基于渗流网络的聚合物基柔性应变传感复合材料研究进展

基于渗流网络的柔性导电高分子复合材料具有制备简便、加工性良好、成本低、电学与应变传感性能可调等优点,是构筑柔性应变传感材料的重要方式,也是目前研究的热点。文中首先介绍柔性力敏材料的渗流网络、导电机理、性能参数及相关数值模拟,并详细介绍了逾渗曲线,然后总结了导电填料含量、形貌与维数、导电填料协同作用、填料与基体间的相互作用以及网络形态结构等因素对力敏性能的影响规律,最后展望了基于渗流网络的聚合物基柔性力敏材料的发展趋势。     

基于炭黑填充导电橡胶的力敏传感器的灵敏度

以通用有效介质理论为基础,给出了,炭黑填充导电橡胶(炭黑/橡胶)的力敏传感器灵敏度计算方程.采用该方程并结合形变和压阻效应,分析了影响力敏导电炭黑/橡胶的灵敏度的主要参数.结果表明:炭黑体积分数是影响力敏导电炭黑/橡胶的灵敏度的主要参数.当炭黑体积分数在临界体积分数附近时,力敏导电炭黑/橡胶的灵敏度为0.1～11.5 MPa-1,其敏感机制主要为压阻效应.当炭黑体积分数在渗流区时,灵敏度为0.2～3.6 MPa-1,其敏感机制还与接触压力的大小有关,压力较小时,主要为压阻效应;压力较大时,主要为应变效应.若炭黑体积分数在传导区,灵敏度为0.3～1.7 MPa-1,其敏感机制主要为应变效应.     

纳米级FeNi粉体/SiR薄膜的制备及力敏特性研究

以60~100nm的FeNi粉体为应力敏感元、硅橡胶为柔性基体,压制成型了粉体分布均匀、粉体含量30.6%(质量分数)、厚度200μm的薄膜,在连续加载/卸载速度为0.1mm/min、测试频率1kHz条件下,研究了正应力和综合应力两种受力条件下薄膜的力敏特性。研究结果表明,通过过渡溶剂液相混合方法可实现纳米级FeNi粉体在薄膜中均匀分布;在正应力条件下,加载过程中σ0.2MPa时,薄膜的灵敏精度|k|值50,当σ为0.2~0.4MPa,|k|值介于37~49之间,薄膜对0.2MPa的正应力敏感;当综合应力σ0.1MPa时,薄膜灵敏精度|k|值在60以上,薄膜对0.1MPa的综合应力敏感;在综合应力加载/卸载条件下,薄膜的弹性后效现象显著,导致力敏稳定性较差;在正应力条件下的力敏特性优于综合应力条件下的力敏特性。     

基于炭黑填充导电橡胶的力敏传感器的灵敏度

以通用有效介质理论为基础, 给出了炭黑填充导电橡胶(炭黑/橡胶)的力敏传感器灵敏度计算方程。采用该方程并结合形变和压阻效应, 分析了影响力敏导电炭黑/橡胶的灵敏度的主要参数。结果表明: 炭黑体积分数是影响力敏导电炭黑/橡胶的灵敏度的主要参数。当炭黑体积分数在临界体积分数附近时, 力敏导电炭黑/橡胶的灵敏度为0.1～11.5 MPa^-1, 其敏感机制主要为压阻效应。当炭黑体积分数在渗流区时, 灵敏度为0.2～3.6 MPa^-1, 其敏感机制还与接触压力的大小有关, 压力较小时, 主要为压阻效应; 压力较大时, 主要为应变效应。若炭黑体积分数在传导区, 灵敏度为0.3～1.7 MPa^-1, 其敏感机制主要为应变效应。     

聚合物/MXene柔性力敏材料制备及应用研究进展

MXene作为一种新型的二维纳米材料,拥有优良的导电性,在柔性力敏材料领域有广泛的应用前景。为了构筑柔性力敏材料,通常将MXene与柔性聚合物或多孔聚合物相结合,从而实现柔性及大形变。柔性力敏材料中,MXene的分布、导电网络结构与形态由制备方法决定,进而决定传感器的类型和应用类型及场合。文中从MXene柔性力敏材料的制备策略角度出发,总结了浸渍法、喷涂法、真空过滤法、冰模板法及其它方法对MXene柔性力敏材料性能的影响,同时归纳了MXene柔性力敏材料在生理信号、细微人体动作、关节运动信号监测以及对信号进行示踪等方面的应用进展。     

基于石墨烯/聚合物的柔性力敏材料研究进展

石墨烯(G)作为一种性能优异的二维纳米材料,其高电导率、灵活性为柔性力敏材料的发展打下了坚实基础,G/聚合物复合材料可用作高弹性和高灵敏度的柔性传感器。文中从材料结构角度归纳G/聚合物柔性力敏材料的研究进展,总结了逾渗导电网络结构、层状结构、网状G填充柔性基体和G填充于网状聚氨酯海绵结构等多种不同结构类型的柔性力敏材料,并对材料结构与形态、机电性能及应用进行了相应的表征和分析,最后展望了G/聚合物柔性力敏材料领域的挑战与发展趋势。     

MXenes在柔性力敏传感器中的应用研究进展

随着可穿戴柔性电子技术的发展, 高灵敏度和宽感应范围的柔性力敏传感器的需求量逐渐增大, 如何选择兼具高导电性和良好柔性的材料作为传感器的敏感材料是获得高性能传感器的关键。近年来, MXene材料因其导电性好、柔韧性高、亲水性好以及合成可控等优点成为一种极具潜力的导电敏感材料。本文就MXene基柔性力敏传感器的类型、敏感材料的微结构设计方式、传感性能及传感机理等方面的研究进展进行了阐述和总结。     

Fe73.5Cu1Nb3Si13.5B9软磁粉/硅橡胶力敏复合材料的逾渗特性

以三元嵌段共聚硅橡胶为基体,Fe_73.5Cu₁Nb₃Si_13.5B₉软磁粉为应力敏感填充粒子,采用机械共混和精密铸压热成型方法制备出系列粉体含量的Fe_73.5Cu₁Nb₃Si_13.5B₉软磁粉/硅橡胶接触应力敏感复合材料,重点研究了其交流阻抗、直流电阻、粒子间及粒子与硅橡胶间相互作用程度等性能的逾渗特性。研究表明,该柔性力敏复合材料具有较显著的交流阻抗双逾渗特性。分析发现,“第一逾渗区”内材料的交流阻抗值由粒子的隧道跃迁主导,“第二逾渗区”内材料的交流阻抗大小取决于Fe_73.5Cu₁Nb₃Si_13.5B₉粒子链间的接触电阻值。     

基于取向结构的聚合物基柔性力敏材料的研究进展

柔性力敏材料是可穿戴材料领域的重要基础材料。与未取向的复合材料相比,具有取向结构的柔性力敏材料拥有更加优异的电学、力敏性及力学性能。文中从制备方法的角度归纳了具有取向结构聚合物基柔性力敏材料的研究进展,包括阵列结构与柔性聚合物复合、静电纺丝法、定向冷冻法及电场取向等,并从形态、结构及电学、灵敏性和力学性能方面对取向结构进行了表征,最后展望了具有取向结构的柔性力敏材料的发展趋势。     

炭黑填充导电橡胶的力敏传感器灵敏系数

以通用有效介质理论为基础, 给出了炭黑填充导电橡胶(炭黑/橡胶)的力敏传感器灵敏系数计算方程。采用该方程并结合应变和压阻效应对"负压力-电阻特性"(NPC)的影响程度, 分析了力敏导电炭黑/橡胶的灵敏系数和工作原理。结果表明: 炭黑体积分数在临界体积分数附近时, 力敏导电炭黑/橡胶的灵敏系数在2.5～13之间, 其工作原理主要为压阻效应。当炭黑体积分数在渗流区时, 灵敏系数在2.5～4.5之间, 其工作原理与接触压力的大小有关。压力较小时, 其工作原理主要为压阻效应; 压力较大时, 其工作原理主要为应变效应。炭黑体积分数在传导区时, 灵敏系数在2.0～2.5之间, 其工作原理主要为应变效应。      

Self-powered pressure sensor for ultra-wide range pressure detection

The next generation of sensors should be self-powered,maintenance-free,precise,and have wide-ranging sensing abilities.Despite extensive research and development in the field of pressure sensors,the sensitivity of most pressure sensors declines significantly at higher pressures,such that they are not able to detect a wide range of pressures with a uniformly high sensitivity.In this work,we demonstrate a single-electrode triboelectric pressure sensor,which can detect a wide range of pressures from 0.05 to 600 kPa with a high degree of sensitivity across the entire range by utilizing the synergistic effects of the piezoelectric polarization and triboelectric surface charges of self-polarized polyvinyldifluoride-trifluoroethylene (P(VDF-TrFE)) sponge.Taking into account both this wide pressure range and the sensitivity,this device exhibits the best performance relative to that of previously reported self-powered pressure sensors.This achievement facilitates wide-range pressure detection for a broad spectrum of applications,ranging from simple human touch,sensor networks,smart robotics,and sports applications,thus paving the way forward for the realization of next-generation sensing devices.Moreover,this work addresses the critical issue of saturation pressure in triboelectric nanogenerators and provides insights into the role of the surface charge on a piezoelectric polymer when used in a triboelectric nanogenerator.     

Measure-theoretic pressure and topological pressure in mean metrics

In this paper, using spanning sets in mean metrics we construct a new definition of measure-theoretic pressure of ergodic measures over a topological dynamical system. And we establish a pressure version of Katok's entropy formula in the case of mean metrics. Furthermore, we also introduce a new definition of topological pressure by replacing the Bowen metrics with the corresponding mean metrics, and prove that the new topological pressure is equivalent to the classical topological pressure. Then the variational principle for the newly defined topological pressure is obtained.     

Inhomogeneous flow and the effective pressure concept in pressure sintering

Many of the models proposed to describe pressure sintering of solids with a randomly distributed porosity have implicit in them the effect of porosity and it is incorrect to incorporate any extra pressure intensification factor. However, usually, pores are segregated into zones which leads to inhomogeneous deformation. A consequence of this inhomogeneity is to enhance densification rates by dislocation creep and particle sliding resulting in an anomalous pressure intensification factor. Some observations on microstructural development during hot isostatic pressing are also made.     

Standardisation of pressure measurement using pressure balance as transfer standard

This paper describes the results of the interlaboratory comparison for pressure measurements of 9 laboratories that are accredited by the National Accreditation Board for Testing and Calibration of Laboratories (NABL). The artifact used for the comparison was a pressure balance covering the pressure range (7 to 70) MPa. The primary objective of this comparison was to assess the laboratory’s technical competence to perform measurements and also to assess the compatibility of the results submitted by the laboratories. The comparison began during March 2008 and ended during April 2010. For assigning the reference values, the pilot laboratory (NPLI) carried out 3 calibrations of the transfer standard; the first one at the beginning, the second at the middle and the last one at the end of the programme. The comparison was carried out at 10 pressure points i.e. (7, 10, 15, 20, 25, 30, 40, 50, 60 and 70) MPa throughout the entire pressure range of (7 to 70) MPa. The measurements were carried out by each laboratory with their own resources (personnel, calibration systems, environmental conditions in their installations). The deviations for each laboratory were compared against the reference values and the compatibility of the results was calculated using the normalized error value method. Out of the total 87 measurement results reported, 68 (78.2%) results are found in good agreement with the results of the reference laboratory. The normalized error (E_n) values of 5 laboratories out of the total 9 were found well within ± 1 over the entire pressure range. However, 2 other laboratories had shown good agreement with the reference values except one pressure point each. The E_n values of one of the participating laboratory were found beyond acceptable limits at all measurements points. Another laboratory had acceptable results only at 3 pressure points. The laboratories with unacceptable results have been advised to review their pressure measurement process. The deviations between laboratory values and of the reference values were found well within the uncertainty band of the reference values for 37% measurement results. The relative deviations for 82 measurement results were found well within 0.05%.     

压力下的炭化(英文)

述评了三类压力下的炭化途径:分解气体自升压状态下的炭化,水热反应和还原CO2成炭。尽管这些在加压状态下形成的不同形态和纳米织构的炭材料具有相当高的收率,然而在很多情况下它们是多种形态炭材料的混合物。述评着眼于温度-压力条件和所用的前驱体的化学组成,讨论了高纯度、分离态的炭球的形成条件。     

Capacitance pressure pickups

The results of experimental investigations of miniature capacitance pressure pickups are reported. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 35–37, May, 1996.     

脉动压力诱导注射成型下的模腔压力响应

自行研制的脉动压力诱导注射成型装置成功地通过聚合物熔体将脉动变化的压力引入到注射成型的充模与保压过程.在该装置上进行实验,实验结果表明:模腔压力的波动频率与活塞杆的振动频率相一致;模腔压力的波动幅值随着活塞杆振幅的增大而增大;活塞杆的振动频率对模腔压力的波动幅值影响较小.