A few things to form a rubber O type of aging

(A) oxygen: oxygen free radical chain reaction in the rubber O ring with rubber molecular chains, cracking or excessive crosslinking, resulting in changes of rubber O ring function. Oxidation is one of the important reasons for the aging of rubber O ring.
(B) ozone: the chemical activity of ozone is much higher than that of oxygen, the damage is greater, it is also the molecular chain cracking, but the effect of ozone on the rubber is not the same with the deformation of the rubber. As for the deformation of the rubber (mainly unsaturated rubber), crack and stress direction, the so-called "ozone cracking"; effect on the deformation of the rubber, only surface oxide film without cracking.
(C) heat: the forward temperature can cause the thermal cracking or thermal crosslinking of the rubber O ring. But the fundamental role of the heat is still activated. Forward speed and activation of oxygen and lax oxidation reaction, and then accelerate rubber oxidation reaction speed, which is a widespread phenomenon of aging - hot oxygen aging.
(D) light: the shorter the light, the greater the energy. The rubber O damage is circled high energy ultraviolet. In addition to the direct cause of the cracking and crosslinking of the rubber molecular chain, rubber absorbs light energy and free radicals, which can lead to and accelerate the process of oxidation chain reaction. The heating effect is played by the outside light. The other characteristic (not the same as the heat effect) is the effect of light on the surface of the oak. With high adhesive rate of the sample, both sides will be a net crack, which is called "light outer crack".