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Tuo Ji Li‐Qun Zhang Wen‐Cai Wang Yu Liu Xiao‐Feng Zhang Yong‐Lai Lu 《Polymer Composites》2012,33(9):1473-1481
Hexagonal boron nitride (h‐BN) fillers were first coated with low‐molecular‐weight polydimethylsiloxane (PDMS) by solution dispersion and then treated in argon plasma for different times. The modified h‐BN fillers were characterized by high‐resolution transmission electron microscopy, X‐ray photoelectron spectroscopy, and contact angle analysis. The results revealed that a thin PDMS film several nanometers thick was tightly coated on the surface of the h‐BN filler after plasma treatment, and this thin film could not be removed by 48 h Soxhlet extraction with n‐hexane at 120°C. Furthermore, the effect of plasma modification on the h‐BN filled silicone rubber composites was investigated. The results indicated that the plasma modification improved the interfacial interaction between h‐BN and the matrix, but hardly affected the distribution state of the h‐BN in the composites. The composites filled with the modified h‐BN exhibit significantly higher thermal conductivity than the composites filled with untreated h‐BN. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers 相似文献
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The electrical conductivity of silicone rubber vulcanizates containing carbon blacks [e.g., acetylene black, lamp black, and ISAF (N-234) black] were investigated. The change in electrical conductivity with varying amounts of carbon blacks and the temperature dependence was measured. The mechanical properties like tensile strength, tear strength, elongation at break, hardness, etc., of the vulcanizates were determined. A comparative study of the electrical conductivity of the composites revealed that the electrical conductivity of the composites made with acetylene black was higher than that of the composites made of other blacks. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1043–1050, 1998 相似文献
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炭黑填充型导电硅橡胶的性能研究 总被引:1,自引:0,他引:1
研究炭黑品种及用量对硅橡胶导电性能和物理性能的影响。结果表明,乙炔炭黑填充的硅橡胶导电性能优于炭黑N234或N293填充的硅橡胶;随着炭黑用量的增大,硅橡胶邵尔A型硬度增大,拉伸强度和拉断伸长率先增大后减小,体积电阻率先增大后趋于稳定。 相似文献
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To attain thermally conductive but electrically insulating polymer films, in this study, polyimide (PI) nanocomposite films with 1–30 wt% functionalized hexagonal boron nitride nanosheets (BNNSs) were fabricated via solution casting and following imidization. The microstructures, mechanical and thermal conductive properties of PI/BNNS nanocomposite films were examined by taking account of the relative content, anisotropic orientation, and interfacial interaction of BNNS and PI matrix. The scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffractometry data revealed that BNNSs with hydroxy and amino functional groups have specific molecular interactions with PI matrix and they form stacked aggregates in the nanocomposite films with high BNNS loadings of 10–30 wt%. The tensile mechanical strength/modulus, thermal degradation temperatures, and thermal conductivity of the nanocomposite films were found to be significantly enhanced with increasing the BNNS loadings. For the nanocomposite films with 1–30 wt% BNNS loadings, the in-plane thermal conductivity was measured to be 1.82–2.38 W/mK, which were much higher than the out-of-plane values of 0.35–1.14 W/mK. The significant anisotropic thermal conductivity of the nanocomposite films was found to be owing to the synergistic anisotropic orientation effects of both BNNS and PI matrix. It is noticeable that the in-plane and out-of-plane thermal conductivity values of the nanocomposite film with 30 wt% BNNS were ~1.31 and ~3.35 times higher than those of neat PI film, respectively. 相似文献
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以甲基乙烯基硅橡胶(MVQ)为主体材料,用氮化硼填充MVQ制备导热橡胶,研究氮化硼用量、粒径等对MVQ导热性能、物理性能和工艺性能的影响。结果表明。随着氮化硼用量的增大。MVQ的热导率增大而工艺性能变差;氮化硼最大适宜用量为150份。小粒径氮化硼填充MVQ的物理性能较好,工艺性能稍差。氮化硼用量小于70份时,粒径为20μm的氮化硼填充MVQ的导热性能较好;氮化硼用量为70~180份时,粒径为6μm的氮化硼填充MVQ的导热性能较好。不同粒径氮化硼按适当比例配合填充MVQ的导热性能优于单一粒径氮化硼填充MVQ.且物理性能改善。 相似文献
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Highly thermally conductive hexagonal boron nitride/alumina composite made from commercial hexagonal boron nitride 下载免费PDF全文
Ching‐cheh Hung Janet Hurst Diana Santiago Maricela Lizcano Marisabel Kelly 《Journal of the American Ceramic Society》2017,100(2):515-519
Hexagonal BN is an unusual material in that it is both highly thermally conductive as well as an electrical insulator. Additionally, hBN is also thermally stable in air. This unusual combination of properties makes hBN of significant interest for thermal management. Unfortunately, hBN is not easily consolidated into substrates without the addition of second phases which generally result in poorer thermal performance. This research investigates the potential to utilize this material to dissipate heat from high‐voltage, high‐power electrical devices. Specifically, a process to coat individual platelets of commercial hexagonal BN powder with a layer of amorphous aluminum oxide was developed. The coated hexagonal BN was then hot‐pressed to form a highly thermally conductive substrate. The process to coat hexagonal BN platelets with aluminum oxide was accomplished by mixing hexagonal BN with AlCl3 containing some water, then evaporation of excess AlCl3 to form a Al, Cl, and O layer on hexagonal BN. This product was then heated in air to convert the surface layer into aluminum oxide. Following hot pressing to 1950°C and 10 ksi, the consolidated composite has through‐plane and in‐plane thermal conductivity of 14 and 157 W·(m·K)?1, respectively, at room temperature. 相似文献
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The silicone rubber with good thermal conductivity and electrical insulation was obtained by taking vinyl endblocked polymethylsiloxane as basic gum and thermally conductive, but electrically insulating hybrid Al2O3 powder as fillers. The effects of the amount of Al2O3 on the thermal conductivity, coefficient of thermal expansion (CTE), heat stability, and mechanical properties of the silicone rubber were investigated, and it was found that the thermal conductivity and heat stability increased, but the CTE decreased with increasing Al2O3 fillers content. The silicone rubber filled with hybrid Al2O3 fillers exhibited higher thermal conductivity compared with that filled with single particle size. Furthermore, a new type of thermally conductive silicone rubber composites, possessing thermal conductivity of 0.92 W/mK, good electrical insulation, and mechanical properties, was developed using electrical glass cloth as reinforcement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2478–2483, 2007 相似文献
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Jia-Le Li Quan-Ping Zhang Xue Liu Rui-Chao Chen Wei-Di Xu Nan Sun Yin-Tao Li Wen-Bin Yang Dui-Gong Xu Yuan-Lin Zhou 《应用聚合物科学杂志》2021,138(31):50774
Flexible materials with excellent radiation shielding and flexibility are essential to the personal protective equipments (PPEs) for protecting workers from nuclear radiations. However, it is an enormous challenge to obtain the desired materials since high loading filler in polymer nanocomposites usually promotes radiation shielding while restrains its flexibility. Here, a facile “thiol-ene click” means is applied to chemically bond high loading boron nitride (BN) nanoparticles with silicone rubber (SR) in SR/BN nanocomposites for thermal neutron shielding. Uniform dispersion of BN nanoparticles and good compatibility of interfaces in the nanocomposites with high loading filler lead to increased flexibility instead of decrease. In particular, the nanocomposite with 40 wt% BN displays 911% of elongation at break that is about 50% enhancement to that of neat SR. Furthermore, higher loading BN in the nanocomposites means better thermal neutron shielding. Namely, enhanced thermal neutron shielding and flexibility is achieved at SR/BN nanocomposite with 40 wt% BN. The present work provides a facile strategy towards superior integrated performance of flexible materials for radiation shielding, such as wearable devices. 相似文献
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Yujun Jia Tosin D. Ajayi Justin Morales Md Atiqur Rahman Chowdhury Godfrey Sauti Sang-Hyon Chu Cheol Park Chengying Xu 《Journal of the American Ceramic Society》2019,102(12):7584-7593
We report the thermal properties of boron nitride nanotube (BNNT) reinforced ceramic composites using the polymer derived ceramic (PDC) processing route. The nano-composites had a BNNT loading of up to 35.4 vol.%. TGA results showed that nano-composites have good thermal stability up to 900°C in air. BNNTs in nano-composites survived in an oxidizing environment up to 900°C, revealing that nano-composites can be used for high temperature applications. Thermal conductivity of PDC reinforced with 35.4 vol.% BNNT was measured as 4.123 W/(m·K) at room temperature, which is a 2100 % increase compared to that of pristine PDC. The thermal conductivity value increases with the increase of BNNT content. A thermal conductivity percolation phenomenon appeared when the BNNT content increased to 36 ± 5 vol.%. The results of this study showed that BNNTs could effectively improve the thermal conductivity of PDC materials. BNNT reinforced PDC could be used as thermal structural materials in a harsh environment at temperatures up to 900°C. 相似文献
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Yujun Jia Tosin D. Ajayi Chengying Xu 《Journal of the American Ceramic Society》2020,103(10):5731-5742
The electrical and dielectric properties of boron nitride nanotubes (BNNTs) reinforced ceramic composites using the polymer-derived ceramic (PDC) processing route were investigated in this work. The electrical resistivity of the pristine PDC increases from 106 to 108 Ω m after the addition of BNNTs. When the BNNT loading was increased to 5 wt%, the average real relative permittivity of the PDC decreased from 2.94 to 2.80, while the quality factor (Q) of the PDC increased from 134.40 to 176.77. The BNNTs can increase the Q factor of the PDC due to the reduction in the porosity cause by the introduction of the BNNTs. Further increasing the BNNT content decreases the real relative permittivity of the nanocomposites and increases the Q factor at high frequency. The average real relative permittivity decreases to 2.29, while the average Q factor increases to 208.60 when the BNNT content is increased to 30 wt%. The dielectric loss after the addition of high fraction of BNNTs can be explained by the Lorentz resonance relaxation process. Results of this work showed that PDC-BNNT nanocomposites are satisfactory electromagnetic transparent materials when the BNNT fraction is less than 10 wt%. 相似文献
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高结构导电炭黑填充硅橡胶复合材料的性能 总被引:12,自引:1,他引:12
研究了导电炭黑(HG-CB)的高结构对乙烯基甲基硅橡胶(VMQ-110)复合材料电性能和机构性能的影响。由TEM观察看出,随HG-CB用量增加,其在硫化胶中形成的导电网络逐渐完善,用量达19份(质量份,下同)时已形成完整的导电网络,导电机理可用电子隧道效应来解释,同时随HG-CB填充量增加,复合材料的拉伸强度、硬度增大,但对VMQ-110的硫化有影响。欠硫现象严重,HG-CB的用量一般控制在10~15份,所得硅橡胶复合材料具有较佳的电性能和机械性能。 相似文献
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S. P. Bogdanov 《Glass Physics and Chemistry》2008,34(2):213-217
The influence of the reduced radius of grains of the graphite-like hexagonal boron nitride (h-BN) on the nucleation of the cubic boron nitride (c-BN) during synthesis from an initiator solution at a high pressure is analyzed. The colloidal mechanism of nucleation is
confirmed experimentally. It is shown that there is a correlation between the nucleus sizes of the hexagonal boron nitride
and the pressure of the onset of nucleation of the cubic boron nitride. The effect of these sizes of the hexagonal boron nitride
on the concentration of crystal nuclei of the cubic boron nitride is studied. The kinetic nucleation curves are obtained.
It is demonstrated that the concentration of crystallization centers depends on the thermodynamic and kinetic parameters,
as well as on the particle size of the graphite-like hexagonal boron nitride.
Original Russian Text ? S.P. Bogdanov, 2008, published in Fizika i Khimiya Stekla. 相似文献