Why do silica gel products become dirty with the increase of use time?

With the increase of the use time of silicone products, we often find that some silicone products become yellow, hard and brittle. Why do they become dirty?To understand why, we must briefly understand the production process of silicone products.Silicone products require refining raw materials, molding, post processing, and other process, the raw material of refining process, in order to make the silicone products to better production and curing, will add some sulfide, the sulfide with the passage of time, gradually will react with oxygen in the air, will appear yellow become dirty.

General yellow brittle silica gel products, it is almost difficult to restore the original appearance, that is, we usually say that the product aging, the length of time it takes to change color and add sulfide, and the number of factors related to the production process.