Using biochar from kitchen bio-waste as a filler material in polymer matrix composite

Microstructure and mechanical properties of polymer matrix composites (PMCs) using as-received biochar derived from kitchen bio-waste and Hexion LR160 epoxy as the matrix material were investigated. The PMCs were produced via glass moulding with higher biochar contents of 10 wt.%, 20 wt.%, and 30 wt.%. Scanning electron microscopy (SEM), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR) were used to analyze the microstructure, chemical composition, and interfacial bonding. SEM analysis revealed biochar agglomeration at lower concentrations and increased homogeneity at higher biochar contents. Raman spectroscopy confirmed biochar’s disordered carbon structure (ID/IG = 1.10), while FTIR analysis identified characteristic functional groups suggesting mechanical adhesion between biochar and the epoxy matrix. Mechanical testing showed a modulus increase from 3.61 GPa (pure epoxy) to 4.98 GPa (PMC-C30). Tensile strength, initially lower than pure epoxy (62.00 MPa), increased from 21.00 MPa (PMC-C10) to 32.2 MPa (PMC-C30) with higher biochar content, indicating its reinforcing potential. Hardness increased from 175 HB (pure epoxy) to 237 HB (PMC-C30), further confirming biochar’s strengthening effect. The results of this study contribute to demonstrating biochar’s potential as a sustainable filler, supporting eco-friendly composite development while reducing the environmental footprint of polymer-based materials.