1. Thermo-oxidative aging
Natural rubber (NR), ethylene propylene rubber (EPM, EPDM), styrene-butadiene rubber (SBR), butyl rubber (IIR), silicone rubber (NVQ), etc. used for capacitor sealing are all thermally oxidized during use. of this form. Because NR contains a large number of unsaturated double bonds, under the combined action of heat and oxygen, the vulcanizate will undergo a degradation reaction, cracking and breaking of molecular chains and cross-linking bonds, resulting in aging.
2. Ozone aging
The content of ozone in the atmosphere is extremely low. During the aging process of rubber, ozone attacks the rubber molecules and expands the rubber, causing cracks on its surface. Ozone reacts with the double bonds in the rubber molecules to form molar ozonides and peroxides, which in turn form ozonides. The ozonide is decomposed into free radicals under the action of light, heat, etc., resulting in a chain growth reaction. In addition, the rubber will produce molecular breakage under the action of stress, without generating ozonide, and the phenomenon of cracking and aging will appear.
3. Fatigue and aging
The fatigue aging of rubber refers to the aging phenomenon that the molecular structure of the rubber material changes under the action of a certain frequency and cyclic stress. It is the result of the activation of two main factors, namely force and heat (due to When the rubber is deformed for many times, a hysteresis phenomenon occurs, which makes the internal heat of the rubber).
