A binary synergistic system consisting of a new magnesium phosphate compound and titanium dioxide for improving the flame retardancy and other key properties of ethylene vinyl acetate

Abstract

Biobased flame-retardant materials, such as phytic acid (PA), have attracted great interest due to their potential for synthesizing environmentally friendly flame retardant materials. In this study, a novel biobased magnesium phosphate flame retardant, MGPA, was synthesized by reacting PA with magnesium hydroxide (MH). The effects of MGPA and titanium dioxide (TiO₂) addition on the flame retardancy, smoke suppression, and key properties of ethylene vinyl acetate (EVA) composites were investigated. Results revealed that at a 19:1 MGPA to TiO₂ ratio, EVA composites experienced a decrease in peak heat release rate (pHRR), total heat release (THR), and total smoke production (TSP) to 209 kW/m², 64 MJ/m², and 9.9 m², respectively. Compared to pure EVA, the EVA/MGPA composite exhibited reductions of 79.7%, 58.4%, and 42.4% in pHRR, THR, and TSP, respectively. Moreover, the EVA/MGPA composite showed improvements in flame potential index (from 0.02 to 0.29), limiting oxygen index (from 17% to 27%), and UL-94 (from No Rated to V-1 level), as well as a significant decrease in light transmittance during flaming combustion. Furthermore, the addition of TiO₂ enhanced the hydrophobicity of EVA/MGPA composites while having negligible effects on mechanical properties.