The influence of polybenzoxazine modified ammonium polyphosphate (BMAPP) on the thermal behavior and flame retardancy of a rigid polyurethane foam (PU) are investigated via thermogravimetric analysis (TG), TG coupled with infrared spectroscopy (TG-FTIR), UL-94 vertical burning testing and limit oxygen index (LOI). The TG testing results indicate that BMAPP can enhance the thermal stability of PU, both under air and nitrogen conditions. The initial degradation temperature of the BMAPP/PU composites is 264 °C in air, which is 22 °C and 30 °C higher than that of ammonium polyphosphate (APP)/PU composites and neat PU, respectively. The reason might be attributed to the better dispersion and compatibility of BMAPP particles in PU compared with APP, which can prevent the PU chain from degrading at low temperatures. The LOI value results demonstrate that BMAPP has higher flame retardancy in PU than APP. Residue analysis implies that polybenzoxazine is partially converted into Si–O as char residue during combustion.
The durability of flame-retardant cotton fabrics has been widely valued. A reactive P/N/B spiro compound in this work, diethanolamine borate methylene phosphonium ammonium salt (DMAPS), was prepared, which could endow cotton fabrics with excellent flame retardance at low concentration. The limiting oxygen index (LOI) of the fabrics treated with 100 g/L DMAPS was increased to 31.6%, and the char length was reduced to 5.9 cm. Continuing to increase concentration of DMAPS, the LOI value could reach about 42.9%. The cone calorimetric test results showed that the peak heat release rate of DMAPS treated cotton fabrics was only 15 kW/m 2 , which was about 92% lower than that of the untreated, and the total heat release rate (THR) was also decreased from 5.0 to 0.9 MJ/m 2 , which decreased by 82% compared with untreated cotton fabrics. The analysis of char residue showed that the polyphosphoric acid formed during the pyrolysis of DMAPS accelerated the formation of the char, while the carbide boron structure remained in the char, stabilizing the char layer, so that the char residue could still maintain the original warp and weft structure of the fabrics. In addition, the treated samples still had fire resistance and self-extinguishing behavior after 10 washing cycles. This study provides a possibility for the preparation of durable flame-retardant cotton fabrics. Graphical abstract An efficient and durable phosphorus–nitrogen–boron synergistic flame retardant for cotton was prepared and applied.
危险品化学品经营许可证（带存储）