Flame Retardancy and Thermal Degradation of Intumescent Flame Retardant Starch-Based Biodegradable Composites

Biodegradable PVA/glycerol-plasticized thermoplastic starch (TPS) and its intumescent flame retardant composites are prepared. Microencapsulated ammonium polyphosphate (MCAPP) was used not only to utilize the charring capacity of the polyhydric compounds but also to restrain the reaction between APP and starch during processing. The flame retardancy and thermal stability of TPS and TPS/MCAPP were characterized by LOI, UL 94, TG, and microscale combustion calorimeter (MCC). TPS/MCAPP composites with only 2 wt % MCAPP can pass V-0 in UL 94 test. However, neat TPS cannot pass any rating. The presence of MCAPP can reduce the total heat release of TPS sharply in MCC test. The thermal degradation and gas products of TPS and TPS/MCAPP were monitored by TG-FTIR and dynamic FTIR. XPS and SEM measurements were utilized to investigate the chemical structure, as well as the surface morphology of the residual char.