Mechanical, dynamic thermal mechanical, and creep properties of hot-pressed wood-plastic composites

To investigate the influence of reinforced fiber size on the service performance of wood-plastic composites (WPCs), high-density polyethylene (HDPE) composites were prepared using poplar fibers of seven different sizes. Their bending and impact properties, dynamic thermal mechanical properties, and 24 h creep-24 h recovery performance were analyzed. The WPCs reinforced with 80 to 120 mesh fibers had the worst mechanical properties. The WPCs reinforced with 10 to 120 mesh fibers had the highest bending strength, reaching 28.1 MPa, while WPCs reinforced with 20 to 40 mesh fibers had the greatest bending modulus of 2.73 GPa. The WPCs with 20 to 80 mesh fibers had the highest impact strength, reaching 7.75 kJ/m2. Excessively large or small fiber sizes did not benefit the mechanical properties of WPCs. As the temperature increased, the storage modulus of WPCs decreased. Additionally, as the mesh size of wood fibers increased, the loss modulus increased, while the loss tangent gradually decreased, resulting in reduced toughness and more pronounced elastic behavior. Under a 50 N load, WPCs with the mixed mesh fiber outperformed WPCs with single mesh fibers in 24 h creep performance, WPCs reinforced with 20 to 80 mesh fiber showing the best creep resistance.