A novel bio‐based charcoal‐forming agent based on chitosan and phytate@Mg to improve the flame retardancy of poly(lactic acid)

Abstract A novel bio‐based carbon forming agent (Mg@PA‐CS) containing P and N elements was were synthesized using the complexation characteristics of chitosan (CS) and phytate (PA). The flame retardant behavior of poly(lactic acid) (PLA)/Mg@PA‐CS/APP composites (addition of 20 wt% of different ratios of Mg@PA‐CS and APP to polylactic acid composites) were investigated by the limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimetry test (CCT), and thermogravimetric analysis (TGA). Due to the biphasic flame retardant and synergistic effect, since the 20 wt% flame retardant system (Mg@PA‐CS:APP = 1:2), PLA composites passed the UL‐94 test V‐0 rating, reached 34% LOI value. The peak heat release rate (PHRR) and total heat release rate (THR) were reduced to 1/2 of the pure PLA, char residue could be as high as 11.49% at 800°C. Moreover, the flame‐retardant mechanism of PLA composites during thermal decomposition was analyzed using a scanning electron microscope (SEM) and the coupling techniques of TGA linked with FT‐IR (TG‐FTIR).