毛髪の損傷度評価法 Ｉ 多点引張試験法による毛髪の引張強度測定

Abstract

As an attempt to globally evaluate the degree of hair damage, a study was carried out on a tensile strength test method of human hair. In order to minimize the variation of measured value, the gauge Iength of sample was shortened to 1mm by fixing both sides of it with tape. Even the same one hair has a different cross-sectional area and shape at each site of it, and microscopic damage may be present on it locally. By shortening the gauge length, measurement of cross-sectional area becomes more accurate and microscopic check of the sample also becomes easy. We named this method ‘the multi-point tension test method’, in which tensile strength could be measured at some points from the root to the tip of each hair. Thereby the degree of time-course damages by the accumulation of daily little damage could be appeared. From the result, Japanese normal hair could be ranked into five levels from the standpoint of hair strength.By this method, the effects of some cosmetics containing collagen or keratin derivatives could be recognized. And the correlations between hair strength and some metals in hair, which move from and/or into the hair easily in various water solution, could be appeared.Besides, the method for the confirmation of sorption of keratin peptide into hair was investigated. This technique, consisting of a circulation-system of keratin peptide into a hair-packed column and the quantification of sorption into the hair from liquid phase, was useful and speedy for the study of characteristics of keratin peptide.