TEMPERATURE-DEPENDENCE OF WATER SELF-DIFFUSION IN THE GEL PHASE OF A POTASSIUM PALMITATE SYSTEM

The temperature dependence of water self-diffusion in the gel and liqu id crystalline phases of the potassium palmitate/water system was exam ined using pulsed field gradient spin-echo (PGSE) low resolution NMR e xperiments. The temperature dependence of the water self-diffusion in lamellar and hexagonal phases was characterised by trends parallel to pure water. The average ''two-site'' self- diffusion model was used to analyse the composition dependence of the self-diffusion coefficients . Temperature dependence of water self-diffusion in the gel phase pres ented different and interesting behaviour. The slopes of the Arrhenius self-diffusion were strongly composition dependent. The results were interpreted as a dependence on T of the bound water fraction, while th e self-diffusion obstruction factor was considered constant.