Fabrication And Performance Investigation Of Functional Carbon Nanotube Film And Its Fiber Composites

Carbon nanotube film/fiber(CNTFF)is a new form material of carbon nanotubes(CNTs).Because CNTFF maintain intrinsic features and eliminate the aggregation tendency of CNT,CNTFF has beencon extensilvely concerned in recent years.The outstanding electrical and mechanical properties promot e CNTFF enable to be potentially applied in various fields,such as composite materials,flexible electrodes and devices,and actuators.For composite materials,the characteristics of lightweight and good compatibility with resin of carbon nanotube film(CNF,also called carbon notube paper,CNP)make it possess huge potential application in functional composite materials,which overcome many problems of CNT composites,such as difficult to composite,easy aggregation,low dopping amount and poor performance.Moreover,CNTFF could be achieved in non-woven or aligned forms via different fabrication strategies and the thickness,electrical and mechanical properties of CNTFF could be controlled.Because of an emerging field,CNTFF materials and its composites has short development history which leads to less study on functional CNTFF composites and lack of fundamental researches based on electrical and electrochemical properties in recent years limiting CNTFF development and application in functional composite materials.Based on the above background,this thesis mainly focusses on the study of CNTFF material and its composites on electrical and electrochemical properties.Non-woven and aligned CNF is prepared by solution filtered and chemical vapor deposition(CVD)methods.For the electrical property,various types of CNF with different electrical conductivity were fabricated by the strategies of heat treatment and metal particle modification and investigated the applications in different conductive required fileds.Based on the good electrical and mechanical performance in the aligned direction of aligned CNF,the aligned two-dimention CNF was transformed to one-dimention carbon nanotube fiber(CNTF)by twisting to form the aligned CNTF possesses nice electrical and mechanical properties.On account of the electrical and mechanical properties of CNTF,an electrochemical actuating CNTF was obtained by functionalizing the CNTF using polyelectrolyte.The composite fiber has many advantages,such as non-toxic,low actuating voltage,fast response time and high energy density,which promote the potential application in the biomedical field.For the solution filtered CNF and its composites,this thesis studies on the fabrication process of CNF obtaining a superior flexibility CNF.The conductivity of pristine CNF is 70～108S/cm with favourable electro-heating performance.Based on good resin compatibility and electro-heating features,the pristine CNT is composited with glass fiber prepreg via integral forming process to manufacture the electro-heating composite.The electro-heating performance was investigated and deicing experiment was carried out of the composite.The residual surfactant in pristine CNF was eliminated by thermolysis and thermo-crosslink to increase the CNF electrical conductivity to 220～245S/cm as well as keeping the initial flexibility,and the rupture stress was increased from 15.4Mpa to 43 MPa.Based on the flexibility and conductivity,the CNF after heating treatment was used as flexible electrodes of supercapacitor and a simple structure flexible supercapacitor was assembled.The flexible supercapacitor was excuated in different shapes to test the flexibility and capacitive property.The results showed the flexible supercapacitor is able to operate in multi-shapes and keep considerable capacitive performance with the maximum specific capacitance of 343.2F/g.The heating treatment CNF was modified by depositing a small amount silver nanoparticles to improve CNF conductivity.In order to maintain the flexibility of pristine CNF,in situ adsorbing-photolysis and spray-photolysis were performed.The conductivity of silver particle modified CNF is upto 1700S/cm and 3810S/cm with a slight modified amount,respectively.The silver particle modified CNF could be used in the high conductivity required fields.On account of the conductivity requirement in the fields of lightning strike protection and infrared stealth and the drawbacks of the traditional commercial materials,silver particle modified CNF was performed as the functional layer of the composites that used in the above engineering fileds.The results indicate the infrared steath composite materials possess relative low infrared emissivilty in the wavelength of 1～13 μm with the minimun value about 0.2.The residual mechanical property of carbon fiber matrix protected by silver modified CNF is 92.1%(compare with control specimen),which is much higher than the value of 62.9% of the specimen without protection.Aligned CNF was drawn from CNT array which was grown by fixed catalyst CVD strategy.Due to the aligned film providing outstanding electrical and mechanical properties in the aligned direction,the two-dimention CNF was twisted to form one-dimention CNTF.The electrochemical actuating fiber was prepared successfully fictionalized by polyelectrolyte based on the specific electrochemical property of the polyelectrolyte,and stretchable and conductive features of CNTF.Because the ionic strength of the electrolyte in the CNTF electrode is changed under alternating voltage,the polyelectrolyte conformation is varied caused by the ionic strength change which leads to the volume change of CNTF.Interaction between polyelectrolyte with CNTF entitles the electrochemical actuating performance.In this thesis,according to the weak research status of CNF/CNTF composites,fabrication strategy and performance of the functional composites of CNF and CNFF based on electrical and electrochemical properties were studied and concluded the influence factors and regularity of the performance.The results will provide research idea for future study of lightweight,high strength and functional composite materials.