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Impact of sodium bicarbonate treatment of waste hemp fibers on the properties of dicyanate ester of bisphenol-A/bisphenol-A-based benzoxazine resin composites

This present study details an experimental investigation on understanding the effects of surface-modified waste hemp fibers on the overall properties of thermosetting resin blends composed of dicyanate ester of bisphenol-A and bisphenol-A-based benzoxazine resins. At first, the hemp fibers were subjected to sodium bicarbonate treatment, and then various experimental tests in terms of the Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis tests were, respectively, carried out to understand the influence of the as-used treatment on the structural, morphological, and thermal properties of the hemp fibers. The obtained results from the surface characterization evidently demonstrated the positive sodium bicarbonate impacts on the properties of the hemp fibers. After that, various amounts of the treated fibers were incorporated within the dicyanate ester of bisphenol-A/bisphenol-A-based benzoxazine resin blends and the obtained composite materials were characterized for their structural, mechanical behavior and thermal properties. The obtained results clearly revealed that the prepared blend composites were identified to possess good bending and impact strength properties; however, a slight decline was observed in the thermal properties. The scanning electron microscopy and Fourier-transform infrared spectroscopy investigations demonstrated a good dispersion of the fibers within the blend matrix, and also an enhanced fiber–blend matrix interfacial adhesion, which were plausibly behind the improved mechanical properties of the prepared blend composites.