Fabrication of flame-retardant wood plastic composites based on wasted bean dregs with recycled PE via mechanochemical crosslinking

Fabricating wood-plastic composites (WPCs) using recycled plastic and wasted biomass materials is one of the effective approaches to alleviate the global energy crisis and reduce carbon emission. However, the unsatisfactory mechanical properties and fire safety hazards significantly limit the application of WPCs. Herein, recycled high density polyethylene (R-PE), bean dregs and intumesce flame retardant (IFR) were melt-blended into flame-retardant WPC by mechanochemical crosslinking. The results show that the as-prepared WPC within 22 wt% IFR achieves a satisfactory UL-94 V-0 rating and a limiting oxygen index of 31.0%, exhibiting a 40%, 27.6%, and 16.4% reduction in peak heat release rate, total heat release and total smoke production respectively compared to controlled WPC. The results also revealed an unexpected improvement in the mechanical performance of WPCs using the strategy (elevation of 73.6% in the elastic modulus and 75.9% in the breaking elongation, respectively), which can be attributed to the improved interfacial compatibility between R-PE, bean dregs and IFR. This work offers an innovative and feasible approach for fabrication of high-performance fire-retardant WPC based on recycling waste plastics and agriculture wastes, and contributing to the circular economy and sustainability in accordance with the greening strategy in the world.