While the performance benefits of silicone rubber are unmatched for high heat and chemically demanding applications, its disadvantages drive ongoing research into improved and more sustainable material options. Here are the main advantages and disadvantages of silicone rubber:
Advantages:
Exceptional Temperature Resistance and Flexibility
Temperature resistance and flexibility are two of silicone’s excellent properties. Based on the variant, this material may withstand temperatures ranging from -150 to 550 ℉ before becoming brittle or melting. It has a tensile strength of 200 to 1500 PSI and a maximum elongation of 700%.
Low Compression Set
Due to low-stress relaxation, silicone rubber retains its original shape when compressed for long periods. Upon release, it will return to nearly 100% of normal dimensions with minimal permanent deformation. This is important for seal and closure applications where memory is critical.
Excellent Weatherability and UV Resistance
Silicone rubber is highly resistant to damage from exposure to sunlight, ozone, and weather. It can last 30-50 years outdoors without breaking down. The silicon-oxygen bonds are too stable to be easily broken by UV radiation. Some surface dulling or chalking may occur but will not impair physical properties.
Chemical Inertness
Silicone rubber is unaffected by exposure to most chemicals and solvents, including acids, bases, oils, and greases. Only strong alkalis or polar solvents like acetone may cause swelling or damage over long-term contact. The non-polar silicon-oxygen bonds and stable polymer structure provide excellent chemical resistance.
Low Conductivity
Silicone rubber is an effective electrical insulator and does not readily conduct heat or electricity. Due to the lack of free electrons in the silicon-oxygen atomic bonds, it has high electrical resistivity.
Biocompatibility
Certain silicones are biologically inert and compatible with medical devices and healthcare applications. Platinum-cured silicones that meet USP Class VI and ISO 10993 standards are commonly used for products like catheters, tubing, and bandages that contact the body.
Disadvantages:
Poor Oil and Tear Resistance
In general, silicone is not oil resistant for lengthy periods and can swell after prolonged contact with oil or petroleum. In addition, silicone is neither abrasion nor tear resistant and becomes stiffer at higher temperatures.
Poor Adhesion
Due to its low surface energy and non-polar nature, silicone rubber does not adhere or bond well to most surfaces. Special primers and surface treatments are required to achieve adequate adhesion for bonding or coatings.
Difficult to Process
Silicone rubber can be challenging to manufacture compared to organic rubbers. It often requires specialized high-temperature equipment and molds and technical expertise to handle. Recycling of silicone rubber is also problematic. These factors contribute to its overall higher cost.
