Abstract
By the pulsed magnetic field gradient method (stimulated echo), the water self-diffusion in natural silk fibers produced by the silkworm Bombyx mori was studied at a water content of the fibers of 0.18 gram H2O per gram dry weight at diffusion times of 10 to 200 ms. It was shown that the dependence of the diffusion coefficients Dexp on the diffusion time Δ is caused by the fact that the diffusion is limited. In terms of a model of plane equidistant permeable barriers, the average interbarrier distance and the barrier permeability were estimated. The maximal value of the diffusion coefficient Dexp in natural silk fibers (at short diffusion times) was 0.06 of the diffusion coefficient of water molecules in the bulk of liquid water. The results obtained were compared to published data on water self-diffusion in hydrated fibers of biopolymers and were discussed in the context of the molecular mobility in natural macromolecular systems with low water content. Copyright © 2003 by MAIK "Nauka/Interperiodica".