Dow publishes thermal conductivity values for ETHAFOAM polyethylene foam products in Technical Data Sheets. To determine the thermal resistance (or "R Value") for any given product, divide the foam thickness in meters (or inches) by the thermal conductivity in W/m.K (or BTU-in/hr-ft2-°F).
For standard ETHAFOAM products with a thermal conductivity of around 0.06 W/m.K (0.4 BTU-in/hr-ft2-°F), this results in a thermal resistance (or "R-value") of approximately 1.0 R per centimeter of thickness (2.5 R per inch of thickness), (R = hr-ft2-°F/BTU). See the Technical Data Sheet of your product of particular interest for a more precise calculation.
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Foams such as ETHAFOAM brand polyethylene foam tend to soften at higher temperatures, as this is a characteristic of the thermoplastic resins from which they are produced. As temperature is raised, the foam may therefore become too soft for some applications.
Unfortunately, there is no consistent industry definition of "maximum use temperature." One standard laboratory test commonly performed on polyethylene foams subjects the foam samples to 24 hours in an oven at 70°C (158°F). The samples are then returned to room temperature and measured for linear dimensional change in all three directions. Under this test, ETHAFOAM products consistently show less than 1% linear change. Results from this test are sometimes used to determine a "maximum use temperature." Note that this test is carried out with no loading placed upon the foam. If the foam is expected to maintain its function and dimensions under a load it may be necessary to reduce the maximum use temperature accordingly. Specific testing under anticipated loads and use conditions is recommended when loads are to be applied at temperatures above around 49°C (120°F).
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The flash point is defined as "the lowest temperature at which a material will give off enough flammable vapor at or near its surface such that, in an intimate mixture with air and a spark or flame, it ignites." (from Dangerous Properties of Industrial Materials, 4th Edition, N. Irving Sax, 1975).
For ETHAFOAM products, the flash point is far beyond the melting point of the polyolefin polymers used to make the foams and is only reached when the foam has been heated considerably beyond the point at which it melts into a pool of liquid polymer. Thus flash point generally is not a concern under normal use and storage conditions.
Flash points for ETHAFOAM products are above 600°F / 315°C or so, depending on the particular polymer used.
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Blowing agent is a substance used to create the bubbles or "cells" in a foam. Without the introduction of blowing agent during the production process, we would have solid plastic instead of foam. The blowing agent used most in ETHAFOAM™ products is a flammable gas called isobutane.
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RapidRelease is Dow's patented process technology for reducing residual blowing agent levels remaining in ETHAFOAM™, SYNERGY™ products to non-flammable trace amounts (below the LFL). Products manufactured with RapidRelease technology have so little remaining blowing agent that they are incapable of producing a flammable blowing agent concentration. As a result, this unique-to-Dow process technology offers fabricators unprecedented standards in safety and convenience by eliminating the need for special shipping, handling, storage, and fabrication considerations.
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Some amount of the flammable blowing agent gas can remain in the foam for a long time. Generally, this is not a flammability concern as long as it stays within the foam. Residual blowing agent that escapes the foam may have the potential to remain in the vicinity of the foam, where it may be possible to build up to a flammable concentration. This is of special concern when the foam is placed in airtight containers.
The concentration of this gas surrounding the foam, then, is of interest in comparison with the Lower Flammability Limit (LFL; also known as LEL, Lower Explosive Limit) for that gas. The LFL is the lowest concentration in air in which a particular gas mixture will burn. If the concentration of a particular combustible gas in air is below the LFL, the air-gas mixture cannot ignite, and that mixture is not flammable. If, however, the concentration of combustible gas in air exceeds the LFL, the air-gas mixture can be ignited by a spark or flame. There is also an Upper Flammability Limit (UFL, also known as UEL, Upper Explosive Limit) above which the air-gas mixture is too rich to burn.
The best way to prevent the possibility of creating a flammable atmosphere in the vicinity of the foam is to reduce the blowing agent concentration remaining in the foam to below-LFL levels that cannot support combustion. Should the remaining blowing agent then escape from the foam, it will only dilute to even lower concentrations from there.
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Dow's commitment to quality systems and producing quality products has always been high. Our commitment to the Environment through our global implementation of Responsible Care® is just as important. Our commitment to excellence in products and services has earned us the premier position among foam producers for decades.
We have not formally applied to ISO 9000 or QS 9000 certification for our plant facilities. However, we are able to respond positively to customer requests regarding products quality control and processes relating to these standards.
Please contact your field sales representative for more information.
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UL 1191:
The US and Canadian Coast Guards approve flotation materials for use in Personal Flotation Devices (PFDs) via the Component Recognition programs of Underwriters' Laboratories and Underwriters' Laboratories Canada, under UL 1191.
Although most ETHAFOAM™ brand foam products will meet the UL 1191 requirements, the only product in the line of ETHAFOAM products for which this certification currently is maintained is ETHAFOAM 221 sheet polyethylene foam.
This means that ETHAFOAM products meet the requirements of this rigorous testing procedure, and that ETHAFOAM 220 and ETHAFOAM 50 products are suitable buoyancy materials for use in buoyancy collar and life jacket applications.
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Antistatic product versions are available in the product lines of ETHAFOAM polyolefin foams. These antistatic foams contain an amine additive to enhance electrostatic performance. This additive "blooms" to the surface of the foam where it attracts a layer of water molecules from the surrounding air, thus providing an electrical conduction path to control static buildup and dissipation.
Samples left undisturbed in storage for up to three years have shown no deterioration in static performance. If the amine layer is disturbed, such as being rubbed or washed off, it will quickly regenerate from the reservoir of additive contained within the foam and restore antistatic performance. If disturbed repeatedly, it is possible to deplete the supply of the additive to the point where static performance is affected. Thus the shelf life obtained will depend upon the storage and use conditions experienced.
With regard to the physical properties of the foam, these products are composed primarily of polyolefin plastic resins, the chemical activity of which is very low. As a result, under most storage and use conditions, very little deterioration is to be expected. For decades, olefin foams have been used extensively in military packaging projects, many of which have anticipated use schedules of twenty years or more.
To avoid deterioration of the foam, the main conditions to avoid are exposure to ultraviolet light and direct contact with strong oxidizing agents, both of which can cause oxidation of the plastic, thus gradually changing the character of the foam from flexible and resilient to friable and brittle. Also, prolonged direct contact with hydrocarbons, such as petroleum products, may cause some softening of the foam, and possible shrinkage of foam dimensions.
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