Composites with recovered polystyrene reinforced with pine or poplar residues following lignin extraction

Sustainable composites were produced by recycling polystyrene (PS) and pine and poplar fiber residues remaining after lignin extraction. Polystyrene was dissolved in acetone and reinforced with wood fiber residues at 10%, 20% and 30%. The mixture was dried at 100 °C for 2 hr, granulated, and pressed at 190 °C under 5 MPa for 20 minutes. Characterizations of samples were performed according to physical (ASTM D1037 for water resistance and ASTM 7032-21 for density measurement), mechanical (ASTM D638 for tensile, ASTM D790 for flexural), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The addition of fiber residue increased (up to 6.7%) the density but decreased the water absorption (WA) (up to 22%) and thickness swelling (TSW) (up to 12%). Fiber residue increased tensile strength (TS) by 46 to 167% and flexural strength (FS) by 45 to 82%. However, it decreased tensile modulus (TM) by 0 to 58% and flexural modulus (FM) by 3 to 12% (excluding pine). However, pine fiber residue increased FM by 2 to 19%. SEM analyses revealed homogeneous distribution of fiber residues.