The effect of surface treatments on properties of various animal fibers as reinforcement material in composites

Abstract

Recently, there has been a rapid growth in research on natural fibers as reinforcement materials in composites. Besides the commonly used cellulosic fibers, protein-based fibers known with their lightness, high elasticity, isolation capability and sustainability, can also be used as an alternative reinforcement material. In composite production, surface modifications are generally implemented in order to increase the compatibility of matrix-filler. In this study, wool, mohair, cashmere and camel fibers were modified with alkali and hydrogen peroxide and the effect of the modifications on fiber was analyzed. The chemical structure of modified and unmodified fibers was investigated by Fourier Transform Infrared Spectroscopy (FTIR), fine structure by X-Ray Diffraction (XRD) and morphological properties by Scanning Electron Microscopy (SEM). Moreover, the moisture content of the fibers was determined. According to obtained results, it is determined that the modification processes changed the intensities of the peaks which are attributed to the functional groups especially for the groups amide and sulphur. After the modification with hydrogen peroxide, new groups were introduced which indicates the oxidation of the disulphide bonds. The intensities of the peaks which are attributed to the crystalline surfaces changed although fibers gave the typical diffraction curves. However, tensile properties of the fibers remained similar to each other. The surface impurities were partially removed and also the scales on the fiber surface were affected with the modifications. After the modifications, the hydrophilicity of the fibers increased with the changes in the cuticle layer.