Effects of Various Methods of Chemical Modification of Lignocellulose Hazelnut Shell Waste on a Newly Synthesized Bio-based Epoxy Composite

In this study, a novel bio-based epoxy resin (ESA) with curable double bonds was synthesized by esterification reaction between sebacic acid (SAc) and epichlorohydrin (ECH). Its chemical structure was confirmed by FT-IR and H-1 NMR. Untreated, alkali treated, acrylic acid (AcA)- and acetic anhydride (AA) modified hazelnut shell waste (HSh) were used as inexpensive reinforcing materials in the ESA matrix system. The composites were prepared with HSh in varied per cent values (10-50 wt%) using the casting technique. The effects of chemical modification and amount of reinforcement materials on the properties of the composites were investigated. The composites were characterized using mechanical tests, as well as SEM, XRD, TGA, and contact angle measurement. The morphological results indicate an improvement in adhesion between the HSh fillers and ESA matrix upon chemical treatments. The modified HShs reinforced composites showed an increase of 7.7-46.2% in elongation at break when compared to the untreated HSh reinforced composite at more appropriate 20 wt% of filler. Also, tensile strengths of all chemically modified HSh composites are higher than that obtained with neat ESA and untreated HSh composites. It was observed that 20 wt% AA-modified HSh composite exhibited higher tensile strength (66 MPa) and elasticity modulus E (6.72 GPa) values. The TGA analysis showed that the HShs can significantly improve the thermal stability of neat ESA. Vicat softening temperature (VST) of composites was obtained higher than epoxy matrix. Additionally, all composites exhibited hydrophobic surfaces. The incorporation of HSh fillers reduces the wetting and hydrophilicity of synthesized epoxy resin.