The second category of rubber products is cellular rubber. The first thing we must know in attempting to sell or engineer a rubber product is whether the desired product is solid or cellular rubber. Cellular (sponge rubber), however, is a little more complicated than solid rubber in that it comes in several different forms. They are open-cell sponge rubber and closed-cell expanded rubber. It also comes in a form known as foam.
Open cell rubber has cells that are open and interconnected to the neighboring cells. This pattern allows air and moisture to seep in easily, giving this rubber an absorbent quality and the ability to regain its physical form after being compressed.
Closed cell or expanded rubber doesn’t allow fluids to seep. This rubber is cheaper and has the ability to float in water which can’t violate its structure. Related topic: Major player of cellular rubber industry.
Closed Cell Rubber
The technically correct term for closed cell sponge is expanded rubber. Closed cell foam is defined as a cell totally enclosed by its walls and; therefore, not interconnecting with other cells. Closed cell foam comes in a wide variety of material and density options. EPDM, neoprene, EPDM/CR/SBR, and PVC/NBR are a few common types of closed cell foam. Closed foam sheets are usually made by introducing a rubber compound to a gas, such as nitrogen, under high pressure. This type of foam may also be made by incorporating gas-forming materials into the compound. The advantages of high density closed closed cell foam compared to open-cell foam include its strength, higher R-value, and its greater resistance to the leakage of air or water vapor. Closed cell foam is; however, denser, requires more material, and is more expensive.
Closed cell rubber can be ideal for sealing as it effectively reduces liquid and gas flow. It is also ideal in industries in which liquid resistance is critical, such as wetsuits, marine waterproof gaskets, rubber washers, rubber roofing, HVAC, and automotive gaskets where the use of closed cell foam gasket material is very common.