Memory foam is polyurethane with additional chemicals increasing its viscosity and density. It is often referred to as “visco-elastic” polyurethane foam, or low-resilience polyurethane foam.
Higher-density memory foam softens in reaction to body heat, allowing it to mold to a warm body in a few minutes. A lower-density memory foam is pressure-sensitive and molds quickly to the shape of a body pressing against it, returning to its original shape once the pressure is removed.
Components used for the production of polyurethane memory foams Components researched: isocynates; methylene chloride, 1,1,1-trichloroethane; acetone; benzene; ethylene oxide; formaldehyde
When new, some memory foams give off a distinct chemical odor, which many people find unpleasant and some say is akin to the smell of paint. This odor decreases with airing, but some remain sensitive. Emissions from memory foam mattresses may cause more respiratory irritation than other mattresses. Memory foam, like other polyurethane products, can be combustible. State and US Federal Laws have been enacted in the USA to require that all bedding, including memory foam items, be resistant to ignition from an open flame such as a candle or cigarette lighter. New bedding laws that went into effect in 2010 change the Cal-117 Bulletin for FR testing. There is concern that high levels of the fire retardant PBDE, commonly used in memory foam, could cause health problems for users.