Eco-friendly composites based on peanut shell powder / unsaturated polyester resin

Different samples of unsaturated polyester composites containing various amounts of untreated and alkali- or silane-treated peanut shell powder were prepared. In order to investigate and understand the changes in the chemical structure of the filler that may occur after the treatments, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction analyses were performed. The prepared composites were investigated in view of their thermal stability, mechanical strength, and water absorption. The results showed that the treatments of the filler enhanced the interfacial adhesion between the fibers and matrix and consequently improvements in the mechanical properties, as well as a reduction in water absorption were gained. These results were strengthened by scanning electron microscopic measurements of the fracture surface of the composites. It has also been found that the flexural strength values of the investigated composites exceed the minimum requirements for the flexural strength of panels for general purposes. Therefore, the prepared composites can be considered as excellent candidates for several potential applications.