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A study of the volume and bounce decrease in hair with ageing using bending elasticity measurements
Author(s) -
Mamada Akira,
Nakamura Koichi
Publication year - 2008
Publication title -
international journal of cosmetic science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 62
eISSN - 1468-2494
pISSN - 0142-5463
DOI - 10.1111/j.1468-2494.2008.00421_1.x
Subject(s) - scalp , young's modulus , composite material , materials science , modulus , ageing , elasticity (physics) , volume (thermodynamics) , bending , anatomy , medicine , physics , quantum mechanics
Hair diameters and bending stresses were measured for chemically untreated regions of hair close to the scalp, collected from 38 Japanese female (age range: 26–51) and 35 Caucasian female (age range: 20–40) volunteers. For the bending stress measurements, a new methodology to obtain averaged Young's modulus has been developed in which 50 fibres are measured together to give reproducible data, overcoming the individual differences in each hair fibre. By comparing the resulting data of the fibres collected from the panelists younger than 40 years of age, no significant difference in Young's modulus between Japanese and Caucasian hair was recognized, and the modulus was c. 10 GPa, regardless of the hair diameter. On the other hand, there existed cases in which fibres showed lower Young's moduli, and these fibres were from senior panelists who were conscious of the decrease in hair volume and bounce with ageing. This result indicates that the decrease in volume and bounce in hair with ageing is not only caused by a decrease in hair diameter and fewer hairs per square centimetre of scalp but also by some internal change in the hair.