scholarly journals Electrical Conductivity of PA6/Graphite and Graphite Nanoplatelets Composites using Two Processing Streams

2021 ◽  
Vol 5 (1) ◽  
pp. 19-31
Author(s):  
M. Umar ◽  
M. I. Ofem ◽  
A. S. Anwar ◽  
M. M. Usman
Keyword(s):  
Electrical Conductivity ◽  
Percolation Threshold ◽  
Carbon Composite ◽  
Graphite Nanoplatelets ◽  
Particulate Carbon ◽  
The Matrix ◽  
Sonication Technique ◽  
Carbon Fillers ◽  
Made In

The percolation threshold (PT) of any polymer/particulate carbon composite depends on the processing, the dispersed state of the filler, the matrix used and the morphology attained. Sonication technique was used to make PA6/G and PA6/GNP composites employing in situ polymerisation, after which their electrical conductivity behaviours were investigated. While overhead stirring and horn sonication were used to distribute and disperse the carbon fillers, the composites were made in 2 streams 40/10 and 20/20. The 40/10 stream implies that while dispersing the carbon fillers in PA6 monomer, 40% amplitude of sonication was applied for 10 minutes whereas the 20/20 stream implies 20% amplitude of sonication for 20 minutes. In both streams, the dispersing strain imparted on the monomer/carbon mixture was 400 in magnitude. Purely ohmic electrical conductivity behaviour was attained at 9.75 G wt. % for IG 40/10 system. For composites in the IG 20/20 system, same was attained at 10.00 G wt. %. Electrical conductivity sufficient for electrostatic discharge applications was achieved above 15 G wt. % in the IG 40/10 system. Using the power law percolation theory, percolation threshold was attained at 9.7 G wt. % loading in IG 40/10 system, while same was attained at 7.6 G wt. % loading in IG 20/20 system. For the GNP based systems, percolation threshold occurred at 5.2 GNP wt. % in the INP 40/10 system whereas same occurred at 7.4 GNP wt. % in the IG 20/20 system.

Semi-Electrical Conductivity of Gelcast Alumina Sintered under Nitrogen Atmosphere

2006 ◽  
Vol 11-12 ◽  
pp. 493-496 ◽  
Author(s):  
Ruben L. Menchavez ◽  
Koichiro Adachi ◽  
Masayoshi Fuji ◽  
Minoru Takahashi
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistance ◽  
Sintered Sample ◽  
Carbon Composite ◽  
Nitrogen Atmosphere ◽  
Potential Candidate ◽  
Nitrogen Gas ◽  
Conductive Property ◽  
Carbon Network

This work demonstrated an in-situ pyrolysis of gelcast alumina under reduction sintering to make alumina and carbon composite in providing semi-electrical conductivity. To increase the carbon content, the monomer was varied in the premix solution with reduction sintering in nitrogen gas. Two-probe method was used to measure electrical resistance of the sintered samples. The results revealed that the increase of monomer addition and sintering treatment were effective in reducing electrical resistance. The lowest value was 3.6×106-cm, which is a potential candidate for electrostatic shielding application. The reduction-sintered sample was re-sintered in an air in order to gain insight on the conductive path due to carbon network. Further tests such as XRD, TGA/DTA, and scanning electron microscopywere used to explain the semi-conductive property of the material.

scholarly journals Electrical, Thermal, and Morphological Properties of Poly(ethylene terephthalate)-Graphite Nanoplatelets Nanocomposites

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Basheer A. Alshammari ◽  
Arthur N. Wilkinson ◽  
Ghzzai Almutairi
Keyword(s):  
Electrical Conductivity ◽  
Percolation Threshold ◽  
Ethylene Terephthalate ◽  
Threshold Value ◽  
Morphological Properties ◽  
Degree Of Crystallinity ◽  
Graphite Nanoplatelets ◽  
Melt Compounding ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene

Graphite nanoplatelets (GNP) were incorporated with poly(ethylene terephthalate) (PET) matrix by melt-compounding technique using minilab compounder to produce PET-GNP nanocomposites, and then the extruded nanocomposites were compressed using compression molding to obtain films of 1 mm thickness. Percolation threshold value was determined using percolation theory. The electrical conductivity, morphology, and thermal behaviors of these nanocomposites were investigated at different contents of GNP, that is, below, around, and above its percolation threshold value. The results demonstrated that the addition of GNP at loading >5 wt.% made electrically conductive nanocomposites. An excellent electrical conductivity of ~1 S/m was obtained at 15 wt.% of GNP loading. The nanocomposites showed a typical insulator-conductor transition with a percolation threshold value of 5.7 wt.% of GNP. In addition, increasing screw speed enhanced the conductivity of the nanocomposites above its threshold value by ~2.5 orders of magnitude; this behavior is attributed to improved dispersion of these nanoparticles into the PET matrix. Microscopies results exhibited no indication of aggregations at 2 wt.% of GNP; however, some rolling up at 6 wt.% of GNP contents was observed, indicating that a conductive network has been formed, whereas more agglomeration and rolling up could be seen as the GNP content is increased in the PET matrix. These agglomerations reduced their aspect ratio and then reduced their reinforcement efficiency. NP loading (>2 wt.%) increased degree of crystallinity and improved thermal stability of matrix slightly, suggesting that 2 wt.% of GNP is more than enough to nucleate the matrix.

Highly electrically conducting poly(L-lactic acid)/graphite composites prepared via in situ expansion and subsequent reduction of graphite

2018 ◽  
Vol 38 (2) ◽  
pp. 167-177 ◽  
Author(s):  
Bai Xue ◽  
Lanxiang Ji ◽  
Jianguo Deng ◽  
Junhua Zhang
Keyword(s):  
Electrical Conductivity ◽  
Lactic Acid ◽  
Percolation Threshold ◽  
Reduction Process ◽  
Expanded Graphite ◽  
Xrd Analysis ◽  
Expandable Graphite ◽  
Subsequent Reduction ◽  
Electrically Conducting

AbstractIn this paper, highly electrically conductive polymeric composites were obtained by low-temperature expandable graphite (LTEG) filling poly(L-lactic acid) (PLLA) in the presence of ascorbic acid via anin situexfoliation and subsequent reduction process during the melt blending. The electrical conductivity of the PLLA/reduced and expanded graphite (R-EG) composites was determined by a four-point probe resistivity determiner and compared with that of the PLLA/expanded graphite (EG) composites. The percolation threshold of PLLA/R-EG blends decreased from 11.2 wt% to 7.1 wt%, which illustrated the superiority of R-EG to the electrically conducting ability of PLLA composites. At the graphite concentration near the percolation threshold, the electrical conductivity of PLLA/R-EG composites was much higher than that of PLLA/EG composites. The effectivein situexpansion and reduction of LTEG were crucial to the overall electrical conductivity of the blends, which was confirmed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. Dynamic rheology analysis confirmed that the connected networks that were the major cause of the rapid increase in electrical conductivity were much more easily formed for PLLA/R-EG blends than those of PLLA/EG blends. Thermogravimetric analysis (TGA) was applied to determine the decomposition and thermal stability of the PLLA/R-EG composites.

Electrical Conductivity Models of the Crust

1975 ◽  
Vol 12 (6) ◽  
pp. 962-970 ◽  
Author(s):  
Z. Dvořák
Keyword(s):  
Electrical Conductivity ◽  
Oceanic Crust ◽  
Type A ◽  
Pore Fluid ◽  
Response Curves ◽  
Conductivity Distribution ◽  
Archie’S Law ◽  
Made In ◽  
Conductivity Models

Compositional crustal models (continental, subcontinental, oceanic) are used as a basis for a construction of the electrical conductivity distribution within the crust. In addition, the procedure incorporates other parameters, such as pressure, porosity, pore fluid salinity, and resistivity. Calculation is made in three steps. First, 'dry' models based on mineral conduction alone are constructed. Second, electrolytic conduction through the pore fluids is estimated from the Archie's Law. Both results are then combined to produce the final, 'wet' models. These appear to agree with generalized conductivity profiles for the stable continental areas, as well as with the published values for the oceanic crust. Magnetotelluric response curves calculated for the final models give, for each crustal type, a band of possible responses which agree well with theoretical and in situ results.

Influences of carbon fillers on electrical conductivity and crystallinity of polyethylene terephthalate

2011 ◽  
Vol 46 (9) ◽  
pp. 1091-1099 ◽  
Author(s):  
Fei Xin ◽  
Lin Li ◽  
Siew Hwa Chan ◽  
Jianhong Zhao
Keyword(s):  
Electrical Conductivity ◽  
Polyethylene Terephthalate ◽  
Scanning Calorimetry ◽  
Conductive Composites ◽  
Melt Compounding ◽  
The Matrix ◽  
Dispersion State ◽  
Forms Of Carbon ◽  
Carbon Fillers ◽  
Melt Annealing

Three forms of carbon, i.e., carbon nanotubes (CNT), conductive carbon black (CCB), and graphite (G), were added to polyethylene terephthalate (PET) to prepare several types of composites, namely, CNT/PET, CCB/PET, G/PET, CNT/CCB/PET, and CNT/G/PET composites, using melt compounding, followed by injection molding. These composites were characterized using field emission scanning electron microscopy, differential scanning calorimetry, and electrical conductivity measurements. It was found that the addition of these conductive fillers could result in the electrically conductive composites directly but the conductivities were dependent on many factors including filler type, content, dispersion state in the matrix, complementary effect of two fillers (i.e., dual fillers), and post melt annealing. Among those carbon/PET composites studied, the highest conductivity that could be reached was 1.2 S/cm, which was 17 orders of magnitude higher than that of the matrix PET. The melt annealing process was found to remarkably enhance the electrical conductivity of carbon/PET composites. CNT, CCB, and G, all could act as nucleating agents but the crystallinity of PET decreased with increasing the filler content in the composites. All types of fillers caused shifting of the crystallization temperature to higher temperatures. The mechanisms for the effects of carbon fillers on electrical conductivity and cystallinity of PET have been proposed and discussed.

scholarly journals Electrophysical Properties of Epoxy Composite Materials Filled with Carbon Black Nanopowder

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Andriy Buketov ◽  
Serhii Smetankin ◽  
Eduard Lysenkov ◽  
Kyrylo Yurenin ◽  
Oleksandr Akimov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Carbon Black ◽  
Percolation Threshold ◽  
Structural Features ◽  
Electrically Conductive ◽  
Percolation Behavior ◽  
The Matrix ◽  
Electrical And Dielectric Properties ◽  
Nanofiller Content

The effect of carbon black (CB) nanopowder on the electrical properties of polymer composite systems based on the epoxy resin is investigated using the method of impedance spectroscopy. It is established that the electrical and dielectric properties of the studied systems significantly depend on the nanofiller content. It is found that electrical conductivity and dielectric constant exhibit percolation behavior when the filler’s content increases. In this case, the electrical conductivity increases exponentially, indicating the formation of filler electrically conductive mesh inside the polymer matrix. A small jump in electrical conductivity when reaching the percolation threshold indicates the formation of indirect contacts between the particles. The value of the percolation threshold of conductivity is 8%. It is shown that the dielectric constant of epoxy nanosystems is almost unchanged in the frequency range of 102–105 Hz. It is related to the structural features of the filler particles, which ensure the existence of a minimal dielectric gradient between the matrix and the filler. It is found that the dielectric constant of the studied systems also shows percolation behavior. The obtained material based on the epoxy matrix is characterized by a high value of dielectric constant, which at a carbon black nanopowder content of 29% is 4680. This material is characterized by relative frequency invariance and a high value of dielectric constant, so it has great potential for practical application.

Electrical conductivity and rheological properties of carbon black based conductive polymer composites prior to and after annealing

2021 ◽  
pp. 096739112110012
Author(s):  
Qingsen Gao ◽  
Jingguang Liu ◽  
Xianhu Liu
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Percolation Threshold ◽  
Rheological Properties ◽  
Network Formation ◽  
Loss Modulus ◽  
Conductive Polymer ◽  
Complex Viscosity ◽  
Electrical Percolation ◽  
Electrical Percolation Threshold

The effect of annealing on the electrical and rheological properties of polymer (poly (methyl methacrylate) (PMMA) and polystyrene (PS)) composites filled with carbon black (CB) was investigated. For a composite with CB content near the electrical percolation threshold, the formation of conductive pathways during annealing has a significant impact on electrical conductivity, complex viscosity, storage modulus and loss modulus. For the annealed samples, a reduction in the electrical and rheological percolation threshold was observed. Moreover, a simple model is proposed to explain these behaviors. This finding emphasizes the differences in network formation with respect to electrical or rheological properties as both properties belong to different physical origins.

scholarly journals Supramolecular ionic polymer/carbon nanotube composite hydrogels with enhanced electromechanical performance

2020 ◽  
Vol 9 (1) ◽  
pp. 478-488 ◽  
Author(s):  
Yun-Fei Zhang ◽  
Fei-Peng Du ◽  
Ling Chen ◽  
Ka-Wai Yeung ◽  
Yuqing Dong ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Ion Mobility ◽  
Artificial Muscles ◽  
Ionic Polymer ◽  
Composite Hydrogels ◽  
The Matrix ◽  
Electromechanical Performance ◽  
Carbon Nanotube Composite ◽  
Robotic Devices

AbstractElectroactive hydrogels have received increasing attention due to the possibility of being used in biomimetics, such as for soft robotics and artificial muscles. However, the applications are hindered by the poor mechanical properties and slow response time. To address these issues, in this study, supramolecular ionic polymer–carbon nanotube (SIPC) composite hydrogels were fabricated via in situ free radical polymerization. The polymer matrix consisted of carbon nanotubes (CNTs), styrene sulfonic sodium (SSNa), β-cyclodextrin (β-CD)-grafted acrylamide, and ferrocene (Fc)-grafted acrylamide, with the incorporation of SSNa serving as the ionic source. On applying an external voltage, the ions accumulate on one side of the matrix, leading to localized swelling and bending of the structure. Therefore, a controllable and reversible actuation can be achieved by changing the applied voltage. The tensile strength of the SIPC was improved by over 300%, from 12 to 49 kPa, due to the reinforcement effect of the CNTs and the supramolecular host–guest interactions between the β-CD and Fc moieties. The inclusion of CNTs not only improved the tensile properties but also enhanced the ion mobility, which lead to a faster electromechanical response. The presented electro-responsive composite hydrogel shows a high potential for the development of robotic devices and soft smart components for sensing and actuating applications.

In situ localization of lectin-binding glycoconjugates in the matrix of growth-plate cartilage

1986 ◽  
Vol 176 (1) ◽  
pp. 65-82 ◽  
Author(s):  
Cornelia E. Farnum ◽  
Norman J. Wilsman
Keyword(s):  
Growth Plate ◽  
Lectin Binding ◽  
Growth Plate Cartilage ◽  
The Matrix
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