The History of Memory or Visco-Elastic Polyurethane Foam

Susan Lewis, Special to The Windsor Star

Published: Thursday, August 28, 2008

Memory foam is made from polyurethane with additional chemicals that increase its viscosity level, thereby increasing its density. It is often referred to as visco-elastic polyurethane foam. Depending on the chemicals used and its overall density, it is firmer in cool temperatures and softer when warm.

Higher density memory foam reacts to body heat that allows it to mould itself to the shape of a warm body within a few minutes.  A lower density memory foam is pressure-sensitive and will mould more quickly to the shape of the body. The example often used to demonstrate its properties is that a hand pressed into the foam and then removed will leave a clear impression in the foam.

According to Wikipedia, memory foam was originally developed by NASA to decrease the very high pressure caused by the extreme g-force occurring during the take-off of the space shuttle. It was never used in the space program but was subsequently used medically, for example by patients who used to lie in bed on hard or very firm mattresses for long periods of time without regularly moving such as being bed-bound after a paralyzing stroke.

The pressure over some of their bony regions decreased or stopped the blood flow to the region causing pressure sores and/or gangrene. Memory foam mattresses helped hugely to decrease such events.

Memory foam was initially too expensive for general use, but in recent years it has become cheaper to produce and is now widely available. Its most common domestic uses are mattresses,

pillows, and mattress toppers.

It still has medical uses, such as wheelchair seat cushions, hospital bed pillows and padding for persons suffering long-term pain or postural problems; for example, a memory foam cervical pillow may alleviate chronic neck pain. Its heat-retaining properties may help some pain sufferers who find the added warmth helps to decrease the pain

A memory foam mattress is usually denser than an ordinary foam mattress. This makes it more supportive - but also heavier. It is often seen as a good compromise between the comfort of a soft mattress and the supportiveness of a firm one. Memory foam mattresses often sell for more money than traditional mattresses but they last longer.

© The Windsor Star 2008

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