Preparation of a novel phosphorus- and nitrogen-containing flame retardant and its synergistic effect in the intumescent flame-retarding polypropylene system

A novel phosphorus- and nitrogen-containing flame retardant (melamine phytate) was synthesized via the reaction between melamine and phytic acid. The chemical structure of melamine phytate (MPA) was confirmed by Fourier transform-infrared spectra (FT-IR) and elemental analysis. And the thermal behavior of MPA investigated by thermogravimetric analysis (TGA) demonstrates that MPA possesses a good char-forming ability at high temperature. Besides, limiting oxygen index (LOI) and vertical burning tests (UL-94) illustrate that polypropylene/melamine phytate/dipentaerythritol (PP/MPA/DPER) (70/22.5/7.5) can reach the LOI value of 28.5% and achieve V-0 rating at the flame retardant loading of 30 wt%. Except that, the thermal weight loss of MPA and DPER in PP composites was investigated by TGA in detail. Moreover, the char residue of PP composite after combustion was systematically analyzed by FT-IR, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), which can further propose and confirm the flame retardant mechanism. POLYM. COMPOS., 36:1606-1619, 2015. (c) 2014 Society of Plastics Engineers