Study On The Construction And Mechanism Of Thermal Drive Carbon Nanotube Spiral Fiber Intelligent Composite

Artificial muscle fiber is a new type of muscle-like behavior material developed in recent years,which can produce reversible contraction,rotation,bending and other muscle behaviors under external stimulation conditions(light,electricity,heat,magnetic,solvent,humidity,etc.).It has stronger driving ability than biological muscle fiber,and it can be used in intelligent robots,artificial organ and other intelligent driving systems.Based on the idea of cross-scale structure design,a new concept of variable stiffness carbon nanotube spiral composite fiber is proposed,which breaks through the controllable assembly technology and composite technology of carbon nanotube spiral fiber,the thermal-induced artificial muscle fiber is obtained,and the driving mechanism of carbon nanotube spiral composite fibers is analyzed.In this paper,the carbon nanotube film is obtained based on chemical vapor deposition.The carbon nanotubes in the prepared film are randomly distributed in a network.The mechanical twisting method is used to obtain straight carbon nanotube fibers.By increasing the degree of twisting,more bundles are formed between the carbon nanotubes.Macroscopically,it shows the increase of fiber tensile strength from 51 MPa to 447 MPa and electrical conductivity from 6.5×104 S/m to 19.5×104 S/m.As the degree of twisting continues to increase,the fiber begins to show a spiral structure and eventually forms a carbon nanotube spiral fiber.The spiral structure can greatly improve the breaking elongation of the fiber by untwisting.The carbon nanotube spiral fiber composite was developed by breaking through the technology of carbon nanotube spiral fiber composite,the epoxy resin can be perfused into the spiral fiber based on the porous structure and pre-stretching of the carbon nanotube fiber.The microstructure of the composites was characterized by the Scanning Electronic Microscope,and the composites maintained the spring-like structure of the carbon nanotube spiral fiber.The tensile strength of the carbon nanotube spiral fiber can be reached to 320 MPa and the Young's modulus was 7.63 GP.Then,the thermal driving behavior of carbon nanotube spiral fiber/epoxy resin composites was studied and the thermal driving mechanism of the composites was analyzed.At a certain temperature range,this carbon nanotube spiral fiber/epoxy resin composite can realize the driving deformation by increasing the temperature,and with the increase of temperature,the driving deformation amount increases gradually.Under condition of 50 ?,the driving deformation amount of carbon nanotube spiral fiber/epoxy resin composite can reach more than 10%.And the thermal drive of the composite can produce more than 10 times the weight of the output force,the output stress can reach 6.6 MPa,equivalent to the human muscle fiber 22 times.It is important that this carbon nanotube spiral fiber/epoxy resin composite has good cycling stability,and its driving deformation remains stable after 100 cycles experiments.Finally,the thermal driving mechanism of this carbon nanotube spiral fiber/epoxy resin composite is analyzed and discussed.