Phenyl silicone rubber is the core material for solving the problem of rubber component hardening and failure in polar-orbiting satellites under extremely cold conditions of -100°C.

Its core logic for solving this problem lies in: by disrupting the regularity of the molecular chains, it inhibits crystallization, thereby pushing the "embrittlement temperature" threshold of rubber into the cryogenic range below -100°C.

The specific solution mechanism and application details are as follows:
1. Core Mechanism: Disrupting Regularity, Inhibiting Crystallization (Preventing Molecules from "Freezing")
Ordinary rubbers (such as natural rubber and dimethyl silicone rubber) harden and fail at low temperatures because their molecular chains are arranged very regularly. At low temperatures, the molecular chains will arrange themselves neatly like soldiers in formation, forming crystalline regions. Once crystallized, the rubber loses its elasticity and becomes brittle like glass.

The solution of phenyl silicone rubber is: Introducing "large-volume" phenyl groups: Introducing large-volume phenyl groups (-C6H5) onto the polysiloxane backbone.

Creating "steric hindrance": Phenyl groups are like a bunch of large boxes crammed into an orderly line, severely disrupting the regularity and compactness of the molecular chains.

Lowering the crystallization temperature: This "disorder" makes it difficult for the molecular chains to form a crystalline structure even at extremely low temperatures, thus maintaining the flexibility of the amorphous state.

2. Key Indicator: Breakthrough in Glass Transition Temperature (Tg)
For rubber materials, the glass transition temperature (Tg) is the "lifeline" for their low-temperature performance. When the temperature is below Tg, the rubber will transition from a highly elastic state to a glassy state (i.e., become hard and brittle).

Ordinary dimethyl silicone rubber: Tg is approximately -123℃ to -115℃. Although very low, there is still a risk of microcrystal precipitation when working for extended periods at -100℃.

Low-phenyl raw rubber (5%~10% phenyl content): By precisely controlling the phenyl content, its Tg can be further reduced, and the crystallization peak disappears.

Data Support: According to research, low-phenyl silicone rubber with specific formulations (such as grade MY3120) can achieve a Tg as low as -105℃, and its compression set at -70℃ still maintains a coefficient of thermal shock of approximately 0.49.

Result: This means that in the polar orbit environment at -100℃, it remains in a "highly elastic state," does not harden, and can maintain its sealing and cushioning functions.

3. Practical Application: Addressing "Cold Welding" and Sealing Failure
In polar orbit satellites, the failure of rubber components (mainly sealing rings and shock-absorbing pads) is not only due to "hardness" but also to "cold flow" or "loss of sealing force" caused by low temperatures.

Phenyl raw rubber solves these problems through the following characteristics: Extremely low compression set: After long-term compression at -100℃, ordinary rubber may "flatten and not return to its original shape," leading to sealing failure. Phenyl raw rubber has excellent resilience, ensuring sealing contact stress.

Resistance to space radiation: Polar orbit satellites are also bombarded by high-energy particles from Earth's radiation belts. High-phenyl-content raw rubber (though slightly less resistant to low temperatures, but with excellent radiation resistance) or blended modified raw rubber can prevent molecular chain breakage (degradation) or cross-linking (hardening) caused by radiation in a vacuum.

Coping with thermal expansion and contraction: Satellites repeatedly switch between shadowed (-100℃) and sunlit (+100℃) zones. Phenyl raw rubber, with its extremely wide operating temperature range (-100℃ ~ 250℃), can withstand such intense thermal cycling without aging or cracking.

In summary, phenyl raw rubber's solution to the -100℃ hardening problem is essentially a molecular-level "space battle." It utilizes the large volume characteristic of phenyl groups to forcibly expand the molecular chains, preventing them from "clustering and crystallizing" at low temperatures, thus allowing the rubber to remain "flexible" even in the extreme cold of polar orbit.