High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limit...High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limits their use,especially in high-temperature environ-ments.A high-temperature resistant flexible piezoelectric film based on graphene oxide(GO)/polyacrylonitrile(PAN)composites was prepared by electrospinning and thermal treat-ment.It was packed into a micro-device,which could work continuously at 500℃.The intro-duction of GO significantly increased the mechanical properties of the PAN nanofibers because the oxygen-containing func-tional groups(electronegative groups)on the surface of the GO initiated a nucleophilic attack on the PAN molecule during heat treatment,enabling the GO to initiate the cyclization of the PAN at lower heat-treatment temperatures.In addition,the abund-ant oxygen-containing functional groups on GO acted as pro-oxidants to hasten the oxidation of PAN during heat treatment.The effects of GO content and heat treatment temperature on the properties of the nanofiber films were investigated.A GO/PAN nanofiber piezoelectric sensor heat-treated at 300℃had a 9.10 V and 2.25μA peak output,which are respectively 101.3%and 78.6%higher than those of the untreated films.Cyclic testing over 5000 cycles at 350℃confirmed the stable out-put performance of the GO/PAN nanofiber piezoelectric sensor.Furthermore,a sensor heat-treated at 400℃had a sensitivity of 1.7 V/N,which is 83.5%higher than that of an untreated one.The results show that the prepared GO/PAN nanofiber piezo-electric sensor combines high temperature resistance,high flexibility,stability and high sensitivity,and may have broad applic-ations in high temperature environments such as the aerospace and petroleum industries.展开更多
为深入了解界面润湿性对流固摩擦能量输出的影响机制,该文利用石墨烯薄膜制作不同界面接触角的俘能结构并进行实验测试。此外,基于分子动力学理论建立Couette模型并进行仿真验证。研究发现,俘能结构输出的电压随着接触角的增大而增加,...为深入了解界面润湿性对流固摩擦能量输出的影响机制,该文利用石墨烯薄膜制作不同界面接触角的俘能结构并进行实验测试。此外,基于分子动力学理论建立Couette模型并进行仿真验证。研究发现,俘能结构输出的电压随着接触角的增大而增加,接触角为69.5°的俘能结构对应输出的电压是0.95 m V,相比接触角为45°时输出的0.57 m V增长67%;输出的电压极性与溶液流动的方向有关;而且电压幅值与溶液流动速度及浓度有关,与流动速度成非线性关系。结合模拟结果提出一种界面润湿性对流固摩擦能量输出效率的影响机制,结果表明:宏观接触角是表征界面对水分子的束缚力的参数,也是影响溶液在界面附近滑移速度的关键因素,溶液离子拖动电子移动速度受滑移速度影响,并将最终决定输出电压大小。展开更多
文摘High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limits their use,especially in high-temperature environ-ments.A high-temperature resistant flexible piezoelectric film based on graphene oxide(GO)/polyacrylonitrile(PAN)composites was prepared by electrospinning and thermal treat-ment.It was packed into a micro-device,which could work continuously at 500℃.The intro-duction of GO significantly increased the mechanical properties of the PAN nanofibers because the oxygen-containing func-tional groups(electronegative groups)on the surface of the GO initiated a nucleophilic attack on the PAN molecule during heat treatment,enabling the GO to initiate the cyclization of the PAN at lower heat-treatment temperatures.In addition,the abund-ant oxygen-containing functional groups on GO acted as pro-oxidants to hasten the oxidation of PAN during heat treatment.The effects of GO content and heat treatment temperature on the properties of the nanofiber films were investigated.A GO/PAN nanofiber piezoelectric sensor heat-treated at 300℃had a 9.10 V and 2.25μA peak output,which are respectively 101.3%and 78.6%higher than those of the untreated films.Cyclic testing over 5000 cycles at 350℃confirmed the stable out-put performance of the GO/PAN nanofiber piezoelectric sensor.Furthermore,a sensor heat-treated at 400℃had a sensitivity of 1.7 V/N,which is 83.5%higher than that of an untreated one.The results show that the prepared GO/PAN nanofiber piezo-electric sensor combines high temperature resistance,high flexibility,stability and high sensitivity,and may have broad applic-ations in high temperature environments such as the aerospace and petroleum industries.
文摘为深入了解界面润湿性对流固摩擦能量输出的影响机制,该文利用石墨烯薄膜制作不同界面接触角的俘能结构并进行实验测试。此外,基于分子动力学理论建立Couette模型并进行仿真验证。研究发现,俘能结构输出的电压随着接触角的增大而增加,接触角为69.5°的俘能结构对应输出的电压是0.95 m V,相比接触角为45°时输出的0.57 m V增长67%;输出的电压极性与溶液流动的方向有关;而且电压幅值与溶液流动速度及浓度有关,与流动速度成非线性关系。结合模拟结果提出一种界面润湿性对流固摩擦能量输出效率的影响机制,结果表明:宏观接触角是表征界面对水分子的束缚力的参数,也是影响溶液在界面附近滑移速度的关键因素,溶液离子拖动电子移动速度受滑移速度影响,并将最终决定输出电压大小。
