掺杂石墨氮化碳与聚磷酸铵复合阻燃环氧树脂

Doped graphitic carbon nitride and ammonium polyphosphate composite flame-retardant epoxy resin

通过诱导三聚氰胺、磷酸氢二铵、硅酸发生缩聚反应而合成了P、Si元素共掺杂的石墨氮化碳(PSiCN),表征了其结构组成和热稳定性;研究了PSiCN与聚磷酸铵(APP)复合阻燃环氧树脂(EP)复合材料的燃烧性能与力学性能。结果表明:PSiCN与APP的加入能够增强EP的热稳定性与成炭性能;添加2%PSiCN和8%APP,EP/2PSiCN-8APP复合材料的氧指数达到了29%;相对于纯EP,复合材料的热释放速率、烟释放速率及热和烟的释放量分别降低了71.1%、65.4%、53%和52.5%。EP复合材料火灾危险性的降低可归结于PSiCN热稳定性的提高及其与APP间的协同作用。此外,复合材料的拉伸强度和弯曲强度也分别提高了3.8%和5.2%。EP复合材料力学性能的提高可归因于芳香环与PSiCN表面的平行排列,以及P/N/Si多元素的协同效应。

A corrugated graphitic carbon nitride(PSiCN)co-doped with P and Si was synthesized by inducing the polycondensation reaction of melamine,diammonium hydrogen phosphate,and silicic acid.Combined with Fourier infrared spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy,and thermogravimetric analysis(TG),the structural composition and thermal stability of PSiCN were characterized.Besides,the thermal stability,combustion,and mechanical properties of PSiCN and ammonium polyphosphate(APP)composite flame-retardant epoxy resin(EP)composites were analyzed by TG,limiting oxygen index(LOI),cone calorimeter(CCT),and electronic universal tester.TG analysis indicated that the residues of PSiCN at 800℃were higher than that of g-CN.After being combined with APP,it can slow down the degradation of composites.The results of the flame retardant test showed that the LOI of EP containing 2%of PSiCN and 8%of APP(2 PSiCN-8 APP)was 29%,which reached the refractory level.Compared with pure EP,the peak heat release rate(pHRR),peak smoke production rate(pSPR),total heat release(THR),and total smoke production(TSP)of EP/2 CN-8 APP composites were decreased by 70.2%,61.5%,33.4%,and 45.5%,respectively,by adding 2%g-CNand 8%APP.The pHRR,pSPR,THR,and TSP of EP/2 PSiCN-8 APP composites were reduced by 71.1%,65.4%,53%,and 52.5%,respectively.It can be seen that PSiCN exhibited a better synergistic effect with APP than g-CN,as well as flame retardancy and smoke suppression properties for EP,which reduced the fire hazard of composites.In addition,compared with EP and EP/2 CN-8 APP composites,the tensile strength of EP/2 PSiCN-8 APP composites increased by 1.9 and 0.6 MPa,and the flexural strength increased by 5.1 and 1.7 MPa,respectively,which enhanced the mechanical properties of the composites.Therefore,PSiCN can solve the defect that APP deteriorates the mechanical properties of materials,and achieved a good synergistic flame-retardant effect with APP,while significantly improving the flame-retardant and smoke-suppressive properties of EP.