Closed Cell Foam
Due the malleable nature of foam, it is very easy to manipulate. Foam can fall under two categories: open cell foam and closed cell foam, each of which can come in a wide range of characteristics. Closed cell foam is a type of foam in which the cells are “closed,” or packed and sealed together, giving the foam a high level of compressive strength and density. Because the cells are so closely packed together and closed off from one another, gas or liquid molecules cannot travel from cell to cell. Closed cell foam is highly recommended as a heat insulator, due to the ability of the cells to expand upon exposure to heated gas. Foam is created when gas bubbles are trapped inside a chemical solution by way of either the application of heat (endothermic reaction), or the mixing of chemicals (exothermic reaction).
As opposed to its open cell counterpart, the cells—or pores—of closed cell foam are not interconnected. Instead, the cells are sealed off from each other and more compact, making the foam more dense and more resistant to pressure. Compare a kitchen sponge, which is made from open cell foam, to a foam mattress, which is made from closed cell foam. Closed cell foam is more supportive and resistant to the elements, as opposed to the less sturdy open cell foam. Some varieties of closed cell foams are more dense than others, and can vary in levels of hardness. Closed cell foam is commonly used in building applications, such as outdoor and marine environments, schools, office buildings, industrial buildings, and residential homes. More specifically, applications that utilize closed cell foam include flotation and nautical buoyancy applications, packaging materials, couches and chairs, foam cushions, foam padding, and foam mattresses. Since foam fabrication processes differ in capabilities and suitability, it is important to consider what type of foam should be used. Foam can be cut in a variety of methods, including die cutting, foam felting and routing, hot wire cutting, and contour cutting. Foam cutting, in addition to the application of pressure and heat, are the most common methods of foam fabrication. Each cutting method can shape a piece of foam material into a desired configuration.
Closed cell foam consists of cells that are not broken within the material, making it much higher in stability and compressive strength, and more resistant to leakage in water vapor and air. The cells exert pressure on each other and make the material highly rigid. Because of these properties, closed cell foam is a highly recommended material for outdoor or heat insulation. Closed cell foam is also the material of choice for flotation and buoyancy devices, because it is impervious to moisture, unlike the porous much less dense open cell foam, which will soak up water.
Although closed cell foam can be used for a variety of applications, it does have several disadvantages. Closed cell foam has a higher material cost. For applications that require foam that is more dense and sturdy, production and material costs will increase. Foam has a tendency to break down over time due to exposure to wear and tear, and it will therefore be required at some point in time to replace the foam, regardless of the application for which it is used. Foam can vary in terms of elongation, thermal conductivity, tear strength, tensile strength, and density. Therefore, it is important to consider each of these characteristics in deciding which foam is appropriate for the desired application.
There are different types of closed cell foams available. Certain types of closed cell foam are as follows:
- Neoprene foam –known for its softness and flexibility, but is also highly durable and resistant to water and other chemicals, as well as hazards such as oxidation, sunlight, and ozone. This foam is used in applications such as soundproofing, insulation, and athletic gear.
- Polyethylene foam – the ideal material for packaging goods for shipping and transportation, due to its abilities of shock absorption and the dampening of vibrations.
- Polystyrene foam - incredibly light in weight, and commonly used in applications such as arts and crafts, insulation, and construction. Polystyrene foam will not rot, and is resistant to mildew or fungi. This foam is more commonly known by its most popular brand name—Styrofoam.
- Gym rubber – technically named polyvinyl chloride nitrile butadiene rubber. This foam is highly flexible, durable, easy to cut, and soft to the touch, making it a recommended material for applications such as exercise mats, camping pads, and kneeling cushions. Other applications for which gym rubber can be used include marine applications, due to its ability to resist moisture.
Closed Cell Foam – American Excelsior Company
Closed Cell Foam – Heubach Corporation