Durable compliant electrode based on graphene and natural rubber

A compliant electrode is a stretchable electronic device that retains good conductivity under stretching or bending. It has been used in various electro‐actuating applications which require large deformations under electrical field. The objective of this work was to fabricate a compliant electrode possessing high electrical conductivity and good mechanical properties. Due to the excellent mechanical properties of natural rubber (NR), it was used as a matrix for the compliant electrode. Graphene was used as a new and innovative conductive filler to provide excellent electrical conductivity. The mechanical properties and electrical properties were investigated by using a rheometer in the tension mode. Both mechanical and electrical properties were improved drastically by introducing graphene into the matrix. The highest electrical conductivity of 0.61 S/cm was obtained from the 35.0 %vol/vol graphene/NR composite, two orders of magnitude higher than that of the commercial compliant electrode. The 5.0 %vol/vol graphene/NR composite was shown and identified here as a promising material for using as a compliant electrode. POLYM. ENG. SCI., 57:129–136, 2017. © 2016 Society of Plastics Engineers     

导电型室温硫化硅橡胶的研究

研究了炭黑的结构和配合量对室温硫化硅橡胶导电性能和力学性能的影响, 以及室温硫化硅橡胶基胶摩尔质量对导电性能的影响。结果表明： ７ 份乙炔炭黑能赋予室温硫化硅橡胶良好的导电性, 当乙炔炭黑用量为１０ 份时, 室温硫化硅橡胶的体积电阻率达到６０ Ω·ｃｍ ; 摩尔质量较低的硅橡胶导电性能更佳; 同时, 乙炔炭黑能提高硅橡胶的拉伸强度和硬度。     

Carboxylated polyurethane anionomers and their composites with polypyrrole

Some polyurethane anionomers synthesized by a two‐step substitution postreaction of urethane hydrogen atoms with CH₂COONa groups were studied. The influence of ionic structures on the mechanical and electrical properties of polymers was followed. The carboxylated polyurethane anionomers were used to obtain electroconductive composites with polypyrrole, by immersion of polyurethane films in aqueous solution of pyrrole and oxidative chemical polymerization of the heterocyclic monomer with FeCl₃. The proportion of polypyrrole in the composites increased by introduction of ionic groups. Stress–strain behavior and electrical conductivity of composites were compared with those of the anionomers. Incorporation of polypyrrole significantly enhanced the electrical conductivity but diminished mechanical properties. Some composites possess both satisfactory conductivity and mechanical properties. The results were explained by the morphological changes induced by ionic group and polypyrrole presence. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1385–1392, 2000     

Effect of CNT decoration with silver nanoparticles on electrical conductivity of CNT-polymer composites

A simple approach to decorate carbon nanotube (CNT) with silver nanoparticles (Ag-NPs) was developed to enhance the electrical conductivity of CNT. CNTs were functionalized using ball milling in the presence of ammonium bicarbonate, followed by reduction of silver ions in N, N-dimethylformamide, producing silver decorated CNTs (Ag@CNTs). The Ag@CNTs were employed as conducting filler in epoxy resin to fabricate electrically conducting polymer composites. The electrical, thermal and mechanical properties of the composites were measured and compared with those containing pristine and functionalized CNTs. It was found that when pH was about six, highly dispersed Ag-NPs can be decorated on functionalized CNTs. The electrical conductivity of composites containing 0.10 wt% of Ag@CNTs was more than four orders of magnitude higher than those containing same content of pristine and functionalized CNTs, confirming the advantage of the Ag@CNTs as effective conducting filler. The ameliorating effect of improved electrical conductivity was not at the expense of thermal or mechanical properties.     

助剂和工艺条件对导电性复合材料性能的影响及其分析

本文以低密度聚乙烯－镍粉为基础成分，引入各种助剂和改变工艺条件，研究了导电性复合材料的导电性和力学强度的变化规律，并考察了其作用机制。结果表明，导电性增加，伸长率和冲击强度就下降，这是由于填料的分散状态及其与聚合物基体的相互作用发生变化造成的。在实际使用中，必须良好地也能够适当地调节这两种性能。     

RGO/ANFs复合气凝胶的制备及电磁屏蔽性能

本研究通过化学水热还原法制备RGO，并将其引入到化学劈裂法制备的ANF基体中，进而采用冷冻干燥法制备了可压缩回弹、高效电磁屏蔽性能的RGO/ANFs复合气凝胶，系统研究了不同RGO添加量对RGO/ANFs复合气凝胶的微观形貌、导电性能、力学性能和电磁屏蔽性能的影响。研究表明：当RGO添加量为20 wt.%时，复合气凝胶电导率达到15.84 S/cm，电磁屏蔽效能高达22 dB， 30%压缩应变时，压缩应力可达21 kPa。气凝胶自身的多孔结构与RGO良好的导电性能共同赋予了复合气凝胶优异的电磁屏蔽性能，这种兼具电磁屏蔽性能与力学性能的复合气凝胶有望应用于通信、微电子和航空航天等领域。     

Electrical properties of polyaniline–polystyrene blends above the percolation threshold

Blends of conductive polymers with classical ones can exhibit good mechanical properties and good electrical conductivity and deserve great attention for application in electronic industrial technology. Conductive polyaniline solutions have been chemically prepared using bis(2-ethyl hexyl)hydrogen phosphate (DiOHP) as the dopant chemical species. The codissolution method leads to conductive polyaniline–polystyrene (PANI–PSt) composites with good mechanical properties. The dependence of electrical conductivity on the volume fraction of PANI in the blend is found to be characteristic of a percolation system. Electrical conductivity and thermoelectric power measurements are interpreted on the basis of hopping mechanisms between polaronic clusters. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1205–1208, 1998     

Dispersion optimization of exfoliated graphene nanoplatelet in polyetherimide nanocomposites: Extrusion,precoating, and solid state ball milling

Polyetherimide (PEId) nanocomposites reinforced with exfoliated graphite (graphene) nanoplatelets (GNP) were fabricated by various processing methods to achieve good dispersion including: melt‐extrusion, precoating, solid state ball milling (SSBM) as well as combinations of these methods. As a result of the precoating approach, the electrical conductivity is greatly increased with a percolation threshold as low as 2 wt% as compared to 10 wt% for melt‐extrusion, with the cost of lower mechanical properties. SSBM was investigated as an alternative process to enhance dispersion, adhesion and to reduce GNP size. High electrical conductivity and improved modulus were achieved by this approach. Further improvements to the mechanical properties could be made by combining the extrusion and SSBM approaches. Examination of the nanocomposite morphology explains the effect of these combined compounding approaches on GNP particle dispersion and their relation to the improved GNP/PEId nanocomposite performance. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

A model of the electrical conductivity of anthracite and graphite dispersions in electrolytes

The electrical conductivity of anthracite and graphite dispersions in the solutions of potassium chloride was measured. A linear increase in the electrical conductivity as a function of the weight fraction of a dispersed phase was observed in the region of electrolyte concentrations of 0.0005?C0.01 M. In 0.1 M solutions, the dependence of the electrical conductivity of a suspension on the weight fraction of a dispersed phase (0.1?C15 wt %) decreased with the subsequent increase. A model was proposed for the electrical conductivity of anthracite and graphite dispersions in electrolytes; in accordance with this model, charge transfer due to the electrophoretic mobility of particles makes the main contribution to an increase in the electrical conductivity. Different electrical conductivity components (specific surface conductivity) calculated from the Bikerman equation and based on the model proposed were compared.     

聚氨酯/碳纳米管复合材料力学及电性能研究

利用超声分散和原位聚合的方法制备了聚氨酯／碳纳米管((PUR／CNTs)复合材料,观察了该复合材料的微观结构,探讨了CNTs含量对复合材料力学性能和电性能的影响。结果表明,CNTs在基体中获得了较好的分散,当CNTs质量分数为2％时复合材料的力学性能得到全面提高,与PUR相比,拉伸强度提高11．6％,拉伸弹性模量提高11．3％,断裂伸长率提高10．4％;复合材料的导电性能得到明显的提高,在CNTs质量分数为0．5％时可用作抗静电材料。     

LDPE／炭黑导电复合材料电学及力学性能研究

研究了炭黑种类及用量、极性共聚物（Ｅ－ＡＥ－ＭＡＨ）、润滑剂种类及用量和交联剂（ＤＣＰ）对ＬＤＰＥ／炭黑导电复合材料电学及力学性能的影响。结果表明,ＨＧ－４型炭黑导电性最好,ＡＣＥＴ炭黑导电性较差。极性共聚物能提高复合材料的导电性和力学性能。高分子蜡改善复合材料电学及力学性能的效果优于液体石蜡。交联剂使复合材料导电性变差,但力学性能提高     

Preparation of graphite composite bipolar plate for PEMFC

This research studied the preparation of graphite composite using liquid thermosetting plastic such as polyester resin (POE), phenolic modified alkyd resin (PhA) and mixed resin (POE with 10% PhA) as a binder. The morphology, physical, electrical and mechanical properties of the graphite composites were analyzed. The results showed that POE could combine with graphite powder (the 66% wt. saturated of graphite powder) better than PhA and mixed resin and gave higher electrical conductivity (4.52 S/cm). It was also found that epoxy resin could improve the mechanical property of composite plate. The addition of TiO₂ and ZnSt slightly decreased the electrical conductivity and the water absorption. Moreover, it was proposed that TiO₂ could improve the mechanical property. Carbon fiber can increase electrical and mechanical properties and water absorption of the composite with POE as a binder. The mixing of wet-lay mixture with graphite, carbon fiber and POE composite improved the mechanical property and decreased the water absorption.     

Influence of preparation methods on the electrical and nanomechanical properties of poly(methyl methacrylate)/multiwalled carbon nanotubes composites

Poly(methyl methacrylate)/multiwalled carbon nanotubes (PMMA/MWCNT) composites were prepared by two different methods: melt mixing and solution casting. For solution casting, two different solvents, toluene and chloroform, were used to prepare PMMA solutions with different concentrations of MWCNT. The dispersion of the CNT in the composite samples was verified by scanning electron microscopy. For the nanocomposites prepared by both methods, the electrical conductivity increased with increasing filler content, showing typical percolation behavior. In addition, an increase of 11 orders of magnitude in the electrical conductivity relative to the matrix conductivity was determined by broadband dielectric spectroscopy and four probe conductivity measurements. A maximum value of σ_DC ～ 1.6 S/cm was found for the highest filler loaded sample (3.67 vol %), which was prepared by solution casting from toluene. Nanoindentation analysis was used to characterize the surface mechanical properties of the composite samples prepared by the different methods. Indentation tests were performed at various penetration depths, and it was revealed that the melt mixing process resulted in stiffer neat PMMA samples compared to the solution casted PMMA samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41721.     

Improving the electrical conductivity of ethylene 1‐octene copolymer/cyclic olefin copolymer immiscible blends by interfacial localization of MWCNTs

The localization of multiwall carbon nanotubes (MWCNTs) in the immiscible blends of ethylene–1‐octene copolymer (EOC) and cyclic olefin copolymer (COC) with the sea–island morphology and electrical conductivity of resulting nanocomposites were investigated. Depending on the feeding orders, as the MWCNTs were located in the COC droplet, the electrical conductivity was obtained as high as 5.71 × 10^?7 S/cm, while the MWCNTs were located in EOC/COC interface, the electrical conductivity increased significantly up to 1.72 × 10^?2 S/cm. The improved electrical conductivity in EOE/COC/MWCNTs nanocomposite is attributed to the interfacial localization of MWCNTs which is resulted from thermodynamic affinity of MWCNTs to COC, as well as an interconnected structure via deformed and swelled COC droplets. Thermodynamic affinity of MWCNTs to COC and established interconnected structure are confirmed by rheological characterization, microscopic observations, dynamic mechanical analysis, and electrical conductivity measurements. Therefore, as a result of selective localization of MWCNTs and well‐designed phase morphology, lower rheological and especially electrical percolation thresholds could be obtained in the ternary nanocomposites compared to the binary systems. POLYM. ENG. SCI., 59:447–456, 2019. © 2018 Society of Plastics Engineers     

The synergistic effects on enhancing thermal conductivity and mechanical strength of hBN/CF/PE composite

In this work, a simple and novel method was applied to prepare polymer composites by taking the advantage of melt flow shear force driving orientation of the fillers. By using this method, hexagonal boron nitride/polyethylene (hBN/PE) and hexagonal boron nitride/carbon fibers/polyethylene (hBN/CF/PE) composites were fabricated to be possessed of high thermal conductivity and mechanical properties. A high thermal conductivity of 3.11 W/mK was realized in the composite containing 35 wt% hBN and 5 wt% CF, which was over 1,200% higher than that of unfilled PE matrix. Under this component, the compressive strength and modulus of hBN/CF/PE composite were determined to be 30.1 and 870.9 MPa, respectively, which were far higher than that of unfilled PE accordingly. The bending performance was also somewhat enhanced. Meanwhile, the bulk resistivity of the composite material reached 2.55 × 10¹¹ Ω·cm, which was basically the same as that of pure PE. The novel composites with high thermal conductivity, excellent mechanical properties, and controllable electrical insulation could be a potential thermal management material for electrical and electronics industries.     

石墨烯/聚苯乙烯复合材料的研究进展及应用

石墨烯是一种新型碳纳米材料,具有独特的力学、热学、光学、电学等性质,将石墨烯与聚合物复合是近年来的研究热点。聚苯乙烯(PS)的可加工性较好、成型收缩率较小、价格低廉、应用广泛,但其硬而脆,耐热性、力学性能和导电性较差,将石墨烯与PS复合能有效改善其综合性能。介绍了石墨烯/聚苯乙烯复合材料的制备方法,分析比较了熔融共混、溶液共混、原位乳液聚合、静电自组装以及微球覆盖还原等5种方法的优缺点;详细阐述了石墨烯或其衍生物改性聚苯乙烯复合材料热性能、电性能及力学性能方面的最新研究进展;最后,分析了复合材料在阻燃、金属防腐、污染物处理、光子晶体等领域的应用现状。     

Structure,properties, and applications of polyacrylonitrile/carbon nanotube (CNT) fibers at low CNT loading

Bi-component, polyacrylonitrile (PAN)/carbon nanotube (CNT) fibers were processed, at different core-sheath area ratios, by gel spinning. A percolated CNT network at 10 wt% CNT in the sheath enhanced electrical conductivity as compared to the neat PAN fiber, while PAN polymer in the core contributed to the good mechanical properties. Fibers with relatively thin sheath allowed overall CNT loading as low as 3.7 wt% to be made with good electrical conductivity, and PAN stabilization by Joule heating was demonstrated. Such fibers with combined good mechanical properties and electrical conductivity can also potentially be used for electrical heating of fabrics, for making smart textiles, and for electromagnetic interference shielding.     

纤维增强CFP/PPS复合材料的制备与性能表征

以碳纤维(CF)和碳纤维粉末(CFP)为导电基体,制备出导电聚苯硫醚(PPS)复合材料.研究了复合材料的形貌、导电及力学性能.结果 表明,CFP能很好地分散在PPS复合材料内部,复合材料的表面电阻可达到103 Ω.同纯PPS复合材料相比,导电性能增加了四个数量级;一定范围内的CFP可以提高PPS复合材料的拉伸强度和冲击...     

Electrical conductivity of concrete containing silica fume

The influence of silica fume on concrete properties represents an important technical research. In general, silica fume tends to improve both mechanical characteristics and durability of concrete. Thus the electrical properties of concrete containing silica fume can be studied to clarify its physical performance during hydration. The electrical conductivity of neat cement, mortar and concrete pastes was measured during setting and hardening. The ordinary Portland cement was partially replaced by different amounts of silica fume by weight. The changes in the electrical conductivity were reported during setting and hardening after gauging with water. The results of this study showed that the electrical conductivity can be used as an indication for the setting characteristics as well as the structural changes of the hardened pastes made with and without silica fume.     

Studies on the preparation and properties of conductive polymers. Part II. Novel method to prepare metallized plastics from metal chelates of polyamides

New metallized films were obtained by the reduction of polyamide metal chelate films with reducing agents. Polyamide metal chelates films exhibited excellent surface resistivity around 10°–10¹ Ω/cm² when treated with sodium borohydride aqueous solutions. Aqueous solutions of polyamide–formic acid with metal salts, and films prepared from those solutions, were analyzed by UV-visible and IR spectroscopy, respectively, in order to investigate and identify the structure of the polyamide metal chelates. Factors that include kinds and concentrations of metal salts, kinds and concentrations of reducing agents, and reduction time, which may affect the conductivity of metallized films, were investigated. The surfaces of these films were treated with sodium borohydride aqueous solution to form a definite metallic luster appearance. The surfaces of these conductive films were proved to be metallized, by means of ESCA analysis. The strongly adhered metal on the films was believed to be responsible for the improvement in electrical conductivity. The mechanical properties and scanning electron microscope (SEM) observations were also studied.