Plastic antioxidants are chemical compounds added to plastic materials to prevent degradation due to heat, light, and other environmental causes. They function by interacting with free radicals produced during the degradation process, inhibiting the chain reaction that leads to further degradation. Plastic antioxidants are found in a variety of plastic polymers such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene. They can be either primary or secondary antioxidants and are introduced throughout the production process. Primary antioxidants are supplied at greater concentrations and are effective in avoiding the early stages of degradation, whereas secondary antioxidants are provided at lower concentrations and are effective in preventing the latter stages of deterioration.