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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How different is human hair ? A critical appraisal of the reported differences in global hair fibre characteristics and properties towards defining a more relevant framework for hair type classification / Gabriela Daniels in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 45, N° 1 (02/2023)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 45, N° 1 (02/2023) . - p. 50-61 Titre : How different is human hair ? A critical appraisal of the reported differences in global hair fibre characteristics and properties towards defining a more relevant framework for hair type classification Type de document : document électronique Auteurs : Gabriela Daniels, Auteur ; Ashiana Fraser, Auteur ; Gillian E. Westgate, Auteur Année de publication : 2023 Article en page(s) : p. 50-61 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Africain(ne)s Asiatiques Caucasien(ne)s Cheveux -- Classification Cheveux bouclés Densité Dermatologie Fibre capillaire Index. décimale : 668.5 Parfums et cosmétiques Résumé : This review critically appraises the reported differences in human hair fibre within three related domains of research: hair classification approaches, fibre characteristics and properties. The most common hair classification approach is based on geo-racial origin, defining three main groups: African, Asian and Caucasian hair. This classification does not account sufficiently for the worldwide hair diversity and intergroups variability in curl, shape, size and colour. A global classification into eight curl types has been proposed but may be too complex for reproducibility. Beyond that, hair cross-sectional shape and area have been found to have an inverse relation to curl: straighter fibres are circular with larger cross-sectional area, whilst the curlier fibres are elliptical with smaller cross-sectional area. These geometrical differences have been associated with bilateral vs homogenous distribution of cortical cell in curly vs straight hair respectively. However, there is no sufficient data demonstrating significant differences in hair amino composition, but proteomic studies are reporting associations of some proteins with curly hair. Eumelanin’s relative abundance has been reported in all hair colours except for red hair which has a high pheomelanin content. Higher tensile and fatigue strength of straight hair are reported, however, curly hair fragility is attributed to knotting, and crack and flow formations rather than the structural variations. African hair has been found to have the highest level of lipids, whilst the water sorption of Caucasian hair is the highest, and that of Asian hair the lowest. Not all comparative studies clearly report their hair sampling approaches. Therefore, to strengthen the robustness of comparative studies and to facilitate cross-study data comparisons, it is recommended that the following hair defining characteristics are reported in studies: hair cross sectional diameter/area, curl type, hair assembly colour, as well as where possible donor data (age/gender) and sample pooling approach. Note de contenu : - METHODS : Historical perspectives on hair classifications - Hair characteristics - Hair fibre properties - Table 1 : Search terms applied for each search topic - Table 2 : Hair density DOI : https://doi.org/10.1111/ics.12819 En ligne : https://drive.google.com/file/d/1b6wOBEKSfPwVcGsNkV8ilEYGvJpQENGH/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38819 [article]

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Protecting hair fibre and colour from solar radiation / Ricard Armengol in PERSONAL CARE EUROPE, Vol. 4, N° 4 (11/2011)  

[article]  inPERSONAL CARE EUROPE > Vol. 4, N° 4 (11/2011) . - p. 95-98 Titre : Protecting hair fibre and colour from solar radiation Type de document : texte imprimé Auteurs : Ricard Armengol, Auteur ; Blanca Martinez-Teipel, Auteur Année de publication : 2011 Article en page(s) : p. 95-98 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cheveux -- Détérioration Cheveux -- Effets du rayonnement solaire Cheveux -- Propriétés mécaniques Cheveux -- Soins et hygiène Cheveux -- Teinture Fibre capillaire Protéines Tryptophane Le tryptophane est un acide aminé, qui dans sa configuration L (L-tryptophane, ne pas confondre avec lévogyre) est l'un des 22 acides aminés constituant des protéines. Dans le code génétique, il est codé par le codon UGG. Il s'agit d'un acide aminé essentiel pour l'humain, c'est-à-dire qu'il doit être apporté par l'alimentation. Propriétés : Il est aromatique, apolaire et hydrophobe (comme la phénylalanine). Très fragile, il est détruit par les acides minéraux, et ne peut être isolé dans les hydrolysats acides des protéines. C'est un acide aminé contenant un hétérocycle indole qui lui confère de propriétés spectroscopiques d'absorption et de fluorescence dans l'UV. En dehors de son utilisation dans la biosynthèse des protéines, c'est le précurseur d'autres composés importants comme la sérotonine, la mélatonine, la bufoténine, etc. Index. décimale : 668.5 Parfums et cosmétiques Résumé : Hair can be easily damaged due to mechanical causes (brushing, friction), chemical causes (colouring, perms, etc.) and environmental causes (solar radiation, etc.), because its structure is very sensitive and fragile. Solar radiation by itself can trigger a series of undesirable results, such as loss of colour, both natural and artificial, and changes in the superficial layer of hair, which affect the appearance and manageability of hair. In fact, it is considered that ultraviolet radiation is one of the most damaging environmental factors. Solar exposure is the main area responsible for the degradation of amino acids in the hair cuticle. These amino acids play a key role in the stability of hair proteins. The aggression of this radiation causes reactions of photooxidation of disulfide bonds, which participate in maintaining the overall integrity of hair keratin. Ultraviolet radiation : - Degrades cysteine to cysteic acid by excision of the S-S and C-S bonds.1 - Degrades the lipids present in the cuticle, particularly in the epicuticle, which play a key role in the properties of the hair surface. Note de contenu : - Mechanical properties of hair - Hair protein degradation - Tryptophan degradation - Hair lipid degradation - Hair brightness assessment - Evaluation of hair colour variation(DeltaE) En ligne : https://drive.google.com/file/d/18Zp_Wbh3O832v_2ATjN0LtiIIB9Osk_5/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40982 [article]

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