What’s the difference between solid rubber and sponge rubber? Both are elastomers, natural or synthetic polymers with elastic properties. Both are also subjected to vulcanization, a process that uses heat and a chemical agent such as sulfur to improve durability. Solid rubber and sponge rubber are available in many of the same compounds, such as EPDM, silicone, and neoprene. They can be extruded into the same shapes or molded into sheets, too.
At the most basic level, the difference between solid rubber and sponge rubber is about air. Sponge rubber contains balloon-like cells or interconnected pockets that either hold air or permit its passage. Solid rubber doesn’t share this cellular structure. Both types of materials provide sealing and insulation, but sponge rubber provides better cushioning. Solid rubber provides stronger impact resistance. Each type of elastomer has its advantages then, but what else do engineers need to know? (more…)