![]() ![]() In 2006, the third generation of memory foam was introduced. 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. Its heat-retaining properties may help some pain sufferers who find the added warmth helps decrease the pain. It has medical uses, such as wheelchair seat cushions, hospital bed pillows and padding for people suffering long-term pain or postural problems for example, a memory foam cervical pillow may alleviate chronic neck pain. Its most common domestic uses are mattresses, pillows, shoes and blankets. Memory foam was initially too expensive for widespread use, but became cheaper. Memory foam mattresses significantly decreased such events. 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 sores or gangrene. Memory foam was subsequently used in medical settings. Their 1991 product, the Tempur-Pedic Swedish Mattress eventually led to the mattress and cushion company Tempur World. 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. Later commercialisation of the foam included use in medical equipment such as X-ray table pads, and sports equipment such as American / Canadian football helmet liners. 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. The temperature-sensitive memory foam was initially referred to as "slow spring back foam" most called it "temper foam". Memory foam was developed in 1966 under a contract by NASA's Ames Research Center to improve the safety of aircraft cushions. Note characteristic polyurethane yellowing caused by light exposure. Memory foam with a slower springback than the foam above. Denser cell structure can also resist the penetration of water vapor, leading to reduced weathering and better durability and overall appearance. Certain memory foams may have a more rigid cell structure, leading to a weaker distribution of weight, but better recovery of the original structure, leading to improved cyclability and durability. There is also a trade-off between comfort and durability. Memory foam's mechanical properties can affect the comfort of mattresses produced with it. Its glass transition temperature can also be modulated by using additives in the foam's material. Thus the foam's properties can be controlled by changing its cell structure and porosity. Smaller pores lead to higher internal surface area and reduced air flow, increasing the adhesion and pneumatic effects. The pneumatic and adhesive effects are strongly correlated with the size of the pores within memory foam. The underlying physics of this process can be described by polymeric creep. If it is too hot, it acts like conventional foams, quickly springing back to its original shape. ![]() The effects are temperature-dependent, so the temperature range at which memory foam retains its properties is limited.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |