Methyl phenyl vinyl silicone rubber

Methyl phenyl vinyl silicone rubber is a product obtained by introducing methyl phenyl silicone chain segments or diphenyl silicone chain segments into the molecular chain of methyl vinyl silicone rubber.

Introducing phenyl groups to the side groups of polysiloxane destroys the regularity of the dimethylsiloxane structure, greatly reduces the crystallization temperature of the polymer, and expands the low-temperature application range of the polymer material. Therefore, in addition to the small compression permanent deformation, wide operating temperature range, antioxidant, weather resistance, shockproof, moisture-proof and good electrical insulation properties of methylphenyl vinyl silicone rubber, methylphenyl vinyl silicone rubber also has excellent Low temperature resistance, ablation resistance and radiation resistance. These properties vary with the phenyl content in the molecular chain. Generally speaking, the phenyl content (ratio of phenyl to silicon atoms) is between 5 and 10%. It is sometimes called low phenyl silicone rubber. It has unique cold-resistant properties and can still maintain the elasticity of rubber at -70~-100℃. It is the best low-temperature performance among all rubbers. In addition, it also contains methyl vinyl silicone. Due to the advantages of rubber and its low cost, there is a strong trend to replace methyl vinyl silicone rubber. When the phenyl content is 20 to 40%, it is called medium phenyl silicone rubber. It has excellent flame resistance and can self-extinguish once it catches fire. When the phenyl content is 40 to 50%, it is called high phenyl silicone rubber. It has excellent radiation resistance, and its gamma-ray resistance is 1xI08 roentgen. Generally speaking, as the phenyl content increases, the rigidity of the silicone rubber molecular chain gradually increases, and the low-temperature resistance of silicone rubber gradually decreases. However, as the phenyl content increases, the flame resistance and radiation resistance of the vulcanized rubber are improved. Illumination.

Methyl phenyl vinyl silicone rubber is one of the important materials in the aerospace industry, cutting-edge technology and other sectors of the national economy. It can be used to make various molded and extruded products and is used as cold-resistant rubber in the aviation industry and for ablation resistance, Seals, gaskets, pipes and rods for heat-aging or radiation-resistant parts.

Fluorosilicone rubber refers to γ-trifluoropropylmethylpolysiloxane. Fluorosilicone rubber has excellent resistance to chemicals, solvents and lubricants. This kind of silicone rubber has a small expansion rate in non-polar solvents, good cold resistance and thermal stability, and good fire resistance, so it is used in aircraft. , rockets, missiles, space flight, petrochemical industry, used as hoses, gaskets, sealing rings, fuel tanks, etc. in contact with fuel oil and lubricating oil. It can also be used to make corrosion-resistant clothes, gloves, coatings, adhesives, etc. .

Since the side chain of the polymer molecule contains β-nitrile ethyl or γ-nitrile propyl strong polar groups, the inter-molecular force is greatly increased and the oil and solvent resistance are improved. At the same time, due to the introduction of a certain amount of nitrile alkyl groups, the regularity of the polymer structure is destroyed and the cold resistance is greatly improved. The type and content of nitrile alkyl groups have a great impact on performance. For example, silicone rubber containing 7.5 mol% of γ-nitrile propyl group has similar low-temperature properties to low phenyl silicone rubber (its glass transition temperature is -114.5°C). Oil resistance is better than phenyl silicone rubber. As the γ-nitrile propyl content increases to 33 to 50 mol%, the cold resistance decreases and the oil resistance improves. Replacing γ-nitrile propyl group with β-nitrile ethyl group can improve the heat resistance of nitrile silicone rubber and can withstand hot air aging at 250°C.

The main advantage of nitrile silicone rubber is that it has excellent oil resistance and bath agent resistance, and can maintain elasticity in the range of -60 to 180°C. Therefore, it can be made into oil-resistant rubber products for use in the aviation industry, automobile industry and petroleum industry; also It can be used as an environmental sealant and fuel tank sealant for high-performance aircraft, and can maintain sealing at temperatures from -54°C to over 200°C. Nitrile silicone rubber can be processed with ordinary equipment.

The main feature of phenylene silicone rubber is its excellent radiation resistance. Its radiation resistance is 10 to 15 times that of general methyl vinyl silicone rubber and 5 to 10 times that of high phenyl silicone rubber. Therefore, it can be used It is used in the aerospace industry, atomic energy industry and nuclear reactors as cables, sheaths, gaskets and heat shrinkable tubes that are resistant to high-energy radiation.

Silicone rubber
The main advantage of silicone rubber is its excellent thermal stability. It does not decompose at 430~480℃, and some can even withstand high temperatures above 500℃. The outstanding weakness of silicone rubber is its poor hydrolytic stability, and it was once considered to have no future. Later, it was discovered that polymers with cyclodisilazane introduced into the main chain have good thermal stability. The cyclodisilazane-containing elastomer modified with silarylene does not lose weight when heated to 425°C in air, and loses only 10% at 570°C, and has good hydrolysis stability.