Memory foam consists mainly of polyurethane with extra chemicals that improve its viscosity and density. It's sometimes called "viscoelastic" polyurethane foam, or low-resilience polyurethane foam (LRPu). The foam bubbles or 'cells' are open, successfully making a matrix by way of which air can transfer. Increased-density memory foam softens in reaction to body heat, allowing it to mold to a heat physique in a few minutes. Newer foams could get better their original form more quickly. Memory foam derives its viscoelastic properties from a number of effects, resulting from the material's inside construction. The community effect is the drive working to revive the foam's structure when it's deformed. This effect is generated by the deformed porous material pushing outwards to restore its construction in opposition to an utilized stress. The pneumatic impact, brought on by the time it takes air to flow into the foam's porous structure. The consequences are temperature-dependent, so the temperature vary at which memory foam retains its properties is restricted. If it is too cold, it hardens.

If it is too scorching, it acts like conventional foams, shortly springing again to its original shape. The underlying physics of this process might be described by polymeric creep. The pneumatic and adhesive effects are strongly correlated with the scale of the pores inside memory foam. Smaller pores result in greater internal surface space and diminished air movement, growing the adhesion and pneumatic effects. Thus the foam's properties will be controlled by altering its cell structure and porosity. Its glass transition temperature can be modulated by using additives in the foam's material. Memory Wave foam's mechanical properties can have an effect on the comfort of mattresses produced with it. There can be a trade-off between comfort and durability. Sure memory foams may have a extra inflexible cell structure, leading to a weaker distribution of weight, however higher restoration of the unique construction, resulting in improved cyclability and sturdiness. Denser cell construction may also resist the penetration of water vapor, resulting in lowered weathering and better durability and general look.

Memory foam was developed in 1966 beneath a contract by NASA's Ames Analysis Center to improve the safety of aircraft cushions. The temperature-delicate memory foam was initially referred to as "slow spring again foam"