The Reasons for the Aging of Rubber Seals
Rubber seals are widely used in the valve sealing, for their excellent properties such as waterproof, flame retardant, high temperature resistance, electrical conductivity, wear resistance and oil resistance. Rubber seals, as indispensable fittings for seal valves such as forged bellow seal valves, also meet EU environmental protection standards.
Four main reasons for the aging of rubber seals are as follows:
1. Ultraviolet Light
The high energy of ultraviolet light will damage the rubber seal by initiating and accelerating the oxidation chain reaction process. For those with high gel content, there will be reticular cracks on both sides, so-called "outer layer cracking".
The chemically active oxygen of ozone is much higher and more destructive. It also breaks the molecular chain of rubber, but the effect of ozone on rubber varies with the deformation of rubber. When Ozone acts on the rubber with deformation (mainly unsaturated rubber), there will be a crack which is straight in the direction of stress, that is, "ozone cracking"; when it acts on a undeformed rubber, only an oxide film is formed on the surface without cracking.
There are two aspects to the effect of moisture: silicone rubber products are easily destroyed when exposed to humid air or when immersed in water. However, under certain circumstances, moisture does not have a destructive effect on rubber, and even has the effect of delaying aging.
4. Mechanical Stress
Under the repeated action of mechanical stress, the rubber molecular chain will be broken to form free enthalpy, which will initiate the oxidative chain reaction and form a force chemical process. In addition, it is easy to cause ozone cracking under stress.