People will get old and rubber will age. After the rubber products are used for a long time, some will become soft and sticky, and some will harden and become brittle. In this case, the original elasticity and strength of the rubber are remarkably lowered, and cracking, chalking, discoloration, and mildew are also caused. Aging is the result of changes in the rubber structure under the influence of various external factors, the most common of which is the thermal aging of heat and oxygen.
Oxidation is one of the important reasons for rubber aging. Oxygen undergoes a free radical chain reaction with rubber molecules in the rubber, and the molecular chain is broken or excessively crosslinked, causing a change in rubber properties. Ozone is much more chemically active than oxygen and is more destructive to rubber.
Increasing the temperature also causes thermal cracking or thermal crosslinking of the rubber, but the basic effect of heat is activation. Increasing the rate of oxygen diffusion and activating the oxidation reaction to accelerate the oxidation reaction rate of the rubber is a ubiquitous phenomenon of thermal oxygen aging. Ultraviolet rays also have a destructive effect on rubber. In addition to directly causing the breakage and cross-linking of rubber molecular chains, rubber absorbs light energy to generate free radicals, which initiates and accelerates the oxidation chain reaction process. In addition, mechanical stress, moisture, chemical media, variable metal ions, high energy radiation, electricity and biology can also age the rubber.
Although the aging of rubber can not be completely avoided, it can be delayed. The most convenient and effective measure is to add anti-aging agent. The anti-aging agent can capture the active substances generated during the thermal aging of the rubber, thereby protecting the rubber.