scholarly journals Thermal conductivity of silicone elastomer with a porous alumina continuum

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 845-853
Author(s):  
Qichao Song ◽  
Bo Wang ◽  
Zhiyu Han ◽  
Zhidong Han
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Medium Theory ◽  
Porous Alumina ◽  
Theoretical Models ◽  
Silicone Elastomer ◽  
Interfacial Thermal Resistance ◽  
X Ray Diffraction ◽  
Medium Theory ◽  
Gel Casting

Abstract In this paper, porous alumina continuum (PAC) was prepared with alumina powders (APs) by the gel-casting method and was applied to obtain silicone elastomer (SR) composites (PAC/SR) by the impregnating process. The structure was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of PAC on thermal conductivity and dielectric permittivity of PAC/SR composites were studied in comparison with AP/SR composites. When the alumina content was 14 vol%, the thermal conductivity of the PAC/SR composites reached 0.84 W·(m·K)−1, which was 3.1 times higher than that of the AP/SR composites. The thermal conductivity of PAC/SR and AP/SR was simulated by theoretical models, and the interfacial thermal resistance was calculated by effective medium theory, which indicated the advantages of PAC in enhancing the thermal conductivity of SR-based composites and the reduced interfacial thermal resistance between PAC and SR.

Effect of Particle Size and Aggregation on Thermal Conductivity of Metal-Polymer Nanocomposite

2016 ◽  
Author(s):  
Xiangyu Li ◽  
Wonjun Park ◽  
Yong P. Chen ◽  
Xiulin Ruan
Keyword(s):  
Thermal Conductivity ◽  
Effective Medium Theory ◽  
Low Cost ◽  
Polymer Nanocomposite ◽  
Theoretical Models ◽  
Effective Medium ◽  
Metal Nanoparticle ◽  
Local Concentration ◽  
Medium Theory ◽  
Aggregation Effect

Metal nanoparticle has been a promising option for fillers in thermal interface materials due to its low cost and ease of fabrication. However, nanoparticle aggregation effect is not well understood because of its complexity. Theoretical models, like effective medium approximation model, barely cover aggregation effect. In this work, we have fabricated nickel-epoxy nanocomposites and observed higher thermal conductivity than effective medium theory predicts. Smaller particles are also found to show higher thermal conductivity, contrary to classical models indicate. A two-level EMA model is developed to account for aggregation effect and to explain the size-dependent enhancement of thermal conductivity by introducing local concentration in aggregation structures.

Particle Aspect-Ratio Effects on the Thermal Conductivity of Micro- and Nanoparticle Suspensions

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
Anna S. Cherkasova ◽  
Jerry W. Shan
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Aspect Ratio ◽  
Effective Thermal Conductivity ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Particulate Composites ◽  
Interfacial Thermal Resistance ◽  
Recent Experimental Data ◽  
Medium Theory

The influence of particle anisotropy on the effective thermal conductivity of a suspension is experimentally investigated. Suspensions of micron-sized, silicon-carbide particles with varying aspect-ratio distributions were prepared and measured. It is shown that the conductivity of the silicon-carbide suspensions can be quantitatively predicted by the effective medium theory of Nan et al. (1997, “Effective Thermal Conductivity of Particulate Composites With Interfacial Thermal Resistance,” J. Appl. Phys. 81(10), pp. 6692–6699), provided the volume-weighted aspect ratio of the particles is used. Recent experimental data on multiwalled-nanotube-in-oil suspensions by Yang et al. (2006, “Thermal and Rheological Properties of Carbon Nanotube-in-Oil Dispersions,” J. Appl. Phys., 99(11), 114307) are also analyzed and shown to be in at least qualitative agreement with the effective-medium-theory prediction that the thermal conductivity of suspensions is enhanced by large aspect-ratio particles.

scholarly journals Effect of Micro- to Nanosize Inclusions upon the Thermal Conductivity of Powdered Composites with High and Low Interface Resistance

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Muhammad Zain-ul-abdein ◽  
Waqas S. Awan ◽  
Hassan Ijaz ◽  
Aqeel A. Taimoor ◽  
Ayyaz Muhammad ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Volume Fraction ◽  
Effective Properties ◽  
Theoretical Models ◽  
Inclusion Size ◽  
Interfacial Thermal Resistance ◽  
Interfacial Resistance ◽  
Filler Volume Fraction ◽  
The Matrix

Materials for thermal management application require better control over the thermophysical properties, which has largely been achieved by fabricating powdered composite. There are, however, several factors like filler volume fraction, shape morphology, inclusion size, and interfacial thermal resistance that limit the effective properties of the medium. This paper presents a methodology to estimate the effective thermal conductivity of powdered composites where the filler material is more conductive than the matrix. Only a few theoretical models, such as Hasselman and Johnson (HJ) model, include the effect of interfacial resistance in their formulation. Nevertheless, HJ model does not specify the nature of the interfacial thermal resistance. Although Sevostianov and Kachanov (SK) method takes care of interface thickness, they, on the other hand, have not taken into account the interfacial resistance due to atomic imperfections. In the present work, HJ model has been modified using SK method and the results were compared with experimental ones from the literature. It has been found that the effect of interfacial resistance is significant in highly resistive medium at microscale compared to nanoscale, such as Cu/diamond system, while, in a highly conductive medium, like bakelite/graphite system, the effect of shape factor is more significant than interfacial thermal resistance.

scholarly journals Thermal Conductivity of Unidirectionally Aligned SiC Whisker Reinforced Al Alloy Matrix Composite with Interfacial Thermal Resistance

2005 ◽  
Vol 46 (2) ◽  
pp. 148-151 ◽  
Author(s):  
Yibin Xu ◽  
Yoshihisa Tanaka ◽  
Masaharu Murata ◽  
Kazushige Kamihira ◽  
Yukihiro Isoda ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Matrix Composite ◽  
Interfacial Thermal Resistance ◽  
Al Alloy ◽  
Alloy Matrix

Enhanced Thermal Conductivity of Composite Materials by Filling Sheet and Fiber Under Effect of Filler Contact

2021 ◽  
Author(s):  
Xiao-jian Wang ◽  
Liang-Bi Wang
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Composite Materials ◽  
Thermal Resistance ◽  
Percolation Threshold ◽  
Filler Content ◽  
Interfacial Thermal Resistance ◽  
Combined Effects ◽  
Enhanced Thermal Conductivity ◽  
The Ideal

Abstract The most common non-granular fillers are sheet and fiber. When they are distributed along the heat flux direction, the thermal conductivity of composite increases greatly. Meanwhile, the filler contact also has large effect on the thermal conductivity. However, the effect of filler contact on the thermal conductivity of composite with directional fillers has not been investigated. In this paper, the combined effects of filler contact, content and orientation are investigated. The results show that the effect of filler orientation on the thermal conductivity is greater than filler contact in low filler content, and exact opposite in high filler content. The effect of filler contact on fibrous and sheet fillers is far greater than cube and sphere fillers. This rule is affected by the filler contact. The filler content of 8% is the ideal percolation threshold of composite with fibrous and sheet filler. It is lower than cube filler and previous reports. The space for thermal conductivity growth of composite with directional filler is still very large. The effect of interfacial thermal resistance should be considered in predicting the thermal conductivity of composite under high Rc (>10-4).

scholarly journals Microwave Dielectric Properties of CCTO/PVA Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
M. P. F. Graça ◽  
K. D. A. Sabóia ◽  
F. Amaral ◽  
L. C. Costa
Keyword(s):  
Complex Permittivity ◽  
Effective Medium Theory ◽  
Ceramic Powder ◽  
Microwave Dielectric Properties ◽  
Weight Fraction ◽  
Dielectric Behavior ◽  
X Ray Diffraction ◽  
Medium Theory ◽  
Classical Models ◽  
High Dielectric

The CaCu3Ti4O12 (CCTO) ceramic powder was inserted in the polyvinyl alcohol (PVA) polymeric matrix, with an increasing weight fraction of the filler, to form a flexible and high dielectric constant composite at the GHz region. The structural characterization of the samples was performed using X-ray diffraction and scanning electron microscopy (SEM). The complex permittivity was calculated by the small perturbation theory using two resonant cavities (2.7 GHz and 5.0 GHz). Several classical models (Maxwell Garnett, Lichtenecker, effective medium theory (EMT), and Yamada) were used to fit the real part of the complex permittivity of the composite as a function of the weight fraction of CCTO powder inserted in the PVA matrix. The best predictions for the dielectric behavior of these samples were obtained with the EMT and Yamada models.

Effective Thermal Conductivity of Functionally Graded Particulate Nanocomposites With Interfacial Thermal Resistance

2008 ◽  
Vol 75 (5) ◽  
Author(s):  
H. M. Yin ◽  
G. H. Paulino ◽  
W. G. Buttlar ◽  
L. Z. Sun
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Functionally Graded ◽  
Interfacial Thermal Resistance ◽  
Conductivity Distribution ◽  
Consistent Model ◽  
The Matrix ◽  
Graded Material ◽  
Perfect Interface

By means of a fundamental solution for a single inhomogeneity embedded in a functionally graded material matrix, a self-consistent model is proposed to investigate the effective thermal conductivity distribution in a functionally graded particulate nanocomposite. The “Kapitza thermal resistance” along the interface between a particle and the matrix is simulated with a perfect interface but a lower thermal conductivity of the particle. The results indicate that the effective thermal conductivity distribution greatly depends on Kapitza thermal resistance, particle size, and degree of material gradient.

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