This investigation revealed the role played by the electrophilicity of the carbonyl on the straightener agent and of the temperature, closely related to the dehydration process. Raman and IR studies indicated the involvement of imine bonds and the occurrence of a sequence of conformational modifications during the straightening procedure. SEM analyses showed the effectiveness of the treatment at the cuticular level.

No abstract

In this article we have evaluated some of the factors (pH, solvent composition and dye structure) that influence the dyeing of hair with dyes from direct semipermanent categories. These dyes, in fact, have been used more and more in cosmetic industry over the last years, due to their lesser aggressiveness vs. hair fibres. Two different dye classes are investigated: phenylene diamine (HC), well known for their low molecular weight and their small size, and a series of Basic dyes, characterized by the same ionic charge (positive) but with different sizes and different polar groups in the molecule. pH and dyebath composition result critical factors controlling the diffusion and adsorption process.

In this work, the effects of a new class of polymers generally used in hair and skin cleansing products, the SoftCAT (SofCAT SL and SoftCAT SX), on the dye uptake on the hair fibre and the fading effects has been studied. These polymers, based on quaternary ammonium salts of hydroxyethylcellulose, are cationic products that differ in viscosity, hydrophobic substitution index (HS) and/or cationic substitution (CS, % N). UV-Vis spectroscopy has been used to analyse the extracted dyes from the hair cuticle and the cortex. The results indicate that the presence of polymers in the dye bath improve both the quality of the dyeing process and the anti-fading effect during the washing cycles. This phenomenon is postulated to be attributable to the polymers hydrophobically bonding with the dyes and so facilitating their increased penetration into the hair.

The aim of this study was to investigate the effect of some cellulose polymers mixed in a semipermanent dyestuff on the dye uptake of yak hair fiber and color fading after repeated washing cycles. Two different classes of commercial polymers were tested: non-ionic and cationic. Formulations based on a mixture of HC and basic dyes, with different molecular sizes, were employed as representative dyestuffs. UV-Vis spectroscopy and colorimetric measurements were used to analyze the extracted dyes from the yak hair cuticle and cortex. The results obtained indicate that the presence of cationic polymers in the dye bath improves both the quality of the dyeing process and the antifading effect during the first washing cycles.