Preparation of a novel biobased flame retardant containing phosphorus and nitrogen and its performance on the flame retardancy and thermal stability of poly(vinyl alcohol)

A novel biodegradable type flame retardants (PCA) based on phosphorylated cellulose derivatives was synthesized by the reaction of phosphorylated cellulose with ammonium hydroxide at room temperature. The chemical structure of PCA was characterized by Fourier transformed infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). A series of poly(vinyl alcohol) (PVA) composites with various PCA contents were prepared by the method of casting evaporation. The incorporation of PCA could effectively improve the flame retardancy of PVA matrix. When the PCA content reached 15 wt%, the PVA/PCA composite met the UL-94 V-0 classification and got the LOI value of 30.0. Thermal and combustion properties of PVA composites were investigated by TGA and MCC. The char yield of PVA composites with 15% PCA at 700 °C in air was as high as 19.71%. Moreover, the MCC result indicated that the incorporation of PCA could decrease effectively the value of peak heat release rate and total heat release of the PVA composites. The mechanical property of PVA/PCA composites was also investigated. The result showed that PVA/PCA exhibited excellent thermal properties and flame retardancy.