Richard D. Sudduth
Abstract
Two full concentration range percolation threshold models were evaluated for three different carbon fillers in both Nylon 6,6 and Lexan. A new Modified Landauer Model was introduced in this study and compared with a Percolation Threshold Model recently published by this author. These models were ...
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Two full concentration range percolation threshold models were evaluated for three different carbon fillers in both Nylon 6,6 and Lexan. A new Modified Landauer Model was introduced in this study and compared with a Percolation Threshold Model recently published by this author. These models were then utilized to address how to best characterize the interfacial surface energy, gpf, for composite electrical conduction measurements using Clingerman’s data. Three different models used for calculating the interfacial surface energies, gpf, were evaluated in this study. It was found that solid measurements used in calculating the Fowkes equation for the interfacial surface energy gave the most consistent correlations. A linear correlation was found between the Fowkes Interfacial surface energy and the b constant designated as the insulation surface interaction magnitude from the new Percolation Threshold Model. In addition, three concurrent mathematical conditions were found to occur at the same concentration for both the new percolation threshold models yielding S-shaped curves in this study. These conditions include the concentration at the Inflection Point, the concentration at the maximum slope and the maximum extrapolated percolation threshold concentration calculated at the same concentration.
Shinichi Watanabe; Misako Fujii; Makoto Okano
Abstract
We report on the optical responses of black rubber samples in the terahertz regime as a function of the carbon black (CB) concentration. We prepared samples with different CB concentrations and investigated their absorbance, birefringence, and the angle of the slow optic axis in the terahertz frequency ...
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We report on the optical responses of black rubber samples in the terahertz regime as a function of the carbon black (CB) concentration. We prepared samples with different CB concentrations and investigated their absorbance, birefringence, and the angle of the slow optic axis in the terahertz frequency range. A monotonic increase of the terahertz absorbance is observed with increasing CB concentration, which indicates that the density of the CB aggregates inside the black rubber plays a crucial role for controlling the absorbance. In addition, a systematic increase of the birefringence is observed with increasing draw ratio, while the spatial fluctuation of the angle of the slow optic axis systematically decreases. This simultaneous behavior indicates that the mechanical stretching of the black rubber sample induces an alignment of the CB aggregates along the stretching direction. These results provide the fundamentals to understand the correlation between the terahertz response and the condition of the CB aggregates inside the samples. The thorough understanding of this correlation is important for future applications.
Carmen G. Renda; Jeferson A. Dias; Roberto Bertholdo; Alessandra A. Lucas
Abstract
The phenolic resin (PR) is widely studied as matrix for composites due to its promising mechanical properties and chemical stability. However, which regard to electrical conduction, PR is a typical insulator (electrical conductivity around 10 -12 S.cm -1 ), limiting its utilization for electric ...
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The phenolic resin (PR) is widely studied as matrix for composites due to its promising mechanical properties and chemical stability. However, which regard to electrical conduction, PR is a typical insulator (electrical conductivity around 10 -12 S.cm -1 ), limiting its utilization for electric conduction’ applications. Expanded graphite (EG) and conductive carbon black (CB) are fillers that have been utilized to increase the electrical conductivity of several polymers, but they have not yet been enough studied to composites materials with PR. Thus, this study aims at asses to produce composites of PR and EG or CB (2% w / w) and verify the influence these fillers on the composites’ electrical properties. The composites were analyzed by FT-IR (Fourier Transform-Infrared Spectroscopy), Impedance Spectroscopy (IS) and Scanning Electron Microscopy (SEM). It was verified that the electric conductivity of the PRs increased due to fillers. The composite PR/CB showed electric conductivity about five orders of magnitude higher than the PR. On the other hand, the composite PR/EG showed greatest electrical conductivity, about seven orders of magnitude higher than the PR (1.1x10 -5 S.cm -1 ). These results have shown the efficacy of those fillers in the increase of the electrical conduction in PR-based composites. Therefore, these composites materials have potential to be used as Electromagnetic Interference (EMI) shielding and electrostatic discharge (ESD).
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