Investigation of Nanotribological Characterization of Stretched European Hair Using Atomic Force Microscopy

In order to understand the influence of stretching on the nanotribological properties of human hair, the European hair with stretching ratios at 20, 40, 60 and 80% were studied using atomic force microscopy (AFM). The results show that appropriate stretching ratios (40-60%) make the European hair surface smoother and the friction measurements also verify the result. When the stretching ratio is 80%, the European hair has the highest coefficient of friction. The reason is that cuticle damages lead to the local ratchet and collision between AFM tip and the sample obviously increased. With the increase of stretching ratios, the adhesive force of European hair is nonlinear change, which is attributed to the influence of contact area, water molecules absorbed and the amount of polar molecules.