Mechanistic Aspects of African Hair Relaxation

This study investigated the mechanisms and effects of relaxer treatments on African hair, focusing on the chemical processes involved in hair relaxation. It was found that relaxers, which use strong bases, induce a spontaneous loss of hair curvature by denaturing the helical filaments in the hair cortex. The study used methods to quantify the time dependence and efficacy of relaxation, revealing a time-lag before straightening begins, followed by first-order kinetics. The diffusion of relaxer agents into hair was studied, showing significant fibre swelling at alkaline pH, which was further increased by reductants. Differential Scanning Calorimetry indicated that relaxer treatments significantly reduced the helix content of hair, correlating with the straightening effect, while the denaturation temperature was less affected. The study concluded that alkali-induced denaturation of helical filaments is the primary mechanism of hair relaxation.