Constructing a rigid-flexible grid structure for simultaneously strengthening and toughening bamboo flour/plastic composites through the introduction of continuous carbon fabric meshes via multi-layer co-extrusion

The defects of low strength, brittle fracture, and creep deformation of traditional wood–plastic composites (WPCs) significantly limit their applications as high-value-added products. This study aimed to develop advanced WPCs with high strength, toughness, and creep resistance via a structural design. A continuous rigid-flexible grid structure, sandwiched by carbon fabric mesh prepreg (CFMP) and casting film (MSF) with high toughness, was introduced into bamboo flour/high-density polyethylene composites (BPCs) via a multi-layer co-extrusion technology. The sandwiched grid structure was in-situ cured in the near-surface layers of BPCs to form a multi-layer composite (BPC-CFMP-F) during co-extrusion. The tensile strength, flexible strength, and impact strength of BPC-CFMP-F were 68.4 MPa, 89.0 MPa, and 22.5 kJ m−2, which are 138.3%, 96.4%, and 87.6% higher than those of BPCs, respectively, and the thermal expansion and 1000-hr creep strain of BPC-CFMP-F decreased by 45.8% and 61.7%, respectively. The simultaneous strengthening and toughening of BPCs were attributable to the rigid-flexible grid structure and the strong interfacial bonding between CFMP and BPCs and the surface- and core-layer BPCs through the grid of CFMP. Owing to these unique features, BPC-CFMP-F is a promising advanced composite with high strength, toughness, excellent creep resistance, and thermal stability for high value-added applications.