In the field of polymer materials, although both rubber and plastic are widely used basic materials, their antioxidant systems exhibit significant differences. The plastic industry generally adopts a classic combination of hindered phenols, phosphites, and thiodiesters, while rubber relies on specialized anti-aging agents such as BHT, IPPD, and 4010NA, and has derived special protection concepts like "internal anti-aging" and "external anti-aging". The root cause of this difference lies in the inherent disparities in their molecular motion states and failure mechanisms.
    Plastics are mostly in a glassy or semi-crystalline state during use, with molecular chain movement restricted, similar to "fixed wood". Their aging is a uniform, gradual degradation process initiated by heat or light, with the main threats coming from high processing temperatures and slow oxidation during static service. Therefore, the plastic antioxidant system focuses on "bulk stabilization", achieving long-term protection by allowing antioxidants to remain uniformly in the matrix and slowly scavenge free radicals and peroxides. Rubber, on the other hand, operates in a high-elastic state for a long time, with chain segments needing to withstand repeated dynamic deformations such as stretching and flexing, similar to "high-frequency moving rubber bands". Its failure is not overall uniform aging, but localized damage concentrated on the surface, defects, and crack tips. Ozone erosion and crack propagation induced by dynamic stress are the main threats. This requires rubber anti-aging agents to have continuous migration capabilities, constantly replenishing vulnerable areas from the interior to form a surface protective layer.
    In terms of material selection, plastic antioxidants tend to have high molecular weight and low diffusivity to avoid blooming, contamination and other issues caused by migration; rubber prefers amine-based anti-aging agents with moderate molecular weight and strong mobility. These substances can efficiently inhibit free radicals continuously generated under dynamic conditions and resist ozone erosion. Even with drawbacks such as discoloration and odor, they are still indispensable in most scenarios.
   The difference between the two antioxidant systems is not due to chemical formulations or industry traditions, but an inevitable result determined by the combined effect of molecular chain working states and failure mechanisms. Plastic antioxidant protection is a "stationary post" static defense, while rubber's is a "patrolling" dynamic defense. The two are respectively adapted to the service characteristics of the materials, ensuring their service life under different working conditions.

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