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Preparation And Strain Senstive Behavior Of Conductive Flexible Fiber Membrane

Posted on:2021-03-29Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y JiaFull Text:PDF
GTID:2381330602473457Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
Conductive polymer composites(CPCs)refers to the preparation of conductive fillers and polymer matrix composite,which have good electrical conductivity,flexibility and easy processing,etc,and CPCs were wildly used in anti-static materials,electromagnetic shielding materials,thermal materials and sensing components.In these areas many researchers have done a lot of research,based on these,flexible wearable strain sensor is realized in the field of human-computer interaction,human health monitoring applications.In this paper,we use electrostatic spinning,ultrasonic dispersion and silver mirror reaction to prepare thermoplastic polyurethane(TPU)/reduced graphene oxide(RGO)/dopamine hydrochloride(PDA)and TPU/PDA/carbon nanotubes(CNTs)/silver nanoparticle(Ag NPs)flexible conductive polymer composites,which not only have a wide strain detection range but also have ultra-high sensitivity.The detailed study of these two flexible conductive fiber membranes is as follows:1.Preparation and performance study of PDA/RGO/TPU strain sensors(1)TPU was made into a flexible substrate by electrostatic spinning,and then coated with RGO conductive filler on the surface of the fiber membrane by ultrasonic method.Finally,dopamine was polymerized on the surface of the RGO/TPU membrane by in-situ polymerization to prepare the PDA/RGO/TPU flexible composite fiber membrane and test its mechanical and electrical properties.(2)Before and after polymerization dopamine,the response performances of the RGO/TPU conductive fiber membrane were tested respectively.The results show that under the same tensile strain the GF of PDA/RGO/TPU conductive composite fiber membrane nearly surpass the RGO/TPU fiber membrane about triple(within 0%-60%tensile strain,the former GF=23.2,the latter GF=12.8).(3)In the tensile sensitivity test,the PDA/RGO/TPU fiber membrane showed a fast response time of 100 ms,Moreover,under different tensile strains,the sensor conforms to ohmic characteristics and exhibits excellent cyclic stability and reproducibility,and the response mechanism of PDA/RGO/TPU fiber membrane in the process of applying tensile strain was analyzed.(4)The PDA/RGO/TPU conductive composite fiber membrane was fixed on each joint of the human body(such as fingers,wrists,elbows,etc.)for real-time monitoring of human movement.(5)The air permeability of the fiber membrane was tested,and the experimental results showed that the water evaporation rate(38%)of the glass bottle covered by the PDA/RGO/TPU fiber membrane was almost equal to that of the open bottle(39%).In other words,the PDA/RGO/TPU sensor has good air permeability,which is conducive to greatly improve the comfort of wearable devices.(6)The sensing performance of the PDA/RGO/TPU sensor to organic gases and different environmental humidity were studied.The results showed that the sensor has significant response performance to the changes of both organic gas and environmental humidity,which indicating that the fiber membrane had excellent environmental monitoring capability.2.The preparation and performance of TPU/PDA/CNTs/Ag NPs flexible conductive composites are as follows:(1)In order to obtain the three-dimensional network structure,we used the method of electrostatic spinning to prepare the TPU flexible base,next,polydopamine is introduced onto the fiber surface as the active site,and then CNTs were immobilized on the fibrous membrane by ultrasonic method to improve the response range,finally,the TPU/PDA/CNTs/Ag NPs(TPCA)flexible conductive composites were prepared by adding silver nitrate to generate silver nanoparticles.The morphology and the particle size of the silver nanoparticles prepared in this paper were analyzed by SEM and XRD.It was observed that the silver nanoparticles were evenly distributed on the surface of the fibers,and the effective coordination between the silver nanoparticles and CNTs enabled the material to obtain a double-conducting network structure.(2)The tensile test of TPCA flexible conductive composite fiber membrane was analyzed and discussed in detialed.The experimental results show that the fiber membrane not only has excellent stretchability(elongation at break about 600%),ultra-wide detection range(500%),ultra-high sensitivity(when the strain reaches 400%,the GF value can reach 1×10~6 level),the response speed is very fast(about 90 ms)and has excellent cycle durability(can go through 10,000 cycles).(3)The cyclic performance of the fiber membrane was tested under the application of different strains.Even if the strain ranged from 0.1%to 500%,the fiber membrane could respond stably.(4)The electric heating performance of the fiber membrane was tested.By applying different low voltages,the fiber membrane could be heated to different temperatures.When the voltage was applied to 1 V,the temperature could be raised to about 55℃.(5)In order to test its performance in practical application,we used the prepared TPCA conductive composite material to stick on the face for air blowing test,fixed on the wrist for wrist joint bending motion,and stuck on the wrist pulse point for pulse monitoring.All these tests showed stable response,which provided a practical basis for its application in wearable devices.
Keywords/Search Tags:Conductive polymer composites, Electrospun fiber film, Flexible wearable strain sensor, Sensitivity, Human movement monitoring
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