The antioxidant activity of amines used in plastic mastermind is generally higher than that of phenolic compounds, so they should have better antioxidant performance. However, amines will change color under the action of oxygen and light in the air, and they are mostly colored and toxic, so they are not often used in the plastic industry.
The synergistic effect should be paid attention to in the application of antioxidants. The following rules can be roughly followed:
1. The combination of main and auxiliary antioxidants can produce the strongest synergistic effect.
2. Inter-use of main antioxidants is a combined system of free radical collectors with the same antioxidant mechanism but different activities.
The principle is that H atoms on a weak free radical collector are constantly transferred to a strong free radical collector, so that the concentration of H atoms on the latter remains unchanged in the oxidation process, and the antioxidant effect of the free radical collector can be fully exerted.
3. Antioxidant and carbon black.
The efficiency of most amines and phenolic antioxidants decreased significantly in the presence of carbon black, which may be caused by carbon black directly catalyzing the oxidation of antioxidants and increasing the rate of antioxidant consumption.
The synergistic effect of sulfur ether bond on carbon black is also related to the special chemical structure of carbon black.
4. Antioxidant and ULTRAVIOLET absorber are used together. It is a stable system of light resistance, heat resistance and oxygen aging.
UV absorbers are used to eliminate the active products formed by antioxidants during light exposure to protect the sulfide from decomposition.