The Relation between Wool Felting and Single-Fiber Properties

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: Effect Of Bilateral Differences Between Scalesmentioning

confidence: 99%

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

Makinson

1968

“…Theories accounting for felting and reduced shrinkage after chemical treatments have been postulated in terms of frictional properties of the fiber [36], fiber stiffness [32,36], fiber swelling [4,18], scale' tip swelling [1], resistance to sliding [30] (which takes into consideration fiber frictional and flexing properties), tendency to curl as a result of differences. in molecular structure between the cuticle and cortex [14], ease of recovery from extension [35], and.…”

Section: Discussionmentioning

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.

“…Temperature and moisture could influence the fiber properties including Hookean modulus and relative rigidity, 22 which have significant effect on the shrinkage rate of untreated wool fabric. [23][24][25] Pierlot pointed out that felting shrinkage is related to glass transition temperature (T g ). At the glass transition temperature, large changes in the mechanical properties of the wool fiber are known to occur, which influence felting.…”

Section: Dimensional Shrinkagementioning

confidence: 99%

Dimensional change of wool fabrics in the process of a tumble-drying cycle

Bao

Shen

Ding

et al. 2019

Currently domestic tumble dryers are popularly used for drying garments; however, excessive drying and the inappropriate way of tumble agitation could waste energy and cause damage to or the dimensional change of garments. Shrinkage of wool fabrics during tumble drying causes a serious problem for wool garments. The current study investigated the shrinkage of untreated and Chlorine-Hercosett–finished wool fabrics at different drying times. Temperature of air in the tumble dryer, temperature of fabric, moisture content of fabric, and dimensional change at different drying times were measured. For the duration of the tumble drying, the rise of fabric temperature and the reduction of moisture content on the wool fabric were investigated to explore their relationship to the shrinkage of wool fabrics in the tumble-drying cycle. It was found that the tumble-drying process can be divided into different stages according to the temperature change trend of wool fabrics. The shrinkage mechanisms of the untreated and the treated fabrics were different. The dimensional change of untreated wool fabric was caused mainly by felting shrinkage during tumble drying. Chlorine-Hercosett–finished wool fabric can withstand the tumble-drying process without noticeable felting shrinkage due to the surface modification and resin coating of surface scales of wool fibers. The finding from the current research provides further understanding of the shrinkage behavior of wool fabrics during the tumble-drying process, leading to optimizing operational parameters at specific stages of a tumble-drying cycle.