具有双层结构的聚电解质和聚苯胺复合湿度传感器

制备了水溶性聚苯胺,将其与聚电解质湿敏材料———交联季胺化聚（4-乙烯基吡啶）复合,构建了具有双层结构的电阻型湿度传感器,研究了其在低湿环境下的湿敏响应特性。     

石墨烯/季胺化聚（4-乙烯基吡啶）复合湿度传感器制备及湿敏性能研究

采用溶液共混方法,制备了还原氧化石墨烯和单溴代季胺化聚（4-乙烯基吡啶）纳米复合湿敏材料和湿度传感器;研究了其对于湿度,尤其是低湿环境下湿度的响应特性。     

超支化聚季胺盐的湿敏响应特性

以超支化结构聚酯为核,制备了超支化聚季胺盐湿敏材料。采用浸涂法制备薄膜电阻型湿敏元件,研究了其湿敏响应特性。发现其在较宽湿度范围(5%～96%RH)具有较高响应灵敏度,且响应快,湿滞小(1%RH)。     

SnO2-K2O-LiZnVO4系材料湿敏性能及导电机理的研究

采用共沉淀法制备出SnO2-K2O-LiZnVO4系湿敏粉体,考察了液相掺杂K 对材料湿敏特性的影响,并用直流特性法对材料的导电机理进行了分析.实验结果表明,适当的K 液相掺杂可使材料具有低湿电阻小,灵敏度适中的特性.直流特性法分析表明,材料属电子-离子混合导电机制,且离子电导成分越多材料的湿敏特性越好.     

不同制备工艺对硅橡胶智能复合材料应变传感肩峰现象研究

导电聚合物复合材料通常使用弹性体作为应变传感材料的基体。然而，弹性聚合物复合材料在电阻-应变响应性能中通常表现出肩峰现象，从而限制应变传感材料的应用。以消除肩峰现象为目的，分别采用机械共混法与溶液共混法制备出多壁碳纳米管(MWCNT)/甲基乙烯基硅橡胶(VMQ)导电纳米复合材料，研究不同制备工艺对复合材料微观形貌、导电性能、应变传感性能的影响。结果表明：机械共混法制备出的复合材料，渗流阈值更低、灵敏度更高，电阻响应信号更加稳定，即使在2 500次循环加载-卸载过程保持良好的稳定性及重复性，没有出现肩峰现象，同时解释了肩峰现象的机理。明确了该应变传感器具有对大变形隔震支座进行实时应变监测的潜力。     

纳米结构聚苯胺及其复合气敏材料研究进展

综述了近十年来聚苯胺导电高分子及其复合物气敏材料的研究进展。重点介绍了纳米结构聚苯胺、聚苯胺与有机高分子复合材料、聚苯胺与纳米结构无机半导体或金属等复合材料的气敏响应特性及敏感机理。讨论了影响聚苯胺基纳米复合材料气敏性能的主要因素,包括复合材料的纳米结构、制备工艺,以及有机高分子,无机半导体及金属等复合材料和检测气体的性质等,提出这类高分子复合气敏材料今后发展的趋势与前景。     

二氧化硅对碳黑/环氧树脂复合材料渗透特性的影响

通过溶剂化过程制备碳黑-二氧化硅-环氧树脂聚合物基复合材料,并研究复合材料的导电渗透特性。当碳黑的体积分数低于15.5%时,复合材料的导电性可以用经典的渗透理论来描述,并发现渗透阈值约为14.7%,这与理论预测值相接近。当碳黑的体积分数高于15.5%时,材料的电导率与理论预测值偏离较大。这可能是因为:此时材料中的二氧化硅的用量较少,其对碳黑颗粒的空间体积排除效应较差;由于氢键和范德华力作用,纳米级的碳黑颗粒容易形成聚集态,这与渗透理论中导电颗粒必须是单个分布的这一前提假设相违背。扫描电镜分析及模拟计算结果支持该结论。     

聚(3,4-乙烯二氧噻吩)-聚苯乙烯磺酸及其复合材料气敏性能研究进展

聚(3,4-乙烯二氧噻吩)-聚苯乙烯磺酸(PEDOT:PSS)作为极重要的一种导电聚合物,由于其简便的制备方法、较高的导电性能、稳定的化学性质、独特的传感机理而逐渐被应用于气体传感器领域。然而,制备具有高灵敏度、良好选择性的PEDOT:PSS基气敏材料仍是一大挑战。文中综述了近几年来基于PEDOT:PSS及其复合物材料的气敏元件的研究进展,重点介绍了纯相PEDOT:PSS、PEDOT:PSS与聚合物复合材料、PEDOT:PSS与无机半导体(金属及金属氧化物)以及与碳材料等复合材料的气敏特性及机理,总结并展望了PEDOT:PSS及其复合材料在结构、工艺等方面的发展趋势。     

纳米SiO_2对压力敏感导电橡胶静态特性和动态特性的影响

以炭黑(CB3100)作为导电相,硅橡胶为基质制备柔性触觉传感器用力敏导电复合材料。通过SiO2填料对导电橡胶的纳米改性,研究了纳米SiO2对导电橡胶静态特性和动态特性的影响。静态特性结果表明,适量纳米SiO2粒子对导电橡胶具有良好改性作用,增强了导电橡胶的导电性,缩短电阻弛豫时间,改善其压力-电阻曲线的线性度,提高导电橡胶对温度的稳定性。动态特性结果表明,SiO2的加入能够缩短阶跃力作用下导电橡胶电阻达到稳定所需的时间,但对响应时间和频率响应无显著影响。此外,SiO2的加入也存在负面影响,如使得阶跃响应信号的峰值时间增长。     

电参数湿敏高分子材料研究进展

对用于电阻型和电容型湿度传感器的湿敏高分子材料的最近进展,进行了介绍和评述,着重说明交联和共聚是制备耐水的湿敏高分子材料的优良方法。     

Anisotropically conductive polymer composites with a selective distribution of carbon black in an in situ microfibrillar reinforced blend

A carbon black (CB) based anisotropically conductive polymer composite (ACPC) was fabricated using an easy method comprising an extrusion-hot stretch-quenching process. The resultant ACPC exhibited a very low percolation and a strong anisotropy in conductivity due to its unique structure in which the dispersed polymer phase was deformed in situ into oriented conductive microfibrils, whose surface region holds the majority of CB particles. The oriented conductive microfibrils constructed different conductive networks in the parallel and perpendicular directions of ACPC, thus leading to a strong electrical anisotropy. The conductive mechanism underlying this material took effect in a complex manner including contact conduction and tunneling conduction.     

导电相对压电复合材料吸声性能的影响

为了研究新型环境声学功能材料, 在压电导电原理的基础上, 制备了以不同含量炭黑为导电相, 以聚氯乙烯为基体材料, 以锆钛酸铅为压电相的压电导电吸声复合材料。通过对复合材料体系的动态力学、电学和声学性能的测试分析, 探讨了压电导电复合材料体系中压电吸声途径的耗能机制。结果表明, 添加体积含量4 %炭黑粉的压电复合材料具有最高的吸声性能。      

炭黑表面接枝改性在智能材料中应用

简要介绍了炭黑粒子表面接枝改性的几种方法及湿 /气 /汽敏材料的制备工艺。描述了功能化炭黑粒子 /聚合物复合材料对溶剂蒸汽、气体、湿度的响应机理及影响响应性的因素     

碳湿敏元件非线性感湿特性的影响因素

研究了不同配比导电炭黑和羟乙基纤维素(HEC)感湿胶制备的碳湿敏元件的感湿特性,探讨了山梨醇增湿剂对感湿非线性特性的影响。对碳湿敏元件的体积电阻率、湿敏特性和复阻抗谱的测试结果表明,炭黑含量和山梨醇含量对非线性感湿特性有很大影响,2%炭黑试样在80%湿度附近开始出现电阻的非线性增大;适量山梨醇使试样的非线性湿度响应移向较低湿度区。试样的复阻抗谱在54%湿度时为1个带拖尾的半圆弧,80%湿度时变为带拖尾的2个半圆弧,更高湿度时是拖尾拉长变形明显的2个半圆弧,表明其等效电路是由包括体电阻、炭黑粒界电阻和电极接触电阻三个阻容并联体的串联组成。半圆弧数目随湿度增加的现象,与感湿膜中水分子增加使不同极化机制的作用变得更加明显有关。     

Proton conductivity of biopolymer–platinum nanoparticle composite under high humidity

A κ-carrageenan–Pt nanoparticle composite (Cg–Pt) was synthesized and its proton conductivity was examined by a complex-plane impedance method. The synthesized Cg–Pt was characterized by transmission electron microscope (TEM) observation, powder X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) absorption measurements, and thermogravimetry/mass spectrometry (TG/MS) analysis. It was revealed that the a.c. electrical conductivity of Cg–Pt strongly depends on relative humidity (RH) and exceeds the conductivity of Cg under conditions of high humidity. From the temperature dependence of the a.c. conductivity, activation energies for protonic conduction were estimated to be 0.47 and 0.34 eV for Cg–Pt and Cg, respectively. The origin of the differences in the conductivities and activation energies are discussed.     

An analytical solution for hydraulic conductivity of concrete considering properties of the Interfacial Transition Zone (ITZ)

As a composite material, hydraulic conductivity of concrete depends on conductivity of its components that are the mortar, aggregates and the Interfacial Transition Zone (ITZ). Since hydraulic conduction is analogous to heat and electrical conduction, analytical models from these analogous areas relating effective conductivity of composite to conductivity of its components can be used to find the effective hydraulic conductivity of concrete as a function of properties of its components, i.e., aggregate, mortar and the ITZ. However, effect of the conduction in the ITZ has not been considered in these models. This paper presents an analytical solution for the hydraulic conductivity of concrete as a three-phase composite material. The solution is an extension to the model originally proposed for conduction of composite media with randomly suspended spheres. Results of the proposed model compare well against the experimental results and those obtained from rigorous numerical analysis using the Finite Element (FE) method. The principal significance of this study lies in the development of a versatile analytical model that can be employed as a quick tool for assessment of hydraulic conductivity of concrete without the need for sophisticated FE models at the meso-scale level. It offers more insight into effect of different components of concrete on its overall conductivity.     

导电硅橡胶泡沫材料的制备与性能研究

在硅橡胶基体中添加碳系导电填料(CB、CNT),利用超临界CO2发泡技术,制备了CB/硅橡胶、CNT/硅橡胶以及CB/CNT/硅橡胶复合导电泡沫材料,研究了混料胶料的流变行为以及发泡前后复合材料电导率、电磁屏蔽效能的变化规律。结果表明,CB与CNT均会阻碍硅橡胶复合材料的初始交联,导电填料含量越多交联越迟缓。CB/CNT/硅橡胶复配体系中更容易形成导电通路,当CB/CNT(1∶1)总含量为8%(质量分数)时,硅橡胶复合材料的电导率可达10^-5 S/cm,其电磁屏蔽效能(EI)为14~26 dB。发泡后,硅橡胶复合材料的电导率及EI值均有所下降。     

DC electrical conductivity of poly(methyl methacrylate)/carbon black composites at low temperatures

The study deals with the dc electrical conduction of poly(methyl methacrylate)/carbon black composites of different carbon black (CB) filler concentrations (2, 6, 12 wt%). The dc electrical conductivity was studied as a function of filler concentration, and temperature in the range (20–290 K). It was found that the composites exhibit negative temperature coefficient of resistivity (NTCR) at low temperatures and enhancement in the dc electrical conductivity with both temperature and CB concentration. The observed increase of conductivity with CB concentration was interpreted through the percolation theory. The dependence of the electrical conductivity of the composites in low temperatures was analyzed in term of a formula in consistence with Mott variable rang hopping (VRH) mechanism. The observed overall mechanism of electrical conduction has been related to the transfer of electrons through the carbon black aggregations distributed in the polymer matrix.     

Investigation of electroconductive films composed of polyvinyl alcohol and graphitized carbon black

Films consisting of the polymer (polyvinyl alcohol (PVA)) matrix and the filler (graphitized carbon black (CB)) were prepared and examined using TMA, contact angle, and conductivity measurements. Existence of weak interaction between the molecules of PVA and the surface of CB was established. The changes occurring in the process of the thermal treatment and the chlorination of composite films were evaluated using the contact angle measurements. The results of DC conductivity measurements were approached using a model of filler cluster formation in the polymer matrix. The model of this concept is based on the percolation theory and the fractal structure of the filler network. The films exposed to environment of a certain relative humidity and the chlorinated films were examined this way. The size of the clusters, which were formed in the matrix of PVA was determined. It was established that the change of conductivity in the process of moisture adsorption runs through the aggregation of clusters.     

Enhancement of dielectric and electrical properties in BT/SiC/PVDF three-phase composite through microstructure tailoring

A polymer composite with high dielectric permittivity was prepared by embedding silicon carbide (SiC) whisker with an average diameter of 500 nm–1 μm in poly(vinylidene fluoride) (PVDF). However, the high dielectric loss and electrical conductivity of the two-phase composite prohibits its potential applications. Barium titanate (BT) particles with average diameter of 100 nm and 1 μm were incorporated as a third phase to fabricate a three-phase composite. The morphology structure, dielectric and electrical properties before and after the addition of BT particles were investigated. The three-phase composite exhibits largely suppressed dielectric loss and electrical conductivity without sacrificing the high dielectric permittivity, which was extremely hard to be realized for two-phase composite. It is also found that the nano-size BT is more favorable in achieving high dielectric permittivity than the micro-size BT, where their dielectric loss and electrical conductivity are similar. Furthermore, electric modulus analysis confirms the largely suppressed electron conduction process which results in the enhanced dielectric and electrical properties in three-phase composite.