Physics:Polyurethane foam

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Short description: Material used for thermal insulation
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. ↑ 1.0 1.1 "What Is Flexible Polyurethane Foam?". Polyurethane Foam Association. https://www.pfa.org/what-is-polyurethane-foam/. 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" (in en). Polymer 20 (2): 247–253. doi:10.1016/0032-3861(79)90229-5. ISSN 0032-3861. https://www.sciencedirect.com/science/article/pii/0032386179902295. 
  3. ↑ Chen, W.; Lu, F.; Winfree, N. (2002-03-01). "High-strain-rate compressive behavior of a rigid polyurethane foam with various densities" (in en). Experimental Mechanics 42 (1): 65–73. doi:10.1007/BF02411053. ISSN 1741-2765. https://doi.org/10.1007/BF02411053. 
  4. ↑ Tu, Z. H; Shim, V. P. W; Lim, C. T (2001-12-01). "Plastic deformation modes in rigid polyurethane foam under static loading" (in en). International Journal of Solids and Structures 38 (50): 9267–9279. doi:10.1016/S0020-7683(01)00213-X. ISSN 0020-7683. https://www.sciencedirect.com/science/article/pii/S002076830100213X. 
  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" (in en). Journal of Applied Polymer Science 108 (3): 1810–1817. doi:10.1002/app.27712. https://onlinelibrary.wiley.com/doi/10.1002/app.27712. 
  6. ↑ Chian, K. S.; Gan, L. H. (1998-04-18). "Development of a rigid polyurethane foam from palm oil" (in en). 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. https://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-4628(19980418)68:33.0.CO;2-P. 
  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" (in en). Journal of Applied Polymer Science 84 (3): 591–597. doi:10.1002/app.10311. ISSN 0021-8995. https://onlinelibrary.wiley.com/doi/10.1002/app.10311. 
  8. ↑ Guo, Andrew; Javni, Ivan; Petrovic, Zoran (2000-07-11). "Rigid polyurethane foams based on soybean oil" (in en). 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. https://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-4628(20000711)77:23.0.CO;2-F. 
  9. ↑ Menges, G.; Knipschild, F. (August 1975). "Estimation of mechanical properties for rigid polyurethane foams" (in en). Polymer Engineering and Science 15 (8): 623–627. doi:10.1002/pen.760150810. ISSN 0032-3888. https://onlinelibrary.wiley.com/doi/10.1002/pen.760150810. 
  10. ↑ Zhu, Menghe; Ma, Zhewen; Liu, Lei; Zhang, Jianzhong; Huo, Siqi; Song, Pingan (2022-06-10). "Recent advances in fire-retardant rigid polyurethane foam" (in en). Journal of Materials Science & Technology 112: 315–328. doi:10.1016/j.jmst.2021.09.062. ISSN 1005-0302. https://www.sciencedirect.com/science/article/pii/S1005030221010550. 
  11. ↑ 11.0 11.1 11.2 Michelle Tsai (13 August 2007). "Get Your Foam On". Slate. https://slate.com/news-and-politics/2007/08/how-come-pieces-of-foam-always-fall-off-the-space-shuttle.html. Retrieved 1 February 2023. 
  12. ↑ "Insulating Foams Save Money, Increase Safety". NASA. 2009. https://spinoff.nasa.gov/Spinoff2009/t_2.html. Retrieved 1 February 2023. 



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