微胶囊化膨胀型阻燃剂的制备及其在聚乳酸中的应用

Preparation of microencapsulated intumescent flame retardant and its use in polylactic acid

为提高阻燃剂的阻燃效率,以聚磷酸铵(A)、微晶纤维素(C)和三聚氰胺氰尿酸盐(M)为基础组分,利用球磨共混和原位合成技术制备了微胶囊化膨胀型阻燃剂M(A&C),并采用熔融共混方法制备阻燃改性聚乳酸(PLA/M(A&C))。利用热重分析仪、红外光谱仪、扫描电子显微镜及X射线光电子能谱仪等对M(A&C)的结构,阻燃改性PLA的热性能、阻燃性能和残炭形貌进行表征与分析。研究结果表明:在阻燃剂添加量保持相等(质量分数分别为3%、5%以及10%)时,PLA/M(A&C)样品的阻燃性均优于四组分直接共混样品PLA/(M+A+C),前者的极限氧指数分别为27%、29%和31.5%,均明显高于后者的24%,25%和28.5%;PLA/M(A&C)-10的综合阻燃性能较佳,垂直燃烧等级为V-0,热释放速率峰值为313 kW/m2,总热释放量为54 MJ/m2,残炭量为16.1%。

In order to improve the flame retardant efficiency,ammonium polyphosphate(marked as A),microcrystal cellulose(marked as C)and melamine cyanourate(marked as M)were selected as the basic components to prepare microencapsulated intumescent flame retardants,noted as M(A&C),via combination of ball-milling and in-situ synthesis techniques.M(A&C)was subsequently incorporated into polylactic acid(PLA)via melt blending method to get the PLA/M(A&C)samples.The structure of MA&C,thermal properties,flame retardancyand residual carbon morphology of flame retardantsamples were characterized with the help of thermogravimetric,Fourier transform infrared,X-ray photoelectron spectroscopy and scanning electron microscope.The results show that PLA/M(A&C)demonstrates better flame retardant ability than PLA/(M+A+C),with the same loadings of flame retardant(3%,5%and 10%mass fraction,respectively).The limit oxygen index of the former samples was 27%,29%,and 31.5%,respectively,which is obviously higher than those of the latter samples(24%,25%,anf 28.5%,respectively).The overall flame retardancy of PLA/M(A&C)-10 is found excellent,achieving UL-94 V-0 grade.The peak heat release rate,total heat release and char residue show obvious flame retardancy properties,with the values of 313 kW/m2,54 MJ/m2,and 16.1%,respectively.