Synthesis Of Phosphours-Nitrogen-Containing Ionic Liquids@NH₂-MIL-101?Al? Composites And Its Flame Retardant On Epoxy Resin

Epoxy resin?EP?has proven to be one of the most important thermosetting resins due to its low cost,convenient curing process,good insulation and excellent chemical resistance.At present,EP has been widely used as adhesives,composite materials and coatings.Unfortunately,EP is highly flammable and generates a large amount of toxic gases during the combustion process,causing serious damage to human safety and the environment.Therefore,it is important to design and develop high-efficiency flame retardants to improve the fire resistance of EP.Recently,Metal-Organic Frameworks?MOFs?have attracted great attention in flame retardant applications due to their high designability.However,the flame retardancy of a single MOF material is often limited.How to make full use of the advantages of MOF materials and improve its performance is still an issue that needs to be studied.In this work,a novel MOF composite?IL@MOF?was designed through the generated cooperative role of MOF and a phosphorus-nitrogen-containing ionic liquid?IL?.Its flame retardant properties and mechanical properties were characterized.In addition,the mechanism of flame retardants on EP was systematically analyzed.The main contents are as follows:1.NH₂-MIL-101?Al?was chosen as the MOFs because of the interaction between-NH₂and EP as well as the carbon-forming thermal insulation effect of the framework structure.At the same time,a new type of ionic liquid which contains flame retardant elements such as phosphorus and nitrogen was designed.IL@NH₂-MIL-101?Al?was prepared by the composite of IL and NH₂-MIL-101?Al?.It combines the advantages of IL with NH₂-MIL-101?Al?.The composite was analyzed by FT-IR,XRD,SEM,TEM,BET,EDS,XPS and TGA characterization methods.The results showed that the IL@NH₂-MIL-101?Al?material was successfully prepared.IL@NH₂-MIL-101?Al?has higher thermal stability and better carbon formation effect with the addition of IL.2.The flame retardant properties of IL,NH₂-MIL-101?Al?and IL@NH₂-MIL-101?Al?with different loadings?1%,2%,3%?were investigated.The thermal stability of the EP composites was researched by TGA.The limiting oxygen index test?LOI?and cone calorimetry test?CCT?were used to study the flame retardancy properties of EP composites.The results showed that the addition of NH₂-MIL-101?Al?and IL@NH₂-MIL-101?Al?can promote the decomposition of EP composites,which were beneficial to restrain the combustion of EP.Among them,IL@NH₂-MIL-101?Al?exhibited the best flame retardant effect on EP.In particular,when the amount of IL@NH₂-MIL-101?Al?was 3%,the LOI value of EP/3%IL@NH₂-MIL-101?Al?increased from 25.8%?pure EP?to 29.8%.Meanwhile,compared to pure EP,the PHRR,SPR and COP values of EP/3%IL@NH₂-MIL-101?Al?decreased by 51.2%,37.8%and 44.8%,respectively.In addition,the introduction of IL evidently improved the phenomenon that the mechanical properties of EP/NH₂-MIL-101?Al?were significantly reduced.3.In order to systematically explore the flame retardant mechanism of EP/IL@NH₂-MIL-101?Al?,FT-IR,XRD,SEM and Raman were used to analyze the residual carbon after the cone calorimetry test.The organic framework in IL@NH₂-MIL-101?Al?can serve as an effective physical barrier to inhibit flame spread.IL can not only effectively capture the free radicals generated by EP degradation and reduce the rate of heat release,but also promote the formation of dense carbon and significantly reduce smoke release.The synergistic effect of IL and NH₂-MIL-101?Al?significantly enhanced the flame retardant and smoke suppression effect of EP.This flame retardant strategy can provide new methods for the design of more flame retardant materials.