What are the reasons for the aging of silicone rubber O-rings?

Some friends who use O-rings often complain about why the silicone rubber O-rings they use are so aged? They have not reached the service life under normal conditions at all! Why is this?

Rubber aging is very common in life, but if the aging is very serious, then you should pay attention, it may be your use method to deal with the problem.

In general, the aging of O-rings is related to 4 factors:

1. Ozone: The chemical activity of ozone is much higher than that of oxygen, and it is more destructive. It also breaks the molecular chain, but the effect of ozone on rubber varies with whether the rubber is deformed or not. When used on deformed rubber (mainly unsaturated rubber), cracks that are straight in the direction of stress action, the so-called "ozone cracks"; when used on deformed rubber, only an oxide film is formed on the surface without cracking.

2. Light: We all know that the shorter the light wave, the greater the energy. The damage to the miscellaneous silicone rubber parts is the high-energy ultraviolet rays. In addition to directly causing the rupture and cross-linking of the rubber molecular chain, ultraviolet rays can also cause the rubber to generate free radicals due to the absorption of light energy, triggering and accelerating the oxidation chain. reaction process. Secondly, direct sunlight will play a role in heating through external light. Another feature of the light effect is that it mainly grows on the surface of the oak.

3. Oxygen: Oxygen undergoes free radical chain reaction with rubber molecules in rubber, and the molecular chain is broken or excessively cross-linked, causing changes in rubber properties. Oxidation is one of the important reasons for rubber aging.

4. Heat: The increase in temperature will cause thermal cracking or thermal crosslinking of the rubber. But the basic effect of heat is activation. Improve the oxygen diffusion rate and activate the oxidation reaction, thereby accelerating the oxidation reaction rate of rubber, which is a common aging phenomenon - thermal oxygen aging.