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向环氧树脂基体中加入纳米填料是实现其多功能化的常用手段, 其中拥有一维纳米结构的氮化硼纳米管 (BNNTs), 因具有超高导热系数、宽能级带隙、高长径比、高力学强度而备受关注. 然而, 表面惰性、易团聚、与环氧树脂之间界面作用弱等缺点极大地制约了BNNTs进一步应用. 基于此, 本文提出采用表面包覆介孔二氧化硅 (mSiO 2), 并接枝硅烷偶联剂功能分子的方法, 优化BNNTs表面特性. 结果表明, 通过表面结构设计及功能化, 可显著改善BNNTs的分散特性, 提升其与环氧树脂的界面作用. 以此所制备的环氧复合电介质可实现力学韧性和导热系数的同步提升, 并兼具较低的介电常数与损耗. 此外, mSiO 2独特的纳米介孔结构赋予复合电介质大量的深陷阱, 有效阻碍了电子的迁移, 进而提高复合电介质的电气强度. 本文为环氧树脂的多功能化提供了新思路, 亦对揭示纳米填料表面特性-复合电介质微观结构-宏观性能之间的关联关系提供了一定实验数据支撑.Adding nanofillers into epoxy resin matrices is a common method to achieve their multi-function. Boron nitride nanotubes (BNNTs) with one-dimensional nanostructures have attracted much attention because of their ultra-high thermal conductivity, wide energy level band gap, high aspect ratio and mechanical strength. Yet, the strong π-π non-covalent bonding and lip-lip interactions make BNNTs prone to agglomeration in the epoxy resin matrix. Moreover, the different physicochemical properties of BNNTs and epoxy resins as well as the chemical inertness of BNNTs surface lead to the lack of effective interfacial interaction between BNNTs and epoxy resin matrix. Therefore, the performance of the epoxy composite dielectric is not enhanced by simple blending solely, but will even have the opposite effect. To address the problems of BNNTs, in this study, the surface structure of BNNTs is constructed from the perspective of interface modulation by using sol-gel method to coat mesoporous silica (mSiO 2) on BNNTs’ surface and further introducing silane coupling agent (KH560). The results indicate that the surface structure of BNNTs can optimize the level of interfacial interaction between BNNTs and epoxy resin matrix, which leads to stronger interfacial connection and elimination of internal pore phenomenon. The dielectric constant and loss of the composite dielectric prepared in this way are further reduced, reaching 4.1 and 0.005 respectively at power frequency, which is significantly lower than that of pure epoxy resin. At the same time, the mechanical toughness (3.01 MJ/m 3) and thermal conductivity (0.34 W/(m⋅K)) are greatly improved compared with the counterparts of pure epoxy resin. In addition, the unique nano-mesoporous structure of mSiO 2endows the composite dielectric with a large number of deep traps, which effectively hinders the migration of electrons, thereby improving the electrical strength of the composite dielectric, and the breakdown field strength reaches 95.42 kV/mm. Furthermore, the interfacial mechanism of BNNTs’ surface structure on dielectric relaxation and trap distribution of composite dielectrics is systematically studied by Tanaka multinuclear model. The above results indicate that the good interfacial interaction between BNNTs and epoxy resin matrix is crucial in establishing the micro-interface structure and improving the macroscopic properties of composite dielectrics. This study presents a novel idea for the multifunctionalities of epoxy resin, and also provides some experimental data support for revealing the correlation among surface properties of nano-fillers, microstructure and macroscopic properties of composite dielectric.
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复合电介质 温度/℃ $ {\omega _1} $/Hz $ {\gamma _1} $ $ {\omega _2} $/Hz $ {\gamma _2} $ $ {\varepsilon _\infty } $ $ {\varepsilon _{\text{s}}} $ Epoxy 150 0.32 0.79 8000 0.60 3.50 22.0 140 0.3 0.91 600 0.60 3.75 10.0 130 0.34 0.99 50 0.45 3.6 7.0 BNNTs 150 0.5 0.9 8000 0.60 4.60 22.0 140 0.5 0.95 5000 0.60 4.60 16.5 130 0.38 0.97 1500 0.50 4.45 10.0 BNNTs@mSiO2-KH560 150 0.25 0.9 8000 0.60 4.90 28.0 140 0.13 0.85 1000 0.45 4.50 24.0 130 0.05 0.65 260 0.45 4.30 15.0 
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复合电介质 标准击穿场强/
(kV·mm–1)形状参数 Epoxy 26.02 4.31 BNNTs-0.5 20.92 4.30 BNNTs-3 36.04 22.89 BNNTs@mSiO2-KH560-0.5 29.69 6.25 BNNTs@mSiO2-KH560-1 42.90 7.35 BNNTs@mSiO2-KH560-2 69.50 6.73 BNNTs@mSiO2-KH560-3 95.42 6.67 下载:
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复合电介质 $ \alpha $ 陷阱 $ \beta $ 陷阱 $ Q $/pC $ E $/eV $ {Q_\alpha } $/pC $ E $/eV $ {Q_\beta } $/pC Epoxy 0.14 134 — — 134 BNNTs 0.07 94 — — 94 BNNTs@mSiO2-KH560 0.20 652 0.82 0.32 652.32 下载:
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复合电介质 韧性/(MJ·m–3) Epoxy 1.01 BNNTs-0.5 1.02 BNNTs-1 1.04 BNNTs-2 1.37 BNNTs-3 1.83 BNNTs@mSiO2-KH560-0.5 1.78 BNNTs@mSiO2-KH560-1 2.21 BNNTs@mSiO2-KH560-2 2.61 BNNTs@mSiO2-KH560-3 3.01 下载:
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