Low-, stray-field imaging and spectroscopic studies of the sodium polyacrylate water uptake

Water uptake in sodium polyacrylate was followed by low-field magnetic reso nance imaging (LF-MRI), at 0.1 T and 5 mT/m, and by stray-field magnetic re sonance imaging (STRAFI-MRI), at 2.9 T and 37.5 T/m, over 50 h. One-dimensi onal (1-D) images were recorded and the model for the diffusion of the liqu id into the polymer was obtained. The complementarity of the techniques is discussed. H-1, C-13 and Na-23 spectroscopic NMR data are also presented. ( C) 2000 Elsevier Science Ltd. All rights reserved.