The Leader Of Special Materials-The Application Of Phenyl Silicone Rubber In Advanced Manufacturing

In recent years, with the increasing requirements for material performance, people are more and more urgent for the research and development and application of new materials. In this context, phenyl silicone rubber, as a silicone rubber material with excellent performance, has attracted widespread attention and interest. The purpose of the development of phenyl silicone rubber is to meet the performance requirements under extreme conditions such as high and low temperatures, and play an important role in the fields of electricity, electronic appliances, automobiles, industrial deep refrigeration, aerospace, engines, etc. By introducing phenyl groups on the side groups of polysiloxane, methyl phenyl tricyclic bodies (A3), methyl mixed cyclic bodies (DMC) and vinyl cyclic bodies (VMC) are co-ring-opened and polymerized, and phenyl silicone rubber exhibits excellent durability and stability under high temperature environments, and can still maintain good elasticity and flexibility under low temperature environments. In addition, phenyl silicone rubber also has high electrical insulation properties, which makes it widely used in the fields of electricity and electronic appliances.

Main classification

Low phenyl silicone rubber

Low phenyl silicone rubber (phenyl content is 5-15%): This type of silicone rubber has good low temperature resistance and high damping characteristics. When the phenyl content is low, the curing temperature can be reduced to -115°C, so that it can still maintain flexibility and elasticity in extremely low temperature environments.

Medium phenyl silicone rubber

Medium phenyl silicone rubber (phenyl content is 15-25%): This type of silicone rubber has ablation resistance and flame retardant properties. The increase in phenyl content can enhance the rubber's ablation resistance and make it more flame retardant.

High phenyl silicone rubber

High phenyl silicone rubber (phenyl content is above 30%): High phenyl silicone rubber has excellent radiation resistance. As the phenyl content increases, the rigidity of the silicone rubber molecular chain increases, making it more resistant to radiation.

Working mechanism

High temperature resistance mechanism

The main chain of silicone rubber is composed of Si-O bonds, and its flexibility and easy curling enable silicone rubber to maintain stability at high temperatures. However, trace amounts of impurities (such as water, hydroxyl groups or residual catalysts) may cause degradation of the main chain, so the heat resistance of silicone rubber is affected by its structure and the nature and content of impurities. The high polarity of the Si-O bond makes it susceptible to attack by polar substances, thereby inducing thermal rearrangement degradation of the main chain. In addition, the oxidation of the side groups will further complicate the reaction process. In the processing of silicone rubber, white carbon black is usually required to enhance its performance. However, the active hydroxyl groups on the surface of silica and the moisture produced by the condensation of adsorbed water and hydroxyl groups will reduce the heat resistance of silicone rubber. In the synthesis process of silicone rubber, it is difficult to completely avoid residual catalysts, and these residues will also have a certain impact on the thermal stability of silicone rubber. Phenyl silicone rubber exhibits excellent heat resistance through its molecular chain structure and composition and sensitivity to impurities and residues, enabling it to operate stably in high temperature environments. This makes phenyl silicone rubber an ideal choice for many applications that require high temperature tolerance.

Cold resistance mechanism

At low temperatures, the thermal motion of rubber molecules is weakened, causing the molecular chain segments to be frozen and lose elasticity. Glass transition and crystallization transition are important processes that affect the cold resistance of rubber. Phenyl silicone rubber destroys the regularity of polydimethylsiloxane molecular chains by introducing phenyl to replace methyl, significantly reducing the crystallization temperature and crystallinity of the polymer, thereby reducing the crystallinity of the vulcanized rubber. In this way, phenyl silicone rubber can maintain elasticity at low temperatures, extending the upper limit of its low temperature working ability. The introduction of phenyl has two functions. First, it prevents the decomposition of silicone rubber side chain groups, thereby avoiding crosslinking or degradation of the main chain of the molecule. Secondly, the introduction of phenyl destroys the regularity of the polydimethylsiloxane molecular chain, reduces the crystallization temperature and crystallinity of the polymer, and improves the cold resistance of the vulcanized rubber. Methyl vinyl phenyl silicone rubber (phenyl silicone rubber) is a high molecular weight linear polysiloxane, which contains phenylsiloxane or methylphenylsiloxane chain segments in its main chain. Phenyl silicone rubber not only has the advantages of methyl vinyl silicone rubber, such as small compression water deformation, wide operating temperature range, aging resistance, shock resistance, moisture resistance and good electrical insulation performance, but also has excellent low temperature resistance, shock absorption, ablation resistance and radiation resistance. By introducing phenyl into the molecular structure, the regularity of the siloxane molecular structure is destroyed, thereby reducing the crystallinity of the polymer and improving its cold resistance.

Performance characteristics

★ Temperature resistance: Compared with the existing methyl vinyl silicone rubber, phenyl silicone rubber has a wider temperature resistance range, from -60℃-280℃ to -70℃-350℃. It can work for a long time at higher temperatures, and the short-term working temperature can even reach -110℃-400℃.

★Ablation and radiation resistance: Phenyl silicone rubber has excellent ablation and radiation resistance. In particular, high-phenyl silicone rubber shows excellent stability and durability when exposed to radiation.

★Cold resistance and flame retardant properties: Medium-phenyl silicone rubber has excellent cold resistance and flame retardant properties. It can maintain good elasticity at extremely low temperatures and has the characteristics of self-extinguishing when subjected to flames.

★Processing performance: Due to processing difficulties, the physical and mechanical properties of medium-phenyl and high-phenyl silicone rubbers are relatively poor, which has certain limitations in production and application.

★Effect of phenyl content on performance: The increase in phenyl content can increase the rigidity of silicone rubber molecules, thereby improving radiation resistance and flame retardancy. However, excessive phenyl content may also lead to processing difficulties and decreased physical and mechanical properties.

Main applications

Phenyl silicone rubber is widely used in the field of electronic appliances. It has advantages in manufacturing low-temperature and radiation-resistant parts, and is often used as sealing rings, gaskets and pipes for electronic components. Phenyl silicone rubber has important applications in the aerospace field. Due to its high temperature and radiation resistance, it is widely used in seals, gaskets and pipes of aerospace devices to ensure reliability in extreme environments. Phenyl silicone rubber is also widely used in the military field. Its low temperature resistance, high damping and ablation resistance make it a key choice for seals, gaskets, pipes and rods in military equipment.