Influence of Nanomaterials in Polymer Composites on Thermal Conductivity

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Wonchang Park ◽  
Kyungwho Choi ◽  
Khalid Lafdi ◽  
Choongho Yu
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Polymer Composites ◽  
Effective Medium Theory ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Drying Methods ◽  
Synthesis Conditions ◽  
Steady State Method ◽  
Thermal Conductivities

Carbon nanotube- or/and graphite-filled polymer composites were synthesized by using simple mixing and drying methods, and their thermal conductivities and structures were characterized by using a steady-state method (ASTM D5470) and scanning and transmission electron microscopies. In order to investigate the influence of synthesis conditions on the thermal conductivity of composites, various concentrations of multiwall carbon nanotubes, graphites, surfactants, and polymer matrix materials as well as two different nanoparticles and solvents were tested. Our composites containing both nanotubes (25 wt. %) and graphites (25 wt. %) with sodium dodecyl benzene sulfonate (SDBS) as a dispersant showed the highest thermal conductivity, ∼1.8 W/m-K at room temperature. The highest conductivity from nanotube/graphite mixtures would be from good adhesion and less voids between nanotubes and polymers as well as excellent thermal conduction from graphite sheets. The thermal conductivities of the composites have been calculated as a function of carbon nanotube concentrations by using a model based on the Maxwell’s effective medium theory, and the most effective method of improving thermal conductivity was suggested.

scholarly journals The Dielectric Properties and Thermal Conductivities of Epoxy Composites Reinforced by Titanium Dioxide

2021 ◽  
Author(s):  
Yuan Jia ◽  
Juxiang Yang ◽  
Weijie Dong ◽  
Beibei Li ◽  
Zhen Liu
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Titanium Dioxide ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Hydrothermal Process ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Ep Matrix ◽  
Thermal Conductivities

Abstract To improve the dielectric properties and thermal conductivities of epoxy resins (EP), titanium dioxide superfine powders with microspheres structure (S-TiO2) were prepared via a hydrothermal process based on the sodium dodecyl benzene sulfonate and hydroxyl silicate. The different content of S-TiO2 was then employed as modifiers to add into EP resin to prepare the S-TiO2/EP composites. The structure and morphology of the prepared S-TiO2 was observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and influences of different addition of S-TiO2 on the thermal conductivity of S-TiO2/EP composites are researched, while their dielectric constant and dielectric loss are also studied. The results suggested that the reasonable content of S-TiO2 can endow the S-TiO2/EP composites with higher dielectric constant without excessive increase their dielectric loss even under the high frequency. Furthermore, the thermal conductivity of S-TiO2/EP are also be improved, which can be attributed to the good thermal conductivity of S-TiO2 itself and the thermal conductivity path formed by S-TiO2 inside the EP matrix.

An Improved Predictive Model for Effective Thermal Conductivity of Polymer Composites With Non-Dilute Filler Concentrations

2019 ◽  
Author(s):  
Kabeer Raza ◽  
Syed Sohail Akhtar ◽  
Abul Fazal M. Arif ◽  
Abbas Saeed Hakeem
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Polymer Composites ◽  
Polymer Matrix Composites ◽  
Effective Medium Theory ◽  
Material Design ◽  
Filler Concentration ◽  
Volume Fractions ◽  
Proposed Model ◽  
Thermal Conductivities

Abstract Most of the predictive models for thermal conductivity of composites are derived based on the assumption that the filler concentration in the matrix is dilute. This assumption leads to inaccurate predictions when filler concentration is essentially non-dilute and hence there is a need to propose a model that could handle a non-dilute filler concentration. In this work an improved and realistic model for effective thermal conductivity of polymer matrix composites with non-dilute filler’s concentrations is derived and validated by experiments. The proposed model can handle fillers with variable size and shapes. The derivation is based on the Bruggeman’s differential effective medium theory where the high volume fractions can be obtained by incrementally adding ‘small volume fractions’ into the ‘existing composite’ at each stage. The proposed model is validated by experimentally produced different series of ceramic particles-polymer composites. Differently sized and shaped alumina (Al2O3) & aluminum nitride (AlN) particulate fillers, and high density polyethylene (HDPE) & polypropylene (PP) matrices were used as the variable ingredients. Using different combinations of filler, matrix and particle size six different series of composites were produced with variable filler concentrations up to 50% by volume. The microstructure of the produced samples was studied by field emission scanning electron microscope to relate the morphology with the predictions. The predictions of proposed model are found in close agreement with the measured thermal conductivities. To understand the detailed effects of different parameters, parametric studies are presented and discussed. It is found that aspect ratio of particulate fillers is the most sensitive parameter to enhance effective thermal conductivity. Overall, the proposed model is proven to be useful in composite material design for heat transfer applications. It is expected that the proposed model will open new doors for the researchers and polymer composite industry to develop new composite designs for achieving ultrahigh thermal conductivities.

Simulation of Thermal Conductivity in Fabricated Variable Volume Fraction Aligned Carbon Nanotube Polymer Composites

2008 ◽  
Author(s):  
Namiko Yamamoto ◽  
Hai M. Duong ◽  
Aaron J. Schmidt ◽  
Brian L. Wardle ◽  
Dimitrios V. Papavassiliou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Polymer Composites ◽  
Polymer Nanocomposites ◽  
Volume Fraction ◽  
Matrix Material ◽  
Nano Composites ◽  
Thermoset Resin ◽  
Macro Scale ◽  
Thermal Conductivities

Thermal conductivities of aligned carbon nanotube (CNT)–polymer nano-composites were estimated using the off-lattice Monte Carlo simulation. High thermal conductivity to density ratio is theoretically and experimentally recognized as one of the exceptional properties of CNTs. Aligned CNTs combined with existing advanced composites are being explored for macro-scale aerospace structures that benefit from thermal tailoring and light weight. Accurate thermal transport models within different polymer nanocomposites, and larger-scale and complexity composites, remain to be developed. The model previously developed for single-walled nanotube (SWNT)-polymer composites was modified to simulate the thermal property of aligned multi-walled nanotube (MWNT)-polymer nanocomposites of different volume fraction. Random walk simulations of thermal walkers are used to determine the interfacial resistance to heat flow inside the nano-composites in the directions parallel and perpendicular to the CNT alignment axis. The thermal equilibrium factor between the MWNTs and the composite matrix material is also determined numerically in this study. The CNT-polymer samples were fabricated for thermal conductivity measurements using two methods: the pump-and-probe method and the infrared microscopy. Aligned SWNT and MWNT forests were grown using chemical vapor deposition (CVD). The MWNTs were mechanically densified up to ∼20% aligned-CNT volume fraction. The MWNT forests were immersed in an aerospace-grade thermoset resin, and cured. Near future work is to compare the simulated effective thermal conductivities of the CNT-epoxy composites with the measured data of the fabricated specimens to determine thermal boundary resistance between CNTs and the polymer.

scholarly journals High-Performance Thermal Management Nanocomposites: Silver Functionalized Graphene Nanosheets and Multiwalled Carbon Nanotube

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 398 ◽  
Author(s):  
Yongcun Zhou ◽  
Xiao Zhuang ◽  
Feixiang Wu ◽  
Feng Liu
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Polymer Composites ◽  
Thermal Management ◽  
High Performance ◽  
Graphene Nanosheets ◽  
Multiwalled Carbon Nanotube ◽  
Processing Unit ◽  
Functionalized Graphene ◽  
Multiwalled Carbon

Polymer composites with high thermal conductivity have a great potential for applications in modern electronics due to their low cost, easy process, and stable physical and chemical properties. Nevertheless, most polymer composites commonly possess unsatisfactory thermal conductivity, primarily because of the high interfacial thermal resistance between inorganic fillers. Herein, we developed a novel method through silver functionalized graphene nanosheets (GNS) and multiwalled carbon nanotube (MWCNT) composites with excellent thermal properties to meet the requirements of thermal management. The effects of composites on interfacial structure and properties of the composites were identified, and the microstructures and properties of the composites were studied as a function of the volume fraction of fillers. An ultrahigh thermal conductivity of 12.3 W/mK for polymer matrix composites was obtained, which is an approximate enhancement of 69.1 times compared to the polyvinyl alcohol (PVA) matrix. Moreover, these composites showed more competitive thermal conductivities compared to untreated fillers/PVA composites applied to the desktop central processing unit, making these composites a high-performance alternative to be used for thermal management.

A closed-form model for estimating the effective thermal conductivities of carbon nanotube–polymer nanocomposites

2018 ◽  
Vol 233 (8) ◽  
pp. 2909-2919 ◽  
Author(s):  
Reza Moheimani ◽  
M Hasansade
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Closed Form ◽  
Polymer Nanocomposites ◽  
Micromechanical Model ◽  
Polymer Nanocomposite ◽  
Interfacial Thermal Resistance ◽  
Full Potential ◽  
Thermal Conductivities

This paper describes a closed-form unit cell micromechanical model for estimating the effective thermal conductivities of unidirectional carbon nanotube reinforced polymer nanocomposites. The model incorporates the typically observed misalignment and curvature of carbon nanotubes into the polymer nanocomposites. Also, the interfacial thermal resistance between the carbon nanotube and the polymer matrix is considered in the nanocomposite simulation. The micromechanics model is seen to produce reasonable agreement with available experimental data for the effective thermal conductivities of polymer nanocomposites reinforced with different carbon nanotube volume fractions. The results indicate that the thermal conductivities are strongly dependent on the waviness wherein, even a slight change in the carbon nanotube curvature can induce a prominent change in the polymer nanocomposite thermal conducting behavior. In general, the carbon nanotube curvature improves the nanocomposite thermal conductivity in the transverse direction. However, using the straight carbon nanotubes leads to maximum levels of axial thermal conductivities. With the increase in carbon nanotube diameter, an enhancement in nanocomposite transverse thermal conductivity is observed. Also, the results of micromechanical simulation show that it is necessary to form a perfectly bonded interface if the full potential of carbon nanotube reinforcement is to be realized.

Change of Thermal Conductivity and Cooling Performance for Water Based Al2O3-Surfactant Nanofluid with Time Lapse

2018 ◽  
Vol 26 (01) ◽  
pp. 1850009 ◽  
Author(s):  
Man Bae Kim ◽  
Hong Gen Park ◽  
Chang Yong Park
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Cooling System ◽  
Pure Water ◽  
Sodium Dodecyl ◽  
Convection Heat Transfer ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Time Lapse ◽  
Convection Heat ◽  
Conductivity Enhancement

An experimental research was performed to study the effect of time lapse on the change of water-Al2O3 nanofluid thermal conductivity and its convection heat transfer. The size of Al2O3 nanoparticle size was 20[Formula: see text]nm and 70[Formula: see text]nm, and initial volumetric concentration range was from 0.5% to 3%. A surfactant was added to the nanofluid and the change of thermal conductivity and convection heat transfer was also measured. The surfactant was Sodium Dodecyl Benzene Sulfonate (SDBS) and its mass fractions in the nanofluid were from 0.5% to 3.0%. Thermal conductivity of water and nanofluid was measured by the transient hot wire method. The accuracy of the measurement method was confirmed by the measurement error with 0.92% for distilled water at 20[Formula: see text]C. The thermal conductivity of the nanofluid without SDBS increased up to 11.3% and the enhancement decreased with time lapse. The reduction of thermal conductivity enhancement with the time lapse could be retarded by the addition of SDBS and its effect became higher with the increase of its mass fraction. The convection heat transfer characteristics of the nanofluid was measured in a small cooling system. Compared with pure water, nanofluid convection heat transfer could be enhanced but higher pressure drop also occurred. Compared with the convection heat transfer enhancement for the nanofluid without SDBS, the addition of SDBS decreased the enhancement at the initial stage of the experiment, but it could retard the reduction of convection heat transfer with time lapse.

Sign in / Sign up

Export Citation Format

Share Document