Rubber sheet has high hardness and general physical and mechanical properties. It can work in air with low pressure and temperature of 20 +140.
Here are the factors that affect the ageing of rubber sheets
1. Mechanical stress. Under the repetitive effect of mechanical stress, the rubber molecular chain will crack to form free radicals, which will trigger the reaction of the oxidation chain and form a mechanochemical process. Mechanical cracking molecular chains and mechanical activation oxidation process. Which one can dominate depends on the conditions under which it is located. In addition, ozone cracking is simply caused by stress effect.
2. Oxygen and oxygen react with rubber molecules in free radical chains, and molecular chains crack or cross-link excessively, resulting in the change of rubber function. The oxidation effect is one of the important reasons for rubber aging.
3. Heat. Advanced temperature can lead to thermal cracking or crosslinking of rubber. But the fundamental effect of heat is still activation. It is a ubiquitous aging phenomenon that the rate of oxygen dispersion and activation oxidation reaction are improved, and then the rate of rubber oxidation reaction is accelerated.
4. The chemical activity of ozone is much higher than that of oxygen and its damage is more serious. It also causes cracking of molecular chains. However, the effect of ozone on rubber varies with rubber deformation or not. When the rubber is deformed (mainly unsaturated rubber), there is a crack in the direction of stress effect, which is called "ozone cracking". When the rubber is deformed, only oxide film is formed on the surface without cracking.
5. Water. The effect of water has two aspects: when rubber is wet in the air, raining or immersed in water, it is simply damaged, because water-soluble substances and water-soluble groups in rubber are extracted and dissolved by water. Caused by hydrolysis or absorption. Especially under the replacement effect of water immersion and air exposure, the damage of rubber will be accelerated. However, under certain conditions, moisture has no damage effect on rubber, and even has the effect of delaying aging.
6. Light. The shorter the light wave, the greater the energy. The rubber is damaged by high energy ultraviolet radiation. In addition to the fact that ultraviolet radiation can directly lead to the cracking and crosslinking of rubber molecular chains, free radicals occur in rubber due to the absorption of light energy, which triggers and accelerates the reaction process of the oxidation chain. Ultraviolet light acts as a heating effect. Another feature of the light effect (which is different from the thermal effect) is that it mainly comes from the appearance of the rubber. The specimens with high gum content exhibit reticular cracks on both sides, which are called "optical outer spallation".
7. Other factors affecting rubber include chemical media, variable valence metal ions, electricity and biology.