The effect of the presence of a macromolecular organophosphorus flame retardant, poly(N‐[3‐oxopropylmethylphosphinate]ethyleneimine), on the flammability, thermal stability, and mechanical properties of polyamides

A macromolecular halogen‐free flame retardant, poly(N‐[3‐oxopropylmethylphosphinate]ethyleneimine) (PN) has been developed. This material contains both phosphorus and nitrogen. A simple and scalable process for chemical synthesis on commercial scale is described. FTIR, 1H and 31P NMR spectroscopy were utilized for characterization. The compound has a glass transition temperature of 82°C and is thermally stable up to 330°C. Samples of polyamide 6 containing 1 to 10 wt% of PN were prepared in a kneader. The flammability of polyamide 6/PN blends was investigated using the UL 94 vertical fire test, limiting oxygen index measurements, cone calorimetry, and the glow wire test. Samples containing loadings of 1 wt% and 10 wt% PN have V‐2 and V‐0 ratings, respectively. Specimen containing polyamide 12/PN blends were prepared by extrusion and injection molding for mechanical characterization.