Learning From Hair Moisture Sorption And Hysteresis
July 2022
in “
International Journal of Cosmetic Science
”
moisture sorption moisture desorption isotherms untreated hair chemically treated hair permed hair bleached hair swelling hysteresis capillary condensation protein chains bonds water molecules active sites matrix breaking symmetry hydrogen bonds relative humidity mechanical behavior cosmetic treatments moisture absorption moisture release hair swelling hair bonds water binding hair structure hair treatments
TLDR Hair moisture behavior helps tell apart different chemical treatments and reveals insights into hair structure.
The study "Learning from hair moisture sorption and hysteresis" analyzed the process of moisture sorption and desorption by human hair to gain insights into hair structure. The researchers recorded the isotherms of moisture sorption and desorption for untreated and chemically treated (permed and bleached) hair, and also considered data of swelling. The results suggested that hysteresis is unlikely caused by capillary condensation, but rather by the mobility of protein chains and the strength of bonds binding water molecules to active sites inside the matrix. The study introduced the concept of "breaking symmetry" as a way to characterize the chemical treatment of hair, with bleaching causing a larger breaking of symmetry than perming due to the creation of new hydrogen bonds. The study also identified two transitions in relative humidity that affect the hair's mechanical behavior. The moisture sorption-desorption process was found to provide valuable information on the structure of the hair and allow a quantitative differentiation among various cosmetic treatments.
