scholarly journals Thermal and Adhesion Properties of Fluorosilicone Adhesives Following Incorporation of Magnesium Oxide and Boron Nitride of Different Sizes and Shapes

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 258
Author(s):  
Kyung-Soo Sung ◽  
So-Yeon Kim ◽  
Min-Keun Oh ◽  
Namil Kim
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Magnesium Oxide ◽  
Adhesion Strength ◽  
Average Particle Size ◽  
Average Particle ◽  
Interfacial Resistance ◽  
Conductive Adhesives ◽  
Adhesion Properties ◽  
Type Size

Thermally conductive adhesives were prepared by incorporating magnesium oxide (MgO) and boron nitride (BN) into fluorosilicone resins. The effects of filler type, size, and shape on thermal conductivity and adhesion properties were analyzed. Higher thermal conductivity was achieved when larger fillers were used, but smaller ones were advantageous in terms of adhesion strength. Bimodal adhesives containing spherical MgOs with an average particle size of 120 μm and 90 μm exhibited the highest conductivity value of up to 1.82 W/mK. Filler shape was also important to improve the thermal conductivity as the filler type increased. Trimodal adhesives revealed high adhesion strength compared to unimodal and bimodal adhesives, which remained high after aging at 85 °C and 85% relative humidity for 168 h. It was found that the thermal and adhesion properties of fluorosilicone composites were strongly affected by the packing efficiency and interfacial resistance of the particles.

Experimental Study of Heat Conduction in Aqueous Suspensions of Aluminum Oxide Nanoparticles

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Y. Sungtaek Ju ◽  
Jichul Kim ◽  
Ming-Tsung Hung
Keyword(s):  
Thermal Conductivity ◽  
Aluminum Oxide ◽  
Average Particle Size ◽  
Oxide Nanoparticles ◽  
Average Particle ◽  
Aluminum Oxide Nanoparticles ◽  
Aqueous Suspensions ◽  
Effective Medium Model ◽  
Transient Hot Wire Technique ◽  
Different Temperatures

We report measurements of the thermal conductivity of aqueous suspensions of aluminum oxide nanoparticles with nominal diameters of 20nm, 30nm, and 45nm and at volume concentrations up to 10%. Potential complications in the pulsed transient hot-wire technique for characterizing nanofluids are examined, which motivate the development of a microhot strip setup with a small thermal time constant. The average particle size is monitored for samples subjected to different durations of sonication and the thermal conductivity is determined at two different temperatures for each of the samples. The present data do not reveal any anomalous enhancement in the thermal conductivity previously reported for comparable nanofluids. The concentration dependence of the thermal conductivity can be explained using the conventional effective medium model with a physically reasonable set of parameters.

Synthesis and Characterization of Metal Nanoparticles and the Formation of Metal-Polymer Nanocomposites

2002 ◽  
Vol 740 ◽  
Author(s):  
Anshu A. Pradhan ◽  
S. Ismat Shah ◽  
Lisa Pakstis
Keyword(s):  
Thermal Conductivity ◽  
Silver Nanoparticles ◽  
Metal Nanoparticles ◽  
High Surface ◽  
Average Particle Size ◽  
Nanocomposite Films ◽  
Process Conditions ◽  
Average Particle ◽  
Sem Images ◽  
Cytotoxicity Studies

ABSTRACTMetal nanoparticles are highly prone to oxidation due to their high surface energy and affinity for oxygen which can lead to the complete oxidation of the particles. Studying and utilizing the unique properties of metal nanoparticles requires minimizing their interaction with the atmosphere. We have used the co-condensation technique to synthesize suspensions of metal nanoparticles in isopropanol. The solvent protects the nanoparticles from the atmosphere and minimizes agglomeration of the nanoparticles. The particles showed a lognormal distribution and the average particle size was below 20nm. Polymer-metal nanocomposites were made by dispersing the metal nanoparticles in PMMA matrix by spin coating and solution casting. Adherent films, fibers and free standing films could be obtained by varying the process conditions. The SEM images show that the nanoparticles in the spun coated films were non-agglomerated and well dispersed over a wide area. Morphology of the spun coated films was different from the solution cast films. Electrically conducting films having interconnected silver particle network could be obtained. Cytotoxicity studies show that the silver nanoparticles and the PMMA-Ag nanocomposite films are antibacterial in nature. We have also dispersed the nanoparticle into pump oil and measured the thermal conductivity of the resultant mixture. The thermal conductivity of the oil could be increased by over 50% by adding an extremely small fraction of the silver nanoparticles.

scholarly journals Thermal Conductivity of a Monolayer of Exfoliated Graphite Nanoplatelets Prepared by Liquid-Liquid Interfacial Self-Assembly

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Jinglei Xiang ◽  
Lawrence T. Drzal
Keyword(s):  
Thermal Conductivity ◽  
Self Assembly ◽  
Average Particle Size ◽  
Peak Shift ◽  
Exfoliated Graphite ◽  
Average Particle ◽  
Graphite Nanoplatelets ◽  
Cross Sectional ◽  
Packed Structure ◽  
Exfoliated Graphite Nanoplatelets

A monolayer film composed of exfoliated graphite nanoplatelets (xGnPs) was extracted from a chloroform-water interface and supported on a glass substrate. The nanoplatelets are interconnected at the edges without overlapping forming a very densely packed structure with uniform thickness. Micro-Raman spectroscopy with a 50 mW 532 nm laser generating heat at the center of a xGnP sample was used to probe the thermal conductivity of the xGnP monolayer at different power levels. The Raman G peak shift of graphite was used to record the local temperature rise in the monolayer. The cross-sectional area of heat conduction is determined by the thickness of individual nanoplatelets. A UV-Vis spectrometer was used to measure the absorption of light by the monolayer. Depending on the interface density, the thermal conductivities are around 380 W/m K and 290 W/m K for monolayers with average particle size of 10 μm and 5 μm, respectively.

Suspension Stability and Thermal Conductivity of Oxide Based Nanofluids with Low Volume Concentration

2010 ◽  
Vol 160-162 ◽  
pp. 802-808 ◽  
Author(s):  
Wei Lin Zhao ◽  
Bao Jie Zhu ◽  
Jin Kai Li ◽  
Yan Xiang Guan ◽  
Dong Dong Li
Keyword(s):  
Thermal Conductivity ◽  
Volume Concentration ◽  
Average Particle Size ◽  
Sio2 Nanoparticles ◽  
Heat Transfer Fluid ◽  
Suspension Stability ◽  
Average Particle ◽  
Step Method ◽  
Low Volume ◽  
Thermal Conductivities

Nanofluid is a new class of heat transfer fluid which contains suspended metallic or nonmetallic nanoparticles in traditional fluid. In this paper, nanofluids containing low volume concentrations (0.1-0.5vol.%) of Al2O3 and SiO2 nanoparticles were produced using a two-step method with ultrasonication and without any surfactant. Suspension stability of nanofluid was characterized and analyzed using zeta potential, average particle size and absorbancy method. The KD2-pro thermal property meter was used to measure the thermal conductivities of Al2O3(40nm)-water and SiO2(30nm)-water nanofluids at different volume concentrations (0.1-0.5vol.%) and temperature(25-50°C). The results show that adding nanoparticles into base fluid can enhance the thermal conductivity greatly. Furthermore, it is also show that the thermal conductivities increase nearly linearly with the nanoparticle volume concentration increasing, and increase significantly with the temperature increasing. A model of thermal conductivity of nanofluid, which has a much better precision, was proposed. But the values of the model are lower than the measured thermal conductivities.

Synthesis and Mechanical Properties Evaluatioin of Waterborne PSA’S with Core-Shell Morphology

2011 ◽  
Vol 691 ◽  
pp. 127-133
Author(s):  
R. Mascorro ◽  
M. Corea
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Acrylic Acid ◽  
Zeta Potential ◽  
Butyl Acrylate ◽  
Acid Content ◽  
Average Particle Size ◽  
Average Particle ◽  
Adhesion Properties ◽  
Ethyl Hexyl

In this work, a series of Pressure Sensitive Adhesives (PSAs) of poly(n-butyl acrylate-2-ethyl hexyl acrylate- acrylic acid) were synthesized via emulsion polymerization. The PSAs particles were carried out in a semicontinuous process. Synthesis was carried out in two stages of thereaction. In the first, a core of poly(butyl acrylate-co-2-ethyl hexyl acrylate) with a composition of 50/50 wt%/wt % was synthesized, while in the second stage, the core was charged in the reactor as a seed; and was recovered with a poly(butyl acrylate-co-2-ethyl hexyl acrylate-co-acrylic acid) shell. The acrylic acid in the shell was varied between 0, 1, 3 and 5 wt%. The PSAs obtained were characterized by dynamic light scattering and zeta potential. The results of dynamic light scattering showed monodispersed particles with an average particle size of 350 nm, while the zeta potential results decreased as the acrylic acid content increased. The mechanical tests showed that the increase in acrylic acid content in the particle shell improves the adhesion properties. For peel adhesion, the maximum value was reached at 3 wt% of acrylic acid.

scholarly journals Research on the Influence of the Manufacturing Process Conditions of Iron Sintered with the Addition of Layered Lubricating Materials on its Selected Properties

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4782
Author(s):  
Wieslaw Urbaniak ◽  
Tomasz Majewski ◽  
Ryszard Wozniak ◽  
Judyta Sienkiewicz ◽  
Jozef Kubik ◽  
...  
Keyword(s):  
Particle Size ◽  
Boron Nitride ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Hexagonal Boron Nitride ◽  
Average Particle Size ◽  
Layered Materials ◽  
Process Conditions ◽  
Average Particle ◽  
Average Grain Size

The purpose of the conducted experiments was to test the selected properties of materials intended for porous sintered bearings containing layered materials in the form of powders with an average particle size of 0.5–1.5 μm, with very good tribological properties. The subject of the research was a sinter based on iron powder with the addition of layered materials; molybdenum disulfide MoS2 (average particle size 1.5 μm), tungsten disulfide WS2 (average particle size 0.6 μm), hexagonal boron nitride, h-BN (average particle size 0.5 and 1.5 μm) with two different porosities. The article presents the results of density and porosity tests, compressive strength, metallographic and tribological tests and the assessment of changes in the surface condition occurring during the long storage period. The use of layered additives allows for an approximately 20% lower coefficient of friction. In the case of sulfides, the technological process of pressing 250 MPa, 350 MPa, and sintering at a temperature of 1120 °C allows us to obtain a material with good strength and tribological properties, better than in the case of h-BN. However, the main problem is the appearance of elements from the decomposition of sulfide compounds in the material matrix, which results in rapid material degradation. In hexagonal boron nitride, such disintegration under these conditions does not occur; the material as observed does not degrade. In this case, the material is characterized by lower hardness, resulting from a different behavior of hexagonal boron nitride in the pressing and sintering process; in this case, pressing at a pressure of 350 MPa seems to be too low. However, taking into account that even with these technological parameters, the obtained material containing 2.5% h-BN with an average grain size of 1.5 μm allowed obtaining a coefficient of friction at the level of 0.41, which, with very good material durability, seems to be very positive news before further tests.

scholarly journals Rapeseed oil additivated with hexagonal boron nitride

2020 ◽  
Vol 12 (2) ◽  
pp. 63-72
Author(s):  
Traian Florian IONESCU ◽  
Adrian-Alin SORCARU ◽  
Dionis GUGLEA ◽  
George Catalin CRISTEA ◽  
Constantin GEORGESCU ◽  
...  
Keyword(s):  
Particle Size ◽  
Friction Coefficient ◽  
Boron Nitride ◽  
Rapeseed Oil ◽  
Mass Concentration ◽  
Hexagonal Boron Nitride ◽  
Average Particle Size ◽  
Average Particle ◽  
Test Parameters ◽  
Tribological Parameters

This paper presents the influence of hexagonal boron nitride (hBN) as additive in refined rapeseed oil in different mass concentration of 0.25%wt, 0.5%wt and 1%wt on the tribological parameters, obtained on a four-ball machine. The test parameters were load: 100 N, 200 N and 300 N and the rotational speed 1000 rpm, 1400 rpm and 1800 rpm, corresponding to the following sliding speed, 0.38 m/s, 0.53 m/s and 0.69 m/s, respectively. The average particle size of hBN is 14 nm. For the tested ranges of the parameters, the additivation of rapeseed oil with hBN does not improve the friction coefficient, but the wear rate of WSD seems to be less sensitive for the more severe regimes when the vegetal oil is additivated.

Microstructural and Thermal Characterization of Diamond Nanofluids

2018 ◽  
Author(s):  
Farzin Mashali ◽  
Ethan M. Languri ◽  
Gholamreza Mirshekari ◽  
Jim Davidson ◽  
David Kerns
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Particle Size ◽  
Base Fluid ◽  
Average Particle Size ◽  
Thermal Characterization ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Heat Transfer Fluids ◽  
Transmission Electron

Conventional heat transfer fluids such as water, ethylene glycol, and mineral oil, that are used widely in industry suffer from low thermal conductivity. On the other hand, diamond has shown exceptional thermal properties with a thermal conductivity higher than five times of copper and about zero electrical conductivity. To investigate the effectiveness of nanodiamond particles in traditional heat transfer fluids, we study deaggregated ultra-dispersed diamonds (UDD) using X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). Furthermore, nanodiamond nanofluids were prepared at different concentrations in deionized (DI) water as the base fluid. Particle size distribution was investigated using TEM and the average particle size have been reported around 6 nm. The thermal conductivity of nanofluids was measured at different concentrations and temperatures. The results indicate up to 15% enhancement in thermal conductivity compared with the base fluid and thermal conductivity increases with temperature and particle loading. The viscosity raise in the samples have been negligible.

scholarly journals Systematic preparation and physical property characterization of a novel stable BiOIO3 nanofluids

2021 ◽  
pp. 337-337
Author(s):  
Ruihao Zhang ◽  
Hao Zhang ◽  
Shan Qing ◽  
Zhang Xiaohui ◽  
Zhumei Luo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Average Particle Size ◽  
Physical Property ◽  
Average Particle ◽  
Step Method ◽  
Heat Transfer Fluids ◽  
New Type ◽  
Near Future ◽  
To Receive

Nanofluids due to their good thermal conductivity and stability, have been proposed as a way to surpass the performance of currently available heat transfer fluids in the near future. In this work?we focuses on the preparation of nanofluids with excellent stability and thermal conductivity, which a new type of stable BiOIO3 (one type of infrared nonlinear optical crystal) nanofluids is successfully prepared by using the two-step method. After the initial physical characterization of BiOIO3 particles, five different dispersants are used to disperse the BiOIO3 nanoparticles, and the best performing nanofluids with a zeta potential value of 144.45 and an average particle size of 22.90nm could be prepared with PVP dispersant. Furthermore, the addition of PVP dispersant in UV-Visible experiments smooth the light absorption curve of the nanofluids, reach a peak of 1.1 at around 350 nm. In the most important thermal conductivity test, the value of thermal conductivity of BiOIO3 nanofluid becomes larger with increasing concentration at 50?C, reaching a maximum value of 1.52 at 0.134vol%, which increases by 0.72 over the same volume concentration of TiO2, indicating the importance of the laminar structure. In view of the excellent properties, new laminar structured nanofluids with light-absorbing properties are expected to receive more attention and exploration in the future

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