An innovative phosphorus and nitrogen based flame retardant showed to be highly effective in fire safety treatment of PLA (polylactic acid, a biodegradable polymer which can be renewably sourced from dairy byproducts). N, N’-diallyl-P-phenylphosphonicdiamide (P-AA) was produced by reacting PPDCl (phenylphosphonic dichloride) with TEA (trimethylamine) for several hours, subjected to filter separation and finally washed with water. It was then mixed into PLA by extrusion.
Just 0.5% P-AA increased the LOI (limiting oxygen index) of PLA by nearly 40% and enabled passing of UL94-V0 at 3.2mm thickness. 1% P-AA enabled UL94-V0 at 1.6mm. The flame retardancy was considered to mainly result from a gas phase action of PO. radicals released by thermal decomposition of P-AA. The 0.5% and 1% loadings of P-AA did not modify the key mechanical properties of the PLA polymer (tensile strength).
“A new super-efficiently flame-retardant bioplastic-poly (lactic acid): flammability, thermal decomposition behavior and tensile properties”, X. Zhao et al, ACS Sustainable Chem. Eng. 2016