Structural studies and diffusion measurements of water-swollen cellophane by NMR imaging

NMR imaging and spatially resolved diffusometry have been used to study the distribution of water within swollen cellophane and measure its diffusion coefficient. Water concentration and diffusion coefficient were found to be essentially constant across most of the film thickness. However, significantly slower diffusion was indicated for water near the film surface (D=0.5×10^–9m²s^–1) compared with water in the centre of the film (D=0.88×10^–9m²s^–1). This was also reflected in lower T₂ values at the edge of the film indicating water with more restricted motion. These observations were interpreted in terms of dense surface regions of cellulose (skin) over a more porous interior (core).