Why is the rubber hose aging?

What is the reason for the aging of rubber hose? With regard to the aging of rubber hose, Wuxi Jinchun Rubber and Plastic Products Co., Ltd. analyzed it from seven aspects, as follows:
1.Oxygen
Oxygen in rubber reacts with rubber molecules in free radical chain, and the molecular chain breaks or over-crosslinks, resulting in changes in rubber properties. Oxidation is one of the important reasons for rubber aging.
2.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 the deformation of rubber. When it is used as rubber for deformation (mainly unsaturated rubber), cracks perpendicular to the direction of stress appear, which is called "ozone cracking"; When acting on deformed rubber, only oxide film is formed on the surface without cracking.
3.Heat
Increasing temperature can cause thermal cracking or thermal crosslinking of rubber. But the basic function of heat is activation. Increase the oxygen diffusion rate and activate the oxidation reaction to accelerate the oxidation reaction rate of rubber, which is a common aging phenomenon - thermal oxygen aging.
4.Light
The shorter the light wave, the greater the energy. The damaging effect on rubber is the high energy ultraviolet ray. In addition to the direct breaking and cross-linking of rubber molecular chain caused by ultraviolet radiation, rubber produces free radicals due to the absorption of light energy, which initiates and accelerates the oxidation chain reaction process. Ultraviolet light plays the role of heating. Another characteristic of light action (different from heat action) is that it mainly grows on the surface of oak. For the sample with high glue content, there will be network cracks on both sides, which is called "light outer crack".
5.Mechanical stress
Under the repeated action of mechanical stress, the rubber molecular chain will be broken to form free radicals, which will trigger oxidation chain reaction and form a mechanochemical process. Mechanical fracture of molecular chain and mechanical activation of oxidation process. Which can take advantage depends on its conditions. In addition, it is easy to cause ozone cracking under stress.
6.Moisture
The role of water is in two aspects: rubber is easy to be damaged when it is soaked in wet air or in water. This is because water-soluble substances and water groups in rubber are extracted and dissolved by water. Caused by hydrolysis or absorption. Especially under the alternating action of water immersion and atmospheric exposure, rubber damage will be accelerated. However, in some cases, water does not damage the rubber, and even has the effect of delaying aging.
7.Others
Factors affecting rubber include chemical media, variable valence metal ions, high-energy radiation, electricity and biology.