六方氮化硼改性聚合物基介电复合材料的研究进展

综述了近年来国内外利用六方氮化硼来改善聚合物基复合材料介电性能的研究工作进展,介绍了多种六方氮化硼的制备方法与不同复合策略的优势与不足。指出了利用六方氮化硼改善聚合物基介电复合材料性能时存在的问题和发展方向。     

六方氮化硼/碳化硅晶须填充改性聚酰亚胺导热绝缘复合材料的制备及表征

采用固相共混方法将六方氮化硼(h-BN)和碳化硅晶须(SiCw)作为导热填料对单醚酐型聚酰亚胺(PI)模塑粉进行改性,然后通过热模压工艺制备PI导热绝缘复合模压材料,并对其性能进行表征。测试结果表明:h-BN可以有效提高模塑料导热性能、热性能和电绝缘性能,但会降低材料力学性能;SiCw可以有效提高复合材料导热性能、热性能和力学性能,但会显著降低电绝缘性能。将h-BN/SiCw复配使用,在显著提高复合材料导热性能和热性能的同时又可保持其良好的力学性能和电绝缘性能。添加30%(质量分数)h-BN/SiCw(3/1),复合材料导热系数提高至1.21 W/(m·K),是未改性PI材料的4.84倍,弯曲强度为142MPa,体积电阻率为1.27×10~(14)Ω·cm,线性热膨胀系数(CTE)显著降低为55.6μm/(m·℃)。     

基于氮化硼取向结构的高导热聚合物基复合材料研究进展

简要介绍了氮化硼的分类、结构特点以及其导热特性。重点概述了近几年基于在聚合物基体中形成氮化硼取向结构制备高导热复合材料的研究进展,分析了磁场诱导法、电场诱导法、剪切诱导法、冰晶诱导法以及热压取向等方法的特点。对氮化硼取向填充的导热聚合物基复合材料的未来发展趋势进行了分析与展望,为低填充、高导热绝缘聚合物基复合材料的开发及应用提供借鉴。     

用于导热绝缘环氧树脂复合材料的氮化硼改性研究进展

环氧树脂是电子器件常用的绝缘高分子基体材料,但存在导热性偏低的问题。六方氮化硼(h-BN)常被用于环氧树脂的导热填料,而h-BN的化学惰性使其在环氧树脂中的分散性和相容性较差,限制了其作用的发挥,因而对其进行改性就成了导热绝缘环氧树脂复合材料制备中需要面对的一个重要问题。本文主要总结了近年来用于导热绝缘环氧树脂复合材料的氮化硼的改性方法及其特点,其中包括剥离、包覆、场取向和杂化等物理方法,以及功能化、偶联剂修饰、活性剂修饰、化学接枝等化学方法,并对BN改性今后的发展趋势进行了讨论。     

聚丙烯/高密度聚乙烯/氮化硼导热复合材料的制备及性能研究

以聚丙烯（PP）/高密度聚乙烯（HDPE）共混物为基体,六方氮化硼（h-BN）为导热填料,聚丙烯接枝马来酸酐（PP-g-MAH）为相容剂,通过熔融共混法制备PP/HDPE/h-BN和PP/HDPE/h-BN/PP-g-MAH导热复合材料。采用导热系数仪、场发射扫描电镜、万能试验机、热分析仪等测试导热复合材料,研究不同含量的h-BN、PP-g-MAH对复合材料导热性、力学性能、结晶性能和耐热性的影响。结果表明：随着h-BN含量的增加,PP/HDPE/h-BN复合材料的弯曲强度、热导率和耐热性提高。当h-BN含量为20%,复合材料的弯曲强度达到41.02 MPa;当h-BN含量为25%,复合材料热导率达到0.372 1 W/（m·K）。h-BN对PP的结晶具有促进作用,提升PP的结晶速率和结晶温度。PP、HDPE与h-BN质量比为64∶16∶15时,添加5%的PP-g-MAH,增强了h-BN和基体材料的界面相容性,复合材料的弯曲强度达到42.72 MPa,拉伸强度达到26.64 MPa,热导率达到0.356 1 W/（m·K）。     

导热绝缘聚合物复合材料研究

介绍了导热绝缘聚合物复合材料,包括复合型塑料、橡胶、胶粘剂和涂层的研究进展及其导热机理、导热模型的研究情况。讨论了影响导热绝缘聚合物复合材料导热性能的因素、提高导热系数的措施及该种复合材料的制备方法,最后阐述了导热绝缘聚合物复合材料的应用及发展方向。     

聚合物/BN导热复合材料研究进展

与其他导热无机粒子相比,氮化硼粒子具有的独特结构及良好的热、电综合性能,是制备高导热、高绝缘聚合物的一类重要导热绝缘填料。综述了微、纳米氮化硼粒子填充导热聚合物的研究进展,重点讨论了氮化硼粒子的物理性能、表面改性、结构及用量等对聚合物导热、绝缘及力学性能的影响。与微米氮化硼相比,氮化硼纳米管及纳米片增强的聚合物具有高导热、高电击穿强度、高绝缘电阻、低介电常数及介电损耗、良好的力学性能。解决导热聚合物高导热与高电击穿强度间的矛盾是聚合物/氮化硼导热复合材料未来发展的方向。     

聚合物基导热绝缘复合材料的制备及逾渗模型的应用

采用乙烯一醋酸乙烯a共聚物和无机导热填料制备聚合物基导热绝缘复合材料,概述了以逾渗理论为基础的热导率计算模型,并应用所制备的导热绝缘复合材料讨论了逾渗模型的准确性。结果表明,SiC填充的复合材料具有较好的导热性能;填料体积分数达0.5时,复合材料的热导率可达1.86 W/(m0K)。研究表明,简单地运用逾渗理论在预测导热复合材料体系的热导率方面准确性不足,需要进一步考虑实际填料粒子分布与理论假设的差异以及界面相的存在等因素的影响。     

Shock-Induced Transformations in Hexagonal Boron Nitride by High-Velocity Thermal Spray

Shock synthesis of cubic BN ( c -BN) was accomplished using high-velocity thermal spray. Al-8Si-20BN (hexagonal BN, h -BN) composite powders were injected into a high-energy flame where the particles partially melted and accelerated to impact on steel substrates. The shock wave generated by the sudden impact of the droplets propagated through the underlying deposit, which experienced a polymorphic transition to high-pressure forms. Transmission electron microscopy revealed that the deposits contained platelike c -BN embedded in h -BN. The c -BN formed with a specific orientation relation, with (0001) h -BN parallel to (111) c -BN and [11–20] h -BN nearly parallel to [2–20] c -BN. As a result of shock propagation, a number of half-Frank loops with Burgers vector ½[0001] were introduced and thin (∼3 nm) layers of amorphous BN ( a -BN), parallel to the (0002) plane, were formed. Significant shearing of the (10–10) plane with respect to the c -axis, delamination, and kink bands were also observed in most of the h -BN grains. The Hugoniot pressure calculation suggested that the impact pressure was sufficient to trigger the nucleation of c -BN.     

绝缘导热高分子复合材料研究

介绍了导热绝缘高分子复合材料的导热性能、导热机理,综述了各类导热绝缘高分子如复合型导热塑料、橡胶、胶粘剂、涂层等的研究,并展望了其应用前景及未来发展方向.     

填充型导热高分子复合材料研究进展

综述了国内外导热绝缘填料、导热非绝缘填料和混杂填料填充的导热高分子材料的研究进展.简要地介绍了导热高分子材料的导热机理.分析了导热高分子复合材料目前存在的一些问题,并对其研究方向给出了一些建议.     

Fabrication of High Thermally Conductive and Electrical Insulating Composites by Boron Nitride-Nanosheet-Coated PEEK Fiber

The development of polyether ether ketone (PEEK)-based thermally conductive insulating composites is required in miniaturized electronic devices with a high power density where heat needs to be evacuated. However, the low thermal conductivity (TC) remains a great challenge, significantly restricting the large-scale applications of PEEK. Here, a novel class of boron nitride nanosheets (BNNSs)/PEEK composites with excellent heat dissipation properties through BNNS-coated PEEK fiber is developed, through simple hot-press sintering. A direct comparison of experimental measurements between the BNNSs/PEEK fiber composites and the BNNSs/PEEK powder composites indicates that the TC is greatly improved in the presence of the well-orientated structure of BNNSs. In addition, the composite with high loading of BNNSs exhibits a combination of high tensile strength and significant electrical insulation (volume electrical resistivity beyond 10⁹ Ω cm). The experimental data demonstrate that it has broad and bright prospects for application in a range of emerging electronic devices, which also provide great potential for enhancing the thermal management application of PEEK-based composites.     

High Thermal Conductivity Nanocomposites Based on Conductive Polyaniline Nanowire Arrays on Boron Nitride

With the development of soft electronics, conductive composites are garnering an increasing amount of attention. The electrical conductivity, thermal conductivity, and electrical stability of conductive composites are all very important. In particular, the thermal conductivity of conductive composites is critical to the stability of their conductive properties. However, little is reported on thermal management in conductive systems. Herein, sufficiently hydroxylated boron nitride nanosheets (BN‐OH)@polyaniline (PANI) composite nanosheets with a high thermal conductivity and outstanding conductance stability are reported. PANI nanowire arrays are aligned vertically on BN‐OH. This well‐ordered nanostructure provides the means to form a good conductive and thermally conductive path. Notably, the composite through‐plane thermal conductivity is 2.1 W m^?1 K^?1(≈1000% that of pure PANI) and that the resistivity of the composite is 1.38 Ω cm. Importantly, the resistivity of the composite remains unchanged after 1 h of work. The results show that this composite has prospective applications for use in soft electronics.     

Preparation of Nanostructured Hexagonal Boron Nitride Powder

In this communication, we describe an inexpensive and feasible method for the preparation of hexagonal boron nitride (h–BN) nanorods in the absence of metal catalyst. Tertiary calcium phosphate (Ca₃(PO₄)₂) and ammonium biborate hydrate (NH₄HB₄O₇·3H₂O) were selected as starting materials where calcium phosphate was used as a diluting agent to prevent the formation of bulk B₂O₃ during the thermolysis of ammonium biborate hydrate. The mixture was nitrided at 900°C in the flowing ammonia and was transformed into h–BN nanorods after subsequent crystallization. After crystallization at 1650°C for 2 h, the unique microstructure of h–BN nanorods was observed.     

填充型导热绝缘高分子复合材料的研究进展

综述了填充型导热绝缘高分子复合材料的应用背景和特点,介绍了该类复合材料的综合性能和研究方面的进展,讨论了导热机制以及不同因素对导热机制的影响,最后,指出了填充型导热绝缘高分子复合材料在研究与开发中面临的问题及发展的趋势。     

导热高分子复合材料的研究进展

文章介绍了导热高分子复合材料的开发及应用近况,概述了各种填充型导热高分子复合材料的研究进展以及其导热机理。最后,对如何提高高分子复合材料的导热性能提出了一些建议及展望。     

PB-1/BN导热复合材料的制备及性能研究

以聚丁烯-1(PB-1)为基体,二维片状氮化硼(BN)为导热填料,采用模压成型的方法制备了PB-1/BN导热复合材料。研究了BN用量对PB-1/BN导热复合材料导热性能、力学性能、流变性能以及结晶性能的影响。结果表明:BN的加入使复合材料的导热性能明显提高,当BN用量为50%时,复合材料的导热系数达到1.28 W/(m·K),与纯PB-1相比提高了266%;随着BN用量的增加,复合材料的力学性能明显下降;同时,其结晶温度和结晶度也有不同程度降低。     

Control of Composition and Structure in Laminated Silicon Nitride/Boron Nitride Composites

Based on a biomimetic design, Si₃N₄/BN composites with laminated structures have been prepared and investigated through composition control and structure design. To further improve the mechanical properties of the composites, Si₃N₄ matrix layers were reinforced by SiC whiskers and BN separating layers were modified by adding Si₃N₄ or Al₂O₃. The results showed that the addition of SiC whiskers in the Si₃N₄ matrix layers could greatly improve the apparent fracture toughness (reaching 28.1 MPa·m^1/2), at the same time keeping the higher bending strength (reaching 651.5 MPa) of the composites. Additions of 50 wt% Al₂O₃ or 10 wt% Si₃N₄ to BN interfacial layers had a beneficial effect on the strength and toughness of the laminated Si₃N₄/BN composites. Through observation of microstructure by SEM, multilevel toughening mechanisms contributing to high toughness of the laminated Si₃N₄/BN composites were present as the first-level toughening mechanisms from BN interfacial layers as crack deflection, bifurcation, and pull-out of matrix sheets, and the secondary toughening mechanism from whiskers in matrix layers.