Hygrostress and Hookean Modulus of Modified Wool Fibers

Abstract

Changes in tension at constant length resulting from the change in relative humidity from 100% to dryness (hygrostress) are presented for normal, reduced, and reduced and methylated wool fibers. The shape of hygrostress-extension curves is discussed in terms of the types of bonds involved and the effect of ordered and less-ordered regions in a fiber. It is concluded that hydrogen bonds and Van der Waals forces are directly involved, and disulfide bonds indirectly by enforcing the in-phase extension of a group of hydrogen bonds associated with ordered regions. No evidence was found in favor of a significant role for hydrophobic bonds. Previous data on the effect of disulfide bonds on the Hookean modulus of wool fibers are consistent with the proposed mechanisms.