Classification, characteristics and differences between silicone rubber and silicone.
2025-10-20
Silicone rubber is a special rubber that is a linear polysiloxane-based polymer, with crosslinking agents, reinforcing fillers and other compounding agents added, and then vulcanized to form an elastomer.
1. Classification of Silicone Rubber
Silicone rubber can be divided into heat-vulcanized type (high-temperature vulcanized silicone HTV) and room-temperature vulcanized type (RTV) according to its vulcanization mechanism. At present, my country's annual production of room-temperature vulcanized silicone rubber is about 1.2 million tons, and the production of high-temperature vulcanized silicone rubber is about 500,000 tons.
2. What are the differences between silicone rubber and the silicone we usually talk about?
| Aspect | Silicone Rubber | Silica Gel |
|---|---|---|
| Characteristics |
1. Excellent low-temperature resistance (operational at -55°C) 2. High gas permeability, highest oxygen transmission rate among synthetic polymers |
1. Strong adsorption capacity, may dry skin 2. Requires protective gear during handling; if entering eyes, rinse immediately with water and seek medical attention |
| Composition | Main chain contains methyl and vinyl siloxane units; phenyl groups enhance high/low-temperature resistance; trifluoropropyl or cyano groups improve temperature/oil resistance | Main component is silicon dioxide (SiO₂) |
3. Characteristics of Silicone Rubber
(1) High and low temperature resistance
Of all rubbers, silicone rubber has the widest operating temperature range (-100 ~ 350℃). For example, properly formulated vinyl silicone rubber or low-phenyl silicone rubber can maintain elasticity after being aged in hot air at 250°C for thousands of hours or at 300°C for hundreds of hours; low-phenyl silicone rubber vulcanizate can still maintain elasticity after being aged in hot air at 350°C for dozens of hours. Its glass transition temperature is -140°C, and its vulcanizate still has elasticity at temperatures between -70 and 100°C. When silicone rubber is used as a heat-resistant coating on the inner wall of a rocket nozzle, it can withstand instantaneous high temperatures of thousands of degrees.
(2) Ozone aging resistance, oxygen aging resistance, light aging resistance, and weathering aging resistance.
After being exposed to sunlight for several years in a free state, the performance of silicone rubber vulcanizate does not change significantly.
(3) Electrical insulation properties.
The electrical insulation properties of silicone rubber vulcanizate change little when exposed to moisture, frequency changes, or temperature increases. The silicon dioxide generated after combustion is still an insulator. In addition, silicone rubber has fewer carbon atoms in its molecular structure and does not use carbon black as a filler. Therefore, it is not easy to burn during arc discharge and is very reliable for use in high-voltage applications. It has excellent corona resistance and arc resistance. Its corona resistance life is 1000 times that of polytetrafluoroethylene and its arc resistance life is 20 times that of fluororubber.
(4) Special surface properties and physiological inertness
Silicone rubber has a lower surface energy than most organic materials and has low hygroscopicity. When immersed in water for a long time, its water absorption rate is only about 1%. Its physical properties do not deteriorate. It has good mildew resistance and does not adhere to many materials. It can act as an isolation agent. Silicone rubber is odorless, non-toxic, has no adverse effects on the human body, reacts slightly with body tissues, and has excellent physiological inertness and physiological aging resistance.
(5) High gas permeability
Compared to other polymer materials, silicone rubber has excellent gas permeability. At room temperature, the permeability of nitrogen, oxygen, and air is 30 to 40 times higher than that of NR. It is also selective in gas permeability, for example, the permeability of carbon dioxide is about 5 times that of oxygen.
(6) Biomedical properties
The characteristics of the molecular structure of silicone rubber give it excellent biomedical properties, which has been proven by the successful application of a large number of animal and human trials.
