六方氮化硼在绝缘导热聚合物复合材料中应用研究进展

本文介绍了六方氮化硼作为高导热、高绝缘性无机填料在聚合物中应用研究进展， 探讨了氮化硼在绝缘导热复合材料应用中的发展方向。     

BN@APP/水性聚氨酯复合材料的制备及其阻燃性能

采用聚磷酸铵(APP)对氮化硼进行表面改性,并进一步制备出聚磷酸铵改性氮化硼(BN@APP)/水性聚氨酯(WPU)复合材料.结果 表明,当BN@APP的添加量为0.75％时,BN@APP/WPU复合材料的拉伸强度是未改性WPU拉伸强度的2.2倍,这是因为BN@APP具有较大的比表面积以及与基体产生较强的相互作用.随着B...     

High thermally conductive PLA based composites with tailored hybrid network of hexagonal boron nitride and graphene nanoplatelets

Bio‐based polymers and multifunctional polymeric composites are promising for the development of new environmentally sustainable materials and are becoming increasingly popular compared to their oil based counterparts. This research aims to develop new multifunctional bio‐based polymer composites with improved thermal conductivity and tailored electrical properties to be used as heat management materials in the electronics industry. A series of parametric studies were conducted to clarify the science behind the hybrid composites' behavior and their structure‐to‐property relationships. Using bio‐based polymers [e.g., polylactic acid (PLA)] as the matrix, heat transfer networks were developed and structured by embedding hexagonal boron nitride (hBN) and graphene nanoplatelets (GNP) in a PLA matrix. The effects of random uniform thermal hybrid networks of hBN‐GNP on improving the effective thermal conductivity (k_eff) of produced composites were studied and compared. Composites were characterized with respect to physical, thermal, electrical, and mechanical properties for practical application in the electronics industry. The use of high thermally conductive hybrid filler systems, with optimized filler content, was found to promote the composites' effective thermal conductivity to more than 12 times over neat PLA. The thermally conductive composite is expected to provide unique opportunities to injection mold three‐dimensional, net‐shape, lightweight, and eco‐friendly microelectronic enclosures with superior heat dissipation performance. POLYM. COMPOS., 37:2196–2205, 2016. © 2015 Society of Plastics Engineers     

Enhanced thermal conductivity of boron nitride epoxy‐matrix composite through multi‐modal particle size mixing

Castable particulate‐filled epoxy resins exhibiting excellent thermal conductivity have been prepared using hexagonal boron nitride (hBN) and cubic boron nitride (cBN) as fillers. The thermal conductivity of boron nitride filled epoxy matrix composites was enhanced up to 217% through silane surface treatment of fillers and multi‐modal particle size mixing (two different hBN particle sizes and one cBN particle size) prior to fabricating the composite. The measurements and interpretation of the curing kinetics of anhydride cured epoxies as continuous matrix, loaded with BN having multi‐modal particle size distribution, as heat conductive fillers, are highlighted. This study evidences the importance of surface engineering and multi‐modal mixing distribution applied in inorganic fillered epoxy‐matrix composite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

A low-density polyethylene composite with phosphorus-nitrogen based flame retardant and multi-walled carbon nanotubes for enhanced electrical conductivity and acceptable flame retardancy

Design and exploitation of flame retardant polymers with high electrical conductivity are desired for polymer applications in electronics. Herein, a novel phosphorus-nitrogen intumescent flame retardant was synthesized from pentaerythritol octahydrogen tetraphosphate, phenylphosphonyl dichloride, and aniline. Low-density polyethylene was combined with the flame retardant and multi-walled carbon nanotubes to form a nanocomposite material via a ball-milling and hot-pressing method. The electrical conductivity, mechanical properties, thermal performance, and flame retardancy of the composites were investigated using a four-point probe instrument, universal tensile machine, thermogravimetric analysis, and cone calorimeter tests, respectively. It was found that the addition of multi-walled carbon nanotubes can significantly improve the electrical conductivity and mechanical properties of the low-density polyethylene composites. Furthermore, the combination of multi-walled carbon nanotubes and phosphorus–nitrogen flame retardant remarkably enhances the flame retardancy of matrixes with an observed decrease of the peak heat release rate and total heat release of 49.8% and 51.9%, respectively. This study provides a new and effective methodology to substantially enhance the electrical conductivity and flame retardancy of polymers with an attractive prospect for polymer applications in electrical equipment.     

填料对电机用轻量化导热灌封胶性能的影响

以端乙烯基硅油、含氢硅油为原料,添加填料、催化剂等制得有机硅灌封胶,探讨了α-氧化铝、球形氧化铝、氮化硼、有机蒙脱土对灌封胶性能的影响.结果表明,单纯采用α-氧化铝作填料时,灌封胶的流动性较差、排泡时间过长;采用相同粒径的球形氧化铝替代α-氧化铝能降低灌封胶的黏度,提高流动性和排泡速度,但会降低热导率,且胶料密度过高;...     

膨胀石墨对乙烯基硅橡胶的阻燃作用研究

将可膨胀石墨(EG)添加到乙烯基硅橡胶中并采用过氧化物硫化制备了硅橡胶材料,对其阻燃性能和燃烧行为进行了研究.结果表明,当EG的添加量为5份时,材料在垂直燃烧测试中通过了UL 94 V-0级,且能离火自熄,极限氧指数达到了33.0％;与纯硅胶材料相比,EG的加入有效降低了材料的热释放和烟释放;材料与火焰接触区域,EG完...     

复合绝缘导热胶粘剂研究

以增韧的酚醛环氧树脂为基体树脂,氮化铝、氮化硼、氧化铝混杂粒子为导热填料制备了-新型绝缘导热胶粘剂。研究了填料用量对胶粘剂热导率、热阻、介电常数、体积电阻率等性能的影响,发现填料用量为40％时胶粘剂的热导率为O．99 W／mK,热阻为0．70℃／W,介电常数6,体积电阻率4．6×1012Ω·cm,20℃、200℃、250℃下的剪切强度分别为13．0MPa、10．0MPa、5．65MPa。研究结果表明该胶具备良好的电绝缘及力学性能,可以长期在150℃温度下使用,与不加导热填料的相同胶粘剂相比,具有良好的导热能力。     

反应型磷氮阻燃剂/可膨胀石墨复配阻燃聚氨酯泡沫

将反应型阻燃剂六(4-磷酸二乙酯羟甲基苯氧基)环三磷腈(HPHPCP)和可膨胀石墨(EG)复配,制备了阻燃聚氨酯泡沫,详细研究了复配阻燃剂对聚氨酯泡沫的物理力学性能、热稳定性以及阻燃性能的影响。结果表明,阻燃聚氨酯泡沫的密度和热导率随着复配阻燃剂中EG含量的增加而升高;压缩强度随着EG含量的增加呈现先增加后降低的趋势。热失重表明复配阻燃剂大大提高了聚氨酯泡沫的热稳定性。聚氨酯泡沫的初始分解温度(T_10%)从212.9℃,分别提高到222.0、231.2和243.2℃;700℃残炭量从7.6%分别提高到26.3%、31.6%和37.9%。聚氨酯泡沫的阻燃性能随着复配阻燃剂中EG含量的增加而提高。阻燃聚氨酯泡沫的极限氧指数从19%提高到29%,均能通过UL-94水平燃烧HF-1等级和垂直燃烧V-0等级。     

The impact of polymer matrix blends on thermal and mechanical properties of boron nitride composites

To improve mechanical and thermal properties of a hexagonal boron nitride platelet filled polymer composites, maleic anhydride was studied as a coupling agent and compatibilizer. Injection molded blends of acrylonitrile butadiene styrene (ABS), high-density polyethylene (HDPE), and maleic anhydride with boron nitride filler were tested for thermal conductivity and impact strength to determine whether adding maleic anhydride improved interfacial interactions between matrix and filler and between the polymers. Adding both HDPE and maleic anhydride to ABS as the matrix of the composite resulted in a 40% improvement in impact strength without a decrease in thermal conductivity when compared to an ABS matrix. The best combination of thermal conductivity and impact strength was using pure HDPE as the matrix material. The effective medium theory model is used to help explain how strong filler alignment helps achieve high thermal conductivity, greater than 5 W/m K for 60 wt % boron nitride. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48661.     

Lightweight and thermally conductive thermoplastic polyurethane/hollow glass bead/boron nitride composites with flame retardancy

Polymeric composites with low density and high thermal conductivity (TC) are greatly demanded in some specific applications such as aeronautics, astronautics, and deep-sea exploration. It is a great challenge to obtain lightweight and thermally conductive polymer composites because the heat fillers have high density (>2 g/cm³) Herein, lightweight and thermally conductive thermoplastic polyurethane/hollow glass bead/boron nitride composites (TPU/HGB/BN) were prepared with the construction of a 3D BN network under the assistance of ultralightweight HGB by a solution-mixing and hot-pressing method. A 3D BN heat network has been constructed in the TPU matrix due to the alignment of the BN platelets along with the HGB microspheres during hot-pressing, which leads to a higher TC (5.34 W/mK) of the TPU/HGB/BN composites with a low density of 1.23 g/cm³, which is close to the density of pure TPU (1.20 g/cm³). In addition, the TPU/HGB/BN composites show good thermal stability with TC losses of 4.24% and 2.22%, respectively, even after treated for 50 hot-cold cycles and heated at 80 °C for 50 h. Moreover, the limiting oxygen index (LOI) of the TPU/HGB/BN composites is 51%, and they can extinguish in 8 s after ignition and exhibit enhanced flame retardancy. This work presents a simple method to design and prepare lightweight, flame retardant and thermally conductive composite materials, which can be used as lightweight thermal management materials.     

Thermally conductive silicone rubber reinforced with boron nitride particle

Thermally conductive silicone rubber used as elastomeric thermal pad is successfully developed with boron nitride powder as conductive filler. The effects of content and particle size of filler on the thermal conductivity and mechanical property of silicone rubber are investigated. The results indicate that the use of hybrid boron nitride with three different particle sizes at a preferable weight ratio gives silicone rubber better thermal conductivity compared with each boron nitride with single particle size at the same total filler content. Furthermore, scanning electron microscopy, differential scanning calorimeter, thermogravimetric, etc., are used to characterize the morphology, curing behavior, thermal stability, and coefficient of thermal expansion (CTE) of the silicone rubber composites. POLYM. COMPOS., 28:23–28, 2007. © 2007 Society of Plastics Engineers     

Mg（OH）2／Al（OH）3对膨胀型防火涂料热分解特性影响的研究

以苯丙乳液为成膜物质,聚磷酸铵、三聚氰胺、季戊四醇为膨胀阻燃体系,分别添加不同量的氢氧化镁、氢氧化铝制备了三种防火涂料。用热重分析仪分别对膨胀阻燃涂料的单组分及涂料的热分解特性进行表征,并用锥形量热仪测试其燃烧性能。实验结果表明,单独用氢氧化镁或氢氧化铝作为添加剂,均会促进涂料的热分解过程,其热释放速率的峰值也会提前。     

无卤阻燃SBR的阻燃性能及热失重行为

利用锥形量热仪(CONE)和热失重分析(TG)研究了化学膨胀阻燃剂(IFR)、氢氧化铝/红磷(Al(OH)3/P)及二者复合阻燃SBR的阻燃性能及热失重行为。结果表明,阻燃剂用量为40份,聚磷酸铵(APP)与季戊四醇(PER)质量比为3∶1时,SBR/APP/PER的热释放速率及生烟速率均大幅度下降,阻燃效果较好;Al(OH)3与P质量比为26∶14时,可有效降低SBR/Al(OH)3/P的热释放速率,但生烟速率较大;将APP/PER∶Al(OH)3/P=1∶1复配,SBR/IFR/Al(OH)3/P的热释放速率和生烟速率没有进一步改善,协同效应不明显。热失重研究表明,空气气氛下,试样SBR/IFR/Al(OH)3/P在300~500℃时,Al(OH)3/P反应使得SBR分解速度下降;在500~800℃时,APP与PER形成炭层,有效地起到隔热隔氧的作用,从而抑制炭黑的分解;两者复合使用,使阻燃SBR分解速度降低,热稳定性提高。     

Carbon-family materials for flame retardant polymeric materials

As an abundant and attractive element, the emergence of new carbon-based materials brings revolutionary development in material science and technology. Carbon-based materials have spawned considerable interest for fabricating polymer composites/nanocomposites with greatly improved mechanical, thermal, gas barrier, conductivity, and flame retardant performance. In this review, the importance of carbon-based materials and the necessity of fire resistance for polymeric materials are initially introduced. Then, the fundamental flame retardant mechanisms and experimental analytical techniques are described to understand the relationship between structures and flame retardant properties. The main section is dedicated to the preparation and properties of multifunctional polymer composites/nanocomposites with carbon-based materials, with special emphasis on the flame retardant properties of these materials. A wide variety of carbon-based materials are discussed for use in flame retardant polymer nanocomposite, including graphite, graphene, carbon nanotubes, fullerenes as well as some new emerging carbon forms (carbon nitride, carbon aerogels, etc). Finally, a brief outlook at the developments in carbon-based materials for flame retardant polymeric composites is given by discussing the major progress, opportunities, and challenges.     

硼-铝在膨胀型阻燃聚丙烯中的协同作用

通过热分析和锥形量热研究了硼-铝在膨胀型阻燃聚丙烯（PP）中的协同作用。热分析显示膨胀型阻燃剂KDIFR中,引入铝元素,由于催化脱水促进降解的作用,使剩碳率降低至14.6 %;引入硼元素,由于促进可燃小分子的生成,催化降解,也使剩碳率降低至5.9 %;硼铝共存时二者之间的协同作用可以降低在高温区的降解速率,提高剩碳率至19.7 %。PP/KDIFR的锥形量热表明,铝元素增大了热释放速率、释热总量、CO、CO₂和烟释放量;硼元素燃烧前期能减少热释放速率、释热总量、CO和CO₂释放量,有明显的抑烟作用,使阻燃效果略有提高。硼铝共存显著降低热释放速率、释热总量、CO、CO₂和烟释放量,大大提高了阻燃效果。     

可膨胀石墨在膨胀型防火涂料中的性能研究

膨胀型防火涂料是防火涂料中的主要类型,具有低烟、少毒、无卤化的特点,受热时发生膨胀,生成导热系数较小的炭质层.延缓热量向基材的蔓延,呈高效的阻燃效果,为灭火赢得宝贵的时间,是实现阻燃剂无卤化的很有希望的途径之一,近年来已经被广泛用于建筑结构的防火处理。     

Influence of filler type and content on thermal conductivity and mechanical properties of thermoplastic compounds

Combining thermal conductivity with electrical isolation is a very interesting topic for electronic applications in order to transfer the generated heat. Typical approaches combine thermally conductive fillers with a thermoplastic matrix. The aim of this work was to investigate the influence of different fillers and matrices on the thermal conductivity of the polymer matrix composites. In this study, various inorganic fillers, including aluminum oxide (Al₂O₃), zinc oxide (ZnO), and boron nitride (BN) with different shapes and sizes, were used in matrix polymers, such as polyamide 6 (PA6), polypropylene (PP), polycarbonate (PC), thermoplastic polyurethane (TPU), and polysulfone (PSU), to produce thermally conductive polymer matrix composites by compounding and injection molding. Using simple mathematical models (e.g., Agari model, Lewis–Nielson model), a first attempt was made to predict thermal conductivity from constituent properties. The materials were characterized by tensile testing, density measurement, and thermal conductivity measurement. Contact angle measurements and the calculated surface energy can be used to evaluate the wetting behavior, which correlates directly with the elastic modulus. Based on the aforementioned evaluations, we found that besides the volume fraction, the particle shape in combination with the intrinsic thermal conductivity of the filler has the greatest influence on the thermal conductivity of the composite.     

Polyurethane Composites Reinforced with Walnut Shell Filler Treated with Perlite,Montmorillonite and Halloysite

In the following study, polyurethane (PUR) composites were modified with 2 wt.% of walnut shell filler modified with selected mineral compounds–perlite, montmorillonite, and halloysite. The impact of modified walnut shell fillers on selected properties of PUR composites, such as rheological properties (dynamic viscosity, foaming behavior), mechanical properties (compressive strength, flexural strength, impact strength), dynamic-mechanical behavior (glass transition temperature, storage modulus), insulation properties (thermal conductivity), thermal characteristic (temperature of thermal decomposition stages), and flame retardant properties (e.g., ignition time, limiting oxygen index, heat peak release) was investigated. Among all modified types of PUR composites, the greatest improvement was observed for PUR composites filled with walnut shell filler functionalized with halloysite. For example, on the addition of such modified walnut shell filler, the compressive strength was enhanced by ~13%, flexural strength by ~12%, and impact strength by ~14%. Due to the functionalization of walnut shell filler with thermally stable flame retardant compounds, such modified PUR composites were characterized by higher temperatures of thermal decomposition. Most importantly, PUR composites filled with flame retardant compounds exhibited improved flame resistance characteristics-in all cases, the value of peak heat release was reduced by ~12%, while the value of total smoke release was reduced by ~23%.     

Synergistic effects on the enhancement of thermal conductive properties of thermal greases

Efficient heat dissipation from electronic devices with high-degree integration and high-power density has become an urgent and complex problem. We report here novel thermal greases with an enhanced thermal conductivity using graphene flakes (GFs), hexagonal boron nitride (h-BN), and hydroxypropyl cellulose (HPC) as fillers. The obtained GF/h-BN/HPC thermal grease at 23 vol % h-BN loading exhibits a thermal conductivity enhancement 555%, compared with the pure PDMS matrix, and also about 50, 169, and 115% higher than that with GF/h-BN, h-BN/HPC and h-BN as the filler for the thermal grease, respectively. We attribute it to the synergistic effects among GF, h-BN, and HPC, due to the formation of thermally conductive networks. This study provides a strategy for preparing thermal greases for thermal management applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47726.