Investigation of solubility in plasticised rubber systems for tire applications

Oligomer resins and process oils are indispensable for rubber technology in order to achieve high-performance tyres on wet roads and ultralow energy consumption with acceptable manufacturability. This study investigates the solubility of oligomer resins, oils and elastomers using differential scanning calorimetry and describes its implication on rubber compound hysteresis loss. Owing to the configurational entropy of mixing, resin molecular weight strongly influences miscibility within binary resin/oil, ternary resin/oil/elastomer and filled rubber compounds. Similarity of chemical structure plays a role in miscibility linked to enthalpic effects. Among Hansen solubility parameters, the polar component correctly ranks the compatibility of resins with oils and elastomers. It has been shown that increased solubility among the resin-oil-elastomer system provides better balance of predicted rolling resistance and wet grip of tread compounds. Therefore, optimisation of rubber properties relies on the adequate selective use of process oils and resins according to their chemical structure and molecular weight.