In the process of long-term storage and use, rubber products will gradually become sticky, hard and brittle or cracked due to heat, oxygen, ozone, ionic mechanical stress of metal antioxidants, light, high-energy rays, and erosion of other chemicals and molds. This physical and mechanical properties decline over time, the phenomenon of reduced elasticity is called rubber aging.
The main factors affecting the aging of rubber are.
1, oxygen: oxygen in rubber with rubber molecules in the free base chain reaction, molecular chain breakage or excessive cross-linking, causing changes in rubber properties.
2, ozone: ozone chemical activity is much higher than oxygen, more destructive, it is the same molecular chain breakage, but the role of ozone on rubber with the rubber deformation or not and different.
3, heat: increase the temperature can cause thermal cracking or thermal cross-linking of rubber. But the basic role of heat or activation. Increase the rate of oxygen diffusion and activation of the oxidation reaction, thus accelerating the rate of rubber oxidation reaction, which is a prevalent aging phenomenon - thermal oxygen aging.
4、 Mechanical stress: under the repeated action of mechanical stress, the rubber molecular chain will be broken to generate free Tsuen, which will trigger the oxidation chain reaction and form a force chemical process. Mechanical breakage of molecular chains and mechanical activation of the oxidation process.
5, moisture: the role of moisture has two aspects: rubber in the humid air drenching or long-term immersion in water, easy to destroy, this is due to the water-soluble substances in rubber and hydrophilic groups and other components are water extraction dissolved, hydrolysis or absorption and other reasons.
6, oil: in the use of long-term contact with oil media, oil can penetrate into the internal swelling of rubber, resulting in the reduction of rubber strength and other mechanical properties.
7, other: the role of the rubber factors such as chemical media, variable metal ions, high-energy radiation, electricity and biology.