Bio-Based Flame-Retardant and Smoke-Suppressing Wood PlasticComposites Enabled by Phytic Acid Tyramine Salt

Using bio-based chemicals and recycling wasteplastics are essential components of the circular economy.Wood-plastic composites (WPCs), fabricated from recycledplastic and wood-processing wastes, are new, green, and environ-mentally friendly materials. However, theirflammability causespotentialfire risks and hazards. Although bio-basedflameretardants possess the essential advantage over inorganic orpetroleum-based chemicals, their application, particularly that offully bio-basedflame retardants, in WPC has been seldom reported.Herein, we designed and synthesized a fully bio-basedflameretardant, phytic acid-tyramine salt (referred to as PATA), using agreen and environmentally friendly approach with only deionizedwater as the reaction solvent. PATA is subsequently utilized inconjunction with ammonium polyphosphate (APP) to synergisti-cally impartflame-retardant properties to WPCs. PATA/APP shows a goodflame-retardant effect, improving theflame retardant andsmoke suppression properties of WPCs. The PATA/APP system can increase the limiting oxygen index by 31% and achieve avertical combustion V-0 rating. Furthermore, the PATA/APP system can reduce the peak heat release rate, total heat release, andmaximum smoke density by 49, 22, and 15%, respectively. The PATA/APP system can generate phosphoric acid substances duringcombustion, which promote the decomposition of woodflour to form stable char layers containing P-N-CorP-O-C structures.Consequently, we provide an environmental-friendly approach to enhance theflame retardancy of WPCs.

Automated summary

Using bio-based chemicals and recycling waste plastics are important for the circular economy. Wood-plastic composites (WPCs) are new and environmentally friendly materials, but their flammability is a concern. This study designed and synthesized a fully bio-based flame retardant, PATA, and used it in conjunction with APP to enhance the flame retardancy of WPCs. The PATA/APP system showed significant improvements in flame retardant and smoke suppression properties of WPCs.