Closed cell sponge rubber material is available in many forms. While a neoprene blend is the most popular it’s also available in EPDM, ECH, SBR nitrile and 100% neoprene. Neoprene blends are typically a combination of neoprene with EPDM and SBR. This provides a set of properties ideal for many types of sealing application, particularly since the closed cell structure makes it easily deformable and yet very springy.
Closed cell sponge rubber material is made by adding a blowing agent to the polymer mix. During heating this gives off a gas that forms bubbles, much as yeast does in bread. Sponge rubber is available in both closed and open cell forms. In an open cell material the bubbles are interconnected and fluids can pass through. In a closed cell rubber each bubble is a separate pocket of trapped gas.
These pockets give closed cell material a soft, springy character. It takes little force to form a seal on two sides, making it good for many gasketing and sealing applications, although compression should not exceed 35%.
Closed cell sponge material takes on the temperature range and chemical resistance of what it’s made from. So for example, a 100% neoprene sponge resists oil, acids, alkalis and ozone and remains flexible from -40 °F to 158 °F
A neoprene/EPDM/SBR blend, like Rubberlite’s SCE41B, resists almost everything except chlorinated solvents. In addition, it has excellent weather-resistant properties, so it’s a good choice for weatherstripping and other outdoor applications.