1, the effect of heat, increase the temperature can cause the thermal cracking or thermal crosslinking of silicone rubber products. But the basic function of heat is activation. Increasing the diffusion rate of oxygen and activating oxidation reaction can accelerate the oxidation reaction rate of rubber, which is a universal aging phenomenon -- thermal oxygen aging.
3, the cause of light, the shorter the wave, the greater the energy. It is the high energy ultraviolet rays that damage the rubber. Uv can not only directly cause the break and crosslinking of rubber molecular chains, but also generate free groups due to the absorption of light energy, which can trigger and accelerate the oxidation chain reaction process. The external light acts as a heating agent. Another feature of the use of light (as opposed to heat) is that it is mainly produced on the surface of the rubber. The two sides of the sample with high glue content will appear mesh cracks, namely the so-called "outer light crack".
4, the role of ozone, ozone chemical reactive oxygen species is much higher, more destructive, it is also the molecular chain fracture, but the effect of ozone on rubber with rubber deformation or not and different. As for the deformation of rubber (mainly unsaturated rubber), and the stress direction of direct cracks, namely the so-called "ozone cracking"; When acting on the deformed rubber, only the surface of the oxide film is formed without cracking.
5, the role of water, the role of water has two aspects: silicone rubber products in the wet air rain or soak in water, easy to destroy, this is because the water-soluble substances in the rubber and water tsuen and other components were dissolved by water extraction. Caused by hydrolysis or absorption. Especially under the alternating action of water immersion and atmospheric exposure, the destruction of rubber will be accelerated. But in some cases, water on rubber has no damage effect, and even has the effect of delaying aging.
6, the role of mechanical stress, under the repeated action of mechanical stress, will make the rubber molecular chain break to generate free tsuen, lead to oxidation chain reaction, the formation of chemical process. Mechanical chain breaking and mechanical activation oxidation process. Which is dominant depends on the conditions in which it is present. In addition, it is easy to cause ozone cracking under the action of stress.
7, other reasons are chemical media, variable metal ions, high-energy radiation, electricity and biology.