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Polyurethane foam is a versatile material that is made with both petrochemical and bio-based chemicals that blend together to form a catalyst causing a chemical change. With the introduction of a blowing agent, those chemicals form a cell structure and the foam is created.
There are several forms of polyurethane: standard flexible, standard rigid, and hybrid.
A hybrid is formed by adding other chemicals to change the physical characteristics of the PU foam. An example would be viscoelastic or memory foam. Another would be HR or high resiliency which is meant to have a greater support level. There are two different base types of urethane foam, polyester or polyether urethane.
The most commonly used are polyether urethane otherwise known as standard flexible polyurethane. Standard flexible polyurethane can be made with a wide range of firmnesses and densities and the two are not at all connected to each other. Firmness or ILD refer to the hardness or compressive resistance of the foam. Density is the measurement of molecular weight by volume and polyurethane foam is measured in pounds per cubic foot.
Density plays a huge role in the quality and cost of the foam. The higher the density the better the quality and the higher the price. You can have very soft foam with a very high density or very firm foam with a very low density, however, the foam that is going to last a long time is high-density foam.
Low-Density Standard Foams
0.90 lb. – 1.35 lb. ft³/s
Medium Density Standard Foams
1.40 lb. – 1.70 lb. ft³/s
High-Density Standard Foams
1.80 lb. – 3.30 lb. ft³/s
Hybrid Polyurethane Foam
1.50 lb. – 7.00 lb. ft³/s
Reticulated Polyurethane Foam
Reticulated foam is a hybrid polyurethane. It starts with either polyester based polyurethane or a polyether based polyurethane, each of which has very distinct properties.
The term reticulated refers to a process that opens the cell completely which allows little to no restriction of either air flow or fluid flow through the foam. This makes the foam usable for a variety of filtration applications. It can also be used to restrict but not eliminate the flow of fluids such as in a fuel tank on an airplane or jet. It also can be quite functional as a seat cushion in outdoor furniture or boat seats.
Like standard polyurethane foam, it is measured in density and ILD but one other measurement is added which is called the PPI or pores per inch. This refers to the size and number of the cells per inch. The smaller the PPI, the larger the cell structure, or vice versa, the larger the PPI, the smaller the cell structure. This is important in determining the application of the foam.
For example, in outdoor furniture, you would want a larger cell to let the water run through it easier or a smaller PPI number. In contrast, you would want a smaller cell for filtering air for an engine or air handling system so we would recommend a foam with a larger PPI.
There are two ways to create reticulated foam. The first is a process where polyurethane foam blocks are placed into a sealed steel chamber and nitrogen gas is pumped into the chamber. The nitrogen gas is then ignited causing a controlled explosion which blows out the windows of the cells. This method creates the most uniform cell structure but costs more to process. The second is what is called a chemical quench. In this process, the foam has a chemical introduced in the pouring process that de-foams the product at just the right time under controlled conditions causing the foam cells to open up. This process is less expensive and produces a slightly more restrictive air flow.
Upholstery grade polyurethane foam is generally higher in density due to the fact that it gets a lot of abuse. This requires the foam to be more durable and more supportive. We have a large selection of upholstery grade foams from soft back foam to firm seat cushion foam.
We also have a full line of latex rubber foam. To know more about latex foam see the latex page.
The most commonly used upholstery grade foam is medium firm (34 to 36 ILD) or firm (40 to 46 ILD) with a density of 1.80 to 2.30 lb. ft³/s. These two items are by far the most popular foam types we sell to the upholstery trade. The quality of the finished product greatly determines which product you select and some applications do not warrant using higher density foam. If a lesser density foam will do the job then we advise our customers to save some money and use the foam that will do the job.
Latex foam rubber is made using natural latex from a rubber tree.
It comes in two forms:
Both have to go through a molding and vulcanizing process. That process requires the latex to be whipped into a frothy suspension and poured into a mold. Then it must be heated to a temperature of 215º Fahrenheit in order to set the rubber.
There are two primary methods of molding the latex. One is called the Dunlop process which is described above. The second is called Talalay process which is similar to the first method but requires more elaborate molds because the suspension must first be vacuumed and frozen before the heating process is done.
The uses of this foam are virtually endless. We would love to speak with you and decide on a high-quality latex foam that is catering specifically to the benefit of your company and your product.
Visco-elastic foam, otherwise known as memory foam is a modified polyurethane foam, otherwise known as a hybrid foam. It is made much the same as conventional polyurethane foam but requires special additives to make it perform with pressure reducing characteristics.
Like other polyurethane foams, the quality is directly related to the density, except the density range starts at around 2.0 lb. ft³/s and goes up to around 7.0 lb. ft³/s.
The best density for a mattress application is 4–5 lb. ft³/s. Due to the higher density and special additives needed to make this type of foam, it is considerably more expensive to produce. Some of the more common uses for memory foams are mattresses, pillows, furniture cushions, and medical cushions.
Polyethylene foam comes in several sizes and densities and is often referred to as plastic foam or Ethafoam, which is a registered trade name of Sealed Air Corp.
Polyethylene is used for many different applications but the most common use is for packaging of fragile or shock sensitive heavy items. This foam is considered closed cell foam which means that the cell structure is made up of thousands of tiny cells of trapped air. This trapped air makes the foam capable of supporting a very heavy load without compressing fully or bottoming out.
The applications for this type of foam are varied and many in number as well as foam type.
Polyethylene comes in several densities ranging from 1.00 lb. to 11.00 lb. ft³/s. The firmness and load capacity increases with each density increase.
Polyethylene foam can be fabricated a number of different ways such as vertical and horizontal saw cut, die cut, or contour cut with a wire saw machine.
Cross-Link Polyethylene Foam
Cross-Link Polyethylene is a modified polyethylene hybrid foam, much like memory foam is to a conventional polyurethane.
As stated before in the polyethylene section, these foams are closed cell and are often referred to as plastic foams. They come in a variety of densities which determine how firm the product is. The higher the density the firmer the material.
Cross-link foam has two major differences to regular polyethylene foam. First, it has a much smaller and more uniform cell structure. This makes it very aesthetically pleasing and much more durable. Second, it is not photo-degradable which means it will not degrade over time and is very UV stable. Another benefit is the buoyancy of the material is high, which makes it great for flotation applications.
One use that is very popular today is FOD (foreign object damage) control. This is where tools used in aircraft repair are placed in foam that is cut out to match the tools shape. The foam is then placed in a tool box tray on a contrasting color base so that when the tool is out of the box it can easily be noticed that it is missing. This prevents tools from being left in an aircraft, causing severe damage to the aircraft.
Cross-link foam has many more applications and we carry a wide variety of these products.
Expanded Polystyrene Foam
Expanded Polystyrene foam, more commonly referred to as styrofoam, is a rigid foam made from polystyrene beads that are poured into a mold and then expanded using steam which fuses the beads together as they expand.
Once they are fused together a block is formed and it can then be cut into sheets of varying thickness or fabricated into other shapes to be used for packaging, insulation, or construction.
It is made in different densities from 1.00 to 3.00 lb. per ft³/s and unlike polyurethane foam, density controls the firmness. The higher the density the firmer the foam will be. Polystyrene is by far the least expensive foam product available and is limited in its uses.
Packaging Foam & Supplies
Allied Foam carries a lot of different foams for packaging and packaging materials such as:
– Bubble Wrap
– Lightweight Foam Wrap
– Open/Closed Cell Foam Sheets
We also have the ability to custom design and produce any of your special packaging needs.