Extraction and characterization of cellulosic fiber from Centaurea solstitialis for composites

With increasing ecological awareness, researchers around the world seek to make composites reinforced with more eco-friendly natural fibers. In this study, Centaurea solstitialis (yellow star thistle) fibers were characterized as a potential natural fiber reinforcement for green composites. Generally, Centaurea solstitialis plants are undesirable because of their detrimental effect on other plants. In this respect, they are generally considered economically worthless in terms of the economical aspect. From this point of view, characterizing Centaurea solstitialis and using them as a natural fiber reinforcement material can be more appropriate in terms of waste management. To characterize the Centaurea solstitialis fibers, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Thermogravimetric Analysis, X-ray Photoelectron Spectroscopy, X-Ray Diffraction Analysis, single fiber tensile test, determinations of density and chemical composition were performed. Centaurea solstitialis fibers have 11.2% hemicellulose and 57.20% cellulose content. The crystallinity index and density of fibers were determined as 71.43% and 1.37 g/cm3, respectively. Also, fibers exhibited relatively high tensile strength with 111.85 ± 24.97 MPa and Young’s modulus with 3.41 ± 0.62 GPa. The thermal resistance temperature of Centaurea solstitialis fibers was found as 273 °C. It is suggested that Centaurea solstitialis fiber is a suitable reinforcement candidate for composites with low density, low cost, abundancy and relatively high tensile strength.