Abstract
Merino wool fibers were treated with aqueous sodium bisulfite (a mild breaking agent for cystine cross-inkages) and followed by the treatment with aqueous alkali (an attacker for ortho-cortex in wool structure). The crimp force i.e. load (P mg) to pull out crimps of a single fiber and the number of crimps per unit length (cm) of extended fiber without stretching were measured before and after above treatments. Stress-Strain curves of the treated fibers, as well as increments of their elastic and plastic regions were also obtained.
The results are summarized as follows:
1) The treatment with sodium bisulfite solution at 20°C for 30 min did not alter the crimp force and the number of crimps, but treatments at 60°C and 80°C for 30 min minimized the crimp force.
2) The number of crimps in wool fiber treated with sodium bisulfite followed by alkali treatment increased remarkably and the crimp configuration became much more homogeneous.
3) Magnitudes of crimp force per crimp decraesed in the following order (independent of pretreatment); in air > in water > in chemical reagent solutions, and they were inversely proportional to degrees of swelling of fibers in measuring media.
4) Percentages of decrease in elasticity in the elastic regions and increase in plasticity in the plastic regions of a fiber seem to be correlated with degrees of swelling of the fibers.
