Synthesis and characterization of bio-based "three sources in one" intumescent flame retardant monomer and the intrinsic flame retardant waterborne polyurethane

The bio-based "Three sources in one" intumescent flame retardant monomer (PAMAD)was prepared from biomass materials phytic acid (PA), melamine (MA) and dimethylolpropionic acid (DMPA). Furthermore, PAMAD was used as a hard-segment chain extender to chemically modify waterborne polyurethane (WPU), and a series of halogen-free, smoke suppression, flame-retardant waterborne polyurethane (PWPU) were prepared, which had cross-linked network structure. The structures of PAMAD and PWPU were confirmed by Fourier transform infrared spectroscopy (FTIR). The flame retardant properties of the PWPU materials were characterized by vertical burning test (UL-94 test), thermogravimetric analysis (TGA), cone calorimeter and so on. The test results showed that the sample PWPU-5, with the content of PAMAD was 11 wt%, achieved a V-0 classification of UL-94 test and the residual carbon increased to 11.97%. Compared with the sample without flame retardant modification, the peak of heat release rate (PHRR) and the total heat release (THR) of PWPU-5 were reduced by 51.2% and 33.8%, respectively. Meanwhile, the release rates of CO and CO2 decreased by 55.8% and 33.3%, respectively.