A Study of Sorbed Water on Cellulose by Pulsed NMR Technique

Abstract

The state of sorbed water on cellulose has been studied by pulsed NMR technique. From the experimental results of spin-lattice relaxation time (T₁) and spin-spin relaxation time (T₂), observed as a spin echo decay time, following conclusions have been derived. (1) Two phases of the sorbed water are classified; the localized and the mobile. (2) The correlation time (τ_N) derived from T₁ using BPP theory, is consistent with that (τ_D) derived from dielectric measurements. (3) T₁ is by one or two order longer than T₂ in contradiction to BPP theory for extremely narrowing case. As an explanation for this fact, we propose that, when we consider about T₂, the effects of magnetic nuclei contained in the absorbent must be taken into account, though no theory is given. (4) The average life-time of water molecule sorbed on cellulose in the localized state is estimated to be several hundredths of a second and to decrease with temperature.