The service life of rubber seal ring is usually affected by mechanical force, oxidation and ozonation. In general, the rubber seal ring becomes brittle, the fatigue crack growth is accelerated, and the life of rubber seal ring will be reduced by reducing the critical fracture energy. The specific factors of rubber seal ring life mainly include the following aspects:
Aging will cause mechanical cracking reaction under the action of mechanical force: due to the viscosity of polymer, the relaxation process of rubber is not completed in the deformation cycle, and then enters the next deformation cycle, which makes the residual stress in the rubber seal ring increase continuously. When the stress gradient is large, it will lead to the direct fracture of rubber molecular chain and the formation of free radicals, which will lead to the oxidation chain reaction of rubber and aging under the action of oxygen.
Aging will activate the oxidative cracking reaction of mechanical force: when the rubber sealing ring is repeatedly deformed in the process of sealing, its mechanical stress will weaken the atomic valence force in the rubber molecular chain, thus reducing its activation energy of oxidative reaction. The reduction of the activation energy of oxidation makes the oxidative cracking of rubber chains easier and plays an accelerating role.
The internal heat generation of rubber sealing ring accelerates the oxidation reaction: when the rubber sealing ring is deformed repeatedly, it will lag behind and cause internal friction, which makes the internal heat generation of rubber, which further accelerates the oxidation chain reaction and aging of rubber.
Ozone cracking of rubber sealing ring: during the aging process of periodic deformation of rubber sealing ring, ozone cracking occurs, which is more significant under high temperature.
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