The protection provided by phenyl raw rubber (usually referring to phenyl vinyl silicone rubber) during spacecraft reentry is not simply about "withstanding" the high temperatures like a shield, but rather through a mechanism of "sacrificing itself to carry away heat."

In short, its core solution can be summarized as: utilizing the breaking and sublimation of chemical bonds to absorb and carry away enormous kinetic energy (heat).

The specific solution path and mechanism are as follows:
1. Core Mechanism: Ablation and Heat Absorption ("Ignition and Exhaustion")

When a spacecraft plunges into the atmosphere at extremely high speeds, the air is violently compressed and subjected to friction, generating aerodynamic heating of up to 2000℃-3000℃.

The key to phenyl raw rubber's solution as the matrix resin for heat-resistant materials lies in the phenyl group in its molecular structure:

Low Chemical Bond Energy: Compared to ordinary methyl silicone rubber, the Si-C and C-C bonds in the phenyl raw rubber molecular chain have lower bond energies.

Preferential Breakage: Under high-temperature impact, these bonds will preferentially break and fracture.

Endothermic Reaction: The breaking of chemical bonds is a strongly endothermic process, absorbing a large amount of external heat energy, thus preventing heat conduction into the spacecraft's interior.

2. Physical Morphology Transformation: Carbonized Layer and Foamed Layer ("Self-Sacrificing Armor")
Phenyl rubber undergoes physical morphology changes during heating, forming a multi-layered protective structure:

Surface Carbonization: The material's surface rapidly oxidizes and dehydrogenates at high temperatures, forming a dense, hard carbonized layer. This carbonized layer acts like "armor," although it is itself a product of ablation, it isolates oxygen, preventing further oxidation and ablation of the internal materials.

Internal Foaming: During thermal decomposition, the material's interior produces a large amount of non-combustible gases (such as methane and hydrogen), causing the material's interior to expand and form a porous carbonized layer or foamed layer.

Low thermal conductivity: This foam structure, filled with still air (or inert gas), has extremely low thermal conductivity (as low as 0.1 W/(m·K)), making it an excellent thermal insulation layer.

Thermal barrier: This "bubble" effectively blocks heat conduction to the interior of the capsule, ensuring the internal temperature of the reentry capsule remains below 40°C, protecting the safety of astronauts and equipment.

3. Synergistic effect of the material system ("composite team"): Pure phenyl rubber cannot withstand such an extreme environment. It is usually used as a matrix in combination with reinforcing materials to form a "team":
Reinforcing skeleton: Usually doped with fillers such as quartz fibers and glass microspheres.

Honeycomb structure: In practical applications, the phenyl silicone rubber matrix is filled in a honeycomb grid (usually phenolic resin reinforced with quartz fiber cloth).

Synergistic effect: Phenyl rubber is responsible for softening, flowing, and carbonizing to absorb heat at high temperatures; quartz fibers provide mechanical strength, preventing the material from being blown away by high-speed airflow, ensuring the structural integrity of the thermal insulation layer during ablation. In summary, the solution to high-temperature ablation using phenyl raw rubber is essentially a form of "consumable thermal protection." It utilizes the pyrolysis and heat absorption properties of the phenyl structure at high temperatures. Through the pyrolysis, carbonization, and foaming of the material itself, it converts aerodynamic heat energy into chemical energy and gas kinetic energy (which is carried away), forming a low thermal conductivity insulating carbon layer on the spacecraft surface, thus protecting the spacecraft itself.