聚酰亚胺复合材料改性方法优化其摩擦学性能的研究进展

聚酰亚胺复合材料是一种常见的摩擦材料，具有良好的抗磨减摩性能。通过总结近几十年来聚酰亚胺复合材料的摩擦学性能的研究情况，综述纤维、晶须、固体润滑剂、纳米材料填充改性、聚合物共混的改性方法，分析并讨论不同改性方法对聚酰亚胺复合材料摩擦学性能的影响。指出对于聚酰亚胺摩擦学研究所面临的问题，并展望未来聚酰亚胺复合材料在摩擦磨损方面的发展方向。     

碳黑、微珠粉填充UHMWPE摩擦学性能研究

比较了碳黑、微珠粉填充UHMWPE复合材料摩擦学行为,用MM-200型摩擦磨损试验机考察了载荷及对摩偶件粒度对碳黑、微珠粉填充UHMWPE复合材料摩擦磨损性能的影响,利用扫描电子显微镜观察磨损表面形貌并分析了磨损机理.结果表明:碳黑可以提高UHMWPE抗磨损的性能,其耐磨性比纯UHMWPE好;而微珠粉填充UHMWPE的耐磨性比纯UHMWPE差,两种材料填充的UHMWPE磨损量随着载荷的增大而加大;对摩偶件的粒度对两种材料填充UHMWPE复合材料的摩擦磨损性能影响较大,偶件表面粒度增大,它们磨损量显著增大.两种材料填充UHMWPE复合材料的摩擦系数相近,且较纯UHMWPE的摩擦系数大,特别是载荷增大和对摩偶件粒度增大时,UHMWPE复合材料的摩擦系数急剧增大.     

纳米SiO2对聚醚砜酮复合材料摩擦学性能的影响

在MM-2000型摩擦磨损试验机上考察了不同载荷和速度下纳米SiO2含量对聚醚砜酮（PPESK）复合材料摩擦磨损性能的影响，并利用扫描电子显微镜（SEM）观察分析PPESK及纳米SiO2/PPESK复合材料磨损表面形貌及磨损机理，结果表明：纳米SiO2不但可以提高PPESK的耐磨性，而且还有较好的减摩作用，在本研究的试验条件下，当纳米SiO2的质量分数为25%时，填充PPESK复合材料具有最佳摩擦学性能。随着载荷的增大，填充PPESK的摩擦系数降低，填料含量在20%质量分数以下时随载荷增大其耐磨性提高较明显，而填料含量超过20%质量分数时载荷对复合材料耐磨性的影响不大。     

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。     

无机颗粒增强聚合物基复合材料耐磨性能影响因素研究进展

为了更好地指导无机颗粒增强聚合物基耐磨复合材料的优化设计,全面回顾了复合材料各组分对复合材料耐磨性能的影响。根据复合材料组成,将无机颗粒增强聚合物基复合材料耐磨性能影响因素分成5类:纳米/微米无机颗粒填充量、纳米/微米填充颗粒粒径、不同粒径无机颗粒的级配、无机颗粒与纤维的协同增强和无机颗粒表面处理。从能量角度,即各因素对材料内部结合键的断裂所吸收的外部冲击功和摩擦功的影响,分析了各因素对复合材料耐磨性能的影响。在回顾前两个因素对复合材料耐磨性影响时,发现都存在使材料耐磨性能最佳的最佳颗粒填充量和最佳颗粒粒径。对于微米颗粒(粒径50μm),颗粒填充量比粒径对复合材料耐磨性能影响更大,应尽可能提高颗粒最佳填充量。对于纳米颗粒,颗粒粒径则是影响材料耐磨性能的关键因素,应尽可能降低最佳颗粒粒径。另外,颗粒的表面改性和级配都能通过提高颗粒最佳填充量和综合力学性能来提高复合材料的耐磨性能。无机颗粒与纳米纤维的混杂填充使复合材料同时具备最优的耐磨性能、摩擦系数以及优异的变载荷适应性。     

纳米改性增强超高分子量聚乙烯复合材料研究进展

纳米材料具有极大的比表面积、宏观量子隧道效应、体积效应和尺寸效应;采用具有特殊性能的纳米材料填充改性聚合物是增强聚合物材料性能的最有效方法之一。通过单相或多相纳米材料填充改性超高分子量聚乙烯(UHMWPE),可使复合材料的性能得到不同程度的改善和提高。综述了纳米材料改性增强UHMWPE复合材料的摩擦学性能、力学性能、电学性能、生物相容性、热学性能等;展望了纳米填充UHMWPE复合材料的发展方向和应用前景;提出采用微量的高性能纳米材料改性聚合物以大幅度提高复合材料的性能是未来研究的重要方向。     

碳系导电填料性质对PVB基功能薄膜结构及电磁屏蔽效能的影响

分别以形状和电导率不同的石墨、镀镍石墨和镀银碳纤维为功能填料,采用溶液流延法制备了聚乙烯醇缩丁醛基导电薄膜,并对薄膜的微观结构和电学性能进行了研究。结果表明:填料性质(包括形状、密度和电导率)对复合材料的分布结构和电学性能有重要影响,纤维状的填料更容易搭接成导电网络。石墨和镀银碳纤维填充体系中,填料在聚合物基体内部分布基本均匀;而镀镍石墨填充体系中,填料在聚合物基体内部形成了梯度分布。不同的分布状态导致材料的导电性能在薄膜的上下表面产生差异并对复合材料的电磁屏蔽效能产生影响。在同等体积含量下,复合材料的电磁屏蔽效能主要受材料电导率的影响,三种复合材料中,镀银碳纤维填充体系的屏蔽效能最高,镀镍石墨填充体系次之,石墨填充体系最低。     

面向低温环境的聚合物摩擦学性能及其改性研究进展

聚合物及其复合材料具有力学性能好、摩擦系数低、耐磨性能强等优点,常被应用于制造摩擦副关键基础件,如密封圈、齿轮、轴承保持架、转子叶片、活塞等.但迄今针对低温工况的聚合物摩擦学研究甚少,主要工作集中在常温和高温工况.面向低温环境的聚合物及其复合材料的摩擦学应用与相关制备、改性工艺的相关理论并不完备,极端服役环境下聚合物的摩擦学损伤失效机理还尚未完全清楚.此外,聚合物材料虽然具有众多优良的性能,但是其表面硬度低、温度影响大、易变形等缺点也同样明显,限制了其在低温摩擦学领域的应用,为此,研究者通过填充填料、表面处理等方法对聚合物进行了改性研究,取得了一定的成果.目前,由于航空航天等前沿技术的不断发展,聚合物在真空低温环境下的摩擦学性能受到了广泛关注,聚四氟乙烯、聚酰亚胺、聚醚醚酮等聚合物自润滑材料已被应用于空间飞行器领域来制作润滑和密封部件.研究者利用石墨、石墨烯、二硫化钼、芳纶纤维、玻璃纤维等对聚合物进行改性,制备了在低温环境下具有低摩擦系数、高耐磨性的聚醚醚酮/石墨、聚四氟乙烯/芳纶纤维、聚四氟乙烯/超高分子量聚乙烯等复合材料,促进了聚合物在低温摩擦学领域的应用.本文系统分析了低温环境下温度、环境介质、滑动速度、载荷、滑动方向等因素对聚合物摩擦学性能的影响,对面向低温环境的聚合物摩擦学改性进行了简要总结,以期促进聚合物低温环境下摩擦学应用及其相关研究的进一步发展.     

碳纤维/聚合物复合材料摩擦学改性研究进展

综述了碳纤维/聚合物复合材料摩擦学改性的研究进展情况,重点分析讨论了碳纤维表面改性、固体润滑剂共混改性、纤维混杂复合改性以及纳米粒子填充改性对碳纤维增强聚合物复合材料摩擦学性能影响的微观机制,并指出多元、多尺度功能性填料协同复合增强是改善该复合材料摩擦学性能的重要手段。     

功能性填料改性聚合物材料的摩擦学研究进展

聚合物材料因其质轻、价廉、耐腐蚀以及优异的自润滑特性而广泛应用于工程机械润滑领域中。加入功能性减摩和增强填料复合改性聚合物树脂可以克服本征型高分子材料的一些固有缺陷,得到低摩擦因数、高耐磨性、高承载力以及耐高温等优异特性的摩擦学复合材料。本文综述了功能性填料如碳基材料、过渡金属硫化物、微胶囊、软金属、陶瓷纳米颗粒、矿物盐以及自润滑高分子对复合材料的减摩抗磨效果及机理。同时,力学性能是保证聚合物材料服役性能和使役寿命的关键参数,也会对材料的摩擦学性能带来显著影响。本文还重点论述了纳米颗粒和纤维等填料对复合材料的增强和增韧机理。最后,展望了功能性填料对力学性能与摩擦学性能的协效作用,以及计算机模拟在复合材料摩擦学中应用的发展趋势。     

PTFE复合材料的摩擦学性能及力学性能

利用MM-200型磨损试验机,对不同填料填充PTFE复合材料的摩擦磨损性能进行了研究,并探讨了淬火处理对PTFE复合材料摩擦学性能及力学性能的影响.研究发现,几乎所有填料均可大大降低PTFE复合材料的磨损,但其对PTFE复合材料性能的影响差别较大.聚苯脂填充PTFE复合材料虽然具有良好的摩擦磨损性能,但是其拉伸强度较小.PI增大了PTFE复合材料的摩擦系数,随着PI含量的增加,PTFE复合材料的拉伸强度增大,而其伸长率则减小.CdO填充PTFE复合材料虽具有良好的摩擦性能,但其伸长率较大.淬火处理使PTFE复合材料的结晶度下降,从而导致PTFE复合材料的硬度减小、耐磨性变差.     

电磁屏蔽复合材料的屏蔽性能预测

建立了填充椭球颗粒电磁屏蔽复合材料等效电磁参数的物理模型,基于变分原理和电磁波传输理论推导出其电磁屏蔽性能的预测公式,计算了不同填充条件下复合材料的屏蔽效能及反射率,分析了填料显微结构特征(浓度、形状、尺寸、分布方式)对复合材料屏蔽性能的影响规律.结果表明,复合材料屏蔽效能和反射率随填料填充浓度、长径比的增加而增大;针形和片形填料优于球形填料且定向分布好于随机分布;材料的反射率在特定的填充浓度及填料尺寸下存在峰值。屏蔽效能的计算结果与实验上填充球形银包羰基铁和镀镍短碳纤维的屏蔽复合材料的测试数据拟合较好。     

Improved breakdown strength and energy density of polyimide composites by interface engineering between BN and BaTiO3 fibers

Conventionally,interface effects between polymers and fillers are essential for determining the breakdown strength and energy storage density of polymer-based dielectric composites.In this study,we found that interface effects between different fillers have similar behavior.BN and BaTi03 fiber composite fillers with three different interface bonding strengths were successfully achieved by controlling composite processes (BT-fiber/BN ＜ BT-fiber@BN ＜ BT-fiber&BN),and introduced into a polyimide (PI)matrix to form composite films.Considerably enhanced breakdown strength and energy storage density were obtained in BT-fiber&BN/PI composites owing to strong interface bonding,compared to other two composite fillers,which are well supported by the data from the finite element simulation.Specifically,PI composites with only 3 wt％ BT-fiber&BN possess an optimized energy storage density of approximately 4.25 J/cm3 at 4343 kV/cm.These results provide an effective way for adjusting and improving the energy storage properties of polymer-based composites.     

碳酸钙填料对不饱和聚酯树脂体积收缩的影响及其机制

研究了CaCO₃填料对不饱和聚酯树脂（UP）体积收缩性能的影响,通过SEM、DSC、TG和溶胀实验研究了其作用机制。填料的加入导致填料/UP复合体系的体积收缩率先上升,后下降;用偶联剂对填料进行表面处理后加入复合体系中发现,复合体系的体积收缩率变小。填料主要通过以下3个方面影响复合体系的体积收缩：填料取代了部分树脂,有利于体系的体积收缩率下降;复合体系固化后在填料及UP界面处形成空隙,有利于复合体系体积收缩率的降低;填料抑制苯乙烯的挥发,导致体系中不饱和聚酯固化密度增大,使体系体积收缩率上升。偶联剂的加入增加了填料与树脂的界面作用力,且可使苯乙烯的挥发量增加,导致其交联密度下降,使体积收缩率下降。     

Characterization of adsorbed silane on fillers used in dental composite restoratives and its effect on composite properties

The purpose was to study the effect of silane treatment of fillers on viscosity, flexural strength, and hydrolytic degradation of experimental dental composite resins fabricated with these fillers. The fillers consisted of a mixture of barium glass and amorphous silica. The resin was mainly based on ethoxylated bisphenol A dimethacrylate and polycarbonate dimethacrylate. The adsorption of silane on the filler surface was characterized by FTIR. There was significant correlation between the adsorbed silane on filler surface and the silane concentration in silane/methanol solution used for filler treatment. The silane concentration varied from 0.75 to 14% by weight. An increase in silane concentration led to a decrease in viscosities of the corresponding composite resins. The flexural strengths of composites with silanated fillers were greater than that of composites with unsilanated fillers: however, no significant difference was found between the flexural strengths of various silanated groups. The resistance to hydrolytic degradation of different composites increased when the fillers were treated with silane and was the highest at 1.1% silane.     

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。      

Synergy in hybrid polymer/nanocarbon composites. A review

The aim of this review article is to report the most recent developments in the understanding of and beliefs about the properties of polymer hybrid composites that are reinforced with various combinations of nanometer-sized carbon and mineral fillers. The discussions are primarily focused on an analysis and comparison of the electrical, thermal, and mechanical properties. It is shown that the introduction of a mixed (hybrid) system of filler nanoparticles into polymer matrices enhances the macro- and microproperties of the composites as a result of the synergistic interactions between the fillers and the simultaneous creation of a unique filler network in the polymer. The synergy of various types of carbon nanofillers and combinations of nanocarbon materials with inorganic fillers manifests itself as modifications of most of the properties of hybrid polymer composites relative to the properties of a polymer system containing a single filler. The reinforcing effect is related to the structure and particle geometry of the hybrid fillers, the interactions between the fillers, the concentrations and the processing methods.The existence of synergy between different types of carbon nanofillers, as well as with mineral fillers, shows great potential and could significantly increase applications of carbon-based nanomaterials.     

PTFE及纳米粒子改性环氧树脂基聚酯织物增强复合材料的拉伸及摩擦学性能

为了研究填料(纳米粒子和PTFE)对聚酯织物增强复合材料的拉伸及摩擦学性能(轴向及偏轴方向)的影响,使用手糊成型的方法制备了四种环氧树脂基聚酯织物增强复合材料.根据拉伸应力-应变曲线和断口形貌图讨论了拉伸断裂机理.使用环-块式结构的Amsler摩擦磨损试验机测试织物增强复合材料的摩擦学性能.结果表明:对于纯环氧树脂/织物增强复合材料来说,聚酯织物在整个织物增强复合材料的拉伸和摩擦磨损测试中起到了主要的抗拉和耐磨作用;但当在环氧树脂中加入填料后,环氧树脂基体在抗拉和耐磨性方面起到了越来越重要的作用.拉伸性能的提高是由于纤维-基体间界面的改善;由于填料具有优异的摩擦磨损性能,从而使织物增强复合材料的摩擦学性能得到了提高;并且纳米粒子和PTFE对于织物复合材料性能的提高起到了协同的作用.织物增强复合材料偏轴方向的拉伸性能和摩擦学性能与其在轴向的拉伸性能和摩擦学性能不同.     

Thermal conductivity of polymer composites with close-packed structure of nano and micro fillers

Thermal conductivity of polymer composites with nano and micro fillers has been investigated numerically and experimentally. The nano fillers used were multi-walled carbon nanotubes (MWNTs) and alumina nanoparticles, and the spherical alumina particles were selected as the micro fillers. A periodic unit cell with a random close-packed structure was created using a packing algorithm that treat the micro filler as spheres. Finite element analyses were also performed to predict the potential of nano fillers to enhance thermal conductivity of the composites and to analyze the effect of microstructure of micro fillers. Additionally, the polymer composites with nano and micro fillers were made and the thermal conductivity of the composites were measured. The results showed that the addition of MWNTs to the matrix lead to a large increase in thermal conductivity of the composites. The proposed thermal model predicted a thermal conductivity in good agreement with experiment.     

Synergetic effects of radiolytically degraded PTFE microparticles and organoclay in PTFE-reinforced ethylene vinyl acetate composites

This article reports exceptional synergistic effects observed in organic–inorganic dual filler containing ethylene vinyl acetate (EVA) composites. Polytetrafluoroethylene microparticles (PTFEMP) were produced by mechanically grinding radiolytically degraded PTFE; composites of EVA containing PTFEMP and organoclay were prepared in different proportions by melt compounding and their mechanical, melt flow, morphological and crystallographic characteristics were examined. Mechanical properties of ternary composites demonstrated high synergy between fillers, leading to manifold increase in the modulus of dual filler filled composites in comparison to single filler systems. Nielsen model fitted well with EVA/PTFEMP system; however it predicted remarkably low values for EVA/PTFEMP/organoclay system, confirming exceptional synergy between two fillers. Melt viscosity of EVA increased substantially on the addition of either of the fillers. X-ray diffraction studies revealed around 10% intergallery expansion in organoclay, in the composites having high loading of PTFEMP; though the crystallinity of EVA did not change.