Study On Modification Of Epoxy Resins By Carbon Nanotubes Functionalized With Ionic Liquids

In this paper,CNTs were modified by ionic liquids and combined into epoxy resins(EP)to prepare nano composites.The dispersion of modified CNTs in matrix and the interface properties were investigated,and the properties of nano composites were also studied in detail.CNTs/EP composites were prepared using 1-butyl-3-methyl imidazolium hexafluorophosphate([BMIM]PF6)as a dispersion agent.The non-isothermal curing kinetics of neat EP,CNTs/EP and CNTs/[BMIM]PF6/EP were investigated by DSC.SEM and DMA were used to study the influence of[BMIM]PF6 on the dispersion of CNTs in EP matrix and the interfacial adhesion.The effects of dosage of[BMIM]PF6 and CNTs on the mechanical properties,thermal stability and flame retardance of EP composites were investigated.The results showed that Sestak-Berggren model can well describe the curing process of the three systems.ILs can enhance the dispersion of CNTs and when adding 0.5%CNTs and 6%ILs,CNTs showed the better dispersion and stronger interface reaction,the mechanics properties of composites increased significantly.The synergy effect of CNTs and ILs improved the flame retardancy of composites.Polymerized ionic liquid(PIL)was synthesized using the 1-vinyl-3-butylimidazolium hexafluorophosphate as monomer and then used to modify the surface of CNTs by ultrasonic dispersing in acetone solution.The modified carbon nanotubes by PIL(PIL-CNTs)were characterized by thermogravimetric analysis(TG),Raman spectroscopy(Raman),Scanning electron microscopy(SEM)and Transmission electron microscopy(TEM).The results showed that PIL can be absorbed on the surface of CNTs and not change the electronic structure of CNTs.The PIL-CNTs showed better dispersion in acetone than pristine CNTs.PIL-CNTs/EP was prepared by incorporating 0.5%PIL-CNTs into EP and DDM as a curing agent.Analysis of dynamical mechanical properties(DMA)indicated that PIL-CNTs/EP displayed substantially higher storage modulus,and glass transition temperature was also increased 5.6℃ and 3.3℃ than those of neat EP and CNTs/EP,respectively.Compared to neat EP,the tensile strength,bending strength and impact strength of PIL-CNTs/EP composites increased 35.2%,26.4%and 45.0%,respectively.The SEM images of fracture surface indicated the dispersion of PIL-CNTs in the matrix and the interfacial adhesion are obviously improved.PIL-CNTs were also prepared by In situ polymerization.X-ray photoelectron spectroscopy(XPS),TG,TEM and Raman analysis showed that PIL can be absorbed on the surface of CNTs and not change the electronic structure of CNTs.The PIL-CNTs were dispersed better in acetone and EP and showed stronger interfacial adhesion with EP than pristine CNTs,as verified by SEM and dynamic rheological analysis.When adding 0.5%PIL-CNTs,the tensile strength,bending strength and impact strength of PIL-CNTs/EP composites increased 38.75%,19.4%and 49.4%;the LOI of composite was 28.5%,the PHRR and SPR obviously decrease,PIL-CNTs can improve the flame retardancy of EP.