功能性石墨烯改善聚合物介电性能的研究进展

目的对近年来使用改性石墨烯改善聚合物基复合材料介电性能的研究进行总结,指出今后的发展方向。方法总结通过石墨烯改性来改善其在聚合物的分散性和提高聚合物基石墨烯复合材料介电性能的方法;对比石墨烯/聚合物复合材料的复合工艺对其介电常数和介电损耗数值的变化,总结不同的改性方法对复合材料介电性能的影响。结论石墨烯作为一种性能较优的导电填料对材料介电性能影响巨大,然而,由于其物理分散性不好,极大地阻碍了石墨烯改性聚合物基高介电复合材料的发展。通过对石墨烯进行功能化改性修饰可以有效提高聚合物基复合材料的介电性能,这种材料可作为电活性聚合物,在很多需要高介电常数的电介质材料领域,如超级电容器、感应器、驱动器、智能包装和机器人等方面得到应用。     

无机颗粒填充聚合物复合材料的介电性能研究

随着埋入式电容器的发展,具有高介电性能聚合物基复合材料的研究显得尤为重要。目前,高介电聚合物基复合材料主要有两种,铁电陶瓷/聚合物复合材料和导电颗粒/聚合物复合材料。综述了这两种复合材料的特点和最新研究进展,概述了可以增强聚合物基复合材料介电性能的方法。首先针对铁电陶瓷/聚合物复合材料介电常数难以提高的缺点,指出通过高介电聚合物基体的选择、陶瓷填料含量与尺寸形貌的控制,可以有效地提高这类材料的介电常数;同时介绍了这类复合材料不同界面结构和稳固界面的重要性,重点阐述了形成化学键连接的"分子桥"结构的方法;然后针对导电颗粒/聚合物复合材料渗流阈值难以控制和介电损耗高的问题,探讨了影响渗流阈值的因素和减小介电损耗的方法;最后基于本课题组在功能性纳米填料、高介电聚合物复合材料的基础研究及应用探索方面的工作积累,对高介电聚合物基复合材料的未来发展方向做出展望。     

填充型聚合物基介电储能复合材料的研究进展

聚合物薄膜电容器具有功率密度超高、击穿场强高、易于生产和密度小等特点,因而被广泛地应用于电力电子设备中.但是由于聚合物本身低的介电常数而导致其能量密度较低,限制了其在新兴领域的应用.通过复合的方式向聚合物基体中加入不同形貌与特性的填料是提高聚合物能量密度的有效途径.本文综述了近年来国内外关于填充型聚合物基介电储能复合材料的研究现状,分类讨论了各种填料的优势与不足,探究了填料与聚合物基体间的界面及相互作用对复合材料介电性能的影响,阐述了填充型聚合物基介电储能复合材料存在的问题和未来的发展方向.     

高介电常数聚合物基复合材料研究进展

本文概述了目前高介电聚合物基复合材料的主要问题,论述了铁电陶瓷、导电颗粒(金属粒子、石墨、碳纳米管)改性高介电复合材料的国内外研究进展;重点介绍了酞菁铜、聚苯胺改性全有机高介电复合材料,探讨了存在的主要问题,并指出提高介电常数、储能密度,减小介电损耗,降低制备成本是未来发展的方向。     

碳纳米管增强聚合物基复合材料进展

碳纳米管具有超常的力学性能、电性能和热性能,碳纳米管增强复合材料被认为是最有潜力的结构功能一体化复合材料.从阻碍碳纳米管复合材料高性能化的主要因素、碳纳米管复合材料增强体、碳纳米管复合材料成型工艺、碳纳米管复合材料性能等方面讨论了碳纳米管聚合物基复合材料的研究现状.     

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。     

压电陶瓷/CIIR复合材料的阻尼性能的研究

以氯化丁基橡胶(CIIR)及其互穿网络为基体,加入压电陶瓷PMN和导电炭黑CB制备PMN/CB/CIIR复合材料,系统研究其的阻尼性能的影响因素以及机理,以获得高介电常数和高阻尼性能的压电陶瓷/聚合物基复合材料,拓展其在介电材料和阻尼材料领域的应用。     

先驱体陶瓷

综述了用先驱体法制备陶瓷纤维、陶瓷基复合材料等的特点及其研究进展,针对制备陶瓷基复合材料基体的有机聚合物先驱体,提出了先驱体必须满足的理化特性和结构特征,同时还针对先驱体法高气孔率及高收缩率的不足,提出了３个解决办法,并着重讨论了活性填料在先驱体裂解制备陶瓷基复合材料中的特点与应用。     

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、...     

高性能钛酸钡/聚合物复合材料的研究进展

具有高介电常数(k)的钛酸钡/聚合物复合材料,兼有钛酸钡陶瓷和聚合物的各自优势,是一种有广泛应用前景的电子材料,因而备受关注。综合给出了近5年来高性能钛酸钡/聚合物复合材料的研究进展,分析指出了原材料选择、制备工艺及其对复合材料介电性能的影响,概括介绍了这类复合材料的主要应用,预测展望了其未来的发展趋势。     

新型高温高介无机/有机功能复合材料

综述了高温高介的无机/有机功能复合材料的应用、近期研究状况、高介机理、原材料选择以及制备过程等重要问题。重点介绍了高介复合材料新的发展方向以及利用高介电的形成机制设计新材料的思想。 强调填料和基体聚合物的选择以及改性是至关重要的。 同时,改善相界面及纳米微粒的表面修饰技术方面还需有所突破,最终实现对材料性能、功能的分子设计。      

1D/2D Carbon Nanomaterial‐Polymer Dielectric Composites with High Permittivity for Power Energy Storage Applications

With the development of flexible electronic devices and large‐scale energy storage technologies, functional polymer‐matrix nanocomposites with high permittivity (high‐k) are attracting more attention due to their ease of processing, flexibility, and low cost. The percolation effect is often used to explain the high‐k characteristic of polymer composites when the conducting functional fillers are dispersed into polymers, which gives the polymer composite excellent flexibility due to the very low loading of fillers. Carbon nanotubes (CNTs) and graphene nanosheets (GNs), as one‐dimensional (1D) and two‐dimensional (2D) carbon nanomaterials respectively, have great potential for realizing flexible high‐k dielectric nanocomposites. They are becoming more attractive for many fields, owing to their unique and excellent advantages. The progress in dielectric fields by using 1D/2D carbon nanomaterials as functional fillers in polymer composites is introduced, and the methods and mechanisms for improving dielectric properties, breakdown strength and energy storage density of their dielectric nanocomposites are examined. Achieving a uniform dispersion state of carbon nanomaterials and preventing the development of conductive networks in their polymer composites are the two main issues that still need to be solved in dielectric fields for power energy storage. Recent findings, current problems, and future perspectives are summarized.     

有限元法研究填料形貌与介电常数对无机/有机介电复合材料介电性能的影响

为了开发高储能密度的无机/有机介电复合材料,本文采用有限元法分别研究了直径为100 nm的球形填料与基体介电常数的比值（k）、球形填料在复合材料中的排列方式、球形填料尺寸（100~300 nm）、纤维状填料长径比（α）和片状填料的球形度（β）对复合材料介电性能的影响。计算结果表明,当k值大于20时,复合材料的介电常数变化不明显;球形填料沿电场方向成链式排列时,复合材料有较大的介电常数,且材料中球形填料附近处存在较大的电位移和较大的电场,说明这种填料排列方式有利于材料介电常数的提高,但会削弱材料的耐击穿能力;当球形填料随机分布时,颗粒尺寸变化对复合材料介电常数的影响不明显。对于纤维状填料,其长径比α越大且长轴沿电场方向分布时,填料自身及周边会产生较大的电位移,表明这种情况有利于复合材料介电常数的提高。对于片状填料,其球形度β越小,填料与基体界面处高电场区域越小,表明材料的耐击穿能力越高。本研究可为高介高储能材料的实验研究提供理论指导。      

Polymer matrix wave-transparent composites:A review

With the rapid development of electronic information technology,antenna systems in the fields of avia-tion,aerospace,transportation,and 5 G communication services are becoming more and more intensive and accurate.Polymer matrix wave-transparent composites with lightweight,low dielectric constant(e)and dielectric loss tangent(tanδ),high temperature resistance,and excellent mechanical properties are urgently needed in order to ensure high-fidelity transmission of electromagnetic wave and protect antenna systems from external interference.This review introduces the wave transmission mechanism,key compositions(polymer matrix&reinforced fibers),and several typical testing methods for dielec-tric properties of polymer matrix wave-transparent composites,mainly elaborates the latest research progress and achievements of polymer matrix wave-transparent composites from polymer matrix,rein-forced fibers and their surface functionalization methods,and presents the key scientific and technical problems that need to be solved urgently in the application of polymer matrix wave-transparent com-posites in the antenna systems.Finally,the future development trends and application prospects of the polymer matrix wave-transparent composites are also proposed.     

纳米颗粒材料的毒性研究与安全性展望

人类接触纳米材料一般通过下面3条途径:呼吸系统;皮肤接触;其他方式,如食用、注射之类.纳米材料通过上述途径进入人体,可能与体内细胞起反应,引起发炎、病变等,因此目前多针对以上接触方式进行纳米颗粒材料的毒性研究.从不同的接触方式介绍了纳米颗粒生物毒性的一些研究情况,对产生生物毒性的原理进行了探索,并对纳米颗粒材料安全性和降低危险性的方法进行了展望.     

Analysis on dielectric loss characteristics of polyvinylidene fluoride and its composites

In this study, barium calcium zirconate titanate nanoparticles and nanofibers (denoted as BZT-BCT NPs and BZT-BCT NFs, respectively) were prepared by the sol–gel method and electrospinning, respectively. Under different temperatures and frequencies, the dielectric spectra of polyvinylidene fluoride (PVDF), BZT-BCT NPs, and BZT-BCT NFs composites were measured. On the basis of the experimental data, the polarisation activation energies of the polymer matrix interfacial polarisation and the dipole turn polarisation were calculated, and the basic polarisation characteristic parameters of the polymer matrix materials and fillers were obtained. Moreover, the effects of the filling phase and filling ratio on the dielectric properties of the composites were studied through applying BZT-BCT NPs and BZT-BCT NFs as the filling phases of the PVDF matrix and PVDF matrix composites. Furthermore, the double-layer low-density polyethylene (LDPE)/PVDF composites as well as the LDPE/PVDF composites uniformly mixed at a volume fraction of 1:1 were prepared, and the interfacial polarisation behaviours of the two materials were studied by dielectric spectroscopy to establish an effective analytical method so as to characterize interfacial polarisation established. The experimental results revealed as follows: interfacial polarisation was a significant mechanism of the polarisation behaviour of the composite materials; the fillers with different shape factors had varying effects on the dielectric constant of composites; meanwhile, the dielectric constant of the composite conformed to the predictions of the effective medium theory model.

     

TEOS surface modification of CLST ceramic particles for PTFE-based composites

PTFE-based ceramic-polymer dielectric composites have been widely researched in the communication field due to their good processing, wide range frequency and temperature stability and being able to provide tunable dielectric constant in a scale. In order to improve the compatibility between the ceramic fillers and polymer matrix without damage of dielectric properties, surface modifiers with less carbon remain are preferred. In this paper, tetraethylorthosilicate (TEOS) is employed as a surface modifier to improve the compatibility between the (Ca, Li, Sm)TiO₃ (CLST) ceramic and PTFE, and the dispersion of the ceramic particles in the matrix. FTIR, XPS and TEM results indicate that TEOS is coated on the ceramic particles successfully and forms a silica coating layer. The surface modification improves the dispersion of particles in PTFE and interface contact between the ceramic fillers and PTFE matrix. These improve the thermal stability and reduce the dielectric loss of the dielectric composites. The CLST/PTFE composite modified by TEOS exhibits a dielectric constant of 6.22 with dielectric loss just 0.0012 at microwave frequencies (around 10 GHz).     

Barium Titanate-Polymer Composites Produced via Directional Freezing

In this study, we use a freeze casting technique to construct ceramic-polymer composites in which the 2 phases are arranged in an electrically parallel configuration. By doing so, the composites exhibit dielectric constant (K) up to 2 orders of magnitude higher than that of composites with ceramic particles randomly dispersed in a polymer matrix. In this technique, an aqueous ceramic slurry was frozen unidirectionally to form ice platelets and ceramic aggregates that were aligned in the temperature gradient direction. Upon freeze-drying, the ice platelets sublimed and left the lamellar ceramic structure intact. The green ceramic body was fired to retain the microstructure, and then the space between ceramic lamellae was infiltrated with a polymer material. The finished composites exhibit the high dielectric constant (1000) of ferroelectric ceramics while maintaining the unique properties of polymer materials such as graceful failure, low dielectric loss, and high dielectric breakdown.