Silicone rubber is a versatile material that is used in a wide range of applications. Its unique combination of properties makes it a good choice for gaskets, seals, and other flexible components that need to endure harsh environments and high temperatures.
Liquid silicone rubber (LSR) is a type of silicone that is available in a liquid form and can be injection molded to produce durable, pliable elastomers. LSRs are formulated to meet the requirements of a particular fabrication process and come in a variety of hardnesses, grades, and color options.
Unlike most thermoplastic elastomers (TPEs), which are made from polymers joined and structured by chemical bonds that melt upon heating and then cool to harden, liquid silicone rubber has a continuous backbone of siloxane. It is then treated with catalysts that create the crosslinks that give silicone rubber its elasticity and resistance to physical stress.
Injection molding is the most common fabrication method for LSRs, as it allows for precise control over the distribution and cure of the resulting silicone parts. During this process, the LSR is heated and injected into a heated mold cavity to create the finished part. To ensure the best results, the injection mold should be designed with the appropriate tolerances to avoid stress and sink. Proper injection molding practices also help to eliminate flash and reduce cycle times and downtime.
While LSRs can be injection molded in a variety of ways, it is best to use a high-purity material to achieve the desired quality. This is especially true for medical applications, which require a medical-healthcare or class VI silicone tested for biocompatibility and FDA food contact compliance. The medical-healthcare and medical-long term implantable grades of silicone LSRs from Dow are specifically formulated for these purposes.
These LSRs feature low compression set and good stability for long-term use. They also have excellent resistance to environmental stresses, such as extreme heat or cold and can withstand frequent exposure to UV radiation. They are also flame-retardant, with most meeting a UL 94 HB rating without additives.
Dow recently introduced two new specialized medical-grade silicones that are ideal for fabrication of soft-skin adhesives and device adhesion materials. The company’s CopyFlex(tm) and IMAGIN3D(tm) are easy to work with because they have simple mix ratios and a very thin consistency that produces accurate replications of fine detail.
Robert McKeown Co. is a trusted fabricating distributor of engineered materials, and we are proud to offer ELASTOSIL(tm) products from Dow. Our experts are available to help you choose the right product for your specific application. You can request a quote or contact us today to get started. We look forward to hearing from you!