What is the purpose of adding antioxidants to polymers?

The purpose of adding antioxidants to polymers is to prevent or slow down the degradation of the polymer caused by oxidation. Oxidation is a chemical reaction that occurs when polymers are exposed to oxygen, heat, light, or other environmental factors. This reaction can lead to chain scission (breaking of polymer chains), crosslinking (formation of bonds between polymer chains), discoloration, embrittlement, and loss of mechanical properties. Antioxidants protect the polymer by reacting with free radicals, which are highly reactive species that initiate and propagate the oxidation process. Antioxidants can be classified as primary antioxidants, which are radical scavengers that directly react with free radicals, or secondary antioxidants, which decompose hydroperoxides, another type of reactive intermediate formed during oxidation. By preventing or slowing down oxidation, antioxidants extend the service life of the polymer, maintain its desired properties, and prevent premature failure. Without antioxidants, polymers would degrade much more quickly, limiting their applications and increasing the need for replacement.