A novel phosphorus and nitrogen containing flame retardant named 1,4-bis(Diethyl methylenephosphonate) piperazine (BDEMPP) was synthesized. The chemical structures of BDEMPP were determined by Fourier transform infrared spectrum (FTIR), nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). The flame retardant rigid polyurethane foams (FR-RPUFs) were prepared by one-pot and free foaming with incorporating BDEMPP/expanded graphite (EG) with polyether polyol and polymethylene polyphenyl isocyanate. The limit oxygen index (LOI), vertical burning (UL94) and cone calorimeter (CONE) test showed that the fire-retardant properties were improved due to the barrier effect of EG and residual char. With addition of 10 wt % EG and 15 wt % BDEMPP, RPUF/10EG/15BDEMPP passed UL94 V-0 with the LOI value of 25.7%. The thermogravimetric analysis (TGA) results revealed that the initial decompose temperature (T_5%) of RPUF/10EG/15BDEMPP was decreased compared with pure RPUF. However, the yield of residual char was increased from 0.35% for pure RPUF to 30.52% for RPUF/10EG/15BDEMPP at 800 °C. EG and BDEMPP had a slight influence on density and compression strength. The density and compression strength of pure RPUF was 45.42 kg m⁻³ and 213 kPa. As for RPUF/10EG/15BDEMPP, the density and compression strength was 44.18 kg m⁻³ and 180 kPa. The morphology and composition of residual char were investigated. The results demonstrated that the intact, compact and thick residual char with abundant of phosphorus and nitrogen was formed to enhance the flame retardancy and smoke suppression.

合成了一种新型的含磷和氮的阻燃剂，称为1,4-双（亚甲基膦酸二乙酯）哌嗪（BDEMPP）。BDEMPP的化学结构通过傅里叶变换红外光谱（FTIR），核磁共振（NMR）和气相色谱-质谱（GC-MS）确定。阻燃硬质聚氨酯泡沫塑料（FR-RPUFs）是通过将BDEMPP /膨胀石墨（EG）与聚醚多元醇和聚亚甲基多苯基异氰酸酯混合而成的，通过一锅法和自由发泡法制备。极限氧指数（LOI），垂直燃烧（UL94）和锥形量热仪（CONE）测试表明，由于EG和残余炭的阻隔作用，其阻燃性能得到了改善。加入10重量％的EG和15重量％的BDEMPP，RPUF / 10EG / 15BDEMPP通过了LO94值为25.7％的UL94 V-0。与纯RPUF相比，RPUF / 10EG / 15BDEMPP的T _5％降低了。但是，在800°C时，残留焦炭的产率从纯RPUF的0.35％增加到RPUF / 10EG / 15BDEMPP的30.52％。EG和BDEMPP对密度和抗压强度影响不大。纯RPUF的密度和抗压强度为45.42 kg m ^-3和213 kPa。对于RPUF / 10EG / 15BDEMPP，密度和压缩强度为44.18kg m ^-3和180kPa。研究了残余炭的形态和组成。结果表明，形成了完整，致密，浓稠的残炭，其中含有大量的磷和氮，从而增强了阻燃性和抑烟性。