IFR/EG与IFR/ZnB阻燃LGFPP的阻燃机理

Flame Retardant Mechanism of LGFPP Flame Retarded by IFR/EG and IFR/ZnB

利用可膨胀石墨(EG)、硼酸锌(Zn B)与膨胀阻燃剂(IFR),研究2种阻燃体系对长玻纤增强聚丙烯复合材料(LGFPP)的强度和阻燃机理的影响,通过氧指数(LOI)和锥形热量仪(CONE)测试,观察了CONE后残余物的宏观表现和燃烧后的微观形态。研究结果表明,IFR/EG体系在阻燃过程中形成膨胀的纤维结构,再迅速扩大形成"海绵"状炭层结构,将内部热和可燃气体扩散到材料之外,延迟燃烧过程,从而提高了部分复合材料的燃烧性能。IFR/ZnB体系主要是在热溶过程中失去结晶结构、释放水,对该过程中产生的可燃气体和小分子容易降低反应热,并在复合材料表面形成具有一定黏度的液体,使IFR中的空隙、空洞结构等消失,导致炭层更密集、更薄,减少燃烧或窒息。经比较发现,与稀释阻燃的IFR/ZnB体系相比,用炭层吸附的IFR/EG体系能更有效地提高LGFPP的阻燃性能。

Long glass fiber reinforced polypropylene(LGFPP)was modified by flame retarded including expandable graphite(EG)and zinc borate(ZnB)with intumescent flame retardant(IFR).Comparing the flame retarding effect of IFR/EG and IFR/ZnB on flame retardancy and flame retadant mechanism of LGFPP by using limit oxygen index(LOI),cone calorimeter(CONE)and observed the macroscopic topography of the residue after the CONE test and the microscopic carbon layer after LOI by scanning electron microscopy(SEM).The results showed that the flame retardancy was improved with IFR/EG and IFR/ZnB added in a way.The flame retardant mechanism of IFR/EG expanded rapidly in the course of flame retardancy and formed a spongy porous expanded carbon layer structure,which diffused heat and combustible gas from inside to outside of the material and slowed down the combustion process.The flame retardant mechanism of IFR/ZnB system was lost the crystal water in the process of thermal decomposition,diluted the flammable gas and small molecular substances in the process of decomposition,and formed a viscous liquid with good fluidity on the surface of the composite,it could seal some crevices and holed produced by IFR,and generated a relatively closed and thin carbon layer to slow down combustion or make it self-extinguishing.The carbon layer barrier mechanism of IFR/EG flame retardant system was more effective in improving the flame retardant performance of LGFPP than the dilution mechanism of IFR/ZnB flame retardant system.