Study On The Properties Of CNT/SBS And Pebax Based Strain Sensing Materials

In recent years,high sensitivity,large tensile range,good stability strain sensor can be used in the field of electronic skin,human motion detection,robot,intelligent wear,and so on.However,type of metal and semiconductor strain gauge can only be used in less than 5% of the strain range,some studies have found that the conductive material and excellent elastic polymer material combination made conductive composite materials,can effectively promote a flexible working range and meet the application requirement of large strain,consisting of conductive network and the interface of conductor with the substrate materials can affect the sensitivity of the device.Nevertheless,it is still a challenge to realize high scalability and sensitivity.The main research directions for improving the performance of the sensor are to select the appropriate polymer and conductive material to synthesize the sensing material,design the microstructure,and improve the preparation process.The strain sensors of high sensitivity and tensile properties were prepared by using carbon nanotube/styrene-butadiene copolymer(CNT/SBS)as conductive composite materials;based on the strain sensing material of poly(ether-block-amide)(Pebax)as the substrate material and multiple conductive materials,and studied the conductive materials,the preparation methods,the influence of the structure on the strain sensor.The main work of this article is as follows:1.The strain sensor was fabricated by a solvent blending of cast SBS-CNT/SBS-SBS(SCS)and CNT/SBS blends membrane.The structure and morphology of the composite were characterized by a variety of detection methods.The results show that SCS and CNT/ SBS composite materials were successfully prepared.The overall conductivity of CNT material was significantly changed,and the seepage threshold value of 0.35 wt.% was calculated after testing.The experimental results show that the strain range of the sandwich structure(167%)is larger than that of the blend structure(120%).At the same strain of 120%,the sensitivity factor(GF)of the sandwich structure is 3003,while the blend structure is GF=2099.It has been proved that the performance of the strain sensor of the sandwich structure is better.The performance of strain sensing materials of different CNT concentrations exhibits obvious differences,and the test conditions such as strain and stretch rate have different degrees of influence on device performance.In addition,the sensor has good repeatability,stability,and can real-time detect the movement of the joints such as fingers,wrists,and knees,which demonstrates strong application potential.2.Utilizing Pebax as a polymer matrix,the carbon black(CB)was added as conductive material,and CB/Pebax strain sensing material was obtained through solution blending,screw extrusion,and injection molding.The study indicates that used of CB to build conductive channel seepage threshold of the composite was high(26.97 wt.%),and a large number of CB was added to form a stable conductive network.The strain sensors of the conductive material(CNT,PANI)are prepared respectively by the same method.The experimental results indicate that the performance of the carbon filling material is superior,and the one-dimensional structure of the filler can effectively reduce the filling quantity,and the conductive material is responsible for performance of the sensor.In order to study the effect of the preparation method and the structure of the device,prepare PANI/Peabx and Pebax/PANI/Peabx sensing materials by in-situ polymerization growth method.The sandwich structure constructed significantly improves the stability of the device.The Pebax/carbon fiber(CF)/Pebax sandwich structure strain sensor was constructed by spraying method and solution blending method respectively.The comparison found that the device prepared by the spray method has higher sensitivity but lower stability,and the device manufactured by the blend method has lower sensitivity but excellent stability.The above results indicate that the material,structure,and fabrication method of the strain sensor have significant effects on the performance of the device.In the future research,the sensing performance can be improved by changing the material,designing the structure,and exploring the fabrication method.