How do antioxidants inhibit the rate of thermal oxidation
Antioxidants are mainly used in plastic resins to delay their thermal oxidative degradation. Due to the effect of heat, oxygen and other factors, plastic polymer will have different degrees of degradation, so we will choose to add antioxidant in the process of plastic resin synthesis and post-treatment, so as to effectively delay the degradation of resin and products or thermal oxygen aging.
According to the molecular structure and action mechanism, the commonly used plastic antioxidants are generally divided into five types: hindered phenolic antioxidants, phosphite antioxidants, thio antioxidants, composite antioxidants and hindered amine antioxidants. The thermal oxidation reaction rate of plastic resins is different due to different molecular structures, polymerization processes, processing technologies, and service environments and conditions There is a great difference between the degree of oxidation and the resistance to thermal oxidation.
Hindered phenol antioxidant is the main antioxidant of plastic materials. Its main function is to react with oxidation free radicals in plastic materials and interrupt the growth of active chain. Hindered phenolic antioxidants can be divided into monophenol, bisphenol, polyphenol and azacyclic polyphenol according to their molecular structure. Their application varieties and addition amount are mainly determined by the molecular structure of plastic resin, polymerization process, processing conditions and product use. Degradation directly has a negative effect on the physical properties, mechanical properties, appearance color and use function of the resin and its products.
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