essential information:

Nano ceria, also known as nano ceria, CAS #: 1306-38-3

Silicone rubber mainly undergoes thermal rearrangement degradation of the main chain in a high-temperature, sealed, and oxygen free state, that is, a depolymerization reaction, which makes the product soft (or softened), resulting in the loss of mechanical strength and its value in use. Under high-temperature and aerobic environmental conditions, the oxidation of polymer side groups mainly occurs, forming alkyl radicals. The coupling reaction of free radicals leads to an increase in the density of sealed cross-links, causing the product to gradually harden and even crack (known as hardening).

Adding cerium oxide to silicone rubber can prevent the oxidation crosslinking and main chain cyclization degradation of polysiloxane side chains. It can prevent free radical reactions caused by oxidation in silicone rubber within a certain temperature range, and can regenerate under the action of O2 in the air; By absorbing trace amounts of acids or alkaline substances that can catalyze degradation reactions in silicone rubber, it provides thermal stability for silicone rubber.

At the same time, the special electronic structure of cerium oxide (the electron layer is not fully filled) makes it easy to form complexes, which inhibit the swelling of rubber in solvents by preventing the chain movement of rubber molecules, thereby improving the oil resistance of rubber.

The addition of cerium oxide to the Key Laboratory of Rubber and Plastic Materials and Engineering at Qingdao University of Science and Technology has a relatively small impact on the mechanical properties of silicone rubber, but it can improve the heat resistance of silicone rubber and significantly improve its oil resistance. The optimal dosage of cerium oxide is 5 parts. According to thermal analysis, compared with the silicone rubber without ceria added, the peak thermal decomposition temperature of silicone rubber with 10 parts ceria added in nitrogen environment increased by 13 ℃. In the first stage of air, the peak thermal decomposition temperature increased by 2518 ℃, and in the second stage, it increased by 911 ℃, indicating that ceria has a thermal stabilization effect on silicone rubber.

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