Flame Retarding and Strengthening Poly(ethylene 2,5-furandicarboxylate-co-ethylene terephthalate) Using Phosphonate Containing Genistein

A bio-based phosphonate 4-(7-((diphenylphosphoryl)oxy)-5-hydroxy-4-oxo-4H-chromen-3-yl)phenyl diphenylphosphinate (DPGE) was synthesized using diphenylphosphinic chloride and genistein. DPGE was used to modify the flame retardancy of poly(ethylene 2,5-furandicarboxylate-co-ethylene terephthalate) (PEFT20) containing 20 mol % 2,5-furandicarboxylic acid. PEFT20 containing 8 wt % DPGE displays a UL-94 V0 rating and a limiting oxygen index of 29.8 vol %. The flame retardant mode is the comprehensive effects of melting-away, gas phase, and condensed phase induced by DPGE. In addition, triglycidyl isocyanurate (TGIC) was incorporated to regulate the mechanical performance of PEFT20/DPGE. The flexural and impact strengths of PEFT20/DPGE are modified greatly. The coupling reactions between PEFT20 and TGIC increase the molecular weight and mechanical properties of PEFT20 blends. But, TGIC counteracts the melting-away effect caused by DPGE. Therefore, too much TGIC causes the decrease in flame retardancy.