微孔发泡聚合物基导电复合材料的研究进展

概述了用超临界流体作为物理发泡剂对聚合物基导电复合材料进行微孔发泡的基本原理,总结了聚合物基导电复合材料及其微发泡复合材料的几种导电机理,简要介绍了近年来微孔发泡聚合物基导电复合材料电学性能的研究现状。并从微发泡聚合物基导电复合材料的基体特性、所使用的导电填料类型、导电填料的含量、填料在基体中的分散方法及微发泡复合材料的泡孔形态等几个方面,分析了影响微孔发泡聚合物基导电复合材料电学性能的主要因素,并展望了新型微孔发泡聚合物基导电复合材料的研究和发展趋势。     

热塑性/热固性聚合物共混体系研究——乙炔端基砜/聚砜共混物的动态固化动力学

近年来,半互穿聚合物网络(SIPN)概念被用来研制能结合热塑性聚合物的加工性和热固性聚合物的高温性能的大分子体系,用于复合材料耐高温树脂基体。例如:乙炔端基酰亚胺低聚物与热塑性聚酰亚胺基SIPN,线性聚酰亚胺与热固性双马来酰亚胺基SIPN以及热塑性树脂与双腈基SIPN已有报道。研究结果表明共混物起到协同作用,易于加工并具有优异的性能。乙炔端基砜(ATS)树脂具有与聚砜树脂相类似的结构,被认为在将来代替环氧用于高性能粘合剂和复合材料树脂基体的候选者之一。其另     

聚四氟乙烯和石墨对聚醚酰亚胺摩擦学性能的影响

将聚四氟乙烯(PTFE)和石墨两类减摩耐磨填料填充到聚醚酰亚胺(PEI)中,表征其摩擦性能,利用扫描电子显微镜分析了磨损表面的显微结构,并分析了磨损机制.研究结果表明,PTFE和石墨的填充明显改善了PEI的摩擦磨损性,摩擦系数降低到0.3以下(纯PEI的摩擦系数为0.41),磨损率降低了3个数量级.在PTFE体系中,PTFE质量分数为10%时,PEI基共混材料的摩擦系数最低为0.23;而在质量分数为15%的石墨体系中,PEI基共混材料摩擦系数最低为0.27.磨损率随着填料含量的增加而逐渐下降,在填料质量分数为20%之后,摩损率下降平缓.因此PTFE和石墨的填充对PEI的摩擦学性能起到了很好的改善作用,而且PTFE比石墨的改善效果更优益.共混物的机械性能测试结果表明,在填料质量分数为5%~15%时,共混物具有良好的机械性能.     

一步法制备蒙脱土-石墨烯协同增强聚乙烯醇复合材料

以蒙脱土(MMT)和石墨烯(rGO)为填料,一步法制备了MMT-rGO/PVA纳米复合材料,并研究了不同MMT/rGO比例对PVA复合膜力学性能的影响.结果表明,剥离的MMT片层能够有效阻止石墨烯在被还原过程中的团聚.MMT-rGO二元填料与PVA间形成氢键,极大地改善了填料与聚合物间的界面结合,能够协同提高PVA复合膜的力学性能.1 wt%MMT-GE(2∶1)/PVA复合材料的拉伸强度和杨氏模量最高,分别为85.1 MPa和1627.8 MPa,比纯PVA分别提高了46%和62%.此方法为制备高性能聚合物复合材料提供了有效的途径.     

含苯乙炔基的可交联聚芳醚酮交替共聚物的合成与热性能

以耐高温高性能树脂-聚芳醚酮作为研究对象, 从改善材料的加工工艺性及提高材料的使用温度出发, 对含有苯乙炔基的交替共聚物进行了系统研究. 实验结果表明, 该系列聚合物固化前具有较好的溶解性, 固化过程中显示出较好的热稳定性, 固化后具有较高的玻璃化转变温度和优异的热稳定性与热氧稳定性, 且降低聚合物的分子量没有对固化物的热性能产生明显影响, 在高性能复合材料基体树脂方面具有潜在的应用价值.     

石墨烯及其聚合物纳米复合材料

石墨烯是一种新型的二维纳米碳材料,具有优异的机械性能、电性能和热性能等,是聚合物纳米复合材料的理想填料。近年来,石墨烯/聚合物纳米复合材料成为聚合物基纳米复合材料的研究热点。本文对石墨烯及其聚合物纳米复合材料的研究进展进行了综述。首先概述了石墨烯的不同制备方法及石墨烯的共价与非共价改性途径。然后重点总结了石墨烯/聚合物纳米复合材料的常用制备方法及其机械性能、导电性、导热性、耐热性及阻隔性能。最后,对该领域所存在的问题进行了总结,并展望了其发展趋势。     

聚合物基纳米复合材料结构设计与电磁屏蔽性能研究

聚合物纳米复合材料以其质量轻、易加工成型、耐化学腐蚀等优秀特性成为电磁屏蔽材料的研究热点.复合材料的导电性是影响电磁屏蔽性能的关键因素,而聚合物基体中导电网络结构则决定了材料内部的电子传输效率,从而在很大程度上决定材料导电性能.合理的结构设计可以解决纳米填料在基体中易团聚、难分散的问题,实现低渗滤阈值、高导电性能/电磁屏蔽与多功能化的统一.我们围绕聚合物纳米复合材料的关键科学问题展开研究,取得一些创新性研究成果:(1)通过填料/基体界面调控,实现复合材料连续导电网络的构筑,制备系列低渗滤阈值聚合物导电复合材料;(2)发展三维导电结构预先构筑新方法,制备出高效导电网络,实现电磁屏蔽复合材料结构功能一体化设计与制备;(3)提出构建多界面结构策略,实现聚合物电磁屏蔽复合材料的轻量化设计.本专论针对我们研究成果进行总结,并对高性能电磁屏蔽纳米复合材料的发展前景进行展望.     

高介电常数、低介电损耗的聚合物基复合材料*

考虑到高介电常数、低介电损耗聚合物基复合材料在电气、电子行业的广泛重要应用,本文对其研究进展进行了回顾。重点讨论了功能填料、聚合物基体及它们两者的相互作用等因素对聚合物基复合材料介电性能的影响规律,试图为建立高介电常数、低介电损耗的聚合物基复合材料的设计和制备原理理清思路。指出该领域在未来的主要发展方向是涉及制备结构、形貌、尺寸可控的新的功能填料,探索新型简单的复合工艺和界面控制技术,从理论上分析建立功能填料的结构和介电性能的关系模型等。     

偶联剂对钛酸钾晶须/双马来酰亚胺树脂摩擦磨损性能的影响

研究了不同偶联剂及钛酸钾晶须添加量对钛酸钾晶须 /双马来酰亚胺树脂复合材料的摩擦磨损性能的影响 .结果发现 ,钛酸钾晶须能明显提高复合材料的耐磨性 ,晶须的加入使材料的磨损率得到显著降低 ;钛酸钾晶须对材料具有一定的润滑性 ,添加晶须后材料的摩擦系数与树脂基体基本相当 ;偶联剂对复合材料的摩擦系数影响不大 ,但是合适的偶联剂对材料耐磨性的提高则具有明显的作用 .晶须添加量较低时 ,复合材料的磨损机理主要为较严重的粘着磨损 ,晶须添加量较高时 ,疲劳磨损占主导地位 .     

HDPE/HIPS/CB复合材料的制备及PTC性能

以高抗冲击聚苯乙烯(HIPS)和高密度聚乙烯(HDPE)为基体,炭黑(CB)为导电填料,采用熔融法制备聚合物基正电阻率温度系数效应(PTC)复合材料.通过扫描电子显微镜(SEM)研究了CB在复合材料两相基体中的选择分布,采用热敏电阻温度(RT)曲线测试仪研究复合材料PTC性能随CB含量的变化规律.结果表明,在HIPS/CB体系中加入HDPE后,复合材料的渗流阈值降低,PTC强度增强,耐电压强度有所提高.     

Comparative study of the effects of nano‐sized and micro‐sized CF and PTFE on the thermal and tribological properties of PEEK composites

The tribological characteristics of PEEK composites fretting against GCr 15 steel were investigated by a SRV‐IV oscillating reciprocating ball‐on‐disk tribometer. In order to clarify the effect of type and size of fillers on the properties of PEEK composites, nano‐sized and micro‐sized CF and PTFE fillers were added to the PEEK matrix. The thermal conductivity, hardness, and fretting wear properties of PEEK composites reinforced by CF or PTFE were comparatively studied. The results showed that the type and size of the fillers have an important effect on both the friction coefficient and wear rate, by affecting their thermal conductivity, hardness, as well as the surface areas of their transfer films. In comparison, the effect on improving the tribological properties of micro‐sized CF was superior to that of nano‐sized CF, while the effect of nano‐sized PTFE was superior to that of micro‐sized PTFE. Considering the acceptable friction coefficient and wear rate of the composite under the fretting wear test, it seemed that 4% nCF, 20% mCF, 2% nPTFE and 10% mPTFE were desired additive proportions. And it also can be found that during the fretting wear test, the abrasive and adhesive wear resulted in accumulative debris at the contacting surface. The transfer films made of debris were formed on the counterfaces.     

The Wear Resistance of Composite Materials Based on Ultra-High-Molecular-Weight Polyethylene with Fillers of Various Types

The tribological properties and wear resistance under different action of composite materials based on of ultra-high-molecular-weight polyethylene (UHMWPE) and fillers of various types such as organomodified montmorillonite (MMT), graphite nanoplates (GNP), molybdenum disulfide, and shungite prepared via polymerization in situ are studied. According to the obtained results, the introduction of these fillers to UHMWPE in the amount of 0.4–7 wt % has almost no effect on the value of the coefficient of sliding friction on steel in the mode of dry friction. Composites with GNP, MoS₂, and shungite are characterized by a significant (two- to threefold) increase in the wear resistance in the case of sliding friction on steel. The abrasive wear of composites in the case of friction on an abrasive paper is substantially affected by the type of filler, the use of MMT was the most effective for increasing the wear resistance of composites. In the case of a highspeed impact effect of water–sand suspensions all the studied composites are characterized by increased wear resistance in comparison with industrial UHMWPE at a low concentration of fillers and by an increase in the wear with the increase of the filler content.     

Research on high temperature friction properties of PTFE/Fluorosilicone rubber/silicone rubber

Silicone rubber (MVQ) has excellent heat resistance, but poor high temperature friction stability, which limits its application in the field of high temperature sealing. Polytetrafluoroethylene (PTFE) is self-lubricating, but its compatibility with rubber is relatively weak. In order to improve the high-temperature friction property of silicone rubber, fluorosilicone rubber (FVMQ) was used as a compatibilizer, and PTFE was added to MVQ by mechanical blending. The friction and wear properties of PTFE/FVMQ/MVQ composites at different temperatures were studied. The results show that compared with MVQ, the mechanical properties of PTFE/FVMQ/MVQ composites was basically unchanged, the coefficient of friction was hardly affected by temperature, and the amount of wear decreased with increasing temperature. PTFE/FVMQ/MVQ composites showed excellent high-temperature abrasion resistance. The high-temperature wear mode was mainly changed from abrasive wear to adhesive wear. The molten layer formed by high-temperature friction can prevent air from directly contacting the surface rubber, which inhibited rubber surface oxidation reaction process.     

Combined effect of fibers and PTFE nanoparticles on improving the fretting wear resistance of UHMWPE‐matrix composites

Ultra‐high molecular weight polyethylene composites reinforced with carbon fibers (CF) and polytetrafluoroethylene (PTFE) were prepared. The effects of fillers on the microstructure and fretting wear behavior of composites were investigated. The results of X‐ray diffraction and scanning electron microscopy measurements indicated that the microstructure of composites were greatly changed, and the distinct interface between fillers and matrix had been formed with the incorporation of CF and PTFE. In addition, results also showed that the simultaneously filled with CF and PTFE at a proper weight fraction contributed to dramatically improving the friction reducing and wear resistance of ultra‐high molecular weight polyethylene. It can be found that there exists synergism between fillers. Copyright © 2015 John Wiley & Sons, Ltd.     

钛酸钾晶须填充环氧树脂复合材料的摩擦磨损特性

以提高环氧树脂的摩擦磨损性能为目的,研究了钛酸钾晶须(PTW)填充环氧树脂复合材料的滑动干摩擦磨损特性,着重探讨PTW含量、摩擦条件等对复合材料摩擦性能的影响.通过对复合材料磨损表面的形貌分析以及复合材料表面硬度的测定,探讨了复合材料的磨损机理.结果表明:PTW能明显提高环氧树脂耐磨性并降低其摩擦系数,w(PTW)=0.08的环氧树脂复合材料的耐磨性比纯环氧树脂提高近10倍,摩擦系数降低35%.     

Effect of nano‐modified SiO2/Al2O3 mixed‐matrix micro‐composite fillers on thermal,mechanical, and tribological properties of epoxy polymers

Thermo‐mechanically durable industrial polymer nanocomposites have great demand as structural components. In this work, highly competent filler design is processed via nano‐modified of micronic SiO₂/Al₂O₃ particulate ceramics and studied its influence on the rheology, glass transition temperature, composite microstructure, thermal conductivity, mechanical strength, micro hardness, and tribology properties. Composites were fabricated with different proportions of nano‐modified micro‐composite fillers in epoxy matrix at as much possible filler loadings. Results revealed that nano‐modified SiO₂/Al₂O₃ micro‐composite fillers enhanced inter‐particle network and offer benefits like homogeneous microstructures and increased thermal conductivity. Epoxy composites attained thermal conductivity of 0.8 W/mK at 46% filler loading. Mechanical strength and bulk hardness were reached to higher values on the incorporation of nano‐modified fillers. Tribology study revealed an increased specific wear rate and decreased friction coefficient in such fillers. The study is significant in a way that the design of nano‐modified mixed‐matrix micro‐composite fillers are effective where a high loading is much easier, which is critical for achieving desired thermal and mechanical properties for any engineering applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Friction and wear behavior of PI and PTFE composites for ultrasonic motors

High‐performance polymer‐based frictional materials have become increasingly important to improve the mechanical output properties of ultrasonic motors. This study discussed the friction and wear behavior of 2 dominating frictional materials of polymer composites for ultrasonic motors, polyimide (PI), and polytetrafluoroethylene (PTFE) filled by aramid fibers (AF) and molybdenum disulfide (MoS₂). To explore the wear mechanisms, the tribo‐pair contact stress was theoretically characterized, and the interface temperature rise was numerically predicted. The predictions showed that the flash temperature on asperity tips could reach the glass transition temperature of the polymer materials. The experimental results indicated that the contact stress and sliding speed have a small effect on the friction of the PI composite but influence considerably the friction of the PTFE composite. A higher contact stress brings about a higher specific wear rate, but a higher sliding speed reduces the wear rate. Compared with AF/MoS₂/PTFE, the AF/MoS₂/PI has much better tribological performance under high loads and speeds.     

Effects of clay and surface plasma‐treated carbon fiber on wear behavior of thermoplastic POM composites

In engineering applications, experimental data and insight from scientific investigations on wear properties of polyoxymethylene (POM) composites are important for engineers to understand how to design and formulate POM materials with high resistance to wear. In this work, clay and carbon fiber were utilized and incorporated into POM and the mechanical and wear properties, in specific wear rate, were then assessed. The experimental results suggested that the addition of clay increased the tensile modulus and strength. The mechanical and wear properties of POM composites were found to improve with the addition of the carbon fiber. Carbon fiber/clay/POM composite exhibited the lowest specific wear rate and friction coefficient.     

A review on plant fiber reinforced thermoset polymers for structural and frictional composites

In recent past years, utilization of synthetic materials has become a matter of immense concern due to increasing environmental awareness in terms of safety, sustainability and maintaining ecological balance. A substantial amount of work has been carried out on various aspects of plant based natural fiber reinforced thermoset polymer composite materials due to their numerous inherent properties like high specific strength, low cost and degradability. Current issues and challenges associated with mechanical and tribological properties of only plant based natural fiber reinforced thermoset composites have been highlighted in the present study. Various factors influencing mechanical and tribological characteristics have been discussed keeping the focus on plant fiber reinforced thermoset composites. A detailed discussion on mechanical (tensile, compressive, flexural, impact strength) and tribological properties (friction and specific wear rate) have been reported. Interfacial adhesion was found to be a dominating factor with respect to mechanical and tribological properties. Wear and frictional characteristics of plant fiber based thermoset composites can be controlled using suitable fillers and reinforcement orientation. A discussion on interfacial adhesion and its effect on composite performance have also been included.