Phenyl silicone rubber is a high-molecular material modified by introducing phenyl groups into the main chain of polysiloxane. The content of phenyl groups in its molecular structure directly affects its performance. This material, with its unique molecular design, demonstrates significant advantages in extreme environments, but also has certain limitations.

Core Advantage
Thermal resistance performance exceeds conventional limits: The low phenyl type (with a phenyl content of 5-15%) exhibits excellent low-temperature resistance, with a glass transition temperature as low as -115°C, remaining flexible and elastic even at -100°C; The high phenyl type (with a phenyl content of over 30%) demonstrates outstanding high-temperature resistance, capable of withstanding short-term working temperatures of up to 400°C and maintaining a stable long-term use temperature of 350°C. This wide temperature range characteristic makes it a key material for aerospace engine seals and polar scientific research equipment.

Radiation resistance and ablation resistance are both enhanced: The high phenyl structure significantly improves radiation resistance by increasing the rigidity of the molecular chains, and can withstand 2.58×10⁸ roentgen gamma radiation without performance degradation. The medium phenyl type (with a phenyl content of 15-25%) has self-extinguishing properties, forming a carbonized layer in flames to prevent the spread of combustion, suitable for high-temperature ablation environments such as rocket engine nozzles.

Excellent electrical insulation and sealing performance: Its electrical insulation strength reaches 20-40 kV/mm, performing well in high-voltage cable sheaths and sealing of electronic components. At the same time, the compression permanent deformation rate is controlled at 30%-60%, ensuring long-term sealing reliability.

Performance limitations
Processing difficulty conflicts with mechanical properties: The introduction of phenyl groups leads to an increase in the rigidity of the molecular chain, resulting in a tensile strength of only 5-12 MPa for medium-high phenyl type vulcanized rubber, with a fracture elongation rate of 150%-500%, which is lower than that of methyl vinyl silicone rubber. During processing, the sulfurization temperature and time must be strictly controlled; otherwise, bubbles or cracking may occur.

Weather resistance and wear resistance are limited: The double bonds in phenyl groups are prone to ultraviolet oxidation, and long-term outdoor use will result in cracking; the softness of the siloxane group makes its wear resistance poor. It needs to be combined with reinforcing fillers in high-frequency vibration scenarios.

Cost and process complexity: The purification of methyl phenyl cyclosiloxane is difficult, and the viscosity surges in the later stage of ring-opening polymerization, resulting in insufficient supply of high-quality products in China, which limits its popularization in civilian fields.

Phenyl silicone rubber has achieved extreme environmental adaptability through molecular structure regulation, but its performance optimization still requires continuous breakthroughs in processing techniques and material modification. The application value of this material in cutting-edge fields such as national defense and aerospace is driving high-performance exploration in polymer science.

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