Papers by Keyword: Conductive

Abstract: Conductive polymers are a class of engineering materials which possess remarkably reversible redox property and atypical combination of characteristics of plastics and metals. The potential usefulness of conductive polymers has grown exceedingly in the technological field such as telecommunication, electronics, storage systems and protective devices. The prospective of conductive polymers has further deepened the interest of researchers for their applications in several areas. Some of the popular types of conductive polymers are polythiophene, polyindole, polyacetylene, polypyrrole, polyphenyl vinylene, polyaniline, Poly (3,4ethylenedioxythiophene), which are produced via redox and chemical (CM) or electrochemical (ECM) oxidation processes. Polymers are doped to introduce charge carriers known as polarons and bipolarons into them, to make them conductive. Conductive polymers have limitations such as a poor mechanical characteristic or poor flexibility, low process-ability and poor biocompatibility, which have made researchers investigate different chemical modification methods. Conductive polymers have potential applications in the field of supercapacitors, solar cells, biosensors, chemical sensors and actuators, tissue engineering, e.t.c. This article has attempted to provide an up to date review on different aspects of conductive polymers such as production, doping, applications and conductivity of selected conductive polymers.

Abstract: The focus of this study was to test a low-cost level plastic printer in the multi-material printing application using principles of design for additive manufacturing (DFAM). Two sample structures were designed in the project. One of the main planning principles of the examples was to integrate multiple functions into one part and intelligently utilize a variety of materials and reduce parts count. The most common material used in the experiments was the basic PLA, which is widely used, easy-to-print and economical alternative. As special materials, electrically conductive PLA-based graphene filament and highly flexible polyurethane-based filament was used. The results show that multi-material printing is also possible with lower cost devices and it makes it easier for smart products to be manufactured cost-effectively. It has also been found that multi-material printing can be technically challenging and that further research and experiments in this subject are needed. In the future, the research topic will be even more interesting as equipment and materials will develop. This paper presents detailed printing parameters for all the materials used in the printing tests.

Abstract: The conductive thin film was made based on bio-based epoxy and graphite compounded with its cross-linker (Methylene Diphenyl Diisocyanate, MDI) and further blended with disparate percentages of pretreated graphite. The preparation of this solution started by drop casting as thin films, where the thickness of thin film was set approximately ~0.1 mm. Optical microscope, Fourier transform infra-red spectroscopy (FTIR) and Ultraviolet-visible (UV-vis) spectrophotometer has been operated to diagnose Graphite/ biopolymer composites in order to have better and accurate results of this work. The current-voltage (I-V) characteristics of the composite thin film samples were measured at room temperature. This study shows the electrical conductivity was discovered and calculated by achieving conductivity of 10³ S/m as a prove that this thin film has the ability to conduct electricity.

Abstract: The conductive and fiction properties of overbased calcium sulfonate complex grease and lithium grease containing carbon black (CB) additive were investigated in detail. The results indicate that CB can dramatically improve the conductivities of the greases. Also the tribol-test results indicate that the CB can dramatically improve the tribological properties of the greases. The lithium greases containing CB, have better tribological properties than overbased calcium sulfonate complex greases. Among the lithium greases, 5% CB contained grease performs the best friction reduction properties, and among the overbased calcium sulfonate complex greases, 6% CB contained grease performs the best friction reduction properties.

Abstract: Recently polymer nanocomposites are used more and more frequently in industry due to the fact that the properties of the polymers can be altered to the specific requirements by the addition of particles and fibers of different properties, shapes. Polymers are poor thermal and electrical conductors, conductive fillers such as metallic powders, carbon black, graphite, are usually incorporated into polymer matrix to produce conducting composites. In this study composites were prepared using ethylenevinyl acetate (EVA) copolymer as matrix filled with two kinds of reinforcement graphite materials: untreated natural graphite (UG) and expanded graphite (EG). Composite samples up to 29.3 % graphite particle volumetric concentrations (50 % mass concentration) were prepared by the melt mixing process in a Brabender Plasticorder. Upon mixing, the EG particles originally 5μm to 6μm in size, exfoliates in the form of nanosheets having a few nanometer thickness; they have very big surface areas with high aspect ratio ranging between 20 and 250, as evidenced by TEM micrographs. From the experimental results it was deduced that the electrical conductivity was not only a function of filler concentration, but also strongly dependent on the graphite structure. The percolation concentration of the filler was found to be (15 to 17) vol% for micro-sized natural graphite, whereas the percolation concentration of the filler in nanocomposites filled with expanded graphite was much lower, about (5 to 6) vol%. The electrical conductivity of nanocomposites was also much higher than the electrical conductivity of composites filled with micro-sized filler at similar concentrations. Similarly, the values of the thermal diffusivity for the nanocomposites, EG-filled EVA, were significantly higher than the thermal diffusivity of the composites filled with micro-sized filler, UG-filled EVA, at similar concentrations. The effect of thermal cycling on the tensile behavior of EVA composites containing 4% and 15% of UG by mass and 6% and 15% of EG by mass were subjected to thermal cycling between-25 to +60 °C. Tension tests were conducted after thermal cycling for 50 and 100 cycles. Tensile strength remained practically unchanged after thermal cycling, while the Young modulus increased appreciably with the number of thermal cycle.

Abstract: By an oxidation-reduction reaction the polyester film would be coated with a layer of tin. The conductivity of polyester film was discussed under different plating time, temperature, and PH. The results showed that when the plating time was 60 minutes, the temperature was 90°C and the PH was 4, the polyester film attained the optimal conductivity. The polyester film could be protected and the combination of magnetic and electrical conduction would be achieved by coating with a layer of magnetic powder after plating.

Abstract: A new type of biomimetic films of bilayer lipid membrane (BLM) supported by conductive hybrid film of Au nanoparticles (Au NPs) and cellulose is developed. The facile preparation method of the conductive hybrid films and the relevant micro conducting mechanism under electrochemical redox environment are revealed. The regenerated cellulose film is prepared from the cellulose/N-methylmorpholine N-oxide monohydrate solution. After the cellulose film is regenerated by deionized water, Au NPs in the colloid react with the newborn cellulose film. Rectangular pieces of dry hybrid films with one ends clamped with copper foil are used as electrodes. The lipid solution of phospholipid and cholesterol with a ratio of 3:1 is brushed onto the surface of dry hybrid films. There are only reducing currents in the cyclic voltammetry responses of biomimetic films under the aqueous electrolyte solution of 0.1 mol/L KCl, 1 mmol/L K₃[Fe (CN)₆] and 1 mmol/L K₄[Fe (CN)₆]. It means that the anions of [Fe (CN)₆]^4- are almost impossible to be oxidized into [Fe (CN)₆]^3- by the positively charged surfaces of Au NPs under voltages below 0.3 V.

Abstract: Intact Fe₃O₄/polyaniline (PANI) composite hollow microspheres were prepared by using hollow glass microspheres (HGS) as substrate. Fe₃O₄ nanoparticles were synthesized by adding surfactant of sodium dodecyl-benzenesulfonate (SDBS). HGS was pretreated by silane coupling agent, and consequently adsorbed magnetic iron oxide. A successive coating of polyaniline layer on HGS/Fe₃O₄ was involved through polymerization of aniline with HCl as dopant, and finally the multifunctional composite hollow microspheres (HGS/Fe₃O₄/PANI) were obtained.The morphology analysis by SEM revealed that the composite microspheres were formed by a layer of dense Fe₃O₄ nanoparticles and a layer of PANI on HGS. It was found that the conductivity of the prepared HGS/Fe₃O₄/PANI was about 10^-3 S/cm, and the magnetization was of 5.60 emu/g, indicating the composite microspheres were multifunctional with conductive and magnetic properties.

Abstract: A series of waterborne cationic polyurethanes dispersions (CWPU) was prepared through prepolymerization method by reacting polyethylene glycol (PEG1000) and isophorone diisocyanate (IPDI) with N-methyl diethanol amine (MDEA) as chain extender. Then FeCl3 was employed as oxidant, therefore CWPU/polypyrrole (CWPU/PPy) conductive composite was prepared by in situ chemical oxidative polymerization of pyrrole (Py) in CWPU dispersions. Effects of molar ratio of FeCl3 to Py, Py concentration on the resistivity of the CWPU/PPy composite films were investigated. The structure, morphology and thermal stability were also characterized by Fourier infrared spectra (FT-IR), light scattering, TEM, and TGA. FT-IR demonstrated the presence of hydrogen-bonding interactions between CWPU and PPy. The average particle size of CWPU/PPy increased from 10.61nm to 30.29nm compared with pure PU, and corresponding size distribution decreased from 0.850 to 0.346. It was also found that CWPU/PPy displayed as spherical morphology, and no aggregation among particles was detected among particles. TGA certified CWPU/PPy was endowed with better thermal stability. In addition, conductivity stability of composites films was also studied. It was found that composite films not only displayed low resistivity but also improved conductivity stability.

Abstract: A novel polyfluorene derivative, poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7- fluorene)-alt-2,7-(9,9- p-divinylbenzene)] (P-1) was synthesized by the palladium-catalyzed Suzuki coupling reaction and it’s quaternized ammonium polyelectrolyte derivatives was obtained through a postpolymerization treatment on the terminal amino groups. The electrochemical and optical properties of the resulting copolymers was fully investigated. The results showed that the new polyfluorene derivative had potential useful in used as materials for electronic conductivity, chemical and biological sensors that derive from its highly conductive and strong fluorescence.