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Gravitational Effects on Closed-Cellular-Foam MicrostructurePolyurethane foam has been produced in low gravity for the first time. The cause and distribution of different void or pore sizes are elucidated from direct comparison of unit-gravity and low-gravity samples. Low gravity is found to increase the pore roundness by 17% and reduce the void size by 50%. The standard deviation for pores becomes narrower (a more homogeneous foam is produced) in low gravity. Both a Gaussian and a Weibull model fail to describe the statistical distribution of void areas, and hence the governing dynamics do not combine small voids in either a uniform or a dependent fashion to make larger voids. Instead, the void areas follow an exponential law, which effectively randomizes the production of void sizes in a nondependent fashion consistent more with single nucleation than with multiple or combining events.
Document ID
19970021685
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Noever, David A. (NASA Marshall Space Flight Center Huntsville, AL United States)
Cronise, Raymond J. (NASA Marshall Space Flight Center Huntsville, AL United States)
Wessling, Francis C. (Alabama Univ. Huntsville, AL United States)
McMannus, Samuel P. (Alabama Univ. Huntsville, AL United States)
Mathews, John (Alabama Univ. Huntsville, AL United States)
Patel, Darayas (Alabama Univ. Huntsville, AL United States)
Date Acquired
September 6, 2013
Publication Date
April 1, 1996
Publication Information
Publication: Journal of Spacecraft and Rockets
Publisher: American Institute of Aeronautics and Astronautics
Volume: 33
Issue: 2
Subject Category
Materials Processing
Report/Patent Number
NASA-CR-204718
NAS 1.26:204718
Accession Number
97N22583
Funding Number(s)
CONTRACT_GRANT: NAGw-812
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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