Water distribution within wetted porous fabric exposed to a thermal radiation characterized by low-field nuclear magnetic resonance

In this short communication, we aimed to elucidate the changes of water distribution and status in wetted porous fabrics during simulating drying process by using low-field nuclear magnetic resonance (LF-NMR). Fabrics were dried under different moisture regain conditions, i.e. 0%, 10%, 25 and 50% on a dry basis, respectively. Distributed exponential analysis of T2 transversal relaxation times revealed that the existence of three distinct water populations: bound water, capillary water and bulk free water at relaxation time ranges of 0~10 ms (T2b), 10~100 ms (T21) and ~1000 ms (T22). Water dynamics during simulating drying process show that the amount of immobile water increased slightly, whereas the amount of mobile water including capillary water and free water decreased. In addition, comparisons among the pore size distribution characteristics of porous fabrics from Mercury intrusion porosimetry (MIP) tests interpret the phenomena that the population of T21 for Aramid IIIA fabric was lowest among all the tested fabrics.