Preparation And Piezoelectric Properties Of Electrospun Oriented Nanofiber Core-spun Yarn

The nanofibers processed by electrostatic spinning technology have continuous one-dimensional linear fiber aggregation characteristics,which can be used to introduce nanotechnology into the traditional textile industry to improve the status of the textile industry.Electrostatic spinning of nanofibers yarn as a new 3 d nano fiber materials,nano fiber not only has small size,large specific surface area,high porosity and doping modification performance advantages,such as excellent anisotropy and because the yarn structure also has the unique optical,electrical,and biological properties,therefore in tissue engineering,wearable sensors and energy storage,and other fields has great application potential.What is more important is that the twisted nanofiber yarns produced by electrostatic spinning technology can meet the requirements of textile weaving in terms of mechanical properties,and can be used as ordinary textile yarns for secondary processing and treatment,and then applied to the processing and manufacturing of traditional textile products to increase the added value of traditional textile products.In this paper,nanofiber oriented core-spun yarn is prepared by using the principle of tip discharge and conjugated electrostatic spinning to induce the nanofiber to have orientation coating on the core yarn introduced by the yarn forming system.A flexible braided wearable stress sensor was constructed by using conductive core yarn as the inner electrode and nanofibers covered by outer layer as the outer electrode.The surface morphology,crystal structure,mechanical properties and pressure sensing properties were studied.The specific research contents are as follows:Firstly,the coating thickness was controlled by changing the ratio of metal target speed to core moving speed(twist per meter,TPM)with silver plated nylon as core yarn and polyvinylidene fluoride nanofiber as cladding yarn through a new yarn forming technology,and its mechanical properties,crystal ratio,crystallinity and piezoelectric properties were studied.The results show that when TPM is 600,core-spun yarns have higher orientation ratio and crystallinity,reaching 0.402 and 49.57%respectively.In particular,when it is used as a piezoelectric material,the piezoelectric voltage constant reaches its maximum value of 0.4323m Vm/N.Second,In order to further improve the piezoelectric properties of nanofiber core-wrapped yarn,by poly(vinylidene fluoride in electrospinning doped Ti O₂ nanometer fiber core-spun yarn epitaxial growth on the surface of silver nanoparticles,and poly(vinylidene fluoride nanometer fiber layer,this paper proposes a directional and three-dimensional layered interlocking structure,the preparation of the test results show that silver nanoparticles good growth in poly(vinylidene fluoride nanometer fiber surface,form the conductive network,increased its piezoelectric properties.Finally,based on the AgNY/PVDF@TiO₂/Ag/PVDF nanofiber composite piezoelectric yarn prepared in this paper,the effects of length and effective area on its piezoelectric properties were discussed.Then,a flexible wearable pressure sensitive nanofiber fabric sensor was constructed by weaving nanofiber composite piezoelectric yarn into nanofiber fabric with plain texture according to the law of one up one down,and the pressure sensing performance of the sensor was tested and analyzed to reveal its sensing mechanism.