Study On Flame Retardancy Of Phosphorus-Containing Ionic Liquid And Graphene Epoxy Resin System

Epoxy resin is a kind of thermosetting resin with excellent properties,but its application is limited by its brittleness and poor flame retardancy.In this paper,a kind of phosphorus-containing ionic liquid was synthesized from DOPO,and it was used to modify graphene for the preparation of epoxy resin composites.The effects of it on the flame retardancy and mechanical properties of epoxy resin composites were studied.Epoxy resin composites were prepared from the synthesized ionic liquid1-methylimidazole-3-6h-dibenzo[c,e][1,2]oxyglycerophosphate-1H-3-ethyl([Dmim]E s),using 4,4-diaminodiphenylmethane(DDM)as curing agent.The effects of the composites on the thermal stability,mechanical properties and flame retardancy of EP were studied.The results show that the flame retardancy of the composites is improved by the introduction of [Dmim]Es without any effect on the mechanical properties of the composites.When the content is only 5wt%,the limiting oxygen index is 33.1%.Based on the π-π stacking effect between imidazole and graphite layer,the dispersion system of ionic liquid([Dmim]Es)and graphene in epoxy resin(EP)was designed.The study on the thermal and flame retardant properties of the composites showed that the modified graphene nanosheets improved the flame retardancy,smoke suppression and thermal stability of epoxy resin.When 5wt% [Dmim]Es and 1%Gra were added,the exothermic rate(HRR)and total exothermic(THR)of the composites decreased by 35% and 30.2% respectively compared with the untreated EP,and the limiting oxygen index reached 33.4%.The mechanical properties test showed that the tensile properties and impact properties of the blends were increased by 13% and 30%respectively.Through SEM observation,the addition of [Dmim]Es improved the dispersion of graphene in EP and changed the mechanical fracture behavior of the material.The results show that the good dispersion of graphene nanosheet modified by ionic liquid [Dmim]Es in the matrix not only brings excellent mechanical properties to epoxy resin(EP),but also has good flame retardant synergistic effect,so it has a broad application prospect in epoxy resin system.