The Theory of Shrinkproofing of Wool

When wool fibers which have been shrinkproofed by either the KMnO 4 /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 deformation 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.

Section: Introductionmentioning

confidence: 99%

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

Makinson

1968

“…Bradbury [3], on the other hand, concluded that a keratin capstan and a capstan made by winding single wool fil>ers round a rod gave similar results. In comparing his conclusions with ours.…”

Section: (B) C Officients Of Frictionmentioning

confidence: 98%

“…This ensured that the forces and the coefficients of friction were measured under similar conditions of pressure. Bradbury has shown [3] that the coefficients of friction are insensitive to changes in To at such a value, so this counterweight was used for all measurements. Pressure P, the normal force per cm on a finer can be found from the formula P = f / p..…”

Section: F~ictional Coefficientmentioning

confidence: 99%

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Frictional Forces on Wool Fibers in a Worsted Fabric

Denby

Andrews

1965

The force needed to move wool fibers in a loose worsted fabric has been measured by extracting fibers from the fabric. The results are compared with the frictional co efficients found by the capstan method, and it is shown that the coefficients measured on a capstan made of yarns are simply related to the forces. The pressure on fibers within the fabric has been determined from these measurements, and all three quantities have been found as a function of washing time during the early stages of felting. The sig nificance of these results to theories of felting is discussed.

“…The results suggest that polymerization occurs readily at a solid-liquid interface; to our knowledge, it has been observed previously only at liquidliquid interfaces. The treatment of wool with aqueous neutral permanganate to achieve shrink resistance was patented in 1947 [37], however, recent authors have been unable to find either shrinkproofing or surface modification by this method [2,5,20,21].…”

mentioning

confidence: 99%

Wool Shrinkproofing Studies

Williams

1963

Potassium perrnanganate in water confers shrink resistance on wool fabric, the degree of initial shrink resistance increasing with addition of inorganic salts. On extended severe washing, fabrics treated in higher salt concentrations felt at a greater rate, once the initial period of shrink resistance has passed, than do fabrics treated in low salt concentrations. On the basis of these observations a theory of felting shrinkage is proposed which defines felting behavior of treated wool in terms of cuticle and cortex modification. Cortex modification need only be in the outer layers.Shrink resistance conferred by cuticle modification is characterized by an initial period during which no felting shrinkage takes place, followed by felting at a rate similar to that of untreated wool. Permanganate in saturated salt is an example of such a cuticle treatment.Shrink resistance conferred by outer cortex modification is not achieved by a shrink resist induction period, but by a reduced rate of felting shrinkage. Examples of shrinkproofing treatments resulting in outer cortex modification are: permanganate in water; dry, acid, and alkaline chlorinations; and the additional shrink resistance, following permanganate oxidation, conferred by residue times in bisulfite beyond that necessary to clear manganese dioxide.In permanganate treatments followed by reductive clearing, the major portion of shrink resistance is imparted during the oxidation stage for treatments in saturated salt, and during the clearing stage for treaments in water.