Antioxidants are capable of delaying or inhibiting oxidative degradation of the material, it also belongs to a kind of stabilizer, a stabilizer is also one of the most widely used.
  1.Harm oxidation of plastic products. As we know, plastic products used for a long time in the air, even at room temperature, its quality will deteriorate. Taking PE as an example, if the product has been isolated from the air, heat to 290 degrees will be decomposed, the quality deterioration. For the majority of plastic varieties, in the manufacture, processing, storage and application process, have a certain degree of sensitivity to oxidative degradation, a small amount of oxygen can make these plastic product strength, appearance and performance change.
  In the oxidative degradation process, the oxidation reaction of plastic is an autocatalytic process, the initial stage of the reaction for hydrogen peroxide, and then decomposed into free radicals, it can generate a new free radical, go round and begin again the oxidation reaction is carried out according to the free radical chain reaction, so that the gradual decomposition of plastics.
  In addition, some variable valence metal ions, such as iron, copper, nickel, cobalt, they pass through the electron transfer can be catalytic decomposition of hydrogen peroxide. In the oxidation process, with the formation of peroxide in the polymer chain and other groups containing hydrogen, will produce a fracture of the macromolecular chain. And in the chain is broken, crosslinking, combined with the free radical can cause the polymer but, whether the chain or crosslinking, mechanical properties of plastics are serious deterioration.
  2.The mechanism of antioxidant. The mechanism of oxidation reaction of antioxidants is complex, generally have the following mechanism:
  Interrupt the chain reaction, as mentioned above, the oxidation reaction of plastics is a kind of chain chain reaction, if we can make this chain reaction interrupt, not the reaction go on, then, the oxidation reaction will not continue, plastic products will not harm from oxidation, mainly belonging to the oxidant such: Zhong Fang amine antioxidants, hindered phenolic antioxidants, quinone antioxidants, carbon black, tertiary amine. The decomposition of peroxide. In the plastic degradation process, peroxide is the autocatalysis therein, and antioxidant and peroxide combined into inactive products, auto inhibition catalysis of oxidant, belonging to this category are: phosphite ester, organic sulfides antioxidant.
  3.The passivation of metal ions. Some transition metal ion on the oxidation reaction of catalytic activity, accelerate the oxidation reaction, if we can put these transition metal ion complexation, they will be stable in a valence state, namely, passive, can weaken the extent of oxidation reactions. Belongs to the oxidant this category are: Double salicylidene two amine, amide and so on grass.