不同混合导电掺和料水泥基复合材料压阻特性的实验研究

利用纳米石墨、炭黑等导电掺料制作的水泥基复合材料的压阻特性可进行交通违规监测.本文实验研究了由石墨、炭黑、碳纤维任意两导电掺料组成的复合导电相制作的高导电长方柱水泥基复合材料,在标准车载大小、不同荷载循环周期作用下的压阻特性.实验表明一定车载力作用下,所选配比情况,含石墨和碳纤维混合掺料的水泥基复合材料的压阻特性最好,含石墨和炭黑复合导电相的次之,含炭黑和碳纤维复合导电相压阻特性不明显.     

炭黑/铝银粉填充导电硅橡胶的性能研究

以炭黑和铝银粉为导电填料,通过溶液共混法制备出导电硅橡胶试样。研究了炭黑/铝银粉对导电硅橡胶导电性能和压阻特性的影响。结果表明,当炭黑含量一定时,随着铝银粉含量的不断增加,导电硅橡胶的电阻先减小后增大;当填料含量一定时,随着压力的不断增加,导电硅橡胶的压阻特性曲线先逐渐下降后趋于稳定;当炭黑含量为30 %（质量分数,下同）、铝银粉含量为3 %时,导电硅橡胶的导电性最好,压阻特性范围也变大。     

炭黑在EVA中的导电性研究

以EVA为高分子聚合物,采用不同级别的导电炭黑,研究了导电炭黑填充高分子聚合物的导电性,讨论了不同级别和不同用量的导电炭黑在聚合物中的分散性,以及对高分子聚合物导电性的影响。实验结果表明,导电炭黑高分子聚合物的导电性主要取决于不同级别的导电炭黑的表面积和结构等特性、炭黑的不同用量以及导电炭黑的聚集体在高分子聚合物的分散程度。     

炭黑/橡胶力敏复合材料压阻特性的研究

采用机械共混法制备炭黑/BR、炭黑/BR/NR和炭黑/甲基乙烯基硅橡胶(MVQ)力敏复合材料,并对其压阻特性进行研究。结果表明,炭黑/MVQ复合材料导电炭黑的逾渗阈值最小,压力敏感特性最强;随着压应力的增大,炭黑/BR、炭黑/BR/NR和炭黑/MVQ复合材料的压阻重复性依次下降。采用多乙烯基硅油和全硫化粉末BR,可改善炭黑/MVQ复合材料的压阻重复性。     

炭黑在高分子聚合物中的导电性研究

以EVA为高分子聚合物，采用不同级别的导电炭黑，研究了导电炭黑填充高分子聚合物的导电性，讨论了不同级别和不同用量的导电炭黑在聚合物中的分散性，以及对高分子聚合物导电性的影响。实验结果表明，导电炭黑高分子聚合物的导电性主要取决于不同级别的导电炭黑的表面性和结构等特性、炭黑的不同用量以及导电炭黑的聚集体在高分子聚合物的分散程度。     

填充型导电硅橡胶的制备与性能研究

用导电炭黑EC-600JD和BP2000与石墨烯纳米片填充硅橡胶制备导电硅橡胶,并测试其电性能和力学性能。结果表明:填充导电炭黑BP2000的硅橡胶的电性能优于填充导电炭黑EC-600JD的硅橡胶;在硅橡胶中填充25份导电炭黑BP2000和一定量石墨烯纳米片,随着石墨烯纳米片用量的增大,导电硅橡胶的电性能逐渐提高,当石墨烯纳米片用量为1份时,导电硅橡胶的力学性能最优,电性能较好,达到电热平衡时间最短,压阻特性最不明显。     

炭黑用量对硅橡胶基力敏复合材料性能的影响

以炭黑为导电功能填料制备炭黑/甲基乙烯基硅橡胶(MVQ)力敏复合材料,研究炭黑用量对复合材料硫化特性、拉伸性能、压缩应力松弛性能、电性能和压阻性能的影响.结果表明:炭黑用量为11～16份时,炭黑/MVQ复合材料电性能达到逾渗阈值.随着炭黑用量的增大,炭黑/MVQ复合材料拉伸强度先增大后减小,最后趋于稳定,而压缩松弛率呈减小趋势.炭黑用量为11份时炭黑/MVQ复合材料的压阻重复性较好.适宜的炭黑用量为10～12份.     

硅橡胶/炭黑复合材料在外场作用下的导电响应行为

通过机械共混法制备了甲基乙烯基硅橡胶(MVQ)/炭黑(CB)复合材料,研究了复合材料的压阻特性、温阻特性、在压缩循环下的压阻稳定性和重复性能以及电阻弛豫特性,并提出了新的压阻数学模型。结果表明,在渗滤阈值附近,MVQ/CB复合材料有最显著的压阻效应;随着CB含量的增加,压阻效应出现一个临界压力;在40℃时复合材料由正温阻特性转变为负温阻特性;通过预压缩和增加压缩循环次数,可以提高压敏导电橡胶的压阻重复性和稳定性。应用隧道电流理论构建的压阻效应数学模型能同时很好地模拟MVQ/CB复合材料的正压阻系数效应和负压阻系数效应。     

聚合物基导电复合材料的导电机理

本文对炭黑填充聚合物和金属填充聚合物的导电特性和影响导电性能的因素进行了综述。简要地介绍蒙特卡罗统计方法、凝胶化理论、有效电场理论以及隧道效应等。     

炭黑导电浆料的制备及电性能分析

以炭黑为导电填料,氯醋树脂、羟丙树脂为固化材料制备了导电浆料,采用XRD、SEM和激光粒度分析仪等对导电浆料炭黑进行分析和表征,结果表明,导电填料炭黑是由100 nm以下的一次颗粒构成的粒度分布在6μm左右的类石墨结构的物质。研究了炭黑添加量对导电浆料粘度和方阻的影响,结果表明,通过调整炭黑的添加量可以改变导电浆料的粘度和方阻,最终制备了粘度适宜,方阻可达358Ω/m2的导电浆料。     

Nonmonotonic piezoresistive effect in elastomeric composite films

We compared the change of electrical resistance with elongation (piezoresistive effect) in thin films made of conductive multiwalled carbon nanotubes embedded in eight different elastomers. Two distinct forms of piezoresistive effect were observed: (i) in the “monotonic” (M) case, the film resistance always increased with the applied strain; (ii) the “nonmonotonic” (NM) case showed an initial increase in the resistance, while with further elongation the resistance began to decrease. By varying the amount of nitrile and/or styrene groups in the polymer matrix one can alter the piezoresistive effect qualitatively: composites with ～25 wt % or more of nitrile or styrene functional side groups exhibited M piezoresistance, while others, with no, or methyl side groups only, showed NM piezoresistance. Influence of the second filler (either conductive carbon black or nonconductive nanoclay) in the ternary composites on the piezoresistive effect was explored. The possibility to modify the piezoresistive behavior of the conductive elastomer composites, for example, via chemical modification of the polymeric matrix, opens up a new venue for practical applications such as diverse types of sensors and, in NM case, complex dynamical systems (bistable elements, electromechanical oscillators, etc.) in the MEMS field. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43518.     

Percolation transition and hydrostatic piezoresistance for carbon black filled poly(methylvinylsilioxane) vulcanizates

The percolation transition and the hydrostatic piezoresistance for carbon black (CB) filled poly(methylvinylsilioxane) vulcanizates were studied as a function of CB volume fraction. A revised tunneling-percolation model based on the method of “subcritical networks” was proposed, which can not only account for the apparent nonuniversal percolation, but also figure out the contribution of changing tunneling current to the hydrostatic piezoresistance. Although there is a general tendency that the relative contribution of tunneling current increases with increasing filler concentration, it is always the variation of effective filler volume fraction which dominates the hydrostatic piezoresistance for the present system, due to the rather limited mobility of the mediating polymer layer between neighboring CB aggregates. The pressure and concentration dependences of the hydrostatic piezoresistance were interpreted in terms of the connectivity and/or the fractal nature of the percolation network. The concentration dependence of hydrostatic piezoresistance could even be associated with the strength of filler-matrix interaction. The baseline drift and poor reproducibility of hydrostatic piezoresistance were ascribed to the residual compressive strain of the rubber matrix, which could not be completely eliminated but could be deducted from the piezoresistance by a novel resistance baseline removal method.     

碳纳米管填充导电橡胶的研究进展

介绍了碳纳米管(CNTs)的处理改性以及CNTs填充导电橡胶的制备方法,分析了CNTs填充导电橡胶的导电机理及导电逾渗行为,并综述了CNTs填充导电橡胶的力敏特性和驰豫现象.     

Liquid‐sensing behaviors of carbon black/polypropylene and carbon nanotubes/polypropylene composites: A comparative study

Liquid‐sensing behaviors of carbon black (CB)/polypropylene (PP) and carbon nanotubes (CNTs)/PP‐conductive polymer composites (CPCs) were studied in detail. It was found that the CB/PP showed a higher liquid‐sensing intensity but a poorer reproducibility toward the “good solvent” xylene. The main origin is that the conductive works formed by CB, the zero‐dimensional filler, are vulnerable to the swelling effect of PP during the immersion‐drying runs (IDRs), whereas CNTs in the CNTs/PP with a large aspect ratio have better capacity in maintaining the conductive networks. To investigate the influence of the remaining solvent on the evolution of conductive networks, liquid‐sensing tests of the two composites after long‐term immersion in xylene were investigated. Results showed that the liquid‐sensing behaviors of CNTs/PP changed less weakly compared with that of the CB/PP. Liquid‐sensing behaviors of the two composites, cyclohexane and tetrachloromethane, to the “poor solvents” were also studied. The results of this article indicate that liquid‐sensing behaviors of the CPCs were affected by the microstructure of the conductive filler, the solubility parameter, and the molar volume of the solvent significantly. POLYM. COMPOS., 36:205–213, 2015. © 2014 Society of Plastics Engineers     

碳纤维水泥基机敏复合材料研究进展

综述了碳纤维水泥基复合材料（CFRC）的压敏性、Seeback效应、温阻效应、焦耳效应和电磁屏蔽效应等机敏特性及其相应机理,并对各种机敏特性在工程中的应用做了概述。     

Piezoresistance and Piezocapacitance Effects in Barium Strontium Titanate Ceramics

A large piezoresistance response to hydrostatic pressure is reported for a series of ceramic compositions in the system barium strontium lanthanum titanate (Ba, Sr, La)TiO₂. This property appears to be closely associated with the Curie region (cubic-tetragonal phase transition) and the phenomenon of a positive temperature coefficient of resistance for these same compositions. The piezoresistance coefficient, similar to the temperature coefficient of resistance, is positive in the Curie region, and is found to range up to the order of 700 X 10 ⁻¹² sq. cm. per dyne. Consistent with the observed piezoresistance effect, a positive piezocapacitive effect, ranging up to the order of 700 x 10⁻¹² sq. cm. per dyne, is observed in these compositions in the absence of the lanthanum impurity which produces semiconduction. It is suggested that these materials may be of interest in pressure-sensitive devices such as acoustic transducers and pressure-sensing elements and in techniques for measuring force and displacement.     

聚苯胺-乙烯三叔丁基过氧硅烷复合膜的制备及其电致变色性能的研究

采用恒电位法在氧化铟导电玻璃上电聚合制备了聚苯胺(PAn),利用溶液复合法合成了掺杂态聚苯胺-乙烯三叔丁基过氧硅烷复合电致变色膜,并对其结构和电致变色性能研究。结果表明,复合电致变色膜在稳定态时仅出现第二氧化峰,在外加电压下其颜色在绿色至紫色之间可逆变化,聚合物中加入偶联剂,可提高电致变色膜与导电玻璃基底的粘结性及改善复合膜的耐溶剂性能。     

Selectively depositing Pt nanoparticles on pre-treated electrically conductive porous alumina and its electrochemical studies

To fabricate a composite modified with uniformly dispersed metallic particles, in this paper, electrical conductive porous alumina (CPA) was firstly pre-treated with mixed acids followed by deposition of Pt nanoparticles via reductive reaction. Crystal structure of uniformly deposited Pt nanoparticles was confirmed to face centered cubic (fcc). Based on characterization results, selective surface modification was achieved by surface pre-treatment, by which various functional groups were grafted onto three-dimensional conductive networks. The electrochemical behaviors of as-fabricated composites conducted in acidic electrolyte confirmed their improved activities, which merited from novel structure of designed electrode.     

Effect of the carbon black structure on the stability and efficiency of the conductive network in polyethylene composites

Composites of high‐density polyethylene (HDPE) with different kinds of carbon black (CB) were prepared through melt blending. The influence of the CB structure on the stability and efficiency of the conductive network in HDPE/CB composites were mainly investigated. Scanning electron microscopy was used to observe the morphology of the CB primary aggregates. The relationship between the temperature‐resistivity behaviors of the composites and the crystallization behaviors of the matrix were also investigated. High‐structure CB built an effective conductive network at a low filler content compared to the low‐structure one because of its branched morphology. Therefore, the composite containing high‐structure CB revealed a lower percolation threshold. The composite containing low‐structure CB obtained a stronger positive temperature coefficient (PTC) intensity because the cluster network was fragile and easily damaged during matrix melting. The reproducibility of the results of PTC effect of the composite containing high‐structure CB was better than that of the composite containing a low‐structure one. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Electrical and mechanical percolation in graphene-latex nanocomposites

Conductive composites based on few layer graphene are of primary interests. In this work latex based composites were produced leading to a specific cellular morphology. Highly conductive graphene-based composite materials have been produced through a solvent-free procedure. Both the mechanical and conductivity behaviors were successfully described using a percolation approach that confirms the presence of a three dimensional filler network efficiently spread across the material. The influence of the aspect ratio between the conductive filler and the latex nanosphere drove the study. It was demonstrated experimentally that the tuning of the cell dimensions of the composite morphology influences the percolation threshold and the reachable maximum conductivity and reinforcement. These experimental results are consistent with phenomenological models based on the statistical percolation theory.