The vast world of silicone rubber unveiled
Answers to your questions on what silicone rubbers are and how they’re made and used in a vast number of applications and industries.
What is silicone rubber?
Silicone rubbers or silicone elastomers are a combination of linear silicone polymers, reinforced by different agents, a crosslinker and a catalyst. Silicone rubber offers varying degrees of viscosity and structural features based on how the basic straight-chain silicone polymer molecule has been combined with the processing temperature: Heat Cured Rubber (HCR), Liquid Silicone Rubber (LSR), and Room Temperature Vulcanization (single component RTV-1 and double component RTV-2).
Depending on their formulation and the curing technology used, silicone rubbers can meet a wide variety of precise processing requirements. Silicones can be reinforced, usually with mineral fillers or silicone resins, it offers different properties for diverse applications, such as temperature resistance, electrical insulation, conduction, heat transfer, fire retardancy, chemical adhesion, etc. Many additives can also be added to ensure specific characteristics for end users, including color, thermal stability, or resistance to aggressive outside elements, ensuring high performances for different applications in the most demanding environments.
How is silicone rubber made?
Silicon, the main chemical element used to make silicones, does not exist in a pure form naturally, and is therefore extracted from silicates (or silica) embedded in sand or rocks. The full silicate-to-silicone value chain includes the extraction of silicon to obtain silicon metal, which is then transformed to obtain silicone intermediates, obtained by mixing grounded silicon with methyl chloride and transformed through different stages of synthesis into chlorosilanes and then siloxanes. Siloxanes are then transformed into rubber silicone ingredients or compounds. The basic silicone raw materials thus obtained, are further modified through various chemical processes to obtain high-performance polymers with specific characteristics, such as their viscosity, insulation properties, heat resistance, tear strength, etc. These silicone polymers are then processed to obtain various types of silicone rubber formulations processed into end products: Heat Cured Rubber (HCR), Liquid Silicone Rubber (LSR) and Room Temperature Vulcanization formulations (single component RTV-1 and double component RTV-2).
What is silicone rubber used for?
Silicone rubber or silicone elastomers are used in a wide variety of applications, thanks to their versatility, their composition, and their different curing properties. Here is a selection of applications:
- Heat Cured Rubber (HCR) silicone is used in the most demanding applications, especially in harsh environments, ensuring long durability of its elastomeric, dielectric and insulation properties, even when exposed to extreme temperatures and environmental aggression. They are used in applications as varied as automotive and railway parts, high-voltage cables, electrical vehicles and medical tubing and prostheses.
- Liquid Silicone Rubber (LSR) is used in precision industries and offers high tear strength, low compression set, good thermal resistance, excellent adhesive strength and sealing capabilities. LSR are also considered as the material of choice for industries such as Automotive or Medical devices for which small and complex elastomeric parts needs to be produced at high speed and optimum productivity. LSR is particularly adapted to new digital, intelligent, and networked industrial processes.
- RTV-1 silicone rubbers are easy to process and effective in a very wide range of sealing, bonding and coating applications, even in harsh conditions. They are used extensively in the most demanding industries: automotive, construction, electrical equipment, electronics and textiles.
- RTV-2 elastomers are remarkably stable in a wide temperature range, from -80°C to +250°C and beyond. They feature excellent dielectric properties and thermal conductivity and resistance, well suited for high-performance electrical insulation and numerous sealing, bonding and coating operations. Their mechanical properties, their low surface tension, their ability to reproduce surface details and their efficient release properties are ideal for molding, printing and prototyping applications.