导热高分子材料研究进展

讨论了提高聚合物导热性能的途径－合成高导热系数的结构聚合物，用高导热无机填料对聚合物进行填充复合。综述了导热高分子材料的研究成果：聚合物导热的基本概念和影响其导热性能的因素及导热系数的预测理论；聚合物基导热复合材料的选材、复合技术及其应用。指出了导热高分子材料的研究方向－－纳米导热填料的研究和开发；聚合物树脂基体的物理化学改性；聚合物基体与导热填料复合新技术的研究和开发；复合材料导热模型的建立、导热机理（特别是聚合物基体与导热填料界面的结构与性能对材料导热性能的影响）及导热通路的形成等；探索高导热本体聚合物材料的制备方法和途径等。对导热高分子材料的研究和开发有重要意义。     

填充型导热聚合物基复合材料的研究进展

阐述了填充型导热聚合物基复合材料的导热机理、导热模型和测试方法等,重点介绍了聚合物基导热复合材料的研究进展及基体、填料、表面改性对复合材料导热性能的影响,最后展望了聚合物基导热复合材料的发展趋势。     

石墨烯基纳米复合材料的研究进展

石墨烯是一种具有二维结构的纳米碳材料,具有优异的导电、导热和机械性能。将石墨烯与无机物或聚合物进行复合是近年来的研究热点,对石墨烯基纳米复合材料进行了综述,概述了国内外石墨烯/无机纳米复合材料和石墨烯/聚合物纳米复合材料的导电性、导热性、机械性能和生物相容性等的研究进展。     

聚合物基纳米复合材料的研究进展

对聚合物基纳米复合材料的研究进展进行了介绍,报道了有关聚合物基纳米复合材料制备方法的研究进展情况,并分别对聚合物/粘土纳米复合材料、环氧树脂基纳米复合材料、聚酯纳米复合材料、聚合物/碳纳米管纳米复合材料的研究发展情况给予了评述,同时对每种体系特点和存在的问题进行了论述,最后着重指出纳米复合材料制备方法、应用以及开发新的聚合物基纳米复合体系是今后的主要研究方向.     

聚合物基绝缘导热复合材料中碳系填料的研究进展

集成电路产业的高质量发展对其产业链中配套材料的绝缘导热性能提出了更高的要求。具有高导热、低密度、活性表界面等优异特性的碳系材料在聚合物基复合材料中的基础研究,对于高性能绝缘导热材料的性能提升及应用发展至关重要。基于此,本文系统地综述了聚合物基绝缘导热复合材料中碳系填料的研究进展。首先,介绍了聚合物基复合材料的导热机制、绝缘机制及绝缘导热兼容机制。其次,对碳系填料的表面处理和空间结构及分布控制方法进行了综述,研究其绝缘导热性能控制机制。最后,对聚合物基绝缘导热复合材料研究工作中尚未解决的科学问题、技术难点及未来发展方向进行了总结和展望。      

纳米填充物对聚合物及其复合材料蠕变性能影响的研究进展

相比于金属基和陶瓷基复合材料,聚合物基复合材料的抗蠕变性能较差,这使聚合物基复合材料的应用受到一定的限制。向聚合物中添加适当的填充物是改善其抗蠕变性能的一种行之有效的方法。文中综述了零维、一维及二维纳米尺寸的填充物对热塑性和热固性聚合物蠕变性能影响的研究进展,并对纳米填充物增强聚合物抗蠕变性的机制进行了分析。详细分析和比较了碳纳米管对环氧树脂蠕变性能影响的研究进展,总结了目前研究的热点和难点,并对未来研究的方向进行了展望。     

聚合物基复合材料的界面结构与导热性能

在整理近年来国内外对聚合物基导热复合材料性能的研究工作的基础上,总结界面结构与界面处理对聚合物基复合材料界面和导热性能的影响,分析目前已有研究中的缺点和不足,提出未来改善界面结合、提高聚合物基复合材料导热性能的具体方法,并指出探究界面结构与热流散射的关系,特别是弱界面结合情况下的热流传导规律,对提高聚合物基复合材料的热导率有很大的指导意义。     

具有三维连续网络结构的聚合物基导热复合材料研究进展

热界面材料可以有效地将高温电子器件的热量快速传递到热管理元件,以缓解电子器件过热而导致的元件寿命恶化的问题。近年来,由聚合物和高导热填料制成的聚合物基复合材料因其密度低、导热性能可调而受到广泛关注。不同于传统的填料随机分散的复合材料,在聚合物基体中构建三维连续网络结构可以显著增加填料/填料接触、降低导热渗透阈值和界面热阻,显著改善复合材料的导热性能。首先,简要分析了聚合物基导热复合材料的导热机制。其次,总结了具有连续网络结构的聚合物基导热复合材料的构筑工艺,主要包括基于三维导热填料网络的预构筑、基于聚合物颗粒/粉末的后加工、基于聚合物纤维/织物的后加工、基于聚合物胶乳的铸膜或絮凝等工艺。再次,系统总结了不同类型的导热填料对聚合物复合材料导热性能的影响,主要包括金属填料、陶瓷填料、碳基填料及其混杂填料等。最后,对具有三维连续网络结构的聚合物基导热复合材料的发展前景进行了展望。     

高导热低填量聚合物基复合材料研究进展

高导热低填量聚合物基复合材料在电子封装和大功率电子设备等领域有着巨大需求。通常高导热聚合物是通过在高分子基体中均匀分散高含量的导热填料来实现的,然而较高填料含量会极大地恶化复合材料力学性能和提升材料经济成本,因此高填量复合材料很难满足当前工业应用上的需求。综述了近年来高导热低填量聚合物基复合材料制备研究进展,简要介绍了导热机制和影响低填量聚合物基复合材料导热性能的主要因素,按照不同填料类型介绍了一些热导率高于1.0 W/（m·K）且填充量低于10vol%的高导热低填量聚合物基复合材料的制备方法和研究进展,展望了高导热低填量聚合物基复合材料的发展方向。     

PMMA纳米复合材料的研究进展和制备方法

主要介绍了PMMA/MWNT纳米复合材料、PMMA/层状硅酸盐纳米复合材料、PMMA/氧化物纳米复合材料这3种常见聚合物基纳米复合材料的制备方法,同时对每种体系特点进行了论述.最后指出纳米复合材料制备方法、应用以及开发新的PMMA基纳米复合体系是今后的主要研究方向.     

聚合物基复合材料的导热性能研究

讨论了聚合物基高导热高绝缘纳米复合材料的导热机理与常用的导热理论模型。考虑到填充率、温度等的影响，用不同的理论模型计算了氧化铝纳米颗粒填充环氧树脂的热导率，并结合相关研究实验对不同的导热理论模型进行分析比较。     

Unit-Cell Simulation of the Thermal Conductivity Processes in Porous Composite Materials

Mathematical models of polymer composite materials and a procedure to calculate the thermal conductivity, effective thermal conductivity, and heat capacity of porous polymer composite materials are proposed. The procedure takes into account the simultaneous effect of the shape of the unit cell and the presence of the boundary layer.     

Numerical Investigation of Heat Transfer of Silver-Coated Glass Particles Dispersed in Ethylene Vinyl Acetate Matrix

The effective thermal conductivity of silver-coated glass spheres dispersed in an ethylene vinyl acetate matrix was investigated numerically as a function of filler concentration. The finite-element method was carried out for modeling the thermal heat transport and to calculate the effective thermal conductivity of the composite for three elementary cells; simple cubic (SC), body-centered cubic (BCC), and face-centered cubic (FCC). The effect of the inclusion/matrix thermal contact resistance and the ratio of thermal conductivities of the filler-to-matrix material are also taken into account. The numerical results are compared with previously published experimental data and some theoretical models. The calculated values of the thermal conductivity of the SC model are in good agreement with the measured results for all the filler volume fractions. Numerical results for FCC and BCC models were found to be in good agreement with analytical models. The results show that the filler/matrix contact resistance has an important effect on the effective thermal conductivity.     

Predicting, Measuring, and Tailoring the Transverse Thermal Conductivity of Composites from Polymer Matrix and Metal Filler

The addition of conductive filler in a polymer matrix is an effective way to increase the thermal conductivity of the plastic materials, as required by several industrial applications. All quantitative models for the thermal conductivity of heterogeneous media fail for heavily filled composites. The percolation theory allows good qualitative predictions, thus selecting a range for some qualitative effects on the thermal conductivity, and providing a way to choose a range for some experimental parameters. The design of such composite materials requires a study of its thermal features combined with different mechanical, ecological, safety, technical, and economical restrictions. A specific small guarded hot plate device with an active guard, conductive grease layer, and controlled variable pressure was used for measurement of the transverse thermal conductivity on 15 mm sided samples of composite parts. Extensive thermal and composition measurements on filled thermoplastics show that the conductivity of the filler, its size and shape, and its local amount are, with the degree of previous mixing, the main factors determining the effective conductivity of composites. For injection-molded polybutylene terephtalate plates, the best filler is the short aluminum fiber. With fibers of 0.10 mm diameter, it is possible to obtain conductivities larger by factors of 2, 6, and 10 than those of polymer for aluminum contents of 20, 42, and 43.5 vol%, respectively.     

Anisotropic thermal diffusivity characterization of aligned carbon nanotube-polymer composites

The anisotropic thermal diffusivity of aligned carbon nanotube-polymer composites was determined using a photothermoelectric technique. The composites were obtained by infiltrating poly-dimethyl siloxane (PDMS) in aligned multiwall CNT arrays grown by chemical vapor deposition on silicon substrates. The thermal diffusivities are insensitive to temperature in the range of 180 K-300 K. The thermal diffusivity values across the alignment direction are approximately 2-4 times smaller than along the alignment direction and larger than effective media theory predictions using reported values for the thermal diffusivity of millimeter thick aligned multiwall carbon nanotube arrays. The effective room temperature thermal conductivity of the composite along the carbon nanotube alignment direction is at least 6X larger than the thermal conductivity of the polymer matrix and is in good agreement with the effective media predictions. This work indicates that infiltration of long and aligned carbon nanotube arrays is currently the most efficient method to obtain high thermal conductivity polymer composites.     

高比例SiC_p/Al复合材料的有效热导率模型

有效热导率是铝基复合材料在电子封装、热控方面应用的重要性能指标.结合复合材料广义自洽微观力学模型,并在Maxwell理论的基础上,初步建立了适合高体积分数SiCp/Al复合材料的有效热导率预测模型.模型不仅考虑了颗粒与颗粒、颗粒与基体间的界面效应,而且在一定程度上也考虑了增强体颗粒的形状.其理论计算结果与实测值吻合较好.     

On the effective thermal conductivity of carbon nanotube reinforced polymer composites

In this paper, a theoretical model has been developed for predicting the effective thermal conductivity of an aligned multi-walled nanotube polymer composite. This model is based on an effective medium theory that has been developed for composites containing aligned spheroidal inclusions with imperfect interfaces. To incorporate the nanotube structure into this theory, a continuum model of the nanotube geometry is developed by considering its structure and the mechanism of heat conduction through it. Results show that the overall conductivity will be much lower than expected due to the fact that in the composite, the outer nanotube layer carries the bulk of the heat flowing through the nanotube. It is also seen that the high nanotube–matrix boundary resistance does not significantly affect the overall conductivity. The effective conductivity was also found to be highly sensitive to the nanotube diameter.     

Thermal conductivity of polystyrene–aluminum nitride composite

The thermal conductivity of polymer composites having a matrix of polystyrene (PS) containing aluminum nitride (AlN) reinforcement has been investigated under a special dispersion state of filler in the composites: aluminum nitride filler particles surrounding polystyrene matrix particles. Data for the thermal conductivity of the composites are discussed as a function of composition parameters (aluminum nitride concentration, polystyrene particle size) and temperature. It is found that the thermal conductivity of composites is higher for a polystyrene particle size of 2 mm than that for a particle size of 0.15 mm. The thermal conductivity of the composite is five times that of pure polystyrene at about 20% volume fraction of AlN for the composite containing 2 mm polystyrene particle size. The relationship between thermal conductivity of composites and AlN filler concentrations has been compared with the predictions of two theoretical models from the literature.     

A poly(vinylidene fluoride) composite with added self-passivated microaluminum and nanoaluminum particles for enhanced thermal conductivity

A polymer composite was prepared by embedding fillers made of self-passivated aluminum particles in two kind of sizes, micrometer size and nanometer size with different volume proportions into polyvinylidene fluoride matrix. The thermal conductivity and dielectric properties of the composite were studied. The results showed that the thermal conductivity of composites was significantly increased to 3.258 W∕mK when the volume proportion of micrometer size Al particles to nanometer size Al particles is at 20:1, also the relative permittivity was about 75.8 at 1 MHz. The effective simulation model values were in good accordance with experimental results.