subject: The Factors Of Rubber Aging [print this page] During the processing, storing and using of rubber and rubber products, owing to the combined action of inside and outside factors, the physicochemical property and mechanical capacity of rubber will break up gradually and then lose its use value. This changing called rubber aging. The appearance shows the phenomenon of tacky, harden, soften, and color changing and so on.
Here are some factors that may cause the aging of rubber and rubber products.
1.Oxygen
Oxidation is the most important reason caused the aging of rubber. Oxygen will have free radical chain reaction with rubber molecule. The molecular chain will break or exceed crosslink. This will cause the changing of rubber performance.
2.Ozone
The chemical activity of ozone is higher than oxygen and the destructive effect is larger. The ozone also will make molecular chain broke. However the effect condition is different according to the transformation of rubber. When used for untransformative rubber, there will be ozoneinducedcracking. When used for transformative rubber, there will only have oxidation film on surface.
3.Hot
The temperature improvement will arouse the thermal cracking or hot crosslink of rubber, but the main function of hot is activation. Improving oxygen diffusion velocity and activate oxidizing reaction, to speed up the oxidizing reaction speed of rubber. This is a common ageing phenomenon Thermal aging.
4.Light
The light which can destroy the rubber is ultraviolet rays with high energy. The ultraviolet ray can directly cause the break of rubber molecule chain. Besides, the rubber will have free radical because of absorb light energy.
5.mechanical stress
Under repeated affect of mechanical stress, oxidation chain reaction will be caused. Under the stress function, ozoneinducedcracking will more easily to be caused.
6.Moisture
The impact of moisture has two sides. Rubber is easier to be destroyed in damp air or soaked in water. While under a special condition, moisture will not do harm to rubber, even has a function of put off aging.
7.Oil
During using, if the rubber products contact with oil medium for a long time, the oil material will enter into rubber and low strength and other performance of rubber.
8.Other factors
Besides the above factors, there are other factors, like chemical mediator, high-energy radiation, electric and organisms and so on, play important roles in aging of rubber.
