DESIGN NEWS REPORT OPEN-PORE POLYURETHANE FOAM AND FELT

E&MP 90.005b

Noise Control

November 25, 1964

[DESIGN NEWS REPORT pamphlet page 1]
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STRUCTURE of open-pore polyurethane foam is 3-dimensional network of interwoven strands and interconnected air cells. Random orientation of strands and air cells minimizes possibility of open flow through channels. There are no connecting membranes between strands as in other foam materials.

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Open-pores polyurethane foam is made by a process that provides an open mesh-like skeletal structure containing a high percentage of void space. As a result, the material is extremely porous and permeable, has a low resistance to flow and is capable of entrapping and holding large amounts of liquid and solid matter.

Good chemical and physical properties make the material well-suited to a variety of applications. These include air and liquid filtration, humidification, demisting, sound absorption and abrasive polishing and cleaning.

Open-pore polyurethane felt is a recently introduced, compressed variation of the standard foam material. The felt provides greater density, smaller pore sizes, finer textures and much higher mechanical strength. To date, primary applications of open-pore felt have been in the field of sound absorption, capillary conveyance of liquids and extremely fine particle filtration.

Porosity and texture

Open-pore foam is produced in a number of standard porosity grades. Rated in terms of pores per lineal inch (ppi), these range from 10 to 100 ppi. Tolerance on porosity is closely controlled and is generally + 5 ppi in most grades.

Texture of the open-pore foam ranges from coarse and abrasive in the 10 ppi grades to soft and downy in the 100 ppi grade. Void volume is constant at 97 percent for all grades. Density is also constant at a nominal 2 lb. per cu ft.

Porosity, density and texture of the open-pore felt depend on the porosity of the original standard foam and on the extent

Original Caption by Science Service
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