Hair relaxation after shaping - A kinetic approach / S. Breakspear in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 46, N° 1 (02/2024)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 46, N° 1 (02/2024) . - p. 130-141 Titre : Hair relaxation after shaping - A kinetic approach Type de document : texte imprimé Auteurs : S. Breakspear, Auteur ; B. Noecker, Auteur ; C. Popescu, Auteur Année de publication : 2024 Article en page(s) : p. 130-141 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cheveux -- Soins et hygiène Cinétique chimique Fibre capillaire Traitement chimique Traitement thermique Index. décimale : 668.5 Parfums et cosmétiques Résumé : - Objective : Hair fibres have been shaped via either a thermal route or via a chemical route. The time-relaxation transients of the shaped hairs in air, and in water, respectively, were evaluated. The collected data were kinetically modelled in order to reveal information about the rate controlling mechanism of the recovery process. - Methods : Hair fibres were thermally shaped at different temperatures between heated plates and left to relax in an environment of controlled humidity and temperature. Different hair fibres were chemically shaped and left to relax in water of different controlled temperatures. Relaxation data were used for modelling the kinetics of the recovery processes by using exponential and logarithmic kinetic laws. The fitting of the models to the two sets of data has been checked by using the residual sum of squares for matching the proper model to each set of data. - Results : The processes of shaping and recovery were assimilated with a sequence of two successive quasi-chemical reactions, occurring at the used temperatures. Based on chemical and physical assumptions, the two groups of experiments were modelled by two different laws: an exponential law, suggesting a first-order process as the rate-determining step of the relaxation of thermally shaped fibres, and a logarithmic law, suggesting a slow relaxation, based on percolation theory, for the chemically shaped fibres. This allowed use of chemical kinetics tools for calculating the values of the activation energy in each case. The evaluated values of activation energy of the relaxation processes for both thermal and chemical shaping were found to be close to each other, in spite of the different methods of shaping. - Conclusion : The kinetic analysis suggests that despite different reaction sequences occurring during the different shaping-relaxation processes, the rate-controlling mechanism that manages the recovery process is the same in all cases; and this process is proposed to be the thiol-disulphide reformation of intra-protein bonds inside hair. Note de contenu : - MATERIALS AND METHODS : Materials - Thermal shaping - Recovery after thermal shaping - Chemical shaping - Recovery after chemical shaping - RESULTS AND DISCUSSION : Thermodynamics of the process - Kinetics of the process - Comparing the kinetic models DOI : https://doi.org/10.1111/ics.12915 En ligne : https://drive.google.com/file/d/1Y6BmSuu9yC_4Ib2IwMEYCVmJHxNTmQz_/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40585 [article]

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