Memory foam consists primarily of polyurethane with further chemicals that increase its viscosity and density. It is also known as "viscoelastic" polyurethane foam, or low-resilience polyurethane foam (LRPu). The foam bubbles or 'cells' are open, successfully making a matrix by means of which air can transfer. Higher-density memory foam softens in reaction to body heat, allowing it to mold to a heat physique in a few minutes. Newer foams may recuperate their original shape more shortly. Memory foam derives its viscoelastic properties from several effects, as a result of the material's inner structure. The MemoryWave Community impact is the drive working to restore the foam's structure when it's deformed. This impact is generated by the deformed porous material pushing outwards to restore its structure towards an applied strain. The pneumatic effect, precipitated by the point it takes air to flow into the foam's porous structure. The effects are temperature-dependent, so the temperature range at which memory foam retains its properties is proscribed. If it is simply too chilly, it hardens.

If it is too sizzling, it acts like standard foams, rapidly springing back to its authentic form. The underlying physics of this process will be described by polymeric creep. The pneumatic and adhesive effects are strongly correlated with the dimensions of the pores inside memory foam. Smaller pores lead to greater inner floor area and reduced air move, increasing the adhesion and pneumatic effects. Thus the foam's properties may be controlled by altering its cell structure and porosity. Its glass transition temperature may also be modulated by utilizing additives within the foam's material. Memory foam's mechanical properties can have an effect on the comfort of mattresses produced with it. There can also be a trade-off between comfort and sturdiness. Certain memory foams may have a more rigid cell construction, resulting in a weaker distribution of weight, but better restoration of the unique structure, resulting in improved cyclability and durability. Denser cell structure can even resist the penetration of water vapor, resulting in reduced weathering and better sturdiness and general look.

Memory foam was developed in 1966 underneath a contract by NASA's Ames Research Middle to enhance the safety of aircraft cushions. The temperature-delicate memory foam was initially known as "gradual spring back foam"; most called it "temper foam". Created by feeding gasoline into a polymer matrix, it had an open-cell solid construction that matched pressure in opposition to it, but slowly returned to its unique form. Later commercialisation of the foam included use in medical gear comparable to X-ray table pads, and sports tools corresponding to American / Canadian soccer helmet liners. When NASA released memory foam to the general public domain within the early 1980s, Fagerdala World Foams was one of the few companies willing to work with it, because the manufacturing process remained difficult and unreliable. Their 1991 product, the Tempur-Pedic Swedish Mattress ultimately led to the mattress and cushion company Tempur World. Memory foam was subsequently utilized in medical settings. For example, when patients were required to lie immobile in bed, on a firm mattress, for an unhealthy period of time, the stress on some of their body regions impaired blood stream, inflicting strain sores or gangrene.

Memory foam mattresses considerably decreased such events, as well as alternating pressure air mattresses. Memory foam was initially too expensive for widespread use, however grew to become cheaper. Its most common domestic makes use of are mattresses, pillows, shoes, and blankets. It has medical makes use of, similar to wheelchair seat cushions, hospital mattress pillows and padding for Memory Wave people suffering long-term pain or postural problems. Heat retention may be an obstacle when utilized in mattresses and pillows, so in second-generation memory foam, firms started using open cell structure to improve breathability. In 2006, the third generation of memory foam was introduced. Gel visco or gel memory foam consists of gel particles fused with visco foam to scale back trapped physique heat, velocity up spring again time and help the mattress really feel softer. Serta's iComfort line and Simmons' Beautyrest line in 2011. Gel-infused memory foam was next developed with what were described as "beads" containing the gel which, as a part-change materials, achieved the desired temperature stabilization or Memory Wave cooling effect by changing from a strong to a liquid "state" inside the capsule.