Memory Foam is composed of polyurethane with additional chemicals that add to its level of thickness. Sometimes, memory foam is referred to as visco-elastic polyurethane foam. Memory foam can be firmer in cooler temperatures and softer in warmer environments, depending on the chemicals used and the overall firmness of the foam. The higher the density of the memory foam, the more the foam will react to body heat and allow for the foam to mould itself to the shape of a warm body within a few minutes. However, lower density memory foam will mold more quickly to the shape of a warm body because lower density memory foam is pressure sensitive.
Originally developed for NASA in the 1970s, it was hoped that memory foam, known as "T-foam" could ease the pressure of G-forces. This was because of its ability to distribute pressure across the entire surface. Memory foam was never used in the space program because it offgassed too much for use in a closed environment. Memory foam is however, used in medical applications. For instance, memory foam comes in handy when a patient is bed-ridden or suffering from pressure sores.
At first, memory foam was too expensive for general use. Recently however, visco-elastic memory foam has become cheaper to produce and is now widely available for home use. In the home, memory foam's most common uses are mattresses, pillows, and mattress pads.
Because a memory foam mattress is normally denser than an ordinary foam mattress, it is more supportive. Memory foam mattresses are often described as having the comfort of a soft mattress, but also the supportiveness of a firm one. Memory foam mattresses are quickly becoming the fastest growing segment of the mattress industry. Other memory foam products, such as pillows and mattress toppers, are also quickly becoming hot products on the market today.