A Bio-Based Flame-Retardant Starch Based On Phytic Acid

Starch, being one of the most abundant polysaccharides in nature, has been modified as starch-based thermoplastic materials for decades. In this work, we have demonstrated a green and facile method for choline phytate (CPA), which is not only a fire retardant but also a plasticizer for starch. Thermoplastic starch (TPS) plasticized with glycerol, CPA, and water was prepared by melt blending. The plasticizing effect was investigated by crystallinity calculation and a tensile test. Also, the flame retardancy of CPA for TPS films was evaluated by combustion tests. As the CPA loading increased, the crystallinity of TPS films decreased from 11.7% to 7.6%. With the addition of 30 phr CPA, the TPS film could pass a UL-94 V-0 rating (1 mm) and the limiting oxygen index was increased to 43.7%. Cone calorimeter characterization revealed that the heat release of SGCPAX composites was efficiently restrained by CPA. The peak of heat release rate was decreased by 68.7% and total heat release was decreased by 33.8% for the TPS films containing 20 phr CPA. The flame-retardant mechanism of CPA in TPS played the key role by the analysis of the char residues.