Advanced Carbon Material Enhanced Syntactic Foam

Carbon materials are widely used in reinforced polymer matrix composites because of their excellent mechanical properties.In this paper,syntactic foams were prepared by using various advanced carbon materials as reinforcing phase,E51 epoxy resin as matrix and hollow glass beads as light fillers.In view of the poor wettability between carbon fibers and polymer matrix,a strong acid oxidation process for carbon fibers was proposed.The effect of carbon fibers on the properties of syntactic foams was studied by numerical simulation.In order to solve the problem of poor dispersion of carbon nanotubes in polymer matrix,a method of covalent and non-covalent modification of carbon nanotubes at the same time has been proposed,which has achieved the goal of hybrid functionalization of carbon nanotubes.Hybrid functionalized carbon nanotubes were used to further enhance syntactic foams.In order to simultaneously utilize the strengthening effect of carbon nanotubes and carbon fibers,the composite reinforcement phase was prepared by using amino carbon nanotubes and carbon oxide fibers,and the effects of composite reinforcement on the properties of syntactic foams were studied.The main conclusions are as follows:1.The combination of carbon fibers with epoxy resin matrix can be improved by mixed acid oxidation.With the increase of the mass fraction of carbon fibers,the duty cycle of the material increases gradually,and the actual density of the material is obviously less than the theoretical density.At the same time,the compressive strength of the material increases first and then decreases.When the content of carbon fiber is 5%,the compressive strength is the highest,which is 41 MPa.2.With the increase of elastic modulus of matrix,the mechanical properties of syntactic foams are improved.The relationship between the elastic modulus of the matrix and the maximum stress of the hollow glass bead spherical shell is linear.The maximum stress of hollow glass bead spherical shell decreases by 3 GPa with the increase of the elastic modulus of the matrix by 0.2 GPa.Carbon fibers enhance syntactic foams by increasing the elastic modulus of matrix and reducing the maximum stress of hollow glass bead spherical shells.Carbon fibers with various orientations can enhance syntactic foams,and carbon fibers can reduce the maximum stress of hollow glass beads on one side.Considering the elastic modulus of the matrix,the maximum stress of hollow glass beads and the maximum stress of the matrix,carbon fibers distributed in the direction of ductile stress have the best reinforcement effect.3.After the hybrid functionalization of carbon nanotubes,the defects on the surface of carbon nanotubes are covered and the molecular integrity is improved.Hybrid functionalized carbon nanotubes have good dispersion in organic solvents and can exist stably for a long time.The compressive strength of syntactic foams can be improved by adding hybrid functionalized carbon nanotubes.When the content of carbon nanotubes is 0.3wt.%,the compressive strength is the highest.Syntactic foams prepared by CNTs-PMPS has the highest compressive strength of 60 MPa.After hybrid functionalization,the aggregation of carbon nanotubes in syntactic foams can be significantly improved without reducing the bonding with polymer matrix,which fully reflects the mechanical properties of carbon nanotubes.4.When carbon fiber modified with carbon nanotube(CF-MWCNT)content is between0.1%and 1.0%,the density of syntactic foams is stable at about 0.6 g/cm~3,and the duty cycle increases gradually.When CF-MWCNT content is 0.5%,the compressive strength is the highest,up to 52 MPa.Carbon fibers modified with carbon nanotubes can improve the bonding between carbon fibers and epoxy resin.Some carbon nanotubes and carbon fibers form carbon fibers/carbon nanotubes/coupling agents/epoxy resin cross-linking network,and some carbon nanotubes are dispersed in epoxy resin matrix,thereby improving the mechanical properties of syntactic foams.