Preparation Of Hyaluronic Acid/multi-walled Carbon Nanotube Fibers And Its Application In Shape Memory Materials

Carbon nanotubes(CNTS)are nanomaterials with perfect structure,excellent physical and mechanical properties and good chemical stability.However,due to the agglomeration of carbon nanotubes and other reasons,the macroscopic material that the carbon nanotube has made,like Bucky paper,has a lower mechanical strength.In order to improve macro material mechanical properties,this article takes multi-walled carbon nanotubes as raw materials,and uses hyaluronic acid with good biocompatibility as dispersant to disperse the mixed solution by ultrasonic method.The multi-walled carbon nanotube fibers are prepared by using wet spinning to pass the spinning solution through the solidifying solution.To solve the problem of weak mechanical properties,the chemical crosslinking method is used to modify it.In order to apply it to artificial muscle or biological actuator materials,the modified fiber is combined with polylactic acid(PLA)material with shape memory function to prepare the multi-walled carbon nanotube fiber-polylactic acid composite.The material can complete the shape recovery under the condition of electric power.The main work is as follows:(1)multi-wall carbon nanotube fibers are prepared by wet spinning with multi-wall carbon nanotubes as raw materials and hyaluronic acid as dispersant.The effects of different dispersing process parameters and spinning process parameters on the mechanical properties of fibers are discussed.The spinning process is optimized to produce carbon nanotube fibers from 0.8 to 1.6 percent of five different concentrations.On the mechanical properties and electrical properties are tested,to determine the concentration of 1.6% fiber tensile strength is highest,23.27 MPa,the resistivity of 1.31 ×10-3 ? m.(2)The morphology,thermal weight loss,infrared spectrum and electrical stability of the fibers are characterized and tested.The results of thermal weightlessness show that the multi-walled carbon nanotube fibers are mainly composed of carbon nanotubes and hyaluronic acid,and the ratio is about 2:1?Material near the temperature of 240 ? hyaluronic acid begins to decompose,part of carbon nanotubes can withstand 1000 ? temperature conditions.The infrared spectra shows that the fiber contained carboxyl and hydroxyl groups.The conductivity of the electrical test material will decrease with the change of shape and bending times,and the resistance will reach 1.34 times of the original state after 500 cycles of bending.(3)By chemical crosslinking,1,6-hexane diamine(HMDA)is reacted with the prepared multi-walled carbon nanotube fibers.The amino group in HMDA binds the polymer chains in the fiber together to enhance mechanical properties.The effect of different crosslinking process parameters on crosslinking effect is discussed.The morphologies,thermal weightlessness,Raman spectrum,mechanics,electrical and electrical stability of the modified multi-wall carbon nanotube fibers are tested.The heat loss results show that the thermal stability of the modified fiber is enhanced.Raman spectroscopy shows that the orientation of carbon nanotubes decreases.Mechanical test results surface mechanical properties increase to 32.21 MPa.The electrical test results show that the conductivity of the material will still decrease with the change of shape and bending times,but the stability of the unmodified fiber is significantly improved,and the resistance will reach 1.29 times of the original state after 500 cycles of bending.(4)The characterization and test of the fiber morphology,mechanics and electrical properties of multi-walled carbon nanotubes with temperature increase are completed.The results show that the polymer in the fiber will decompose and precipitate with the increase of temperature.Mechanical and electrical test results show that the tensile strength at 300 ? temperature could sharply reduce to 7.26 MPa,the resistivity decreases with the increase of temperature and,at 300 ? temperature reduces to 6.66% of the initial state.The resistivity will increase again when room temperature returns.To remove the polymer multi-walled carbon nanotube fibers resistivity changes with the temperature test,the results show that the resistivity is roughly linear decrease with temperature increasing,at 300 ? decreases to 32.86% of the initial state.(5)The preparation of multi-walled carbon nanotube fiber-PLA shape memory composite material is completed,and its morphology,thermal weightlessness,shape memory function and mechanics are characterized and tested.The results of thermal weightlessness shows that the multi-walled carbon nanotube fibers account for 10.6% of the composite materials.The shape memory test shows that the material could recover 61.1% of its shape within 4min24 s.The mechanical test results shows that the tensile strength of the composite material reaches 20.51 MPa,in which PLA could realize the mechanical enhancement function of the multi-walled carbon nanotube fibers.