Editing Memory foam (section)

== History ==
[[File:MemoryFoam-slow.jpg|thumb|Memory foam with a slower springback than the foam above. Note characteristic [[Polyurethane#Effects of visible light|polyurethane yellowing caused by light exposure]].]]
Memory foam was developed in 1966 under a contract by [[NASA]]'s [[Ames Research Center]] to improve the safety of aircraft cushions. The temperature-sensitive memory foam was initially referred to as "slow spring back foam"; most called it "temper foam".<ref name=spinoff>{{cite web|url=http://www.sti.nasa.gov/tto/Spinoff2005/ch_6.html|archive-url=https://web.archive.org/web/20090320071931/http://www.sti.nasa.gov/tto/Spinoff2005/ch_6.html|title=spinoff 2005-Forty-Year-Old Foam Springs Back With New Benefits|archive-date=20 March 2009|url-status=dead|work=nasa.gov}}</ref> Created by feeding gas into a polymer matrix, it had an open-cell solid structure that matched pressure against it, yet slowly returned to its original shape.<ref name=cosmosmag>{{cite web|url=http://www.healthyfoundations.com/blog/?p=848|title="Eight spin-offs from space" Article from Cosmos Magazine|work=The Healthy Foundations Blog|url-status=dead|archive-url=https://web.archive.org/web/20140201174813/http://www.healthyfoundations.com/blog/?p=848|archive-date=2014-02-01|access-date=2014-01-25}}</ref>

Later commercialisation of the foam included use in medical equipment such as X-ray table pads, and sports equipment such as [[Football helmet|American / Canadian football helmet]] liners.

When NASA released memory foam to the public domain in the early 1980s, [[Fagerdala World Foams]] was one of the few companies willing to work with it, as the manufacturing process remained difficult and unreliable. Their 1991 product, the [[Tempur-Pedic]] Swedish Mattress eventually led to the mattress and cushion company Tempur World.

Memory foam was subsequently used 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 pressure on some of their body regions impaired blood flow, causing [[pressure sore]]s or [[gangrene]]. Memory foam mattresses significantly decreased such events, as well as alternating pressure air mattresses.<ref name=spinoff/><ref>{{Cite journal |last=Brownlie |first=J. |last2=Clarke |first2=M. C. |date=1993 |title=Experimental and spontaneous mucosal disease of cattle: a validation of Koch's postulates in the definition of pathogenesis |url=https://pubmed.ncbi.nlm.nih.gov/8407250 |journal=Intervirology |volume=35 |issue=1-4 |pages=51–59 |doi=10.1159/000150295 |issn=0300-5526 |pmid=8407250}}</ref>

Memory foam was initially too expensive for widespread use, but became cheaper. Its most common domestic uses are mattresses, pillows, shoes, and blankets. It has medical uses, such as wheelchair seat cushions, hospital bed pillows and padding for people suffering long-term pain or postural problems.

===Gel===
Heat retention can be a disadvantage when used in mattresses and pillows, so in second-generation memory foam, companies began 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 reduce trapped body heat, speed up spring back time and help the mattress feel softer. This technology was originally developed and patented by Peterson Chemical Technology,<ref>{{cite web|last=Peterson|first=Bruce W|title=Mr.|url=http://patents.justia.com/patent/20130296449|work=Polyurethane Gel-Like Polymers, Methods and Use in Flexible Foams|url-status=dead|archive-url=https://web.archive.org/web/20140419013634/http://patents.justia.com/patent/20130296449|archive-date=2014-04-19|access-date=2014-04-18}}</ref> and gel mattresses became popular with the release of 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 [[phase-change material]], achieved the desired temperature stabilization or cooling effect by changing from a solid to a liquid "state" within the capsule. Changing physical states can significantly alter an element's heat absorption properties.

Since the development of gel memory foam, other materials have been added. [[Aloe vera]], [[green tea extract]] and [[activated charcoal]] have been combined with it to reduce odors or provide [[aromatherapy]] while sleeping. [[Rayon]] has been used in woven mattress covers over memory foam beds to wick moisture away from the body to increase comfort. Phase-change materials (PCMs) have also been used in covers on memory foam pillows, beds, and mattress pads. Materials other than polyurethane also have the properties necessary to make memory foam. [[Polyethylene terephthalate]], one such polymeric material, provides certain benefits over polyurethane, such as recyclability, lightness, and [[thermal insulation]].<ref>{{cite journal |last1=Santo |first1=Loredana |last2=Bellisario |first2=Denise |last3=Quadrini |first3=Fabrizio |title=Shape Memory Behavior of PET Foams |journal=Polymers |date=25 January 2018 |volume=10 |issue=115 |page=115 |doi=10.3390/polym10020115 |pmid=30966151 |pmc=6415055 |doi-access=free }}</ref>