Memory foam, as the name suggests, is a type of foam with memory as it can provide support and comfort according to our body and remember to do necessary adjustments according to the body condition if they change. They naturally relieve tossing and turning while absorbing body heat and relieving pressure. They were made for use in Space shuttles earlier by NASA to reduce effects of gravity on the astronauts but were later abandoned. It was then used for bed-bound patients with paralysis and coma.
Memory foam is now used to make mattresses, pillows and toppers. It is cheap and easily available everywhere. Polyurethane is the base material by which memory foams are made and further supporting chemicals are added to increase the visco-elasticity of the foam which in turn increases its density. Polyurethane foam is a fully cross-linked reaction product of polyhydroxy polyol, toluene di-isocyanate, catalysts, surfactants, pigments, and water. Polyurethane foam product is a polymeric material consisting of repeating units of carbon, hydrogen, oxygen, and nitrogen. It is firmer in cool temperatures and softer when warm due to its density and chemical composition. Our body heat reacts to this memory foam and the mattress then moulds itself to take the required shape and provides warmth.
A memory foam with lower density is pressure-sensitive and will mould more quickly to the shape of the body. These foams equalize the pressure on the entire surface of body; reduce pain and stress thereby providing comfort. A memory foam mattress is usually denser than an ordinary foam mattress which makes it more supportive but also heavier. The heavier the foam is, the longer it will maintain it's shape without sagging or losing it's restorative properties and denser the foam, the longer it will last.
The property of firmness (hard to soft) of foam is used in determining comfort. Firmness is measured by Indentation Force Deflection of foam. IFD measures the force (in pounds) required to make a dent of 1" into a foam sample 15" x 15" x 4" by a 8 inch diameter (50 sq in) disc - known as IFD @ 25% compression. IFD rating for Super soft is IFD 10 and for semi rigid it is IFD 20 however most mattresses are firm (IFD 12 to IFD 16).
