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Start Over Topic electrical resistivity
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1. Leveraging compressive stresses to attenuate the electrical resistivity of buckypaper.

Author

Kumar, Vijay, Haspel, Henrik, Nagy, Krisztina, Rawal, Amit, and Kukovecz, Akos

Subjects
*MULTIWALLED carbon nanotubes, *STRAINS & stresses (Mechanics), *ELECTRICAL resistivity, *PAPER, *ELECTRODES, *VAN der Waals forces
Abstract

Buckypaper (BP) is a planar film that consists of random network of multiwall carbon nanotubes (MWCNTs) held together by weak van der Waals interactions at tube-tube junctions. Although individual carbon nanotubes (CNTs) possess remarkable electrical properties, the electrical resistance of pristine BP is usually too high for practical applications. However, the electrical resistivity of BP can be attenuated by applying modest compressive stresses. Herein, we report an analytical model for predicting the electrical resistivity of BP under defined level of compressive strain. The predictive piezoresistive model of BP was developed by formulating a direct relationship with the structural parameters, physical and electrical properties of CNTs. The basis of the piezoresistive model relied upon the geometrical probability approach in combination with classical Hertzian contact mechanics and constriction resistance techniques. A comparison has been made between the theoretical and experimental results of electrical resistivity of BPs with varying densities. A reasonably good quantitative agreement was obtained between the theory and experiments. The main source of error was caused by the uncertainty in the measurement of the initial BP thickness. Through theoretical modeling, the initial volume fraction of CNTs was found to be one of the key parameters that modulated the piezoresistive behavior of BP. [ABSTRACT FROM AUTHOR]

Published
2016
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2. Differences in structure and property of carbon paper and carbon cloth diffusion media and their impact on proton exchange membrane fuel cell flow field design

Author

Prathap Haridoss and V. M. Radhakrishnan

Subjects
Pressure drop, business.product_category, Materials science, business.industry, Electrical engineering, Proton exchange membrane fuel cell, A-carbon, B. Fabric, Carbon cloths, Carbon paper, Channel widths, E. Electrical, E. Mechanical, Electrical property, Electrical resistivity, Electrical resistivity measurements, Flow channels, Flow-field design, Fuel cell electrodes, Gas diffusion media, Lower stress, PEM fuel cell, Potential drop, Proton exchange membranes, Reactant gas, Structure and properties, Diffusion in gases, Electric conductivity, Flow fields, Mathematical models, Paper, Proton exchange membrane fuel cells (PEMFC), Protons, Structural design, Carbon Papers, Diffusion, Fuel Cells, Mathematical Models, Pressure Gradient, Resistivity, Structural Design, Electrical resistivity and conductivity, Electrode, Compressibility, Gaseous diffusion, Composite material, business, Voltage drop
Abstract

Gas diffusion media (GDM) and flow fields perform the task of distributing the reactant gases uniformly over the active electrochemical area in proton exchange membrane (PEM) fuel cells. Carbon paper and carbon cloth are two commonly employed gas diffusion media in PEM fuel cells, and they differ widely in their structure and properties. Since the path of the reactant gases to the catalyst in the fuel cell electrodes involves passing through the flow fields as well as the GDM, a good design for a fuel cell requires an understanding of the interaction between these components. The focus of the present work is to study the impact of the difference in structure and properties of the diffusion media used, on the design of the PEM fuel cell flow field. Carbon paper and carbon cloth were characterized for the pressure drop they cause when used as GDMs, for channel intrusion, compressibility and electrical resistivity. Carbon cloth exhibits about 43-125% more intrusion into the channel in comparison with carbon paper for the conditions tested. This intrusion results in increased pressure drop in the flow channel especially at higher channel widths and at higher compression. Compression studies reveal that carbon cloth lacks compression rigidity and suffers considerable strain at lower stress values whereas carbon paper is relatively rigid in nature. The results indicate that the intrusion of carbon cloth into the channel, constraints the channel width in a flow field design if it were to be used with a carbon cloth GDM as opposed to a carbon paper GDM. Electrical resistivity measurements were carried out and a simple mathematical model has been developed for the potential drop in the GDM. The model indicates that even from the perspective of electrical properties, use of carbon cloth GDM constraints the channel width that is permissible in flow field design. � 2010 Elsevier Ltd.

Published
2011
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3. Sintering condition effect on the characteristics of ink-jet printed silver pattern on flexible cellulose paper

Author

Mun, Seongcheol, Yun, Sungryul, Jung, Hyejun, and Kim, Jaehwan

Subjects
*SINTERING, *INK-jet printers, *CELLULOSE, *SILVER nanoparticles, *PAPER, *TEMPERATURE effect, *ATOMIC force microscopes, *ELECTRIC conductivity, *SCANNING electron microscopy, *ELECTRIC resistance
Abstract

Abstract: This paper reports sintering condition effect on an ink-jet printed conductive pattern of silver ink made on a cellulose paper. To fabricate the conductive pattern on the cellulose paper, silver ink is ink-jet printed and the influence of sintering temperature and time is investigated in terms of electrical resistivity and morphology by using scanning electron microscope and atomic force microscope. Two-level baking process composed of soft baking and hard baking is found to be effective for silver nanoparticle network. The sintering temperature and time are strongly associated with the conductivity of the ink-jet printed pattern. [Copyright &y& Elsevier]

Published
2012
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