The Swelling Behavior of Hair Studied Through the Structural Change of Keratin Protein During the Permanent Waving Treatment

This study investigates the swelling behavior of human hair during permanent waving (pw) treatment, focusing on the structural changes in intermediate filaments (IF) of α-keratin protein. The research reveals that both the microstructure and macrostructure of IF begin to change simultaneously at the initial stage of pw treatment without an induction period. The reducing treatment partially destroys the structure of microfibrils, but this is considerably restored by the subsequent oxidizing treatment. The study employs techniques such as SAXS and CP/MAS 13C NMR to analyze these changes, using 1.0 mol/L ammonium thioglycolate solution as the reducing agent. The findings contribute to understanding the detailed swelling behavior of hair during pw treatment.