含磷阻燃固化环氧树脂复合材料的制备及性能研究

Study on the preparation and curing flame retardant of epoxy resin containing phosphorus

以1-氧-4-羟甲基-2,6,7-三氧杂-1-磷杂双环[2.2.2]辛烷(PEPA)和偏苯三甲酸酐(TMA)为原料合成了集阻燃固化功能于一体的化合物PEPA-TMA,并将其作为阻燃固化剂与三聚氰胺氰尿酸(MCA)复配,制备了不同含磷量的阻燃环氧树脂EP/PAPE-TMA/MCA。采用极限氧指数(LOI)和垂直燃烧(UL-94)研究了阻燃树脂的阻燃性能,采用热重分析(TGA)研究了阻燃树脂的热分解过程,用扫描电镜(SEM)观察了阻燃树脂燃烧炭层的形貌。研究结果表明,当含磷质量含量达到2.5%时,阻燃EP/PAPE-TMA/MCA体系的阻燃效果达到最好,LOI值为31.2%,垂直燃烧UL-94通过V-0级,800℃时材料的残炭量达到33.7%。TGA研究表明PEPA-TMA对EP/MCA体系的热起始分解温度没有太大影响,但提高了材料在高温时的热稳定性和成炭性能。通过SEM观察得到炭层密度增加,起到了隔热、隔氧作用,发挥了凝聚相阻燃作用。此外,MCA在燃烧过程中有NH_3等不燃气体逸出,有效地稀释了气相中的氧气浓度,发挥了气相阻燃作用,对材料的阻燃有协同作用。

A novel curing and flame-retarding agent（PEPA-TMA）synthesized via 2,6,7-trioxa-l-phosphabicyclo-[2.2.2]-octane-4-methanol（PEPA）was reacted with trimellitic anhydride（TMA）.Flame retardancy of EP/PEPA-TMA/MCA was investigated by limited oxygen index（LOI）and UL-94 vertical burning test.The thermal decomposition of EP/PEPA-TMA/MCA was investigated by TGA analysis.Morphology of char combustion of EP composite was observed by SEM.The results showed that the most effective amount of phosphorus was 2.5wt%.LOI value was 31.2% and UL-94 vertical burning reached V-0grade.The TGA tests demonstrated that the initial decomposition on temperature of MCA/EP changed hardly with PEPA-TMA loading,but the thermal stability of MCA/EP at high temperature was enhanced and promoted charring forming.SEM observed that the increase of char residue can greatly hamper the transfer of heat and oxygen in the combustion layer and matrix,thus leading to flame retardant in condensedphase.Moreover,MCA released inert gases such as NH3 during the flame process.These inert gases diluted the flammability gases such as oxygen from combustion,thus leading to flame retardant in gasphase,had a synergistic effect of flame retardant for EP composites.