In the recycling systems of space stations (such as Tiangong Space Station) (including subsystems for electrolytic oxygen production, carbon dioxide reduction, and condensate treatment), the biggest challenge for seals is not simply high temperatures, but rather "zero failure throughout the entire life cycle," "ultra-low gas release," and "resistance to various media."

Phenyl vinyl rubber (hereinafter referred to as phenyl rubber) can solve this problem primarily due to its molecular structure's "three highs and one low" characteristics (high stability, high radiation resistance, high adaptability, and low gas release). The specific solution logic is as follows:

1. Solving the "vacuum gas release" problem (core pain point) The space station is a closed, manned environment. Any release of volatile organic compounds (VOCs) can contaminate the cabin air, endangering astronauts' health or corroding precision instruments.

* Problem: In a vacuum environment, the low molecular weight chains of ordinary silicone rubber break and escape (gas release), causing the material to become brittle and hardened, ultimately leading to seal failure.


* Solution for Phenyl Raw Rubber:
* Steric Hindering Effect of Rigid Phenyl Groups: Phenyl is a large, rigid group. When introduced into the main chain, it acts like a "windbreak," hindering the free rotation and thermal motion of the molecular chain. This significantly reduces the probability of chain breakage and the volatility of small molecules.

* Data Support: Research shows that phenyl silicone rubber with a specific formulation, when kept under vacuum (10⁻⁴ Pa) and 125°C for 24 hours, exhibits a total mass loss (TML) of <1% and condensable volatiles of <0.1%, far superior to ordinary methyl vinyl silicone rubber. This ensures "zero-pollution" sealing for 15 years or more in orbit.

2. Addressing Fatigue Failure under "Wide Temperature Range Alternating Cycles": The space station orbits the Earth every 90 minutes, experiencing a high-low temperature cycle (+120°C in sunlight, below -100°C in shadow).
* Problem: Ordinary rubber crystallizes and hardens (becomes brittle) below -70°C, causing the sealing ring to lose its elasticity during thermal expansion and contraction, resulting in leakage.
* Solutions for Phenyl Raw Rubber:
* **Inhibition of Crystallization:** The introduction of phenyl groups disrupts the regularity of the silicon-oxygen chains, making crystallization difficult. This allows phenyl raw rubber to have a brittle temperature as low as -110°C or even -120°C.
* **Long-lasting Elasticity:** At extremely low temperatures of -100°C, phenyl silicone rubber retains its flexibility and resilience. This means that the sealing ring can still maintain a tight seal after thousands of thermal cycles, without cracking due to brittleness.

3. Resisting Aging from Space Irradiation: Space stations are exposed to cosmic rays, high-energy particles, and atomic oxygen for extended periods.
* **Problem:** Irradiation can cause the main chain of ordinary rubber to break (degrade) or become over-crosslinked (hardened), leading to material pulverization.
* **Solutions for Phenyl Raw Rubber:**
* **Energy Absorption Properties of Phenyl Groups:** The benzene ring structure has conjugated large π bonds, which can absorb the energy of high-energy radiation and convert it into heat, thus protecting the fragile Si-O main chain. * Data Support: At radiation doses as high as 4.4 × 10⁴ rad, the tensile strength and elongation of phenyl silicone rubber exhibit extremely low changes (<5%), and the compression set change is also far lower than that of ordinary silicone rubber. This ensures that the seals will not harden and fail under strong radiation environments.

4. Compatibility with Complex Media in Regeneration Systems Regeneration systems involve water, oxygen, condensate from urine treatment, and even phosphorus-containing flame-retardant hydraulic oils.
* Problem: Ordinary sealing materials swell or degrade after prolonged contact with these media.
* Phenyl Raw Rubber Solution:
While the introduction of phenyl slightly reduces tolerance to non-polar oils, it exhibits excellent stability to polar media (such as water and alcohols) and oxidizing environments (pure oxygen atmosphere). This is crucial for sealing in high-pressure oxygen environments in electrolytic oxygen generation systems.

Conclusion: Phenyl vinyl raw rubber, through "phenyl modification" in its molecular structure, perfectly balances "flexibility" and "rigidity." It is not only the "lifeline" for sealing the hatches and windows of the Tiangong space station, but also the "stabilizing force" for sealing the pumps, valves and pipelines in the recycling system, ensuring that the oxygen and water for astronauts in space can be safely recycled, truly achieving "absolute safety".