焦磷酸哌嗪/三聚氰胺阻燃环氧树脂的应用研究

Research and Application of Pyrophosphoric Acid Piperazine/Melamine System in Flame Retardant Epoxy Resin

以磷酸及哌嗪为起始原料制备了二磷酸哌嗪,然后经缩聚得到焦磷酸哌嗪(PPAP)。采用红外光谱对产物PPAP的结构进行了表征,并通过热重分析研究了PPAP的热稳定性及成炭性能。然后将PPAP与三聚氰胺按9:1的质量比复配后添加到环氧树脂(EP)中,并以间苯二胺(PDA)为固化剂制备阻燃EP复合材料,通过极限氧指数(LOI)和垂直燃烧(UL 94)测试研究了材料的阻燃性能。结果表明:产物PPAP的起始热分解温度为262℃,残炭率(800℃)为16.4%,表明PPAP具有良好的热稳定性及成炭性能。当复合阻燃剂的总添加量仅为6%时,材料即可通过UL 94V-0级垂直燃烧测试,同时其LOI达到32.1%,表明PPAP/三聚氰胺阻燃体系对EP具有良好的阻燃作用。

The piperazine diphosphate was firstly prepared from the original materials of phosphoric acid and piperazine, then the piperazine diphosphate was condensed at high temperature, and the product of pyrophosphoric acid piperazine（PPAP） was obtained. The structures of PPAP were characterized by Fourier transforms infrared spectrometry（FTIR）, and the thermal stability and charring performance of PPAP were investigated by thermogravimetric analysis（TGA）. The synthesized PPAP was mixed with melamine according to the mass ratio of 9：1, and then incorporated into epoxy resin（EP） and cured with m-phenylenediamine（m-PDA） to prepare flame retardant EP thermosets, then the flame retardancy of the EP composites was investigated by limiting oxygen index（LOI） and vertical burning（UL 94） tests. The results indicate that： the initial thermal decomposition temperature of PPAP is 262℃, and the char residue rate at 800℃ is 16.4%, which reveals that the prepared PPAP possess excellent thermal stability and charring ability. The flame retardant EP thermosets can pass UL 94V-0 test, with the LOI value of 32.1% when the total loading amount of flame retardant is only 6%. The fact reveals that the flame retardant system of PPAP/melamine possesses high flame retardant efficiency for EP thermosets.