Some New Observations on the Effects of Mild Shrinkproofing Treatments on Wool Fibers

Abstract

When wool fibers which have been shrinkproofed by either the KMnO₄/salt process or a dry chlorination process are examined with the optical microscope, normally, very little effect of the treatment can be seen. However, if they are straightened for the examination, a number of differences between treated and control fibers can easily be seen, especially if water is present. The principal effects are that the scales on the treated fibers, but not on the untreated, become less prominent as the fibers are straightened and that this change is much greater on the side which was the intrados of the crimp curve than on the extrados. Microscopic observation of fibers sliding on each other or over a diffraction grating also reveals effects of the treatment: the deforma tion of the scales of treated fibers is more plastic and less elastic than that of untreated and the sliding of the treated fibers is more heavily damped. From these and other observations, the conclusion has been drawn that these treatments degrade the protein inside the scales so that it becomes more viscous and less elastic, particularly when it is swollen by or dissolved in water. The epicuticle appears to be unbroken and still elastic.

These results throw some light on the well-known disagreement between different workers about the changes produced in the coefficients of friction of wool fibers by the KMnO ₄/salt treatment.

¹ In the comprehensive study of crimp recovery by Banbaji et al. [Textile Res. J. 32, 568-572 (1962)], the fiber was allowed to contract slowly and continuously. The observa tions described here refer essentially to discontinuous re covery.