Polyurethane foam

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An assortment of polyurethane foam products for cushioning and insulation

Polyurethane foam is a specialist material used for thermal insulation and other applications. It is a solid polymeric foam based on polyurethane chemistry.

Flexible polyurethane foam

The so-called flexible polyurethane foam (FPF) is produced from the

isocyanates, a process pioneered in 1937.[1] FPF allows for some compression and resilience that provides a cushioning effect. Because of this property, it is often used in furniture, bedding, automotive seating, athletic equipment, packaging, footwear and carpets.[1]

Rigid polyurethane foams

Rigid polyurethane foam has many desirable properties which has enabled increased use in various applications, some of which are quite demanding.[2][3] These properties include low thermal conduction making it useful as an insulator. It also has low density compared to metals and other materials and also good dimensional stability.[4] A metal will expand on heating whereas rigid PU foam does not. They have excellent strength to weight ratios.[5] Like many applications, there has been a trend to make rigid PU foam from renewable raw materials in place of the usual polyols.[6][7][8]

They are used in vehicles, planes and buildings in structural applications.[9] They have also been used in fire-retardant applications.[10]

Space shuttles

Polyurethane foam has been widely used to insulate fuel tanks on Space Shuttles. However, it requires a perfect application, as any air pocket, dirt or an uncovered tiny spot can knock it off due to extreme conditions of liftoff.[11] Those conditions include violent vibrations, air friction and abrupt changes in temperature and pressure. For a perfect application of the foam there have been two obstacles: limitations related to wearing protective suits and masks by workers and inability to test for cracks before launch, such testing is done only by naked eye.[11] The loss of foam caused the Space Shuttle Columbia disaster. According to the Columbia accident report, NASA officials found foam loss in over 80% of the 79 missions for which they have pictures.[11]

By 2009 researchers created a superior polyimide foam to insulate the reusable cryogenic propellant tanks of Space Shuttles.[12]

References

  1. ^ a b "What Is Flexible Polyurethane Foam?". Polyurethane Foam Association. Retrieved 1 February 2023.
  2. ISSN 0032-3861
    .
  3. ISSN 1741-2765
    .
  4. ISSN 0020-7683
    .
  5. doi:10.1002/app.27712
    .
  6. ISSN 0021-8995
    .
  7. ISSN 0021-8995
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  8. ISSN 0021-8995
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  9. ISSN 0032-3888
    .
  10. ISSN 1005-0302
    .
  11. ^ a b c Michelle Tsai (13 August 2007). "Get Your Foam On". Slate. Retrieved 1 February 2023.
  12. ^ "Insulating Foams Save Money, Increase Safety". NASA. 2009. Retrieved 1 February 2023.
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