Formation and Characterization of Hollow Microtubes by Thermal Treatment of Human Hair

In this study, hollow microtubes were prepared via stepwise thermal treatment of human hair waste in the middle temperature range from 200 to 450 °C. The effect of the treatment temperature on the thermal decomposition of the hair was examined in terms of the dimension and wall thickness of the microtubes. The thermal decomposition behavior of the hair was analyzed via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The structure and morphology of the hollow microtubes were examined using scanning electrochemical microscopy (SEM) and elemental analysis (EA). The thermal and morphological observations reveal that the thermal decomposition of the hair started from the core medulla section with the melting of the α-helical structure in the cortex at about 250 °C. As the heat treatment temperature further increased to 450 °C, the degradation of the cortical structure expanded to the outside, and the wall thickness of the hollow microtube decreased. Finally, the hollow microtube structure was completed, and the scaled structure in the cuticle layer became compact and smooth. Therefore, the hollow microtube structure might be a result of the melting and degradation of the cortex and medulla. The adsorption capacity of the hollow microtubes was also evaluated using n-hexane and water.