MRI of adsorbed water in solid foams at 21.1 T

Abstract

In a number of practical situations there is a critical need to evaluate the distribution of small amounts of water absorbed throughout a solid foam sample. One of these pertains to Spray On Foam Insulation (SOFI) NCFI 24124, a thermal insulation material used on the liquid hydrogen and oxygen tanks of the Space Shuttle at Kennedy Space Center (KSC). However, several problems including infinitesimal amounts of water and inevitable water binding to the foam makes the MR signal weak especially for high resolution MRI. The 900 MHz ultra wide bore (UWB) NMR spectrometer at the National High Magnetic Field Laboratory (NHMFL) provides a unique opportunity to perform this evaluation due to its high MRI sensitivity at 21.1 T and its ability to examine large volume samples. The recent upgrade of the UWB900 MHz MRI scanner (August, 2010), allows for ultra-short echo time (UTE) 3D MRI performance. The standard MR imaging technique in this case is not suitable, as it will yield a zero signal. Here we report the first 3D MR images of bound water and water content in solid foam NCFI 24124 samples conditioned to match launch pad conditions.