How memory foam reacts to heat

Memory foam is made from polyurethane with additional chemicals that add to 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 cooler temperatures and softer in warmer environments. Higher density memory foam reacts to body heat which 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. Image File history File links Img_firmness. ... A polyurethane is any polymer consisting of a chain of organic units joined by urethane links. ... Viscosity is a measure of the resistance of a fluid to deform under shear stress. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... Viscoelasticity, also known as anelasticity, describes materials that exhibit both viscous and elastic characteristics when undergoing plastic deformation. ... A polyurethane is any polymer consisting of a chain of organic units joined by urethane links. ... Sea foam on the beach Foam on a cappuccino Fire-retardant, foamed plastic being used as a temporary dam for firestop mortar in a cable penetration in a pulp and paper mill on Vancouver Island, British Columbia, Canada. ...

Memory foam was originally developed by NASA to ease the pressure of extreme G-force during space shuttle take off. It was never used in the space program, but was subsequently used in medical applications, for example with patients suffering from pressure sores or bed-bound for a long period. This article is about the American space agency. ... The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ... Bedsores, also called pressure sores or decubitus ulcers, are ulcers (sores) caused by prolonged pressure or rubbing on vulnerable areas of the body. ...

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 applications are mattresses, pillows and mattress toppers (also known as mattress pads). It remains useful in medical-related 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 are also helpful to some pain sufferers, who find the added warmth helps alleviate pain. A pillow top queen-size mattress. ... Decorative tapestry pillow A pillow is a large cushion support for the head, usually used while sleeping in a bed, or for the body as used on a couch or chair. ... Mattress toppers are designed to lie atop an existing mattress. ...

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 than traditional mattresses but they last longer.

When new, memory foam often gives off a distinct chemical odour which many people find unpleasant (and some say smells like paint). This fades with airing, but some people remain sensitive to it. Emissions from memory foam mattresses may cause respiratory irritation more than other mattresses.^[1]

The hardness or softness of memory foam plays an important role in ensuring comfort. Its firmness is determined by its IFD rating. Indentation Force Deflection measures the amount of force, in pounds, required to indent a 50 square inch disc (8 inch diameter disc) into a 15"x15"x4" viscoelastic foam sample and make a 1" indentation. This is commonly known as IFD @ 25% compression. IFD ratings for memory foam range between super soft (10) and semi-rigid (120). Most memory foam mattresses are 12-16 IFD firm.

See Also

• Tempur-Pedic

Logo for the Tempur-Pedic company. ...

References

1. ^ Anderson RC, Anderson JH, Respiratory toxicity of mattress emissions in mice, Archives of Environmental Health, Jan-Feb 2000

External links

• Polyurethane Foam Association
• Memory Foam Guide
• Firmness Ratings of Memory Foam Mattresses
• [1]
• How to Choose a Memory Foam Mattress