水杨醛基席夫碱阻燃剂对EP热性能及阻燃性能的影响

Effect of Salicylaldehyde Schiff base flame retardant on thermal performance and flame retardant performance of EP

为探究不同P/N含量对EP复合材料阻燃性能的影响及不同席夫碱官能团数量对EP复合材料热性能的影响,以水杨醛(SAL)、3-氨基-1,2,4-三氮唑(ATZ)、对苯二胺(PPD)、三聚氰胺(MEL)和9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)为原料,分别制备了3种新型含磷席夫碱阻燃剂SAPO、SPPO、SMPO,SAPO是三氮唑-席夫碱阻燃剂,SPPO是苯环-席夫碱阻燃剂,SMPO是三嗪-席夫碱阻燃剂。采用1H-NMR、FT-IR表征3种阻燃剂的结构,同时证明成功合成3种阻燃剂。3种阻燃剂不仅结构组成不同,席夫碱官能团数量也不同:1 mol SAPO、SPPO、SMPO分别含有1、2、3 mol席夫碱官能团。使用垂直燃烧测试、极限氧指数测试、热重分析、锥形量热测试探究EP复合材料热性能和阻燃性能。结果显示,与EP相比,EP/6%SAPO、EP/6%SPPO、EP/6%SMPO的垂直燃烧测试均达到UL-94 V0等级;LOI值分别达到32.9%、32.3%和33.5%;残炭量分别增加到23.6%、24.7%和25.1%;PHRR值分别降低了20.2%、25.8%、27.9%;THR值分别降低了15.2%、17.8%、20.3%。EP复合材料的阻燃性能随着P/N含量增加而增强;热性能随着席夫碱官能团数量增加而增强。阻燃机理主要归因于P元素在气相捕获自由基切断链式反应、在凝聚相促进炭化脱水形成炭层,隔绝气体交换和热传导;N元素在燃烧时释放不可燃气体,降低可燃气体浓度,带走热量。

In order to explore the effect of different P/N contents on the flame retardant properties of EP composites and the effect of different Schiff Bases functional groups on the thermal properties of EP composites,three new phosphorus-containing Schiff Bases flame retardants of SAPO,SPPO and SMPO were prepared using salicylaldehyde(SAL),3-amino-1,2,4-triazole(ATZ),p-phenylenediamine(PPD),melamine(MEL)and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)as raw materials,SAPO is triazole-Schiff Base flame retardant,SPPO is benzene ring-Schiff Base flame retardant,SMPO is triazine-Schiff Base flame retardant.1H-NMR and FT-IR were used to characterize the structures of the three flame retardants,and the successful synthesis of the three flame retardants was demonstrated.The three flame retardants are not only different in structural composition,but also in the number of Schiff base functional groups:1 mol SAPO,SPPO,SMPO contain 1 mol,2 mol,3 mol Schiff base functional groups,respectively.Vertical combustion testing,limiting oxygen index testing,thermogravimetric analysis and Cone calorimetry testing were used to explore the thermal properties and flame retardant properties of EP composites.The results showed that the vertical combustion testing of EP/6%SAPO,EP/6%SPPO and EP/6%SMPO all reached V0 level,the LOI values reached 32.9%,32.3%,33.5%,respectively,the carbon residue increased to 23.6%,24.7%,25.1%,respectively,the PHRR values decreased by 20.2%,25.8%,27.9%,respectively,the THR values decreased by 15.2%,17.8%,20.3%,respectively.The flame retardant properties of EP composites increased with the increase of P/N content.The thermal properties are enhanced with the increase in the number of Schiff Bases functional groups.The flame retardant mechanism is mainly attributed to the capture of free radicals by P element in the gas phase,the chain reaction of cutting off the chain,and the promotion of carbonization and dehydration in the condensed phase to form a carbon layer,which isolates gas exchange and heat conduction.N element releases noncombustible gas when burned,reducing the concentration of combustible gas and taking away heat.