Preparation and characterization of the chestnut shell/kaolin reinforced hybrid polyester composite

This study aims to produce polyester composites by using the ground chestnut shell and/or kaolin filler which is food waste of a company producing chestnut candy; to examine the mechanical, physical and thermal properties and to determine the best recipe for composite production. In our study, the ground chestnut shell was added to the composite mixture in volume ratios ranging from 3% to 10%. Besides, to improve the properties of composite samples, two different types of kaolin were reinforced by 3% by volume. The compositions and crystal structures of the kaolin used were selected differently from one another; they were coded as white and gray kaolin. In the mixture, recipes cobalt was used as an accelerator, methyl ethyl ketone peroxide as hardener and polyethylene graft maleic anhydride as a binder. Scanning Electron Microscope (SEM) images of the ground chestnut shell and kaolin reinforcement samples were taken before the test and X-ray Fluorescence (XRF) and X-Ray Diffraction (XRD) analyses of kaolin samples were performed. Strength and elastic modulus values were obtained by performing three-point bending tests of composite materials produced by manual casting molding. Also, the impact strength of composite materials was examined by the impact test. The physical properties of the composite samples were also determined by density and water absorption test. The thermal properties of the samples were characterized by thermal gravimetric analysis (TGA) and microstructures were characterized by SEM images.When white kaolin supplement and 3% ground chestnut shell are used together, it has been observed that it creates a synergistic effect on composite samples and improves the mechanical properties of the materials. According to the impact test results, the amount of energy absorbed by the materials decreased with the increase of ground chestnut shells. However, kaolin supplementation contributed to the increase in absorbed energy. The ground chestnut shell and kaolin supplementation increased the bulk density of composites, a reduction in water absorption % and open porosity %.