Chitosan/Phytic Acid Polyelectrolyte Complex: A Green and Renewable Intumescent Flame Retardant System for Ethylene–Vinyl Acetate Copolymer

We describe the preparation and characterization of a green and renewable polyelectrolyte complex (PEC) containing phosphorus, nitrogen and carbon elements, based on the ionic complexation between chitosan and phytic acid. Introduction of this PEC to ethylene–vinyl acetate copolymer (EVA) leads to an improvement of the flame retardancy. As for the EVA/PEC composites with 20.0 wt % of PEC (EVA/20PEC), the char residue at 600 °C is 12 wt % higher than that of the pristine EVA under nitrogen atmosphere. Compared to the pristine EVA, the peak heat release rate and total heat release of EVA/20PEC show 249 W g–1 and 5.6 kJ g–1 decreases, respectively. The char residue of EVA/20PEC is full and compact, demonstrating excellent intumescent effect. Introduction of this PEC also contributes to a slight increase of the Young’s modulus while maintains the excellent ductility. This work provides a new approach for the development of environmentally friendly intumescent flame retardant system.