There are two main types of antioxidants used in plastics primary and secondary antioxidants. Primary antioxidants, such as hindered phenols and phosphites, work by scavenging free radicals produced during the initial stages of oxidation. This action prevents the propagation of oxidative reactions, thereby extending the life of the material. Secondary antioxidants, like aromatic amines, function by stabilizing hydroperoxides, which are byproducts of the oxidation process, effectively interrupting the chain reaction that leads to further degradation.