Factors that cause rubber aging

A) Oxygen: oxygen in rubber with rubber molecules free base chain reaction, molecular chain fracture or excessive crosslinking, causing rubber properties change. Oxidation is one of the important reasons for rubber aging.
B) Ozone: Ozone chemical reactive oxygen is much higher, more destructive, it is the same to break the molecular chain, but the effect of ozone on rubber varies with rubber deformation or not. When used as a rubber for deformation (mainly unsaturated rubber), cracks appear in the direction of direct stress action, that is, the so-called "ozone cracking "; When acting on the deformed rubber, only the surface of the oxide film is formed without cracking.
C) Heat: Increasing the temperature can cause thermal cracking or thermal crosslinking of rubber. But the basic function of heat is activation. Increasing the oxygen diffusion rate and activation oxidation reaction, thereby accelerating the rubber oxidation reaction rate, which is a universal aging phenomenon - hot oxygen aging.
D) Light: The shorter the light wave, the more energy. The damaging effect on rubber is the high energy ultraviolet light. In addition to directly causing the break and crosslinking of rubber molecular chains, ultraviolet rays can produce free groups due to the absorption of light energy, triggering and accelerating the oxidation chain reaction process. The external light acts as a heating agent. Another characteristic of the use of light (as opposed to heat) is that it is mainly produced on the surface of the rubber. The sample with high rubber content will have a network crack on both sides, that is, the so-called "optical outer crack ".
E) Mechanical stress: Under the repeated action of mechanical stress, the rubber molecular chain will be broken to generate free tsuen, which will trigger oxidation chain reaction and form a mechanochemical process. Mechanical breakage of molecular chains and mechanical activation and oxidation processes. Which will prevail depends on the conditions in which it is situated. In addition, it is easy to cause ozone cracking under the action of stress.
F) Moisture: The role of moisture has two aspects: When rubber is rained in wet air or soaked in water, it is easy to destroy, which is due to the water-soluble substances in rubber and water Tsuen and other components are 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. However, in some cases, the moisture does not damage the rubber, and even has the effect of delaying aging.
G) Other: The action factors on rubber are chemical media, variable metal ions, high-energy radiation, electricity and biology