Ageing effects on the diameter, nanomechanical properties and tactile perception of human hair.
BACKGROUND
The typical changes to hair associated with ageing are greying, thinning, dryness and brittleness. Research on the influence of ageing on hair properties will enable a detailed understanding of the natural ageing process.


METHODS
The studies were carried out using an SEM (scanning electron microscope), a TriboIndenter and an artificial finger. Three characteristic features of tactile perception that could reflect the perceptual dimensions of the fineness, roughness and slipperiness of hair were extracted. The influences of ageing on the diameter, surface topography, nanomechanical properties and tactile perception of hair were determined.


RESULTS
In the three age group hair samples, the children's group hair samples have the smallest diameter. The hair cuticles in the children and young adult groups were relatively complete and less damaged than in the elderly group. The hardness and elastic modulus of the young adult group's hair samples were higher than those in the elderly and children's groups. For all groups, loss modulus E" was smaller than storage modulus E'. Vertical deviations (R) and coefficient of friction (μ) increased, and spectral centroid (SC) decreased, with the increase in age. Ageing decreased the tactile perception of hair.


CONCLUSIONS
Ageing influences the diameter, surface topography, hardness, loss modulus, storage modulus and tactile perception of human hair.
School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou, 221116, China.|School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, 221116, China.
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W
Tang
School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou, 221116, China.
S G
SG
Zhang
School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou, 221116, China.
J K
JK
Zhang
School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou, 221116, China.
S
S
Chen
School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou, 221116, China.
H
H
Zhu
School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou, 221116, China.
S R
SR
Ge
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D002648:Child; D002675:Child, Preschool; D006197:Hair / Q000502:physiology*; D006801:Humans; D007223:Infant; D008875:Middle Aged; D036103:Nanotechnology; D014110:Touch / Q000502:physiology*; D055815:Young Adult
ageing; diameter; hair; nanomechanical properties; tactile perception