Preparation Of Graphene Functional Fillers And Their Effects On Degradation And Flame Retardancy Of Polyethylene

Thanks to the excellent mechanical,electrical,thermal and optical properties,graphene is considered as an ideal filler and is widely used in the research and application of polymer composites.Graphene fillers are characteristic of multifunctional characteristics.For example,the UV resistance of the composites can be improved by using the ?-? conjugated structure and free radical quenching characteristics of graphene,while the flame retardancy of the composites can be improved by using the free radical trapping effect of graphene and the barrier effect of lamellar structure.From the perspective of flame retardancy and degradation,graphene nanoplatelet(GNP)was combined with flame retardant and catalyst to prepare graphene flame retardant filler and graphene catalytic filler,which were used in polyethylene(PE)composites.The effects of graphene functional fillers on the degradation and flame retardancy of polyethylene were studied.Magnesium hydroxide/graphene flame retardant filler(GNP/MH and GO/MH)was synthesized by one-pot hydration method with light burned magnesium as raw material in the presence of GNP or graphene oxide(GO)dispersion.The method was revealed to synthesis hexagonal flaky MH and realize the uniform dispersion of GNP and GO.The interaction between GNP and magnesium ions significantly improved the hydration rate of MH.Three different kinds of Ni based metal organic framework materials(Ni-MOFs)were prepared by solvothermal method.Graphene supported Ni-ZIF(Ni-ZIF@GNP)was successfully prepared with GNP methanol dispersion,and the uniform dispersion of GNP was realized.Accordingly,the graphene catalytic filler was obtained by using the MOF catalyst and GNP.PE based composites was obtained by adding graphene functional filler and MOF,MH,GNP,respectively.The thermal degradation,UV degradation,flame retardancy and combustion behaviors of the composites were compared between different composites.The results showed that the activation energy of thermal degradation of PE was improved by Ni-ZIF,GNP and Ni-ZIF@GNP with the order of GNP>Ni-ZIF@GNP>Ni-ZIF.The UV resistance of the composites was evaluated by relative carbonyl index.Compared with PE,the composites containing 1 wt.% Ni-ZIF@GNP with better UV resistance was obtained by showing the decreased relative carbonyl index by 33.33%.When the content of flame retardants was 60 wt.%,the oxygen index of the composites with as prepared MH and graphene flame retardant functional fillers was higher than that of natural brucite and synthetic MH products.MH and graphene flame retardant functional fillers significantly reduced the peak heat release rate(p HRR)during the combustion of the composites.The p HRR of the composites with 40 wt.% MH and graphene flame retardant functional fillers was decreased by 56% than that of PE.