Mechanical Characterization of Curly Hair: Influence of Nonconventional Hair Straightening Treatments

The study investigated the effects of nonconventional hair straighteners, specifically formaldehyde and glyoxylic acid, on the mechanical properties of curly hair. Using various advanced techniques, the research found that formaldehyde significantly decreased break stress and break extension, indicating substantial hair damage, while glyoxylic acid had a milder impact. Both treatments increased shear modulus, reduced water sorption, and caused surface damage to the hair. The study concluded that understanding these effects is crucial for developing effective and safe hair straightening products, highlighting the importance of evaluating hair properties for cosmetic development.