antiozonantantioxidant

An antiozonant antioxidant is a chemical compound added to materials, particularly polymers and rubber, to protect them from degradation caused by ozone. Ozone is a highly reactive form of oxygen that can attack the double bonds present in many polymer chains, leading to chain scission, cracking, and a loss of mechanical properties. Antiozonants work by scavenging ozone molecules before they can react with the polymer or by forming a protective layer on the surface of the material.

There are two main classes of antiozonant antioxidants: those that are consumed during the protection process and those that migrate to the surface to form a physical barrier. The former typically react with ozone through a chemical mechanism, effectively neutralizing it. These can be sacrificial, meaning they are used up in the process of protecting the polymer. The latter class, often referred to as migratory antiozonants, are designed to bloom to the surface of the rubber or polymer over time. Once on the surface, they can react with ozone or form a physical film that prevents ozone from reaching the polymer matrix.

Common examples of antiozonant antioxidants include derivatives of p-phenylenediamine (PPDs) and certain types of amines and phenolics. The choice of antiozonant depends on the specific polymer, the intended application, and the expected environmental conditions. For instance, applications exposed to high ozone concentrations or prolonged sunlight may require more robust antiozonant protection. These additives are crucial for extending the service life of many rubber products, such as tires, hoses, seals, and footwear.