Abstract
The effect of temperature on the physico-mechanical properties of samples of Bombyx mori natural silk fibers with low water content (0.07 gram H 2O per gram dry weight) was studied. The elastic properties of silk fibers were estimated using stress-strain curves. It was found that the maximal stresses σmax in the linear elastic region of tension of silk fibers decreased with an increase in the fiber diameter. Heat treatment of silk fibers (at 100°C) led to a decrease in σmax. Electron micrographs of the surface of silk fibers and their cross sections were obtained. Using the data of NMR relaxation study of natural silk fibers (free induction decay curves), the second moments of the shape of the NMR line were calculated. The intra- and intermolecular contributions to the second moment were analyzed. The results indicate strong interaction of silk polymers with water and low molecular mobility. The interaction of silk polymers with water and the role of intermolecular bonds in the changes in the structural-functional properties of natural silk under the action of external factors are discussed. Copyright © 2004 by MAIK "Nauka/Interperiodica".