Vinyl silicone oil and methyl vinyl silicone rubber (raw rubber) are prone to yellowing after being stored for a period of time. This is due to the high temperature oxidation of vinyl in the air. In addition, raw materials D4 or DMC are impure, and many impurities will also yellowing. Here are some solutions to solve the yellowing of vinyl silicone oil and raw rubber.

1. The reaction temperature should not be too high, and the average batch production should not exceed 160 ℃.
2. The vacuum degree of the reactor must be good, not to mention the absolute pressure of at least 99%, and nitrogen protection.
3. The quality of vinyl end capping agent or ring is better, and Cl ion and impurity end capping agent must be controlled below dozens of ppm.

Water content is related to polymerization, but does not affect yellowing. H2O is equivalent to end capping agent, and 107 glue is added to the product at most. The lower the viscosity or the higher the vinyl content, the easier the yellowing is. The yellowing problem can be controlled by doing the above three points. In addition, antioxidant can be added to increase the yellowing resistance.

For vinyl silicone oil, please check the details:
https://www.htvsilicone.com/product-side-chain-type-vinyl-silicone-oil-iota272.html