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Ching-ping Wong - One of the best experts on this subject based on the ideXlab platform.
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nacre inspired polymer composites with High Thermal Conductivity and enhanced mechanical strength
Composites Part A-applied Science and Manufacturing, 2019Co-Authors: Tao Zhang, Yimin Yao, Jiajia Sun, Xiaoliang Zeng, Rong Sun, Linlin Ren, Mingmei Wang, Ching-ping WongAbstract:Abstract Polymer composites with High Thermal Conductivity are attracting increasing interest as Thermal-management materials owing to material abundance, easy processing and low cost. However, conventional preparation of Thermally conductive polymer composites through adding High-loading inorganic fillers usually suffers from poor mechanical properties. Here, inspired by the microstructure of natural nacre, we report on fine ordered Ag-BN/epoxy resin composites via interfacial manipulation of boron nitrides with Ag nanoparticles and hot-pressing induced orientation process. The as-prepared nacre-like compounds have both High Thermal Conductivity (up to 23.1 W m−1 K−1) and mechanical strength (tensile strength of 80.3 MPa). This work provides a novel insight into the fabrication of polymer composites with superior mechanical strength in Thermal management field.
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the preparation of sio 2 bn epoxy composites with High Thermal Conductivity and excellent thermomechanical property
International Conference on Electronic Packaging Technology, 2017Co-Authors: Yuan Gao, Rong Sun, Pengli Zhu, Ching-ping WongAbstract:With the electronic packaging techniques and electronic equipments toward a High integration and miniaturization development, High Thermal Conductivity and excellent thermo-mechanical properties of polymer-based composites have attracted significant attentions in the recent years. SiO 2 as a common inorganic filler has been widely used in electronics packaging materials, due to its low coefficient of Thermal expansion, High storage modulus, High glass transition temperature and stable chemical properties. Although the filling of SiO 2 can improve the thermo-mechanical properties of polymer-based composites, its lower Thermal Conductivity limits its application in the field of electronic packaging. Boron nitride (BN), so-called “white graphene”, which has excellent physical and chemical properties, such as excellent mechanical strength, low coefficient of Thermal expansion, High resistance to oxidation, outstanding corrosion resistance and High Thermal Conductivity. Therefore, we hope to combine the excellent properties of SiO 2 and BN to prepare polymer-based composites with High Thermal Conductivity and excellent thermo-mechanical properties. In our work, the SiO 2 @BN hybrids with core-shell structure were successfully prepared by High temperature calcination in nitrogen, and then filled into the epoxy resin to obtain the SiO 2 @BN/epoxy composites. When the SiO 2 @BN content was 50 wt%, the Thermal Conductivity of composites is 2.73 Wm−1K−1, which is about 4.07 times of neat epoxy. The storage modulus (50 °C) and glass transition temperature of the 50 wt% SiO 2 @BN/epoxy composites are 6.09 GPa and 188.4 °C, which is 3.72 GPa Higher than that of the neat epoxy and 54.9 °C Higher than the glass transition temperature of the neat epoxy. In addition, the coefficient of Thermal expansion of the 50 wt% SiO 2 @BN/epoxy composites is 31.5 ppm/°C, which is 36.9 ppm/°C lower than the coefficient of Thermal expansion of the neat epoxy.
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A Combination of Boron Nitride Nanotubes and Cellulose Nanofibers for the Preparation of a Nanocomposite with High Thermal Conductivity
ACS Nano, 2017Co-Authors: Xiaoliang Zeng, Yimin Yao, Jiajia Sun, Jian-bin Xu, Rong Sun, Ching-ping WongAbstract:With the current development of modern electronics toward miniaturization, High-degree integration and multifunctionalization, considerable heat is accumulated, which results in the Thermal failure or even explosion of modern electronics. The Thermal Conductivity of materials has thus attracted much attention in modern electronics. Although polymer composites with enhanced Thermal Conductivity are expected to address this issue, achieving Higher Thermal Conductivity (above 10 W m–1 K–1) at filler loadings below 50.0 wt % remains challenging. Here, we report a nanocomposite consisting of boron nitride nanotubes and cellulose nanofibers that exhibits High Thermal Conductivity (21.39 W m–1 K–1) at 25.0 wt % boron nitride nanotubes. Such High Thermal Conductivity is attributed to the High intrinsic Thermal Conductivity of boron nitride nanotubes and cellulose nanofibers, the one-dimensional structure of boron nitride nanotubes, and the reduced interfacial Thermal resistance due to the strong interaction betwe...
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silver nanoparticle deposited boron nitride nanosheets as fillers for polymeric composites with High Thermal Conductivity
Scientific Reports, 2016Co-Authors: Yimin Yao, Xiaoliang Zeng, Rong Sun, Ching-ping Wong, Fangfang WangAbstract:Polymer composites with High Thermal Conductivity have recently attracted much attention, along with the rapid development of the electronic devices toward Higher speed and performance. However, a common method to enhance polymer Thermal Conductivity through an addition of High Thermally conductive fillers usually cannot provide an expected value, especially for composites requiring electrical insulation. Here, we show that polymeric composites with silver nanoparticle-deposited boron nitride nanosheets as fillers could effectively enhance the Thermal Conductivity of polymer, thanks to the bridging connections of silver nanoparticles among boron nitride nanosheets. The Thermal Conductivity of the composite is significantly increased from 1.63 W/m-K for the composite filled with the silver nanoparticle-deposited boron nitride nanosheets to 3.06 W/m-K at the boron nitride nanosheets loading of 25.1 vol %. In addition, the electrically insulating properties of the composite are well preserved. Fitting the measured Thermal Conductivity of epoxy composite with one physical model indicates that the composite with silver nanoparticle-deposited boron nitride nanosheets outperforms the one with boron nitride nanosheets, owning to the lower Thermal contact resistance among boron nitride nanosheets’ interfaces. The finding sheds new light on enhancement of Thermal Conductivity of the polymeric composites which concurrently require the electrical insulation.
Pingkai Jiang - One of the best experts on this subject based on the ideXlab platform.
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Nanostructured electrical insulating epoxy thermosets with High Thermal Conductivity, High Thermal stability, High glass transition temperatures and excellent dielectric properties
IEEE Transactions on Dielectrics and Electrical Insulation, 2015Co-Authors: Hailin Mo, Xingyi Huang, Shengtao Li, Fei Liu, Ke Yang, Pingkai JiangAbstract:The need for improving performance of electronic devices and electrical equipment has always resulted in new High-performance electrical insulating materials. One important issue is the necessity to use dielectric polymers with Higher Thermal conductivities. In this study, by forming ordered nanostructure in epoxy resin via introducing 4, 4'- dihydroxydiphenyl (DHDP), electrical insulating epoxy thermosets simultaneously having High Thermal Conductivity, High Thermal stability, High glass transition temperatures and excellent dielectric properties were successfully prepared. The introduction of DHDP not only increases the rigidity of the modified epoxy chains but also results in ordered nanostructure in the modified epoxy thermosets, which is considered as the main factor for the performance improvement of the modified epoxy thermosets.
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alumina coated graphene sheet hybrids for electrically insulating polymer composites with High Thermal Conductivity
RSC Advances, 2013Co-Authors: Rong Qian, Xing Zhai, Pingkai JiangAbstract:Graphene has attracted considerable attention as a promising candidate to improve the Thermal Conductivity of polymers owing to its extremely High intrinsic Thermal Conductivity (∼5300 W m−1 K). However, graphene-based composites show a High electrical Conductivity even with a low loading of fillers, which greatly limits their applications in electronic devices. Herein, we present a new class of fillers of alumina-coated graphene sheet (GS@Al2O3) hybrid fillers via an electrostatic self-assembly route. This unique structural design combines the advantages of both the GS and Al2O3, resulting in PVDF/GS@Al2O3 composites that show not only High Thermal Conductivity, but also retain High electrical insulation. For instance, the Thermal Conductivity of PVDF composites with 40 wt% GS@Al2O3 is up to 0.586 W m−1 K and the volume resistivity is above 4 × 1014 Ω cm. Moreover, this self-assembly route is a simple and scalable strategy for fabricating High performance Thermally conductive materials.
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Polyhedral oligosilsesquioxane-modified boron nitride nanotube based epoxy nanocomposites: An ideal dielectric material with High Thermal Conductivity
Advanced Functional Materials, 2013Co-Authors: Xingyi Huang, Pingkai Jiang, Yoshio Bando, Chunyi Zhi, Toshikatsu TanakaAbstract:Dielectric polymer composites with High Thermal Conductivity are very promising for microelectronic packaging and Thermal management application in new energy systems such as solar cells and light emitting diodes (LEDs). However, a well-known paradox is that conventional composites with High Thermal Conductivity usually suffer from the High dielectric constant and High dielectric loss, while on the other hand, composite materials with excellent dielectric properties usually possess low Thermal Conductivity. In this work, an ideal dielectric Thermally conductive epoxy nanocomposite is successfully fabricated using polyhedral oligosilsesquioxane (POSS) functionalized boron nitride nanotubes (BNNTs) as fillers. The nanocomposites with 30 wt% fraction of POSS modified BNNTs exhibit much lower dielectric constant, dielectric loss tangent, and coefficient of Thermal expansion in comparison with the pure epoxy resin. As an example, below 100 Hz, the dielectric loss of the nanocomposites with 20 and 30 wt% BNNTs is reduced by one order of magnitude in comparison with the pure epoxy resin. Moreover, the nanocomposites show a dramatic Thermal Conductivity enhancement of 1360% in comparison with the pristine epoxy resin at a BNNT loading fraction of 30 wt%. The merits of the designed composites are suggested to originate from the excellent intrinsic properties of embedded BNNTs, effective surface modification by POSS molecules, and carefully developed composite preparation methods.
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large dielectric constant and High Thermal Conductivity in poly vinylidene fluoride barium titanate silicon carbide three phase nanocomposites
ACS Applied Materials & Interfaces, 2011Co-Authors: Yong Li, Xingyi Huang, Pingkai Jiang, Shengtao Li, Zhiwei Hu, T TanakaAbstract:Dielectric polymer composites with High dielectric constants and High Thermal Conductivity have many potential applications in modern electronic and electrical industry. In this study, three-phase composites comprising poly(vinylidene fluoride) (PVDF), barium titanate (BT) nanoparticles, and β-silicon carbide (β-SiC) whiskers were prepared. The superiority of this method is that, when compared with the two-phase PVDF/BT composites, three-phase composites not only show significantly increased dielectric constants but also have Higher Thermal Conductivity. Our results show that the addition of 17.5 vol % β-SiC whiskers increases the dielectric constants of PVDF/BT nanocomposites from 39 to 325 at 1000 Hz, while the addition of 20.0 vol % β-SiC whiskers increases the Thermal Conductivity of PVDF/BT nanocomposites from 1.05 to 1.68 W m–1 K–1 at 25 °C. PVDF/β-SiC composites were also prepared for comparative research. It was found that PVDF/BT/β-SiC composites show much Higher dielectric constants in compariso...
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A review of dielectric polymer composites with High Thermal Conductivity
IEEE Electrical Insulation Magazine, 2011Co-Authors: Xingyi Huang, Pingkai Jiang, Toshikatsu TanakaAbstract:The continuing miniaturization of electronic devices and the increasing power output of electrical equipment have created new challenges in packaging and insulating materials. The key goals are to develop materials with High Thermal Conductivity, low coefficient of Thermal expansion (CTE), low dielectric con stant, High electrical resistivity, High breakdown strength, and most importantly, low cost. Polymeric materials have attracted increasing interest because of their excellent processability and low cost; however, most polymers are Thermally insulating and have a Thermal Conductivity between 0.1 and 0.5 W-m-ι-K"1. One approach to increase the Thermal Conductivity of a polymer is to introduce High-Thermal-Conductivity fillers, such as aluminum oxide, aluminum nitride, boron nitride, silicon nitride, beryllium oxide, or diamond. In this review paper, we explore how dielectric polymer composites with High Thermal Conductivity have been developed.
Xingyi Huang - One of the best experts on this subject based on the ideXlab platform.
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Nanostructured electrical insulating epoxy thermosets with High Thermal Conductivity, High Thermal stability, High glass transition temperatures and excellent dielectric properties
IEEE Transactions on Dielectrics and Electrical Insulation, 2015Co-Authors: Hailin Mo, Xingyi Huang, Shengtao Li, Fei Liu, Ke Yang, Pingkai JiangAbstract:The need for improving performance of electronic devices and electrical equipment has always resulted in new High-performance electrical insulating materials. One important issue is the necessity to use dielectric polymers with Higher Thermal conductivities. In this study, by forming ordered nanostructure in epoxy resin via introducing 4, 4'- dihydroxydiphenyl (DHDP), electrical insulating epoxy thermosets simultaneously having High Thermal Conductivity, High Thermal stability, High glass transition temperatures and excellent dielectric properties were successfully prepared. The introduction of DHDP not only increases the rigidity of the modified epoxy chains but also results in ordered nanostructure in the modified epoxy thermosets, which is considered as the main factor for the performance improvement of the modified epoxy thermosets.
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Polyhedral oligosilsesquioxane-modified boron nitride nanotube based epoxy nanocomposites: An ideal dielectric material with High Thermal Conductivity
Advanced Functional Materials, 2013Co-Authors: Xingyi Huang, Pingkai Jiang, Yoshio Bando, Chunyi Zhi, Toshikatsu TanakaAbstract:Dielectric polymer composites with High Thermal Conductivity are very promising for microelectronic packaging and Thermal management application in new energy systems such as solar cells and light emitting diodes (LEDs). However, a well-known paradox is that conventional composites with High Thermal Conductivity usually suffer from the High dielectric constant and High dielectric loss, while on the other hand, composite materials with excellent dielectric properties usually possess low Thermal Conductivity. In this work, an ideal dielectric Thermally conductive epoxy nanocomposite is successfully fabricated using polyhedral oligosilsesquioxane (POSS) functionalized boron nitride nanotubes (BNNTs) as fillers. The nanocomposites with 30 wt% fraction of POSS modified BNNTs exhibit much lower dielectric constant, dielectric loss tangent, and coefficient of Thermal expansion in comparison with the pure epoxy resin. As an example, below 100 Hz, the dielectric loss of the nanocomposites with 20 and 30 wt% BNNTs is reduced by one order of magnitude in comparison with the pure epoxy resin. Moreover, the nanocomposites show a dramatic Thermal Conductivity enhancement of 1360% in comparison with the pristine epoxy resin at a BNNT loading fraction of 30 wt%. The merits of the designed composites are suggested to originate from the excellent intrinsic properties of embedded BNNTs, effective surface modification by POSS molecules, and carefully developed composite preparation methods.
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large dielectric constant and High Thermal Conductivity in poly vinylidene fluoride barium titanate silicon carbide three phase nanocomposites
ACS Applied Materials & Interfaces, 2011Co-Authors: Yong Li, Xingyi Huang, Pingkai Jiang, Shengtao Li, Zhiwei Hu, T TanakaAbstract:Dielectric polymer composites with High dielectric constants and High Thermal Conductivity have many potential applications in modern electronic and electrical industry. In this study, three-phase composites comprising poly(vinylidene fluoride) (PVDF), barium titanate (BT) nanoparticles, and β-silicon carbide (β-SiC) whiskers were prepared. The superiority of this method is that, when compared with the two-phase PVDF/BT composites, three-phase composites not only show significantly increased dielectric constants but also have Higher Thermal Conductivity. Our results show that the addition of 17.5 vol % β-SiC whiskers increases the dielectric constants of PVDF/BT nanocomposites from 39 to 325 at 1000 Hz, while the addition of 20.0 vol % β-SiC whiskers increases the Thermal Conductivity of PVDF/BT nanocomposites from 1.05 to 1.68 W m–1 K–1 at 25 °C. PVDF/β-SiC composites were also prepared for comparative research. It was found that PVDF/BT/β-SiC composites show much Higher dielectric constants in compariso...
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A review of dielectric polymer composites with High Thermal Conductivity
IEEE Electrical Insulation Magazine, 2011Co-Authors: Xingyi Huang, Pingkai Jiang, Toshikatsu TanakaAbstract:The continuing miniaturization of electronic devices and the increasing power output of electrical equipment have created new challenges in packaging and insulating materials. The key goals are to develop materials with High Thermal Conductivity, low coefficient of Thermal expansion (CTE), low dielectric con stant, High electrical resistivity, High breakdown strength, and most importantly, low cost. Polymeric materials have attracted increasing interest because of their excellent processability and low cost; however, most polymers are Thermally insulating and have a Thermal Conductivity between 0.1 and 0.5 W-m-ι-K"1. One approach to increase the Thermal Conductivity of a polymer is to introduce High-Thermal-Conductivity fillers, such as aluminum oxide, aluminum nitride, boron nitride, silicon nitride, beryllium oxide, or diamond. In this review paper, we explore how dielectric polymer composites with High Thermal Conductivity have been developed.
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ferroelectric polymer silver nanocomposites with High dielectric constant and High Thermal Conductivity
Applied Physics Letters, 2009Co-Authors: Xingyi Huang, Pingkai JiangAbstract:Ferroelectric polymer nanocomposites with silver (Ag) nanoparticles as inclusions were prepared and the dielectric properties and Thermal Conductivity were studied. The results showed that the nanocomposites have High dielectric constant and High Thermal Conductivity. When the loading level of Ag nanoparticles is 20.0 vol %, the dielectric constant and Thermal Conductivity of the nanocomposites were 120 at 103 Hz and 6.5 W/mK, respectively. Our results also showed that there is no percolation in the nanocomposites when Ag loading range is within 20.0%.
Xiaoliang Zeng - One of the best experts on this subject based on the ideXlab platform.
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nacre inspired polymer composites with High Thermal Conductivity and enhanced mechanical strength
Composites Part A-applied Science and Manufacturing, 2019Co-Authors: Tao Zhang, Yimin Yao, Jiajia Sun, Xiaoliang Zeng, Rong Sun, Linlin Ren, Mingmei Wang, Ching-ping WongAbstract:Abstract Polymer composites with High Thermal Conductivity are attracting increasing interest as Thermal-management materials owing to material abundance, easy processing and low cost. However, conventional preparation of Thermally conductive polymer composites through adding High-loading inorganic fillers usually suffers from poor mechanical properties. Here, inspired by the microstructure of natural nacre, we report on fine ordered Ag-BN/epoxy resin composites via interfacial manipulation of boron nitrides with Ag nanoparticles and hot-pressing induced orientation process. The as-prepared nacre-like compounds have both High Thermal Conductivity (up to 23.1 W m−1 K−1) and mechanical strength (tensile strength of 80.3 MPa). This work provides a novel insight into the fabrication of polymer composites with superior mechanical strength in Thermal management field.
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A Combination of Boron Nitride Nanotubes and Cellulose Nanofibers for the Preparation of a Nanocomposite with High Thermal Conductivity
ACS Nano, 2017Co-Authors: Xiaoliang Zeng, Yimin Yao, Jiajia Sun, Jian-bin Xu, Rong Sun, Ching-ping WongAbstract:With the current development of modern electronics toward miniaturization, High-degree integration and multifunctionalization, considerable heat is accumulated, which results in the Thermal failure or even explosion of modern electronics. The Thermal Conductivity of materials has thus attracted much attention in modern electronics. Although polymer composites with enhanced Thermal Conductivity are expected to address this issue, achieving Higher Thermal Conductivity (above 10 W m–1 K–1) at filler loadings below 50.0 wt % remains challenging. Here, we report a nanocomposite consisting of boron nitride nanotubes and cellulose nanofibers that exhibits High Thermal Conductivity (21.39 W m–1 K–1) at 25.0 wt % boron nitride nanotubes. Such High Thermal Conductivity is attributed to the High intrinsic Thermal Conductivity of boron nitride nanotubes and cellulose nanofibers, the one-dimensional structure of boron nitride nanotubes, and the reduced interfacial Thermal resistance due to the strong interaction betwe...
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silver nanoparticle deposited boron nitride nanosheets as fillers for polymeric composites with High Thermal Conductivity
Scientific Reports, 2016Co-Authors: Yimin Yao, Xiaoliang Zeng, Rong Sun, Ching-ping Wong, Fangfang WangAbstract:Polymer composites with High Thermal Conductivity have recently attracted much attention, along with the rapid development of the electronic devices toward Higher speed and performance. However, a common method to enhance polymer Thermal Conductivity through an addition of High Thermally conductive fillers usually cannot provide an expected value, especially for composites requiring electrical insulation. Here, we show that polymeric composites with silver nanoparticle-deposited boron nitride nanosheets as fillers could effectively enhance the Thermal Conductivity of polymer, thanks to the bridging connections of silver nanoparticles among boron nitride nanosheets. The Thermal Conductivity of the composite is significantly increased from 1.63 W/m-K for the composite filled with the silver nanoparticle-deposited boron nitride nanosheets to 3.06 W/m-K at the boron nitride nanosheets loading of 25.1 vol %. In addition, the electrically insulating properties of the composite are well preserved. Fitting the measured Thermal Conductivity of epoxy composite with one physical model indicates that the composite with silver nanoparticle-deposited boron nitride nanosheets outperforms the one with boron nitride nanosheets, owning to the lower Thermal contact resistance among boron nitride nanosheets’ interfaces. The finding sheds new light on enhancement of Thermal Conductivity of the polymeric composites which concurrently require the electrical insulation.
Toshikatsu Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Polyhedral oligosilsesquioxane-modified boron nitride nanotube based epoxy nanocomposites: An ideal dielectric material with High Thermal Conductivity
Advanced Functional Materials, 2013Co-Authors: Xingyi Huang, Pingkai Jiang, Yoshio Bando, Chunyi Zhi, Toshikatsu TanakaAbstract:Dielectric polymer composites with High Thermal Conductivity are very promising for microelectronic packaging and Thermal management application in new energy systems such as solar cells and light emitting diodes (LEDs). However, a well-known paradox is that conventional composites with High Thermal Conductivity usually suffer from the High dielectric constant and High dielectric loss, while on the other hand, composite materials with excellent dielectric properties usually possess low Thermal Conductivity. In this work, an ideal dielectric Thermally conductive epoxy nanocomposite is successfully fabricated using polyhedral oligosilsesquioxane (POSS) functionalized boron nitride nanotubes (BNNTs) as fillers. The nanocomposites with 30 wt% fraction of POSS modified BNNTs exhibit much lower dielectric constant, dielectric loss tangent, and coefficient of Thermal expansion in comparison with the pure epoxy resin. As an example, below 100 Hz, the dielectric loss of the nanocomposites with 20 and 30 wt% BNNTs is reduced by one order of magnitude in comparison with the pure epoxy resin. Moreover, the nanocomposites show a dramatic Thermal Conductivity enhancement of 1360% in comparison with the pristine epoxy resin at a BNNT loading fraction of 30 wt%. The merits of the designed composites are suggested to originate from the excellent intrinsic properties of embedded BNNTs, effective surface modification by POSS molecules, and carefully developed composite preparation methods.
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development of epoxy bn composites with High Thermal Conductivity and sufficient dielectric breakdown strength parti sample preparations and Thermal Conductivity
IEEE Transactions on Dielectrics and Electrical Insulation, 2011Co-Authors: Zengbin Wang, Tomonori Iizuka, Masahiro Kozako, Yoshimichi Ohki, Toshikatsu TanakaAbstract:The aim of this research is to find a way to achieve the epoxy composites with both High Thermal Conductivity and acceptable dielectric breakdown (BD) strength. As High Thermal Conductivity, low permittivity and low Thermal expansion coefficient of filler can endow composite with Higher Thermal Conductivity, Higher BD strength and lower Thermal expansion coefficient respectively, BN (boron nitride) with High Thermal Conductivity, low permittivity and low Thermal expansion coefficient was adopted as main filler in the research. Thermal Conductivity was investigated in this part. The BD strength of samples will be discussed in Part II. Neat epoxy and other 25 kinds of epoxy/BN composites were prepared by a hot press method. Most of BN fillers were surface modified with silane coupling agent through ethanol/water reflux method to improve Thermal Conductivity. The values of 2.91 W/m·K, 3.95 W/m·K and 10.1 W/m·K as Thermal Conductivity were obtained for the composites that was single-loaded with h-BN(hexagonal boron nitride), c-BN (cubic boron nitride) or conglomerated h-BN, respectively. They were further improved to 5.26 W/m·K, 5.94 W/m·K and 12.3 W/m·K, respectively, by adding extra smaller A1N (aluminum nitride) to fill the voids in sample. Thermal Conductivity of samples changes with the ratio of c-BN and h-BN when c-BN and h-BN were co-loaded. A value of 5.74 W/m·K as maximum was obtained at their ratio of 1 to 1 when total filler content is 80 wt%. A much Higher value of 7.69 W/m·K was obtained by adding extra AIN. From the experiment data, it is concluded that the filler orientation in vertical direction of sample surface and the decrease of voids in sample are very important to obtain High Thermal Conductivity, and that the filler surface modification is also necessary to improve Thermal Conductivity especially for epoxy/c-BN composites, and addition of nano silica in small amount can also increase Thermal Conductivity if sample is prepared appropriately.
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development of epoxy bn composites with High Thermal Conductivity and sufficient dielectric breakdown strength part ii breakdown strength
IEEE Transactions on Dielectrics and Electrical Insulation, 2011Co-Authors: Zengbin Wang, Tomonori Iizuka, Masahiro Kozako, Yoshimichi Ohki, Toshikatsu TanakaAbstract:The aim of this research is to find a way to achieve the epoxy composites with High Thermal Conductivity and acceptable dielectric breakdown (BD) strength. A value 12.3 W/m·K is the Highest Thermal Conductivity obtained for epoxy composite in Part I. Dielectric breakdown performances such as short-time dielectric breakdown strength (BD strength), partial discharge (PD) resistance and BD time for composites were investigated in the Part II. In general, micro filler inclusion will increase Thermal Conductivity and decrease dielectric breakdown performance. Influencing factors are considered to be the orientation of filler, the content of void space, the content ratio in the case of co-mixing, the addition of nano filler, and filler surface modification. Twenty six kinds of composites were prepared in consideration of the above influencing factors. There are two options for most appropriate ones among the composites evaluated in the research. One is an epoxy/ conglomerated h-BN composite with co-loaded nano SiO2 and micro AIN filler. It has 12.3 W/m·K in Thermal Conductivity, 75.1 kVpeak/mm in BD strength and 260 % of BD time for neat epoxy. It is most suitable when low BD strength and High Thermal Conductivity is needed. The other one is an epoxy/ h-BN composite with co-loaded nano silica and AIN filler for requirement of very High BD strength but lower Thermal Conductivity. Optimum Thermal Conductivity is obtained if flaky h-BN filler is oriented in parallel to heat flow. Since it is difficult to realize full orientation, the use of conglomerated h-BN filler is a suitable option. Optimum BD performance is obtained if void space is reduced by certain methods such as co-dispersion of different size fillers and addition of nano filler.
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A review of dielectric polymer composites with High Thermal Conductivity
IEEE Electrical Insulation Magazine, 2011Co-Authors: Xingyi Huang, Pingkai Jiang, Toshikatsu TanakaAbstract:The continuing miniaturization of electronic devices and the increasing power output of electrical equipment have created new challenges in packaging and insulating materials. The key goals are to develop materials with High Thermal Conductivity, low coefficient of Thermal expansion (CTE), low dielectric con stant, High electrical resistivity, High breakdown strength, and most importantly, low cost. Polymeric materials have attracted increasing interest because of their excellent processability and low cost; however, most polymers are Thermally insulating and have a Thermal Conductivity between 0.1 and 0.5 W-m-ι-K"1. One approach to increase the Thermal Conductivity of a polymer is to introduce High-Thermal-Conductivity fillers, such as aluminum oxide, aluminum nitride, boron nitride, silicon nitride, beryllium oxide, or diamond. In this review paper, we explore how dielectric polymer composites with High Thermal Conductivity have been developed.