THE EFFECT OF CHLORINATION OF FRICTION AND SURFACE MORPHOLOGY OF DARK BROWN AND BLOND HUMAN HAIR FIBERS

The cumulative effects of chlorination in dilute solutions on the surface properties of dark brown and blond human hair were investigated. Two experiments were performed. In the first, hair was soaked in 10 ppm chlorine solution adjusted to pH levels of 2, 7 and 10 for durations up to 30 hours. In the second experiment, a cosmetic treatment (hydrogen peroxide bleaching, oxidative dyeing or permanent waving) was applied to hair either before or after chlorination in 10 ppm, pH 7 solutions for durations up to 30 hours. The fiber properties analyzed included interfiber friction by the twist method, surface morphology by scanning electron microscopy, weight loss, reduction in force and work required to extend wet fibers 20 percent, and dry flexural properties by knot strength measurements.; The pH of the chlorine solution greatly affected the properties of the hair fibers. Chlorination in pH 2 solutions caused rapid changes in frictional values and surface morphology. Chlorination in the acid solution also caused the greatest weight loss and reduction in force and work to extend fibers. Chlorination in pH 7 solutions caused a gradual but observable change in the fiber properties. Chlorination in pH 10 solutions had little effect on fiber properties. Fibers chlorinated in the pH 2 and pH 7 solutions exhibited greater flexibility than the fibers of the control or the pH 10 samples.; When hair was subjected to both chlorination and a cosmetic treatment, changes seen in fiber properties were greater when a cosmetic treatment was applied prior to chlorination. The greatest change seen was in the reduction of force or work required to extend a wet fiber 20 percent. Very little change was observed in surface properties and weight loss. When a cosmetic treatment followed chlorination, all properties of the fiber were affected. These included the weight loss, the tensile, and the surface, the latter referring to friction and morphology. There was little effect of the cosmetic treatments on the flexural properties of the fibers.