Preparation Of Graphene/Magnesium Hydroxide/Polyethylene And Their Flame Retardant Properties

With the increasing demand for environmentally friendly flame retardant materials,magnesium hydroxide(MH)as a green environmental friendly flame retardant has attracted much attention.The abundance of magnesium deposits in China provides a resource advantage for the research and application of MH flame retardants.However,due to the limited flame retardancy efficiency and the large amount of MH addition,the mechanical and processing properties of flame retardancy materials deteriorate,so the high efficiency flame retardancy of MH is still a research topic.In this paper,the preparation process of hexagonal flake MH by hydration method was studied with light burned magnesium as raw material.Graphene/magnesium hydroxide composite flame retardant(GNP-MH)was prepared by in situ hydration.The compound flame retardant was further modified by organic silicone oil and CEPPA.By Limiting oxygen index(LOI)and vertical burning test,thermogravimetric analysis and cone calorimeter test,the flame retardant properties of the composite 、the thermal degradation process and combustion behavior was studied.The results showed that : 1)Hexagonal flake MH was successfully prepared by hydration method using light magnesium as raw material,with particle size of 0.11-0.76 μm and crystallinity of 97 %.0.2 GNP-MH was prepared by hydration method in situ,the characteristic morphology and structure of MH coated graphene sheet were obtained;2)GNP-MH composite flame retardant has good flame retardant effect.At the packing amount of 50 wt.%,compared with MH/PE,the LOI of 0.2 GNP-MH /PE is improved by 6.4 %.Composite flame retardants have good flame retardancy effect.Compared with MH/PE,the LOI of 0.2GNP-MH/PE increased by 6.4 %,Composite flame retardants improved the combustion behavior of composite materials,the ignition time(TTI)increased by 25 s,the heat release peak(p HRR)decreased by 10.4 %,the total heat release(THR)decreased by 12.3 %,and the total smoke release(TSP)decreased by 8.3 %,Carbon residue increased by 5.3 %;3)The modification of flame retardants by organosilicone oil and CEPPA has been realized.The modifier has significant influence on flame retardancy and combustion behavior,Compared with 0.2 GNP-MH/PE,organic silicone oil modified system LOI increased by 22 %,p HRR decreased by 18.6 %,THR decreased by 32.8 %,TSP increased by 4.7 %,and residual carbon increased by 22.8 %,The LOI of CEPPA modified system was not significantly improved,the vertical combustion test grade reached V-0,p HRR decreased by 14.7 %,THR decreased by 14.1 %,TSP decreased by 27.3 %,and the residual carbon content increased by 10.3 %,which revealed the ternternical synergetic flame retardant effect between organic silicone oil and CEPPA modifiers and GNP and MH.