The design of renewable and fully biobased flame retardants (FRs) with high efficiencies and mechanical reinforcement functions for epoxy resin (EP) can greatly advance their potentials to satisfy sustainability. Although some biobased fire retardants have been successfully developed so far, most of existing biobased FRs are often not fully biobased and their syntheses normally involve the use of a large volume of organic solvents in addition to complicated synthesis processes. Herein, we report a facile and green strategy to synthesize fully biobased FR (P-MCC@CS@PA-Na) by surface-functionalizing microcrystalline cellulose (MCC) with chitosan (CS) and sodium phytate (PA-Na) via layer-by-layer assembly in water. The results show that incorporating 15 wt % P-MCC@CS@PA-Na enables EP composite to pass a UL-94 V-1 rating with a limiting oxygen index of 26.2%. Meanwhile, the peak heat release rate, total heat release, peak smoke production release, total smoke production, the fire growth rate, and the fire retardancy index of the EP/15 wt % P-MCC@CS@PA-Na are greatly reduced, indicating a good fire retardance. Notably, the well-designed P-MCC@CS@PA-Na simultaneously strengthens and toughens the EP because of uniform dispersion and a favorable interfacial compatibility between P-MCC@CS@PA-Na and the EP matrix. This work provides a green strategy for the fabrication of highly efficient multifunctional fully biobased FRs for polymers.

No abstract

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.