(2) aging and returning to the original

Unlike vulcanized reversion, rubber grommets are not formed by sulphur, but are later found in storage or use. The factors that contribute to the aging of the original are from the outside world, including the use of high temperatures, long-term direct sunlight, continuous exposure to high-energy radiation. The underlying cause is also the cleavage of sulfur bonds in the crosslinked structure, leading to material degradation. Although the bond energy of the mono- and disulfide bonds is higher, it is still lower than the carbon-carbon bond, and it is easy to cause reversion under the action of external conditions.

For some rubber grommets, because of the lower vulcanization temperature, lower than 140 ° C, the risk of reversion is reduced, and the principle of aging is the main problem.

In this regard, white rubber grommets are a typical example. Especially the light-colored rubber grommet, the most likely to encounter aging and return to the original, the surface is sticky. Other household products, such as hot water bottles, are exposed to high-temperature hot water, and are often placed in the sun to dry after use. They are easily affected by heat and ultraviolet rays, and are easy to aging.

In summary, the essence of the reversion is that the cross-linking of vulcanizates is affected by external factors and the chain is degraded. In a broad sense, it can also be understood as the aging of vulcanized rubber under specific conditions.