Analysis of the torsional storage modulus of human hair and its relation to hair morphology and cosmetic processing

Through measurements of three different hair samples (virgin and treated) by the torsional pendulum method (22°C, 22% RH) a systematic decrease of the torsional storage modulus G' with increasing fiber diameter, i.e., polar moment of inertia, is observed. G' is therefore not a material con...

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Bibliographic Details
Published in:	Journal of cosmetic science 2014-03, Vol.65 (2), p.59-68
Main Authors:	Wortmann, Franz J, Wortmann, Gabriele, Haake, Hans-Martin, Eisfeld, Wolf
Format:	Article
Language:	eng
Subjects:	Biomechanical Phenomena - physiology Hair - chemistry Hair - drug effects Hair - physiology Hair Preparations - pharmacology Humans
Online Access:	Get full text
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Summary:	Through measurements of three different hair samples (virgin and treated) by the torsional pendulum method (22°C, 22% RH) a systematic decrease of the torsional storage modulus G' with increasing fiber diameter, i.e., polar moment of inertia, is observed. G' is therefore not a material constant for hair. This change of G' implies a systematic component of data variance, which significantly contributes to the limitations of the torsional method for cosmetic claim support. Fitting the data on the basis of a core/shell model for cortex and cuticle enables to separate this systematic component of variance and to greatly enhance the discriminative power of the test. The fitting procedure also provides values for the torsional storage moduli of the morphological components, confirming that the cuticle modulus is substantially higher than that of the cortex. The results give consistent insight into the changes imparted to the morphological components by the cosmetic treatments.
ISSN:	1525-7886 2689-5153