六方氮化硼/纳米纤维素气凝胶孔结构调控及其复合膜导热性能研究

Study on Pore Structure Regulation of h-BN/TOCNF Aerogel and Thermal Conductivity of Its Composite Film

关键词:  六方氮化硼  TEMPO氧化纳米纤维素  气凝胶  复合膜  绝缘性能  导热性能

Key Words:h-BN  TOCNF  aerogel  composite film  electrical insulation property  thermal conductivity

摘要:为解决微型化电子电器设备内部的散热问题，本研究设计、制备了具有不同孔结构的六方氮化硼（h-BN）/TEMPO氧化纳米纤维素（TOCNF）气凝胶，后复合TOCNF，制备了h-BN/TOCNF复合膜。结果表明，当h-BN与TOCNF固含量比为3∶1时，在气凝胶内部，h-BN可以沿着TOCNF骨架形成三维网络状导热通道，此时TOCNF对h-BN间产生的热阻最小，且能够对h-BN起到良好的分散作用，导热通道的构建效率最高，制备的复合膜导热系数高达1.355 W/（m·K），相比于纯TOCNF膜提高了228%；体积电阻率为4.53×10¹⁴ Ω·cm，具有良好的绝缘性能。此外，通过热重（TG）分析发现，h-BN/TOCNF复合膜的初始分解温度约为210℃，具有良好的热稳定性；且h-BN/TOCNF复合膜具有优异的力学性能，其中h-BN和TOCNF固含量比为1∶1时，复合膜的强度最好，断裂伸长率约为13%，拉伸强度为24.8 MPa，随着h-BN含量的增加，复合膜的断裂伸长率变低，拉伸强度变化不大。

Abstract:To solve the heat-dissipation issue of miniaturized electronic and electrical equipment， the hexagonal boron nitride （h-BN）/TEMPO-oxidization nanocellulose （TOCNF） aerogels with different pore structure were designed and prepared in this study， which was then compounded with TOCNF to fabricate h-BN/TOCNF composite films. The results showed that when the ratio of h-BN to TOCNF was 3 ∶ 1， h-BN could form a 3D thermal conductive pathway along the TOCNF framework inside the h-BN/TOCNF aerogelin which TOCNF generated the minimum thermal resistance between h-BNs and played a favorable role in dispersing h-BNs， showing the maximum structuring efficiency of the 3D thermal conductive pathway. The thermal conductivity of the h-BN/TOCNF composite film was as high as 1.355 W/（m·K）， 228% higher than that of the pure TOCNF film， the volume resistivity was 4.53×10¹⁴ Ω•cm， indicating good electrical insulation property. In addition， thermogravimetric （TG） analysis showed that the initial decomposition temperature of h-BN/TOCNF composite film was about 210°C， showing good thermal stability. Furthermore， desirable mechanical properties of h-BN/TOCNF composite film were endowed， the elongation at break and tensile strength of h-BN/TOCNF1 were 13% and 24.8 MPa when the ratio of h-BN to TOCNF was 1 ∶ 1， respectively. It was worth noting that with the increase of h-BN loading， the elongation at break of the composite films decreased， while the tensile strength had negligible variation.