ABSTRACT In the aging of natural rubber (NR), ozone is a critical factor that initiates oxidative degradation, limiting service life. The acetone‐soluble matter (AS), containing phenolic and alcoholic antioxidants, is known to enhance NR's aging resistance. However, the specific mechanism by which AS mitigates ozone aging remains unclear. This study investigates the impact of AS on the network structure and thermo‐oxidative aging of both unvulcanized and vulcanized NR. Crosslinking density and Differential Scanning Calorimetry (DSC) analyses show that AS modifies the network, reducing crosslinking density from 1.21 × 10 −4 to 0.98 × 10 −4 mol cm −3 and lowering the glass transition temperature from −60.15°C to −61.60°C, indicating a plasticizing effect. Surface and mechanical tests confirm AS significantly improves ozone resistance. Adding 1 part per hundred rubber (phr) of AS extends crack initiation time by 67%, from 1586 to 2650 s, and increases tensile strength retention after aging from 76.51% to 90.21%. These results advance the understanding of how AS interacts with ozone at the molecular level to protect NR. The findings provide novel insights into ozone aging mechanisms and offer practical guidance for formulating more durable NR products, thereby extending their lifespan and promoting sustainable use in ozone‐prone environments.
Zheng et al. (Tue,) studied this question.