Abstract
Abstract A universal structural model for human hair has been proposed in order to understand the physical properties of hair. The model consists of two structural parts, both of which have two states (Two-part/two-state model). The transition temperature (Tc) between the two states of one part is about 70 °C, and that of the other part is about 0 °C in a water medium. These transition temperatures depend highly upon the water content of the hair. A higher transition temperature is observed in hair having a lower water content. Above the transition temperatures, both parts of the hair are soft and plastic (a melted state); they are hard and elastic (a solid state) below the transition points. One part of hair which has a higher transition temperature (ca. 70 °C in water) is assigned to be macrofibril and exo-cuticle consisting of keratinous proteins; the other part with a lower Tc (ca. 0 °C) is inter-macrofibrillar materials, a cell-membrane complex (CMC), and the endo-cuticle of non-keratinous proteins and lipids. This structural model was derived from the results of thermal-setting and relaxation experiments as well as TEM observations after permeating a dye with a high electron density (Erythrosin B).
Published Version
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