New Insight on the Friction of Natural Fibers. Effect of Sliding Angle and Anisotropic Surface Topography

Abstract

The friction anisotropy of human hair has been investigated as a function of angle using AFM fiber probe measurements to evaluate the role of cuticle alignment. It is found that friction hysteresis, the difference in friction coefficients between sliding with or against the cuticle direction, is essentially nonexistent for native human hair. For damaged human hair, however, a clear friction hysteresis is observed, which appears to be a periodic function of the angle between the fibers. The implication is that antiparallel sliding is not in itself sufficient for friction isotropy but that lifting of the cuticle edges is required. A methodology to perform friction analysis independently for trace and retrace was therefore developed, which is applicable to any type of AFM lateral force measurement. It explicitly accounts for roll, noncircular cross section, and off-axis alignment as well as baseline drift, which allows real anisotropy in the friction coefficient to be deconvoluted from these artifacts.

Tribological Properties between Taut Hair Fibers in Wet Conditions: A New Shampoo Formulation for Eliminating Stick‐Slip Friction

“…However, there is no large difference for the stick‐slip amplitudes in two opposite sliding directions for damaged hair, as shown in Fig. 5b, which seems inconsistent with the AFM study (Mizuno et al, 2013).…”

“…The two hair fibers come in contact in crossed cylinder geometry, and the upper hair fiber does not completely trace the surface profile of the cuticle roughness (little mechanical interlock of the cuticles (Adams et al, 1990)). Mizuno et al measured kinetic friction force between hair fibers positioned in a crossed cylinder geometry using an AFM setup (hair fiber probe was used) and studied the effect of sliding direction on friction ( Mizuno et al, 2013). They observed no apparent sliding direction effect for the kinetic friction coefficient μ k of native (healthy) hair.…”

“…A completely different approach was established by Mizuno et. al.; they attached a piece of single hair fiber on an AFM tip and measured adhesion and friction forces between crossed hair fibers (Mizuno et al, 2010(Mizuno et al, , 2013. Although these methods enable the measurement of friction force between hair fibers, we believe that they are not very suitable to evaluate the friction (stiction) properties that govern hair tangling because of the following reasons: i.…”

“…Tribological properties of hair surfaces have been studied for many years, and several measuring methods have been developed (Aita and Nonomura, 2016; Bhushan et al, 2005; Breakspear et al, 2005; Chevalier, 2017; LaTorre and Bhushan, 2005; Max et al, 2010; Mizuno et al, 2013; Robbins, 2012; Sinclair, 2007; Tanamachi et al, 2010). Some of them measure friction between hair and other materials (plates (Bhushan et al, 2005), force probes (Aita and Nonomura, 2016), and atomic force microscope (AFM) tip (Bhushan et al, 2005; LaTorre and Bhushan, 2005)), which are not suitable for our purpose.…”

“…al . ; they attached a piece of single hair fiber on an AFM tip and measured adhesion and friction forces between crossed hair fibers (Mizuno et al, 2010, 2013). Although these methods enable the measurement of friction force between hair fibers, we believe that they are not very suitable to evaluate the friction (stiction) properties that govern hair tangling because of the following reasons: Hair fibers are being pulled or taut at the tangling point, which is not the case in the methods described above. Tension force applied to hair fibers at the tangling point should produce a relatively large load between contacting hair surfaces.…”