Epoxy biocomposites-based chemically treated coffee dystrophy and castor oil

Abstract

An agro-waste such as coffee beans has been used to generate cellulose particles. Coffee roast which is brown in color, was treated with 6% sodium chlorite solution, followed by alkali treatment. This chemically treated mass was subjected to acid treatment with 20% sulfuric acid. Cellulose microwhiskers were released. These micro particles were examined by an X-ray diffractometer (XRD). X-Ray diffraction study of these white cellulose particles and the residue showed a highly crystalline nature of the cellulose particles. The fourier transform infrared (FTIR) spectra were carried out to further investigate any structural changes after chemical treatment. The spectra of the treated powder showed lesser peak intensity at 1630 cm⁻¹. This peak is related to the aromatic ring of lignin. Thus, indicating that the removal of aromatic rings of lignin and polysaccharides after hydrolysis process, simultaneously increases degree of crystallinity. Composites of epoxy resin with a conventional amide-type hardener reinforced with renewable materials were investigated in the presence of castor oil (CO). The renewable material was extracted from coffee beans using various chemical agents. The extracted renewable material has been incorporated into epoxy resin. The composites were evaluated by FTIR to check any interactions. The remarkable hint is the increased intensity of the peak located at 3941 cm⁻¹ being assigned to the –NH₂ of the amine cured epoxy. The increment in the intensity is being attributed to the enhanced degree of interaction between the multifunctional CO and the amine cured epoxy resin as mentioned earlier. Tests of tensile and impact strength properties were carried out and Izod impact was determined at room temperature. It has been found that the incorporation of CO has significantly increased the elongation at break. The impact resistance of the composites with CO has significantly increased as compared to the control and the samples without CO. Scanning electron microscopy (SEM) images were taken to assess the effects of reinforcement and homogenization of the composites. It was noticed that the incorporation of the CO has turned the topography of the samples to a smooth surface with respect to rugged phase of the samples without CO.