新型聚合物基气敏传感器用导电材料研究进展

按复合材料型传感器、杂合材料型传感器和传感器阵列分类,综述了新型炭黑(CB)填充聚合物气敏传感器用导电材料的研究进展,描述了这种传感材料的气敏响应性能,讨论了影响材料气敏性能的一些因素,并对材料的响应机理作了初步探讨。     

CB-g-WPU/WPU复合材料的制备与气敏响应性能

通过对导电填料炭黑（CB）进行官能化，在CB表面引入羧基官能团，利用CB表面的羧基等活性官能团与端异氰酸酯基聚氨酯预聚物反应得炭黑接枝水性聚氨酯（CB-g-WPU），采用乳液共混法制备得CB—g-WPU／WPU气敏导电复合材料，并对CB—g-WPU／WPU复合材料的气敏响应行为进行了研究。X射线光电能谱（XPS）、傅立叶变换红外光谱（FTIR）、热重分析（TGA）等分析结果表明聚氨酯接枝到了炭黑表面；SEM分析表明，炭黑经过接枝改性后均匀分散在基体WPU中。该法制备的CB—g-WPU／WPU复合材料逾渗值低、气敏响应度大、响应范围广，是一种综合性能优异的气敏导电复合材料。     

CB/PLA与CB/RF/PLA导电高分子复合材料气敏性能对比

通过熔融共混法制备了炭黑(CB聚乳酸(PLA和CB/苎麻纤维(RFPLA导电高分子复合材料(CPCs。扫描电镜(SEM观察发现导电填料在CB/PLA中分散良好。通过预混合的方法,可以先使CB和PLA良好接触,随后的熔融加工过程中,CB/RF/PLA中CB粒子分布在RF附近,这种纤维搭接的CPCs逾渗值比CB/PLA更低。气敏测试对比研究发现,含RF的导电复合材料在不良溶剂中响应度高,重复性好;在良溶剂中,响应时间长,气敏稳定性好。为制备逾渗值低,气敏性能优良的可降解CPCs提供了新思路。     

炭黑/水性聚氨酯复合材料的制备与气敏性能研究

在环境友好的水性聚氨酯（WPU）基体乳化前加入导电填料炭黑（CB），制备了CB／WPU气敏复合材料，并研究了其气敏响应和吸收行为。研究表明，CB／WPU复合材料对有机溶剂蒸气的吸收量与气敏响应度之间没有定量关系，气敏响应时间要比吸收平衡时间小得多，当吸收尚未达到平衡时，复合材料的电阻早已达到最大值。气敏响应度的大小与有机溶剂的溶度参数尤其极性分量有关，基体和溶剂的总溶度参数相差越小，气敏响应度越大。     

PVA/CB复合材料气敏性能研究

以聚乙烯醇为基体,以炭黑为导电性添加剂,通过共混法制得常温响应聚乙烯醇/炭黑(PVA/CB)气敏导电薄膜,研究了复合薄膜材料在乙醇蒸气中的室温气敏性能。研究结果表明,PVA/CB复合材料的气敏性能跟炭黑的分散性、含量、材料的厚度等因素有关。炭黑分散性越好,气敏性越好;炭黑含量存在一最佳值;材料厚度增加,阻碍气体的扩散导致气敏性降低。     

聚乙二醇接枝炭黑纳米导电复合材料气敏性研究

以聚乙二醇接枝炭黑(PEG—g—CB)为导电粒子，不同相对分子质量的聚乙二醇(PEG)为基体，制备了PEG／PEG—g—CB纳米导电高分子复合材料，并研究了其气敏性能。结果发现，该复合材料在PEG极性溶剂蒸汽中电阻响应快，而在非极性溶剂蒸气中电阻几乎不改变；PEG的晶相结构以及CB的接枝与否对响应重复性有很大影响。     

导电聚合物气敏传感器研究进展

气敏传感器是利用材料的气敏特性实现目标气体浓度检测的电子元器件,在生产安全、环境监测、临床医学等领域均有广泛应用。气敏材料主要分为金属氧化物半导体材料、导电聚合物(CP)材料、金属有机框架材料。导电聚合物因其成本低、易于合成,在室温下对氨气等有害气体表现出良好的响应的特点而受到广泛关注。近年来导电聚合物复合物的研究也极大地提高了导电聚合物的气敏性能。分析了导电聚合物电阻调控机理,重点介绍了近年来对氨气、二氧化氮、硫化氢等气体的导电聚合物及其复合物的气敏传感器的研究进展,简要介绍了导电高分子在甲醇、三乙胺、一氧化碳等气体检测中的研究情况,最后展望了导电聚合物在气体传感领域的应用前景。     

填充型导电高分子基气敏纳米复合材料研究进展

简单介绍了填充型导电高分子基气敏纳米复合材料相对传统气敏材料的优势,综述了近些年来对该复合材料的研究进展,重点从导电逾渗理论和导电逾渗值方面进行综述,并以炭黑填充体系、碳纳米管填充体系以及其它填充体系对该复合材料的研究现状进行了阐述。最后对填充型导电高分子基气敏纳米复合材料的发展趋势进行了展望,指出降低导电逾渗值、构建完善的导电网络、提出更加完善和实用性广的逾渗模型,以及提高复合材料气敏响应灵敏度和恢复能力将是今后的研究重点。     

取向微孔结构的PVA/CB导电复合材料对流动有机蒸汽的响应行为

通过定向冷冻干燥法,制备了取向微孔结构的导电聚乙烯醇/炭黑(PVA/CB)复合材料。研究分析了该导电复合材料的微观结构、逾渗行为及其对有机蒸汽的响应行为。结果表明:大量的CB聚集体不均匀地分布在该PVA/CB复合材料的微孔壁上,并且孔壁之间的CB搭接成较完善的导电通路,通过计算可得出该导电复合材料的逾渗阈值为16.9%;该PVA/CB复合材料在流动的四氢呋喃(THF)、丙酮、丁酮和苯蒸汽中的最大响应率分别为204、183、95、44,其响应率的不同是由于这4种有机蒸汽对PVA基体具有不同的溶胀效果。     

聚甲基丙烯酸丁酯／炭黑导电复合材料在有机蒸气中的电阻响应

研究了由原位聚合法制备的聚甲基丙烯酸丁酯／炭黑（PBMA／CB）复合材料在有机溶剂蒸气中的电阻响应。结果表明，复合材料在有机溶剂蒸气中的电阻响应显著依赖于聚合物基体与有机溶剂的相容性，而且其电阻响应程度大小可以由聚合物摹体和有机溶剂之间的三维溶度参数差之和（△δ^2）来衡量；温度会显著影响复合材料在有机溶剂蒸气中的电阻响应时间，对电阻响应程度也有一定程度的影响，这一结果与聚合物基体的玻璃化转变温度有关；复合材料对有机蒸气的最大电阻响应程度随有机蒸气分压呈现指数级增长；自然老化会导致复合材料电阻响应程度的下降，但恢复性能显著提高，负蒸气系数效应（NVC）强度减弱。PBMA／CB复合材料可以作为气敏材料用于检测有机溶剂蒸气。     

Gas sensitivity of carbon black/waterborne polyurethane composites

The synthesis of conductive composites consisting of waterborne polyurethane (WPU) and carbon black (CB) is reported. Besides the low percolation threshold (0.7-0.95 wt%), the composites are quite sensitive to organic solvent vapors regardless of their polarities as characterized by the drastic changes in conductivity. In the case of polar solvents, negative and positive vapor coefficient phenomena of the composites were successively observed with a rise in CB content. It was found that different mechanisms are responsible for the broad applicability of the composites as candidates for gas sensing materials owing to the different interactions among the matrix polymer, the filler particles and the solvent molecules.     

Conducting property of carbon black filled poly(ethylene glycol)/poly(methyl methacrylate) composites as gas‐sensing materials

To reveal the role of crystalline polymers in carbon black (CB) filled amorphous polymer composites and improve the mechanical properties of composite films, CB/poly(ethylene glycol) (PEG)/poly(methyl methacrylate) (PMMA) composites were synthesized by polymerization filling in this work. The electrical conductive property and response to organic solvent vapors of the composites were investigated. The composites, characterized by a relatively low percolation threshold (～ 2.1 wt %), had lower resistivity than CB/PMMA composites prepared with the same method because of the different dispersion status of CB particles in the matrix polymer. The concentration and molecular weight of PEG notably influenced the electrical response of the composites against organic vapors. The drastic increase in the electrical resistance of the composites in various organic vapors could be attributed mainly to the swelling of the amorphous polymer matrix in the solvent but not to that of the crystalline polymer. These findings could help us to understand the conductive mechanism and electrical response mechanism of the composites as promising gas‐sensing materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

A novel sensor for organic solvent vapors based on conductive amorphous polymer composites: carbon black/poly(butyl methacrylate)

Summary Conductive composites from carbon black/poly(butyl methacrylate) (CBPBMA) are synthesized through polymerization filling. The experimental results indicate that relatively low percolation threshold (∼6wt%) is associated with the composites. When the composites are exposed to good solvent vapors of the matrix polymer, the electric resistance of the composites drastically increases by over lo⁴ times. In the case of poor solvent vapor, however, the electrical response of the composites is rather weak, demonstrating selective gas sensibility. In addition, environment temperature exerts great influence on the responsivity of the composites against organic vapors. The higher the temperature, the faster and the stronger the electrical response. It was also found that the response of electric resistance of the composites against good solvent vapors is provided with sufficient reproducibility and stability. It can thus be concluded that the CB/PBMA composites can be used as promising gas sensing materials in practice. Received: 2 December 2002/Revised version: 27 January 2003/ Accepted: 8 February 2003 Correspondence to Ming Qiu Zhang     

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     

Effect of morphology on the electric conductivity of binary polymer blends filled with carbon black

Several carbon black (CB)‐filled binary polymer blends were prepared in Haake rheometer. Distribution states of CB and effect of morphology on the electric conductivity of different ternary composites were investigated. Under our experimental condition CB particles located preferentially at the interface between polymethyl methacrylate (PMMA) and polypropylene (PP) in PMMA/PP/CB composites, in high‐density polyethylene (HDPE) phase in PP/HDPE/CB composites, and in Nylon6 (PA6) phase in polystyrene (PS)/PA6/CB, PP/PA6/CB, PMMA/PA6/CB, and polyacrylonitrile (PAN)/PA6/CB composites; the ternary composites in which CB particles locate at the interface of two polymer components have the highest electric conductivity when the mass ratio of the two polymers is near to 1 : 1. The ternary composites in which CB particles located preferentially in one polymer have the highest electric conductivity usually when the amount of the polymer component having CB particles is comparatively less than the amount of the polymer component not having CB particles; if the formulations of PS/PA6/CB, PP/PA6/CB, and PMMA/PA6/CB composites equaled and PA6/CB in them is in dispersed phase, PS/PA6/CB composites have the highest electric conductivity and PP/PA6/CB composites have the lowest electric conductivity; suitable amount of PS or PAN in PA6/CB composites increase the electric conductivity due in the formation of a parallel electrocircuit for electrons to transmit. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Chemical sensing materials. I. Electrically conductive SEBS copolymer systems

Chemical sensing materials based on conductive carbon black (CB) filled [styrene‐ethylene butylene‐styrene] triblock‐copolymers (SEBS) were investigated. Several types of SEBS copolymers were studied, differing in composition and melt viscosity. The sensing is based on electrical conductivity changes upon solvent sorption/desorption. Compression molding SEBS composites containing various amounts of CB were prepared. Their electrical conductivity was measured and samples containing CB, preferentially located in the continuous ethylene/butylene (EB) phase, at a level near the corresponding percolation threshold were used for the sensing experiments. The conductivity was measured during several exposure/drying cycles. Structure characterization included scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and calorimetry (DSC). The SEBS composites exhibit large reversible changes in conductivity upon exposure to a limited number of solvents, e.g., acetone, n‐heptane, and air drying cycles. This behavior was related to the sorption kinetics, affected by the solvent characteristics (solubility parameter, polarity, molecular volume and vapor pressure). The samples' resistance tended to return to their initial value upon short drying of acetone, and longer drying of other studied solvents. The nature of the SEBS, the CB content, and mixing temperature are all significant parameters, determining the sample's structure and the resultant sensing property. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Improved stability of volume resistivity in carbon black/ethylene-vinyl acetate copolymer composites by employing multi-walled carbon nanotubes as second filler

Semiconductive polymer shielding layers of power cable require stable volume resistivity to protect the insulation layer from stress enhancements when carbon black (CB)/polymer composite undergoes thermal cycles. For the CB-filled polymer composites, CB would often re-aggregate when temperature is close to the melting point of polymer matrix, so that the conductive network would be destroyed. Re-distribution of CB and re-formation of conductive CB network under thermal cycles might be the main reason for the instability of volume resistivity. In this work, the re-aggregation of CB in the CB/polymer composites was disclosed. Besides, a small amount of multi-walled carbon nanotubes (MWNTs) was employed as cofiller with CB to improve the stability of volume resistivity of the polymer composites under thermal cycles. The total weight fraction of conductive fillers (CB or CB cofilled with MWNTs) was set as 35 wt%. Compared with the polymer composites loaded with CB solely, the volume resistivity of the composites filled with CB-MWNTs was much more stable with changing temperature. This can be attributed to the enhancement of conductive networks when the MWNTs are employed as second conductive filler.     

超高分子量聚乙烯对有机PTC复合材料的超强稳定作用研究

利用传统的熔融 混合方法制备碳黑填充的聚丙烯 (PP) /超高分子量聚乙烯 (UHMWPE)复合物。当PP/UHMWPE混合比大于 3 / 7,碳黑填充PP/UHMWPE复合物的PTC和NTC效应类似于碳黑填充的纯净PP聚合物。然而当重量比等于或小于 3 / 7时 ,复合物所表现的PTC效应非常相似于碳黑填充的纯净的UHMWPE聚合物。在复合物中应用粘度非常高的聚合物作为一种组分可以有效消除NTC效应