Epoxidised Natural Rubber ( ENR )/Wollastonite Composites for Tyre Inner Liners: A Practical Replacement for Butyl Rubber in Industrial Applications

This study aimed to develop epoxidised natural rubber (ENR)‐based rubber compound formulations as an alternative to butyl rubber for tyre inner liners. The effects of different vulcanization systems, designed to achieve similar curing behavior in NR‐based carcass compounds and ENR‐based liner compounds, were evaluated. The selected vulcanization system was applied to other compound formulations in subsequent stages to enhance adhesion and gas barrier properties. The impact of high‐aspect‐ratio wollastonite on interfacial adhesion was evaluated for the first time in an ENR matrix. Additionally, the effects of varying wollastonite concentrations on the adhesion and gas barrier properties of the liner compound were examined. The compounds were assessed based on their rheological, physical, and mechanical properties, adhesion strength, gas permeability, and topographical characteristics. It was concluded that the coagent‐induced vulcanization system was the most effective for co‐vulcanization of NR and ENR. Additionally, adhesion and gas barrier properties were significantly enhanced by incorporating relatively low amount (5 phr) of wollastonite into ENR without notable changes in mechanical properties. The proposed formulation demonstrated adhesion between the carcass and liner compound that is approximately eight times higher than existing butyl liner applications while achieving lower gas permeability than butyl rubber.