Preparation And Research Of Carbon Nanotube/Shape Memory Epoxy Resin Composites

Shape memory polymers have the characteristics of large recoverable strain,strong shape retention ability and repeated memory effect,which are ideal for deployable structures.High strength and stiffness are difficult to achieve with SMAs alone,but their mechanical and memory properties may be improved when SMAs are prepared with reinforcing fibers,particles,and fillers.Shape memory polymer composites are highly potential structural functional materials,and have very broad prospects in spatially unfolding structures.At present,the research on shape memory polymers is more focused on thermoplastic polymers,and less research or analysis on thermosetting polymers.Dynamic imine bonds(Schiff base bonds)have many advantages such as wide source of raw materials and industrialization prospects,and have become a research hotspot in this field.In order to meet the requirements of high performance and high stability of materials in aerospace,weaponry and other military industries,this paper uses p-hydroxybenzaldehyde and 4,4'-diaminodiphenylsulfone(DDS)to prepare epoxy resin modifiers.When the epoxy resin E51 is cured,dynamic imine bonds are introduced into the cross-linked network to prepare an epoxy resin with both performance and shape memory properties,and the mechanical properties and shape memory of the material are further enhanced by adding carbon nanotubes.performance.The work of this paper mainly includes:(1)The epoxy resin modifier(PHS)was synthesized,and the structure was characterized by infrared spectrometer(FT-IR),1H-NMR and 13C-NMR;The decomposition temperature range of the obtained PHS is 350-450°C.(2)Using DDS as curing agent,the effect of PHS content on the properties of epoxy resin(E-51)system was studied.E-51/DDS/PHS(respectively EDP0,EDP2.5,EDP5,EDP7.5 and EDP10)resin castings were prepared.The mechanical property test of the modified resin system showed that the flexural and impact properties of EDP5 were compared with other groups.The best score,and the best tensile properties of EDP7.5.By changing the content of epoxy modifier PHS,it can be found that when the content of PHS increases,the storage modulus of the system increases,the highest is 2449 MPa,and the glass transition temperature(Tg)first decreases and then increases.The highest Tg was 210.6?,which was 16.5? higher than the smallest EDP5.The shape recovery time of the EDP system increases with the increase of PHS content.At220 °C,the fastest deformation recovery time is 106 s for EDP10,while the slowest EDP2.5 is163 s.The shape memory recovery rate increases with the temperature.slows down with time.Through non-isothermal DSC test,the curing reaction mechanism of EDP modified resin was analyzed,and the average activation energies of EDP0,EDP2.5,EDP5,EDP7.5 and EDP10 were calculated by Kissinger,Ozawa and Flynn-Wall-Ozawa methods,respectively.are 69.32,73.91,69.32,72.54 and 80.38 k J/mol,and the non-isothermal curing reaction kinetic model of EDP5 was solved by Malek method.(3)On the basis of EDP modified resin,nanoparticle filler carbon nanotubes were introduced,and EDPC composite material system was prepared.By comparing with the EDP system,the effect of carbon nanotube content on the gel time,viscosity and mechanical properties of epoxy resin was analyzed.Effects of properties,thermodynamic mechanical properties(DMA),thermogravimetric loss,shape memory properties.The mechanical properties test results show that the mechanical properties are the best at 2 wt% carbon nanotubes,the bending strength is 145.53 MPa,the impact strength is 42.65 k J/m2,and the tensile strength is 88.17 MPa;After carbon nanotubes are added to the modified epoxy resin system,the storage modulus of the composite will increase,and the highest is 2867 MPa of EDPC52.5;the Tg of the system will also increase after adding carbon nanotubes,and the Tg It will increase with the increase of carbon nanotube content;through the thermogravimetric analysis of the EDPC system,it is found that the thermal decomposition process of the EDPC system is basically the same as that of the EDP system.?,but with the addition of carbon nanotubes,the carbon residue rate of the EDPC system increases,and the carbon nanotubes enhance the thermal conductivity of the material,so that the temperature of T5%,T20% and Tp at different heating rates is higher than that of the EDP system.The shape memory test results show that the addition of carbon nanotubes shortens the shape recovery time of the EDPC system.With the increase of carbon nanotube content,the shape recovery rate becomes faster and faster.The shape memory recovery time is at least 100 s.