HPDSC evaluation of cosmetically treated human hair

We have carried out a comparative high-pressure differential scanning calorimetry (HPDSC) investigation of bleached and permanent waved human hair, focusing on the way the denaturation reaction of the hair protein is affected by the two cosmetic treatments. We have measured the values of enthalpy, peak temperature and the height of the peak for all the samples and noticed how the values change with the type and duration of the treatment. The results show that the bleaching process affects both the amorphous matrix and the crystalline α-helix region quicker and to a larger extent than perm waving does. The process becomes severe after 2-3 times bleaching 10 minutes each. In all the cases we have been able to fit with simple equations the change of the values of the parameters with the duration of the treatment. The empirical relationships are semilogarithmic, in case of bleaching, and linear, for perm waving, respectively.