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 reaction of polyols and 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. ^ McIntyre, A.; Anderton, G. E. (1979-02-01). "Fracture properties of a rigid polyurethane foam over a range of densities". Polymer. 20 (2): 247–253. doi:10.1016/0032-3861(79)90229-5. ISSN 0032-3861.
  3. ^ Chen, W.; Lu, F.; Winfree, N. (2002-03-01). "High-strain-rate compressive behavior of a rigid polyurethane foam with various densities". Experimental Mechanics. 42 (1): 65–73. doi:10.1007/BF02411053. ISSN 1741-2765.
  4. ^ Tu, Z. H; Shim, V. P. W; Lim, C. T (2001-12-01). "Plastic deformation modes in rigid polyurethane foam under static loading". International Journal of Solids and Structures. 38 (50): 9267–9279. doi:10.1016/S0020-7683(01)00213-X. ISSN 0020-7683.
  5. ^ Thirumal, M.; Khastgir, Dipak; Singha, Nikhil K.; Manjunath, B. S.; Naik, Y. P. (2008-05-05). "Effect of foam density on the properties of water blown rigid polyurethane foam". Journal of Applied Polymer Science. 108 (3): 1810–1817. doi:10.1002/app.27712.
  6. ^ Chian, K. S.; Gan, L. H. (1998-04-18). "Development of a rigid polyurethane foam from palm oil". Journal of Applied Polymer Science. 68 (3): 509–515. doi:10.1002/(SICI)1097-4628(19980418)68:3<509::AID-APP17>3.0.CO;2-P. ISSN 0021-8995.
  7. ^ Hu, Yan Hong; Gao, Yun; Wang, De Ning; Hu, Chun Pu; Zu, Stella; Vanoverloop, Lieve; Randall, David (2002-04-18). "Rigid polyurethane foam prepared from a rape seed oil based polyol". Journal of Applied Polymer Science. 84 (3): 591–597. doi:10.1002/app.10311. ISSN 0021-8995.
  8. ^ Guo, Andrew; Javni, Ivan; Petrovic, Zoran (2000-07-11). "Rigid polyurethane foams based on soybean oil". Journal of Applied Polymer Science. 77 (2): 467–473. doi:10.1002/(SICI)1097-4628(20000711)77:2<467::AID-APP25>3.0.CO;2-F. ISSN 0021-8995.
  9. ^ Menges, G.; Knipschild, F. (August 1975). "Estimation of mechanical properties for rigid polyurethane foams". Polymer Engineering and Science. 15 (8): 623–627. doi:10.1002/pen.760150810. ISSN 0032-3888.
  10. ^ Zhu, Menghe; Ma, Zhewen; Liu, Lei; Zhang, Jianzhong; Huo, Siqi; Song, Pingan (2022-06-10). "Recent advances in fire-retardant rigid polyurethane foam". Journal of Materials Science & Technology. 112: 315–328. doi:10.1016/j.jmst.2021.09.062. 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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