What’s the Difference Between Open and Closed Cell Foam Sheets?

Rubber Sheet StockAn open and closed cell foam supplier may seem like a niche market, but the two types of foams have many industrial applications. More than selecting a rubber sheet or compound, each material has distinct structures to meet specific requirements, depending on the use. Foam, in general, is made from polymers such as polyurethane, polyethylene, EPDM rubber, PVC/Nitrile, and acrylic, to name a few. Gas is dissolved under high pressure into the polymer while it is still in its liquid state. The reaction causes the formation of thousands upon thousands of tiny bubble-like cells in the polymer as it cools. Whether the reaction results in the formation of open cell foam or closed cell foam depends on the production process. The difference between the two cell foam sheets relates to its permeability and performance. The differences are important as each has specific applications. Here’s what you need to know open or closed cell foam sheets and their applications before purchasing.

What is Closed Cell Foam?

Closed cell foam is a lightweight, versatile, flexible material that’s made up of internal pores, tiny air pockets or cells, which are compacted together like inflated balloons nesting in the weaving of a net. During the expansion and curing process of the foam, the gas bubbles used in its production are locked in place to create the closed cells. Though the cells that are tightly packed against each other, they are not interconnected. The configuration forms rigid, moisture resistant foam with high structural integrity and excellent compression strength. It’s semi-impermeable to vapors and can resist solvents and chemicals, as well as mold and fungi. Closed cell foam is also four times denser than open cell foam. Its density also means it’s more expansive to manufacture.

What is Open Cell Foam?

Open cell foams are in general lighter in weight and less dense compared with closed cell foams. That’s because the cell formation within the material is broken, i.e., the ‘netting’ is open and not filled with inflated balloons. Though the making of open cell foam is similar to closed cell foam, the difference lies in the expansion and curing process. The gas used in its production is released into the atmosphere rather than locked within. This interlocks and interconnects the cells creating a soft, sponge-like cushion material. The porous nature of open cell foam gives it an absorbent quality with the capability to recover its physical form even after compression. The material also allows air and moisture to permeate the cell easily.

What is Closed Cell Foam Used For?

Applications for of closed cell foams are seemingly limitless. It can either be die-cut or custom-formed. Because of its excellent protective cushioning, and moisture and air resistance, it can be cut to custom foam protective packaging for storage and shipping of fragile tools, electronics, glass, jewelry, etc. Its thermal properties and shock absorption give it exceptional noise, vibration, and harshness (NVH) reduction. It’s the choice material for seals, gaskets, pads, insulation, sealing, and the like.

Closed cell foam applications are used in a variety of industries such as construction and building for insulation and sealing, in HVAC systems and appliances, gas and oil equipment, medical disposable devices, and in aerospace, aircraft, and automotive parts and production.

Polymers used in closed cell foam include: EPDM Sheet, PVC Foam Rubber, Neoprene Sheet, SBR Sheet, Neoprene PVC/Nitrile Foam, EPDM Foam Rubber

What is Open Cell Foam Used For?

Though open cell foams can be utilized in many of the same applications and industries as closed cell foams, there are substantial differences between the two. Open cell foams do not have ozone-depleting gases and do not contain volatile organic compounds. Its porous properties trap most airborne foreign particles, which make it ideal for reducing dust and allergens. Its acoustic properties minimize noise transmission and make it good for sound control and soundproofing. Its thermal properties and high expansion capacity make it ideal for interior insulation.

You’ll find open cell foam used in furniture upholstery, sound control in or around door panels, instrument panels, headliners in vehicles, etc., recording studios, protective packaging, filtration systems for permeable air, vapor, or moisture requirements, and much more.

Polymers used in open cell foam include Polyurethane sheet, acrylics, silicone, Reticulated Polyurethane Foam, Open Cell Nitrile Foam, Open Cell EPDM Foam, among many others.

Choosing the right foam for your manufacturing, building, or other industrial application will depend on the situation. Knowing the difference between the two foams can make the decision that much easier, or any further questions you may have, that much easier to ask. In either case, consult an expert at Manufacturer’s Rubber & Supply with any questions or any specific requirements.

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