Description

Phenolic antioxidant coordination effect
1, synergistic effect

When two chain-terminating antioxidants such as hindered phenols and used, the high activity of the antioxidant gives hydrogen atoms, so that the free radicals are inactive; and low activity of the antioxidant can be for the high activity of the antioxidant supply of hydrogen atoms to regenerate it, so that the long-term effectiveness of the effectiveness of the antioxidant effect is better. Different spatial obstruction of the antioxidant when used in conjunction, but also inhibit the free radical transfer effect. For example, after the termination of peroxyl radicals (ROO・) by highly active hindered phenols, the aryloxyl radicals generated can easily trigger oxidative aging of macromolecules. The low activity hindered phenol can make the aryloxyl radicals to generate the high activity hindered phenol, thus avoiding the chain transfer effect caused by the interaction of aryloxyl radicals and macromolecules.

Hindered phenol and hydroperoxide decomposer and use, on the one hand, can make the main antioxidant regeneration, on the other hand, can decompose hydroperoxide, synergistic effect is stronger, is the current plastics antioxidant is often used in the ‘golden partner’, such as antioxidant 1010 and antioxidant 168 of the use of the antioxidant. The same molecule with two or more different stabilisation mechanisms and the synergistic reaction, known as self-synergistic effect. For example, the antioxidant 300 and the antioxidant 2246-S, simultaneously function as primary and secondary antioxidants.

In addition, the main antioxidant and ultraviolet absorber, metal ion passivator may also produce synergistic effect. Composite stabiliser of the main antioxidant for phenolic antioxidants, such as antioxidant 1010, antioxidant 1076, antioxidant 264, etc., the secondary antioxidant for the phosphite, antioxidant 168, the mainstream composite antioxidant varieties on the market are mostly imported products.

2, against the effect

Two kinds of antioxidants and with each other to weaken their beneficial effects, there is a confrontation effect, such as amines and phenolic antioxidants on polyethylene plastics is the main antioxidant is effective, carbon black is also very effective antioxidant, but when amines or hindered phenolic antioxidants added to the polyethylene containing carbon black, the two are not only no synergistic effect, but rather than the original stability of their respective effects are worse, that is, the antagonistic effect is produced. This antagonistic effect is not only related to the type of antioxidant, but also with the resin varieties also have a relationship, such as in ABS plastics and carbon black and hindered phenol, not only no antagonistic effect, but also showed a greater synergistic effect.

3, strong oxidation effect

When the concentration of antioxidant in the polymer system exceeds a certain value, the antioxidant directly with the molecular oxygen reaction increased, antioxidant molecules are prone to the formation of new free radicals and produce a strengthened oxidation reaction. Therefore, the general use of antioxidants have a critical concentration of the best use of the concentration range, otherwise the dosage is too much instead of producing a strengthened oxidation reaction, thereby accelerating the aging of polymers.