Under low temperature conditions, the evaluation of the sealing performance of phenyl vinyl silicone (often referred to as phenyl silicone rubber or PVMQ) needs to consider multiple aspects, including its elasticity, crystallinity, glass transition temperature at low temperature, and the sealing effect in practical applications. The following is a detailed evaluation of the sealing performance of phenyl vinyl silicone under low temperature conditions:

I. Low temperature elasticity and crystallinity
Low temperature elasticity:
Phenyl silicone rubber can maintain good elasticity at low temperatures. This is due to the introduction of phenyl groups in its molecular chain. This large volume group can destroy the regularity of the polymer chain, thereby reducing the crystallization temperature and inhibiting the crystallization process. Therefore, phenyl silicone rubber is not easy to harden at low temperatures and can maintain good sealing performance.
According to research, the glass transition temperature (Tg) of phenyl silicone rubber is about -110℃, and there is no crystallization melting transition, which allows it to maintain elasticity at low temperatures and is conducive to sealing.
Crystallinity:
Phenyl silicone rubber has low crystallinity, which helps to maintain its elasticity at low temperatures. Compared with dimethyl silicone rubber and methyl vinyl silicone rubber, phenyl silicone rubber has a lower crystallization melting temperature and a slower crystallization rate. For example, the crystallization half-cycle of silicone rubber containing 8% to 10% methylphenylsiloxane chain segments at -78°C is 4000 minutes, while silicone rubber containing a higher phenyl content does not even crystallize at lower temperatures.

2. Sealing effect in practical applications
Sealing performance:
Under low temperature conditions, the sealing performance of phenyl silicone rubber mainly depends on its low temperature elasticity and adaptability to low temperature environments. Because it can maintain elasticity at low temperatures, it can fit tightly to the sealing surface to prevent gas or liquid leakage.
Especially at extremely low temperatures (such as liquid nitrogen temperature), phenyl silicone rubber can provide good sealing conditions, and its sealing performance can be maintained as long as it is not directly exposed to nitrogen for a long time.
Application examples:
Phenyl silicone rubber is widely used in aerospace, cryogenic engineering, refrigeration equipment and other fields. For example, in liquid nitrogen storage and transportation systems, phenyl silicone rubber seals can effectively prevent liquid nitrogen leakage and ensure the safe operation of the system.