To paraphrase, the sort of cells (open up or shut) both permit or stop the passage of liquids or gases. But isn’t the nitrogen that’s used in shut-mobile sponge rubber a form of gasoline? And aren’t gases Utilized in foam rubber? It’s time and energy to take a deeper dive. https://jaidenigdby.theideasblog.com/34149580/rubber-foam-versus-sponge-rubber-an-overview