新型阻燃剂PAPP的合成及其在热塑性弹性体中的应用

Synthesis of A Novel Flame Retardant PAPP and Its Application in Thermoplastic Elastomer

以磷酸和哌嗪为原料,经两步脱水反应分别合成了中间体二磷酸哌嗪和磷氮型阻燃剂聚焦磷酸哌嗪（PAPP）。采用傅里叶红外光谱（FTIR）、核磁共振氢谱（1H-SSNMR）、核磁共振磷谱（31P-SSNMR）及元素分析对二磷酸哌嗪和PAPP的结构进行了表征,并采用热失重分析（TG）对PAPP的热稳定性和降解行为进行了研究。结果表明：与二磷酸哌嗪相比,PAPP的红外谱图中呈现出PAPP的特征结构P—O—P的吸收峰;二磷酸哌嗪和PAPP分子中均含有3种不同结构的氢原子,二磷酸哌嗪在高温下大量脱水生成了PAPP;对P谱峰面积积分,计算出PAPP的聚合度约为26,二磷酸哌嗪和PAPP的理论C、H、N、P含量与实际测试值吻和;PAPP的初始分解温度为305℃,800℃时的残炭率为10.4%,表明PAPP具有较高的热稳定性。随着PAPP用量的增加,热塑性弹性体（TPE）/PAPP复合材料的极限氧指数（LOI）逐渐提高,TPE/PAPP（40%）复合材料的垂直燃烧等级达到UL 94V-0级,表明PAPP是一种阻燃性能优异的新型阻燃剂。

A intermediate piperazine diphosphate and a novel halogen-free nitrogen phosphorus flame retardant pyrophosphate piperazine（piperazine polypyrophosphate, PAPP） was synthesized through two steps dehydration reaction with phosphoric acid and piperazine as raw materials. The fourier infrared spectrum（FTIR）, solid state nuclear magnetic resonance hydrogen spectrum（1 H-SSNMR）, solid state nuclear magnetic resonance phosphorus spectrum（31 P-SSNMR） and elemental analysis have been used to characterize the structure of PAPP. The thermo-gravimetric analysis（TG） was also used to analyze the thermal stability properties and degradation behaviors of PAPP. The results show that： compared with piperazine diphosphate, the infrared spectrum of PAPP shows the absorption peak of PAPP characteristic structure P— O— P. It also can be seen that the piperazine diphosphate and PAPP molecules contain three different structures of hydrogen atoms, piperazine diphosphate dehydrates at high temperature to form PAPP of hydrogen atoms. The integration of P spectrum peak area can calculate the degree of polymerization of PAPP, about 26. Moreover, the elemental analysis results show that the theory contents of C, H, N and P of diphosphate piperazine and PAPP are same to actual test values. Thermo-gravimetric test results show that the initial decomposition temperature（T5%）of PAPP is 305℃ and the char residue of PAPP is 10.4% at 800℃, indicating that PAPP has high thermal stability. With the increase of the amount of PAPP, the limit oxygen index（LOI） of the thermoplastic elastomer（TPE）/PAPP composites increases gradually. The vertical combustion grade of TPE/PAPP（40%） composites reaches UL 94 V-0 grade, indicating that PAPP is a new type of flame retardant with excellent flame retardancy.