The kinetics of moisture sorption by hair

The study analyzed the kinetics of moisture sorption by human hair using dynamic vapour sorption (DVS) to understand hair structure and behavior in response to moisture. It examined untreated, heat-shaped, and bleached hair, as well as separated cuticle and cortex. The research introduced a time-dependent rate constant to describe moisture sorption kinetics, highlighting differences between cuticle and cortex and the role of chain entanglement. A transition at 30% relative humidity was identified, linked to structural changes and increased water accommodation. The study quantified the influence of fibre density on sorption and suggested that analyzing sorption kinetics, alongside hysteresis, provides a comprehensive understanding of hair moisture management.