Comparison of Mechanical Properties of Lignin/High‐Density Polyethylene ( <scp>HDPE</scp> ) Composites and Wood/ <scp>HDPE</scp> Composites

ABSTRACT Lignin is a plant‐derived, the second most abundant natural polymer, and a waste byproduct of the pulp industry. Incorporation of lignin into plastic composites using scalable approaches is commercially favored and low carbon‐cost. Potential end applications for lignin plastic composites (LPCs) could be found in buildings and furniture where wood plastic composites (WPCs) are used in various components. This study compares the mechanical properties of LPCs and WPCs, aiming at the examination of the viability of the use of LPCs as alternative materials to WPCs in the building industry. Sodium ligninsulfonate (SLS)‐based LPC blended with high‐density polyethylene (HDPE) (45 wt.%) and maleic anhydride grafted polyethylene (MAPE) as a compatibilizer (5 wt.%) reached flexural strength (35.17 and 30.92 MPa respectively) and moduli (2.87 and 1.79 GPa respectively) comparable to benchmarking WPCs. Lignin dealkaline (LD)‐based LPC exhibited higher ultimate strain but lower strength than SLS‐based LPC, probably due to fragmentation during the post‐sulfite treatment steps.