free energy components of the compounds. The correlation between adhesion force and TWA was evaluated together with vulcanisation kinetic parameters in order to understand the adhesion mechanism. ENR incorporation was found to improve adhesion between selected tyre compounds, remarkably.