Tribological and Mechanical Properties of Brazilian Hair. (December 2017)

• Record Type: Journal Article
• Authors: Elzubair, A.; de Oliveira, N.F.; Munhoz, F.; Flor, C.; Fiat, F.; Baghdadli, N.; Camargo, S.S.; Luengo, G.S.
• Is Part Of: Biotribology. Volume 12(2017)
• Page Start: 33
• Page End: 42
• Publication Date: 2017-12
• Subjects: Brazilian hair -- Nanotribological properties -- Nanoindentation -- Differential friction effect; Biological interfaces -- Periodicals; Biomedical materials -- Periodicals; Biomechanics -- Periodicals; Tribology -- Periodicals; 610.2805
• DOI: 10.1016/j.biotri.2017.06.001
• Languages: English
• ISSNs: 2352-5738

Abstract

Abstract: Background: The high Brazilian ethnical mixture combined with the country climate conditions make Brazilian hair an uncommon category that is still scarcely studied. Methods: Brazilian hair of types II to V was investigated by nanoscratch and nanoindentation techniques. The results were statistically analyzed using ANOVA (p ≤ 0.05 level) and statistical correlation between the measured parameters was studied by linear regression. Results: Nanoscratch at low loads showed for hair types II and III a pronounced elastic recovery with little damage, while for types IV and V a more plastic and brittle behavior with higher friction in the direction from tip to root was observed. At high loads the tip reached the cortex and elastoplastic deformation, plowing, fracturing and chipping of cuticle cells occurred in all types. Quasi-static nanoindentation yielded average values H = 0.22 ± 0.06 GPa and E = 4.7 ± 0.8 GPa. Dynamic nanoindentation showed increasing H and E values when going from types II to V. Discussion: The static H and E values of Brazilian hair are consistent with the high Brazilian ethnical mixture. Nanoscratch failure mechanisms can be explained based on the dynamic H and E values. The scratch resistance in the direction from root to tip is associated to the cuticle mechanical properties, but in the opposite direction increased mechanical property values lead to increased damage. The surface friction behavior is determined by roughness of the fibers, however, when the tip goes into the cortex friction decreases due to its softer nature. Highlights: Brazilian hair is an uncommon hair category that is still scarcely studied. Its mechanical property values are approximately half way between those of Caucasian and African hairs. The friction effect of the Brazilian hair may be determined by surface topography and roughness.