Ozone resistance of three natural antioxidants in solution polymerized styrene-butadiene rubber—Molecular simulation and experimental study

Rubbers containing a high number of unsaturated units face significant challenges due to ozone aging. In industrial production, p-phenylenediamines are commonly used as synthetic antiozonants to protect against ozone degradation. However, their potential adverse effects on human health and the environment are gradually being recognized. Experimentally selecting antioxidants is costly and subject to numerous restrictions. Consequently, developing a new strategy for efficiently screening eco-friendly antioxidants is crucial. This study involved a comparative analysis of three natural antioxidants and examined the factors influencing their ozone resistance through multi-scale molecular simulation methods. Subsequently, these antioxidants were incorporated into a solution polymerized styrene-butadiene rubber matrix. Their performance was experimentally validated and compared with the standard N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine control. Analysis of the properties and microstructure in the experiments revealed the following order of ozone resistance: α-tocopherol > sinapic acid > gallic acid. This ranking aligns well with the predictions of the simulations. This study aims to augment the understanding of the anti-ozone actions of antioxidants and to propose a novel method for designing new antiozonants.