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排序方式: 共有619条查询结果,搜索用时 15 毫秒
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Min Jung Kang Youn Hee Kim Gun Pyo Park Mi Sun Han Woo Nyon Kim Sang Do Park 《Journal of Materials Science》2010,45(19):5412-5419
The effects of liquid-type nucleating silane additives on the cell structure, mechanical strength, and thermal insulating
properties of the polyisocyanurate (PIR) foams have been studied. The PIR foams synthesized with hexamethyldisilazane (HMDS)
as a silane additive showed the smaller average cell size and lower thermal conductivity than those of the PIR foams prepared
with the hexamethyldisiloxane, dimethoxydimethylsilane, and hexadecyltrimethoxysilane. When HMDS was added, average cell size
of the PIR foam was becoming smaller due to lower surface tension of the polyol solution, thereby the nucleation rate and
number of bubbles produced were increased and then the cell size becomes smaller. The additives likely act as nucleating agents
during the formation of PIR foams. The smaller cell size appears to be one of the major reasons for the improvement of thermal
insulation properties and mechanical properties of the PIR foams. From the results of cell size, thermal conductivity, and
mechanical strength of the PIR foams, it is suggested that the HMDS may be the efficient liquid-type additive for the reduction
of cell size and improvement of the thermal insulation property of the PIR foams. 相似文献
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V. I. Gun’ko L. I. Onishchenko I. Yu. Grebennikov A. Ya. Dmitrishin S. O. Toporov E. N. Slepets 《Surface Engineering and Applied Electrochemistry》2008,44(2):154-158
The influence of structural materials on the basic electrophysical characteristics (relative permittivity, loss tangent, volume electric resistivity, and electric strength) of phenylxylilethane is considered in this paper. 相似文献
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V. I. Gun’ko L. I. Onishchenko I. Yu. Grebennikov A. Ya. Dmitrishin S. O. Toporov 《Russian Electrical Engineering》2008,79(7):405-406
The results of investigations of the influence of high temperatures and pressure on the electric strength of polymethylsyloxane liquid PMS-20 and castor oil saturated by elegas (SF6) are presented. The research data can be applied to the design of electrotechnical devices, specifically high-voltage pulse capacitors Published by way of discussion. 相似文献
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Jinwoo Choi Dong Gun Kam Daehyun Chung Srinivasan K. Govind V. Joungho Kim Swaminathan M. 《Advanced Packaging, IEEE Transactions on》2007,30(2):180-190
This paper presents near-field (NF) and far-field (FF) analysis of alternating impedance electromagnetic bandgap (AI-EBG) structure in packages and boards. Three test vehicles have been designed and fabricated for NF and FF measurements. Simulation results using a full-wave solver (SONNET) have been compared with measurement results. This paper investigates the radiation due to return current on different reference planes. The analysis results from simulations and measurements provide important guidelines for design of the AI-EBG structure based power distribution network for noise isolation and suppression in mixed-signal systems 相似文献
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Petroleum‐based pitches were used as filler materials to study the effects of heat‐treatment‐induced changes in pitch structure on the thermal conductivity of epoxy‐based composites. The heat treatment was performed in two steps: the first involved heating the pitch to 250 °C in order to remove the low‐molecular‐weight compounds from the pitch, and the second involved heating the pitch to either 430 or 450 °C. There was no significant difference in the curing behavior of the diglycidyl ether of bisphenol A (DGEBA)/pitch composites, regardless of the heat‐treatment temperature. However, the thermal conductivity of the DGEBA/pitch composites improved with increasing heat‐treatment temperature, and the epoxy composite prepared with pitch heat‐treated at 430 °C exhibited the maximum thermal conductivity. This can be attributed to structural changes in the pitch, such as the distance between adjacent planes (d‐spacing), crystallite height (Lc) and crystallite width (La). Although Lc of the pitch increased with increasing heat‐treatment temperature, the d‐spacings and La decreased. These results suggest that the heat treatment of the pitch led to a well‐stacked crystalline structure. However, compared with the pitch heat‐treated at 430 °C, that heat‐treated at 450 °C exhibited lower thermal conductivity in the DGEBA/pitch composite because of the low La, resulting in the loss of basal carbon as a consequence of in situ gasification, and pyrolysis of the low‐molecular‐weight compounds in the pitch. © 2013 Society of Chemical Industry 相似文献
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