Quite the opposite, sponge rubber routinely starts with expandable rubber types like EPDM or neoprene. The rubber compound is then supplemented that has a chemical blowing agent, which, on heating, decomposes and releases gases. This process results in the enlargement from the rubber plus the formation of a sponge-like construction. https://rubberfoamversusspongerub60482.dm-blog.com/33693952/rumored-buzz-on-huamei-rubber-foam