DMAc/H2O/LiCl as efficient system for bleaching human hair and subsequent use in transparent composite films.

Abstract A DMAc/H 2 O/LiCl system was used to bleach human hairs high efficiently. Hypothesized bleaching mechanism of DMAc/LiCl to human hairs was proposed based on its selective high-swelling ability against scale layer. This composite-structure based hypothesis was in accordance with the altered morphology of expanded gaps between scale layers of human hairs after bleaching via SEM and TEM. FTIR further confirmed this mechanism from the chemical structure aspect. Optimized bleaching condition of 5 g/L FeSO 4 and 6:4 vol ratio of DMAc to H 2 O under 30 min resulted in human hairs with balanced whiteness of up to 50.8 and a fracture strength of 15.73 cN/dtex. Composite keratin (from bleached human hairs)/PVA/alginate film showed the advantages of this DMAc/H 2 O/LiCl system in color, as evidenced by a better transparency without deteriorating the mechanical properties. Highlights • Regeneration of human hairs by improved bleaching efficiency. • Regulation of bleaching efficiency by controlling mass transfer of H2O2. • Accelerated bleaching mechanism. • Alleviate the burden of human hairs to the environment. • Transparent composite keratin (from bleached human hairs)/PVA/alginate film without deteriorating the mechanical properties. [ABSTRACT FROM AUTHOR]