Full definition
Silicone rubber, specifically vinyl-methyl-siloxane (VMQ), is a unique type of elastomer characterized by its silicon-oxygen backbone (Si-O-Si). Unlike traditional organic rubbers that rely on a carbon backbone, VMQ offers an extraordinary temperature range, functioning effectively in environments from -60°C to +230°C, with special grades capable of withstanding temperatures up to +300°C. This property makes it particularly valuable in applications where high thermal stability is essential. VMQ is classified under ASTM D2000 as FC/FE/GE, which indicates its varying resistance properties based on specific grades. The biocompatibility of VMQ rubber is another critical advantage, compliant with FDA standards (21 CFR 177.2600) and recognized as USP Class VI, making it suitable for medical and food-grade applications. This material's non-toxic and odorless nature further enhances its appeal in sensitive environments, such as food processing and healthcare.
Another remarkable feature of VMQ is its resistance to environmental factors such as ozone and UV radiation, allowing for prolonged outdoor use without significant degradation. The electrical insulation properties of silicone rubber also make it a preferred choice for applications requiring non-conductive materials, such as in electrical connectors and automotive components. However, VMQ is not without its limitations. It possesses relatively low tensile strength, typically ranging from 5 to 10 MPa, which is weaker compared to other common elastomers. Additionally, VMQ exhibits poor abrasion resistance and is not ideal for environments with hydrocarbon solvents or steam exposure. Despite these drawbacks, the versatility and performance characteristics of VMQ make it a popular choice across various industries.
Silicone rubber is widely utilized in food-grade seals, gaskets for bakery oven conveyors, and beverage dispensers, demonstrating its safety and durability in food applications. In the medical field, it is used for tubing and implants, ensuring patient safety while maintaining high performance. The automotive industry employs VMQ for spark plug boots and high-temperature gaskets, while LED encapsulation applications benefit from its excellent thermal stability and electrical insulation properties. Liquid silicone rubber (LSR) is also gaining traction for injection molding, offering precise and intricate designs for various applications. Key manufacturers of VMQ include Wacker (Elastosil), Dow (Silastic), Shin-Etsu, and Momentive, which provide a range of products suited to different industrial needs.