Study On The Damage To Epicuticle Of Human Hair Fibers By UVB Radiation

In this paper, Wilhelmy method was employed to measure the dynamic contact angles between human hair fibers and probe liquids, and the measuring conditions were investigated ahead. Three kinds of agent, i.e. water, diiodomethane and formamide, were selected as probe liquids. Hair fibers punctured vertically the surface of such liquids at the optimized rate of 80μm/sec. Based on the experimental date, several methods were approached to evaluate the surface free energy of human hair fibers. The results showed Lifshitz-van der Waals acid-base approach and Geometric-mean method were more suitable for evaluating the surface free energy and its components under all the experimental conditions than Zisman appraoch, Neumann equation-of-state theory and Harmonic-mean method.Thereby the damage to surface of human hair fibers by UVB radiation was characterized with the components of surface free energy and their distribution. It was found that both the ratio of the polarity (Geometric-mean method applied) and the values of the base-component (Lifshitz-van der Waals acid-base approach applied) increased with increasing of the dosage of UVB radiation, however the van-der Waals force almost keep stable at the same time. Allw?rden test was performed for the hair fiber samples under all UVB radiating conditions. By photo microscopy, the epicuticle of hair fibers was found damaged on the integrity of membrane as UVB radiation, comparing with the control. The trend of base-component or polar-component demonstrated a good agreement with Allw?rden test.In this paper, a method for determination of a sunscreen agent, i.e. Dimethylpabamidopropyl lauryldimonium tosylate (DDABDT) with reversed-phase high-performance liquid chromatography (RP-HPLC) has been established. The peak for DDABDT in samples was identified in HPLC without any interference from other components, which was confirmed with HPLC-MS analysis. The method is simple, accurate and sensitive and has been applied satisfactorily for determination of the DDABDT in shampoo and hair adsorbed.