Ice-Prevention and De-Icing Capacity of Epoxy Resin Filled with Hybrid Carbon-Nanostructured Forms: Self-Heating by Joule Effect

In this study, CNTs and graphite have been incorporated to provide electrical conductivity and self-heating capacity by Joule effect to an epoxy matrix. Additionally, both types of fillers, with different morphology, surface area and aspect ratio, were simultaneously incorporated (hybrid CNTs and graphite addition) into the same epoxy matrix to evaluate the effect of the self-heating capacity of carbon materials-based resins on de-icing and ice-prevention capacity. The self-heating capacity by Joule effect and the thermal conductivity of the differently filled epoxy resin were evaluated for heating applications at room temperature and at low temperatures for de-icing and ice-prevention applications. The results show that the higher aspect ratio of the CNTs determined the higher electrical conductivity of the epoxy resin compared to that of the epoxy resin filled with graphite, but the 2D morphology of graphite produced the higher thermal conductivity of the filled epoxy resin. The presence of graphite enhanced the thermal stability of the filled epoxy resin, helping avoid its deformation produced by the softening of the epoxy resin (the higher the thermal conductivity, the higher the heat dissipation), but did not contribute to the self-heating by Joule effect. On the other hand, the feasibility of electrically conductive epoxy resins for de-icing and ice-prevention applications by Joule effect was demonstrated.

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A Simple Model for the Effective Thermal Conductivity of a Particulate Mixture

Applied Mechanics and Biomedical Technology ◽

10.1115/imece2002-32493 ◽

2002 ◽

Cited By ~ 1

Author(s):

Mehrdad Massoudi ◽

Tran X. Phuoc

Keyword(s):

Thermal Conductivity ◽

Effective Thermal Conductivity ◽

Heat Dissipation ◽

Accurate Estimate ◽

The Self ◽

Control Measures ◽

Heating Process ◽

Self Heating ◽

History Of ◽

Phenomenological Coefficients

When a coal stockpile is stored in the presence of air, slow oxidation of the carbonaceous materials occurs and heat is released. If the rate of heat generation within the stockpile is greater than the rate of heat dissipation and transportation to the external environment, the self-heating of the coal stockpile ensues. The self-heating of coal stockpiles has a long history of posing significant problems to coal producers because it lowers the quality of coal and may result in hazardous thermal runaway. Precise prediction of the self-heating process is, therefore, necessary in order to identify and evaluate control measures and strategies for safe coal mining, storage and transportation. Such a prediction requires an accurate estimate of the various processes associated with the self-heating which are impossible unless the appropriate phenomenological coefficients are known. This note is to present a simple approach to determine the effective thermal conductivity of a granular porous medium such as a coal stockpile.

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Exceptionally high thermal and electrical conductivity of three-dimensional graphene-foam-based polymer composites

RSC Advances ◽

10.1039/c5ra27223h ◽

2016 ◽

Vol 6 (27) ◽

pp. 22364-22369 ◽

Cited By ~ 64

Author(s):

Zhiduo Liu ◽

Dianyu Shen ◽

Jinhong Yu ◽

Wen Dai ◽

Chaoyang Li ◽

...

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Polymer Composites ◽

Epoxy Matrix ◽

Three Dimensional ◽

Neat Epoxy ◽

Graphene Foam

Three dimensional graphene foam incorporated into epoxy matrix greatly enhance its thermal conductivity (up to 1.52 W mK−1) at low graphene foam loading (5.0 wt%), over an eight-fold enhancement in comparison with that of neat epoxy.

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Characterizing the Stability of Carbon Nanotube Enhanced Water as a Heat Transfer Nanofluid

ASME 2010 Pressure Vessels and Piping Conference: Volume 9 ◽

10.1115/pvp2010-25709 ◽

2010 ◽

Author(s):

Brian K. Ryglowski ◽

Randall D. Pollak ◽

Young W. Kwon

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Electrical Conductivity ◽

Phase Change ◽

Heat Dissipation ◽

Coolant Fluid ◽

Conductivity Enhancement ◽

Design Variables ◽

The Stability ◽

The Many

Heat dissipation is a major challenge for many technologies. Possible solutions include thermal energy transfer via coolant fluid to a phase change material (PCM), with higher thermal conductivity a design goal. In recent years, heat transfer nanofluids (fluids with suspended nanoparticles) have received attention based on their potential for improving thermal conductivity. Carbon nanotubes (CNTs) are an attractive additive due to their enhanced thermal conductivity and ability to remain suspended over long times. However, characterizing their potential is difficult due to the many design variables and the need for repeated thermal conductivity tests for comparison. Since thermal conductivity enhancement is dependent on a dispersed nanotube network, the electrical conductivity of CNTs can be exploited to monitor the stability of such nanofluids, as such testing is quick and simple. The aim of this research was to evaluate electrical conductivity testing as a means to monitor stability of CNT-enhanced distilled water as a PCM, with varying CNT size, type, and concentration; and various other processing variables. The prepared nanofluids were tested after repeated phase change cycles. Results indicate that electrical conductivity testing is a practical means of monitoring the nanofluid stability, and CNT-based nanofluids show both promise and limitations as a PCM.

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Numerical studies on the heat dissipation process in elastomers under rotating loading direction

Journal of Rubber Research ◽

10.1007/s42464-021-00136-1 ◽

2021 ◽

Author(s):

M. Abdelmoniem ◽

B. Yagimli

Keyword(s):

Heat Dissipation ◽

Viscoelastic Model ◽

Material Model ◽

Fatigue Tests ◽

Shear Loading ◽

The Self ◽

Self Heating ◽

Applied Loading ◽

User Subroutine ◽

Numerical Studies

AbstractElastomeric components such as car bearings and vibration dampers are subjected to dynamic loads with various amplitudes and loading directions during operation. To better understand the lifetime expectancy of these components it is required to implement a material model that sufficiently accounts for the material thermo-mechanical behaviour. This paper implements a finite viscoelastic model which includes heat dissipation and addresses the effect of inelasticity on the self-heating and the applied loading conditions. The material model is implemented in a user subroutine and finite element calculations are carried out on a simple shear loading with rotating directions. The self-heating effect and the resulting variation of the dissipation induced forces are shown and discussed. With the aid of the presented material model, thermo-mechanically coupled simulations can be performed. Based on the results, the required loading limits and boundary conditions for the mechanical fatigue tests can be defined to minimise the thermal fatigue effects.

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Characterization of Thermo-Electric Interface Material with Carbon Nanotubes

MRS Proceedings ◽

10.1557/proc-1056-hh12-06-ff13-06-gg15-06 ◽

2007 ◽

Vol 1056 ◽

Author(s):

Piyush R Thakre ◽

Yordanos Bisrat ◽

Dimitris C Lagoudas

Keyword(s):

Thermal Conductivity ◽

Carbon Nanotubes ◽

Electrical Conductivity ◽

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Epoxy Matrix ◽

Loss Modulus ◽

Single Wall Carbon Nanotubes ◽

Electrical Percolation

ABSTRACTAn approach has been presented in the current work to fabricate and characterize nanocomposite systems for optimizing electrical and thermal properties without sacrificing mechanical properties. An epoxy matrix based nanocomposite system has been processed with different volume fractions of carbon nanotubes. The purpose was to tailor macroscale properties to meet competing performance requirements in microelectronics industy. The nanofiller consisted of comparatively low cost XD grade carbon nanotubes (XD-CNTs) that are optimized for electrical properties. This system was compared with another system consisting of single wall carbon nanotubes (SW-CNTs) as nano-reinforcements in epoxy matrix. The electrical percolation threshold (about seven orders of magnitude increase in electrical conductivity) measured by dielectric spectroscopy was found to be at lower loading weight fraction of SWCNTs (0.015 weight %) as compared to XD-CNTs (0.0225 weight %). However, the electrical conductivity after percolation was higher for XD-CNTs reinforced epoxy with respect to SW-CNTs filled nanocomposites. The governing mechanisms for this phenomenon were investigated using transmission optical microscope. The enhancement in thermal conductivity, measured using differential scanning calorimetry, was found to be moderate at lower weight loadings corresponding to electrical percolation. However, a 90% improvement in thermal conductivity was observed for 0.3 weight percent of XD-CNTs. Dynamic mechanical analysis was performed to measure the storage and loss modulus along with the glass transition temperature. No significant change in modulus values and glass transition temperature was measured for nanocomposites varied filler contents with respect to neat matrix.

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Improvement in Self-Heating Characteristic by Utilizing Sapphire Substrate in Omega-Gate-Shaped Nanowire Field Effect Transistor for Wearable, Military, and Aerospace Application

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19149 ◽

2021 ◽

Vol 21 (5) ◽

pp. 3092-3098

Author(s):

Young Suh Song ◽

Hyunwoo Kim ◽

Junsu Yu ◽

Jongho Lee

Keyword(s):

Computer Aided Design ◽

Field Effect ◽

Field Effect Transistor ◽

Heat Dissipation ◽

Silicon On Insulator ◽

The Self ◽

Self Heating ◽

Aerospace Applications ◽

Radiation Resistant ◽

Effect Transistor

In this study, we propose an omega-shaped-gate nanowire field effect transistor (ONWFET) with a silicon-on-sapphire (SOS) substrate. In order to investigate improvements in the self-heating characteristic with the use of a SOS substrate, the lattice temperature is examined using a Synopsys Sentaurus 3D Technology computer-aided design (TCAD) simulator with the results compared to those with a silicon-on-insulator (SOI) substrate. To validate the proposed structure with the SOS substrate, the locations of hot spots and heat dissipation paths (heat sinks) depending on the substrate materials are also analyzed. The electrical characteristics, specifically the on-current (Ion), off-current (Ioff), and subthreshold swing (SS), were investigated as well. Hence, it is demonstrated here that incorporating a SOS substrate can improve both the self-heating characteristic and the SS at the same time. Therefore, enhanced logic devices are feasible if using an ONWFET with a SOS substrate. Examples include wearable devices and military and future aerospace applications achieved by the radiation-resistant material Al2O3 that has high thermal conductivity.

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Dielectric Properties of Epoxy-Matrix Composites with Tungsten Disulfide Nanotubes

Journal of Nanomaterials ◽

10.1155/2019/5761439 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8

Author(s):

Povilas Bertasius ◽

Mark Shneider ◽

Jan Macutkevic ◽

Vytautas Samulionis ◽

Juras Banys ◽

...

Keyword(s):

Electrical Conductivity ◽

Epoxy Resin ◽

Polymer Matrix ◽

Epoxy Matrix ◽

Electrical Contacts ◽

Tungsten Disulfide ◽

Electromagnetic Properties ◽

Matrix Composites ◽

Pure Epoxy ◽

Electrical Percolation

Addition of conductive nanotubes to an insulating polymer matrix has been proven as an efficient strategy that can improve the electromagnetic shielding performance, due to the high aspect ratio of nanotubes. Herein, a set of epoxy-matrix composites filled with 0.15-1.6 vol% of tungsten disulfide (WS2) nanotubes being of 30-120 nm in diameter and 5-20 μm in length has been produced. Electromagnetic properties of the prepared composites were probed in the frequency range from 20 Hz to 1 MHz in a temperature range from 250 K to 500 K. Broadband properties of these materials are controlled by the dynamics of epoxy resin molecules, and no electrical percolation was observed up to the highest concentration (1.6 vol%) of WS2 nanotubes. The value of dielectric permittivity for all composites is not bigger than 6 at room temperature and 1 kHz frequency, and the electrical conductivity of composites is about 10-6 S/m at 500 K, which demonstrate that the composites are suitable for antistatic applications at higher temperatures. The relaxation time follows the Vogel-Fulcher law, and the Vogel temperature T0 has the minimum for the WS2 nanotube concentration 0.15 vol%. Above 410 K, the electrical conductivity determines the properties of the investigated composites due to nonzero electrical conductivity of epoxy resin. The value of DC electrical conductivity for pure epoxy at T=450 K is 0.3 μS/m, while the DC conductivity of the composites slightly increases with the WS2 concentration. Therefore, the electrical contacts between WS2 nanotubes and polymer matrix are rather ohmic. Additionally, the activation energy is almost independent on the concentration of WS2. However, it is higher in composites than in pure epoxy resin.

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