不同炭黑对聚丙烯／炭黑复合材料导电性能的影响

研究了四种不同的导电炭黑与聚丙烯复合制得的复合材料的体积电阻率与炭黑含量的关系，确定了复合体系中炭黑的渗滤阈值。用扫描电镜(SEM)观察了不同炭黑含量的复合材料的断面形貌，用透射电镜(TEM)观察分析了四种炭黑的结构及粒径，并对其比表面积进行了测定。结果表明：炭黑不同，得到的复合材料的渗滤阈值有很大差别。炭黑结构性越高，比表面积越大，粒径越小，其导电性能越好，得到的渗滤阈值越低。特别是具有空壳结构的炭黑，其渗滤阈值明显低于其他三种炭黑。     

改性炭黑填充聚丙烯复合材料导电性能研究

将改性炭黑/聚丙烯熔融共混,制得复合导电材料,研究了填充不同种类的改性炭黑及其质量分数对复合材料导电性产生的影响。结果显示,复合材料呈现显著的渗滤效应,渗滤阈值约为10%;复合材料中填充改性炭黑后,其渗滤阈值下降至约8%。填充的炭黑种类不同,得到的复合材料的渗滤阈值存在较大的差异。复合材料的导电性能与炭黑比表面积也相关,炭黑比表面积越大,粒径越小,导电效果越好。     

聚丙烯/玻璃纤维/导电炭黑复合材料性能的研究

通过熔融挤出的方法,制备了聚丙烯/玻璃纤维/导电炭黑复合材料,并系统研究了不同玻璃纤维和导电炭黑含量对复合材料导电性能、力学性能、收缩率及结晶行为的影响。结果表明,玻璃纤维的加入能促进炭黑形成导电网络,有效降低逾渗阈值;玻璃纤维具有明显的增刚和降低收缩率的作用;且玻璃纤维和炭黑的加入均降低了聚丙烯的结晶能力。     

炭黑质量分数对炭黑/聚丙烯复合材料导电性影响

采用熔融共混制备炭黑(CB)/聚丙烯(pp)导电复合材料,研究炭黑质量分数对复合材料导电性的影响。结果表明,复合材料具有明显渗滤效应,渗滤值在8%左右,炭黑经偶联处理后,渗滤值降低到5%,体积电阻率降低3个数量级;同时发现"逾渗阈值"现象出现的原因,与热力学理论吻合较好,即随着炭黑含量的增加,复合体系界面能出现饱和、过剩,当体系界面过剩达到一定值后,粒子开始形成导电网络,宏观表现为复合材料体积电阻率突降。     

炭黑填充抗静电聚丙烯的研究进展

表面电阻率为10^6-10^9Ω/sq的炭黑填充聚丙烯是电子电器工业用塑料制品的理想抗静电材料。本文综述了炭黑填充抗静电聚丙烯的研究进展。以围绕降低渗滤阈值，为综合改善炭黑填充聚丙烯的电性质、力学性质和成型加工性能而进行的理论研究，从渗逾理论向双重渗逾理论进而向三重渗逾理论发展创新的过程并在相应的理论指导下，相继开发了二元复合体系、三元复合体系、四元复合体系的炭黑填充抗静电聚丙烯复合材料。其中新型的四元复合体系的炭黑填充抗静电聚丙烯复合材料将会成为炭黑填充抗静电聚丙烯的发展方向，而新型的极低炭黑填充的四元复合体系抗静电聚丙烯将会成为研发的焦点和热点。     

PEEK抗静电复合材料的研究

制备了聚醚醚酮/炭黑(PEEK/CB)、聚醚醚酮/碳纤维(PEEK/CF)抗静电复合材料。结果表明,在PEEK/CB复合体系中,炭黑渗滤区含量为3%⁵%,较低的炭黑含量确保了复合材料优异的力学性能;在PEEK/CF复合体系中,碳纤维渗滤区含量为15%5%,较低的炭黑含量确保了复合材料优异的力学性能;在PEEK/CF复合体系中,碳纤维渗滤区含量为15%²0%;扫描电镜(SEM)结果证明:炭黑在PEEK基体中达到纳米级分散,形成空间导电网络结构,这种结构提高了复合材料的抗静电性能。     

填充型多相聚合物导电复合材料的PTC效应

以聚丙烯和低密度聚乙烯共混物为基体,用碳黑为填充材料制备了复合导电材料,导电性能的测试表明多相复合体系的渗滤阈值低于两相复合体系的渗滤阈值。对复合材料PTC效应的分析以及对材料的热性能测试结果表明碳黑在共混体系中的分布。同时探讨了体系碳黑含量的变化对PTC效应的影响。     

炭黑填充聚丁烯复合材料导电性能的探讨

研究了炭黑/聚丁烯复合材料的导电性能。结果表明:同炭黑/聚乙烯、炭黑/聚丙烯复合材料类似,炭黑/聚丁烯复合材料具有明显的渗滤效应,不同炭黑的渗滤阀值相差较大。影响复合材料导电性能的因素有:炭黑添加量、炭黑表面化学性质、炭黑结构。     

UHMWPE/炭黑抗静电复合材料的研究

制备了导电炭黑(CB)填充UHMWPE抗静电复合材料。实验结果表明,在经表面固相接枝改性的UHMWPE/CB复合体系中,炭黑渗滤区含量为5%~7%,表面电阻ρs从1014Ω下降到107Ω,较低的炭黑含量确保了复合材料优异的耐磨性;同时扫描电镜(SEM)表征证明炭黑在改性UHMWPE中达到纳米分散,形成双重纳米导电网络结构,这种双重纳米导电结构提高了复合材料的抗静电性能、力学性能和热变形温度。     

导电炭黑在聚丙烯／环氧树脂共混物中的分布

利用扫描电子显微镜、光学显微镜、抽提实验和热重分析方法研究了导电炭黑在聚丙烯/环氧树脂共混物中的分布。结果表明,在共混物中,炭黑优先分布在具有高极性、低熔融黏度的环氧树脂相中,形成较强的相互作用。炭黑的加入改变了环氧树脂分散相的形貌,使其由球形颗粒转变为伸长结构。在共混物中加入相容剂,环氧树脂颗粒的尺寸显著减小,导致聚丙烯/环氧树脂/炭黑复合体系的电阻率升高。将炭黑先与聚丙烯熔融共混,再加入环氧树脂,部分炭黑从聚丙烯相向环氧树脂相迁移,这进一步证明了炭黑和环氧树脂之间有较强的亲和作用。     

Electrical properties and morphology of polypropylene/epoxy/glass fiber composites filled with carbon black

The volume resistivity and percolation thresholds of carbon black (CB) filled polypropylene (PP), PP/epoxy, and PP/epoxy/glass fiber (GF) composites were measured. The morphology of these conductive polymer composites was studied with scanning electron microscopy (SEM). The effects of the GF and epoxy contents on the volume resistivity were also investigated. The PP/epoxy/GF/CB composite exhibited a reduced percolation threshold, in comparison with that of the PP/CB and PP/epoxy/CB composites. At a given CB content, the PP/epoxy/GF/CB composite had a lower volume resistivity than the PP/CB and PP/epoxy/CB composites. SEM micrographs showed that CB aggregates formed chainlike structures and dispersed homogeneously within the PP matrix. The addition of the epoxy resin to PP resulted in the preferential location of CB in epoxy, whereas in the PP/epoxy/GF multiphase blends, because of the good affinity of CB to epoxy and of epoxy to GF, CB particles were located in the epoxy phase coated on GF. The decreased percolation threshold and volume resistivity indicated that conductive paths existed in the PP/epoxy/GF/CB composite. The conductive paths were probably formed through the interconnection of GF. Appropriate amounts of GF and epoxy should be used to decrease the volume resistivity and provide sufficient epoxy coating. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1142–1149, 2005     

Electrically conductive composites based on epoxy resin containing polyaniline–DBSA‐ and polyaniline–DBSA‐coated glass fibers

Four kinds of polyaniline (PANI)‐coated glass fibers (GF–PANI) combined with bulk PANI particles were synthesized. GF–PANI fillers containing different PANI contents were incorporated into an epoxy–anhydride system. The best conductivity behavior of the epoxy/GF–PANI composites was obtained with a GF–PANI filler containing 80% PANI. Such a composite shows the lowest percolation threshold at about 20% GF–PANI or 16% PANI (glass fiber‐free basis). The PANI‐coated glass fibers act as conductive bridges, interconnecting PANI particles in the epoxy matrix, thus contributing to the improvement of the conductivity of the composite and the lower percolation threshold, compared with that of a epoxy/PANI–powder composite. Particularly, the presence of glass fibers significantly improves the mechanical properties, for example, the modulus and strength of the conductive epoxy composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1329–1334, 2004     

增强增韧抗静电尼龙612材料的制备及性能

采用熔融共混法制备了增强增韧抗静电尼龙(PA)612材料,探讨了抗静电剂种类及用量对PA612材料抗静电性能的影响,同时研究了玻璃纤维(GF)和增韧剂三元乙丙橡胶接枝马来酸酐用量对材料力学性能的影响。抗静电性能测试结果表明,石墨烯、碳纳米管在表面电阻方面的渗流阀值明显小于导电炭黑,即石墨烯、碳纳米管对PA612的抗静电效果优于导电炭黑;高用量下,添加碳纳米管的材料表面电阻比添加石墨烯的低一个数量级,但碳纳米管的成本较高。力学性能测试结果表明,GF能大幅提高材料的拉伸与弯曲强度,增韧剂能大幅提高材料的冲击性能,当增韧剂质量分数不高于10%时,材料的拉伸与弯曲强度下降幅度较小。当抗静电剂石墨烯、GF及增韧剂质量分数分别为3%,40%和10%时,制得的PA612材料具有较好的综合性能,其拉伸强度为120 MPa,弯曲强度为210 MPa,常温缺口冲击强度为10 k J/m~2,-45℃缺口冲击强度为9.6 k J/m~2,表面电阻为1×1011Ω,可满足PA612在储存、运输和使用过程中的抗静电要求。     

聚丙烯/马来酸酐接枝聚丙烯/环氧树脂/玻璃纤维复合材料的制备及其性能研究

通过双螺杆挤出机制备了聚丙烯/马来酸酐接枝聚丙烯/环氧树脂/玻璃纤维（PP/PP-g-MAH/EP/GF）复合材料,并研究了PP-g-MAH含量、EP含量及固化剂对复合材料力学性能的影响。结果表明,PP-g-MAH含量为10份,含有固化剂EP的含量为3份时,复合材料的综合力学性能最佳;与不加EP的复合材料相比,其拉伸强度、弯曲强度、冲击强度分别提高了41 %、47 %、86 %。扫描电子显微镜分析表明,EP的加入明显改善了GF和PP基体的黏结强度。     

Low percolation threshold and high conductivity in carbon black filled polyethylene and polypropylene composites

High electrically conductive composites have been manufactured using twin and single screw extruders from carbon black with polyolefin. High density, low density polyethylene, polypropylene, polyethylene/polypropylene copolymer, and maleic anhydrite grafted polypropylene have been compounded with three carbon blacks (CBs), i.e., Black Pearl, Printex, and Ketjen, respectively. The lowest percolation threshold (0.8 vol %) for conductive composite was obtained using Ketjen CB blended with high density polyethylene (HD3690, MFI = 36 g/10 min). Polypropylene composites also achieved low percolation thresholds of 1.5 vol % when compounded with Printex or Ketjen CB. Decreasing melt viscosity of polymer matrix resulted in decreasing resistivity of composites. Ketjen CB showed the best conductive behavior for both polyethylene and polypropylene composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Improvement of Hardness and Wear Resistance of Glass Fiber-Reinforced Epoxy Composites by the Incorporation of Silica/Carbon Hybrid Nanofillers

The tribological performance of hybrid composite (epoxy reinforced with woven, nonwoven tissue glass fibers, silica and carbon black nanoparticles) was investigated. Two methods were used to ensure good dispersion of nanoparticles in epoxy resin which were ultrasonic processor and magnetic stirrer. The effect of silica and/or carbon black nanoparticle content on microindentation hardness and wear properties of the neat glass fiber-reinforced epoxy composites was investigated. The results from the wear test indicated that, under all applied loads, incorporation of silica and carbon black nanoparticles either single or combined significantly improved the wear resistance of neat glass fiber reinforced epoxy. A significant increase in hardness of the hybrid nanocomposite laminates was achieved. Analysis of variance was developed to study the optimal wear testing parameters on composite samples. The most significant parameter is the time, followed by nanoparticle (silica and carbon black) content.     

AC conductivity of carbon fiber–polymer matrix composites at the percolation threshold

This paper reports results on experimental investigation of the conductivity behavior of carbon fiber filled polymer composites at the percolation threshold. Two types of carbon fiber‐epoxy matrix composites have been studied and comparison of the measured data has been made. These two types of composites differ in the surface modification of carbon fibers (in one case the surface of carbon fibers is covered with polymer beads using the microencapsulation technology, in the other their surface stayed unmodified). Experimental data reveal that surface modification of carbon fibers influences greatly the DC conductivity (percolation threshold moves to higher concentrations) but does not influence the AC electrical properties. From the frequency dependence of conductivity upon fiber concentration it becomes clear that it is not possible to predict the high frequency conductivity (electromagnetic interference shielding properties) based on the DC conductivity. Percolation behavior of conductivity as a function of conductive filler concentration is typical only for DC or low frequency AC conductivity. The percolation threshold gradually vanishes for high frequencies of electromagnetic field. The temperature dependence of electrical properties has also been studied. Composites with concentration near the percolation threshold show the switch‐off effect (at the specific temperature the DC conductivity drops by several orders of magnitude). This switch‐off effect does not occur for high frequency AC conductivity.