炭黑填充聚丙烯/尼龙6/玻璃纤维复合材料的制备及表征

以聚丙烯(PP)和尼龙6(PA6)的共混物为基体材料,以导电炭黑(CB)和玻璃纤维(GF)作为填料,通过熔融共混的方法制备了导电复合材料。研究了GF和CB质量分数对复合材料热稳定性、导电性能、力学性能和微观形貌的影响。结果表明:CB粒子选择性分散在PA6中,同时PA6包覆在GF表面,通过具有较大长径比的纤维相互搭接形成连续的网络结构,从而显著降低复合材料的逾渗阈值。在相同CB质量分数下(2%),PP/PA6/GF/CB的表面电阻率相对于PP/PA6/CB体系降低了5个数量级。此外,引入GF后,材料的热稳定性和拉伸强度都有所提高。     

聚丙烯/石墨纳米复合材料的导电性能研究

磨盘碾磨固相剪切复合技术(S3C)是制备聚合物 石墨导电复合材料的有效途径,所得聚丙烯 膨胀石墨复合材料具有纳米插层复合结构,石墨纳米片层的相互搭接可形成导电网络,具有纳米间隙的石墨插层结构可形成隧道电流,从而大幅度降低复合体系的导电逾渗阈值,在低填充量实现聚合物复合材料高电导性,与熔体共混相比,导电逾渗阈值由4 .3vol%降低到0 . 5 5vol% ,在石墨含量为4 .0 1vol%时,电导率提高10个数量级.     

iPP/HDPE/CB三元导电复合材料的导电与流变行为

利用界面能原理使CB选择性分布于HDPE中成为复合导电相,固定CB在HDPE中的质量分数(20 wt％),控制CB/HDPE导电相在iPP中的含量,制备出一系列三元(iPP/HDPE/CB)导电复合材料,并研究其导电逾渗和流变逾渗行为.结果表明,在复合导电相含量为20 wt％时复合材料内即形成导电网络,在复合导电相含量30 wt％时出现流变网络.只有当复合导电相在材料中形成连续相时(60 wt％),损耗因子在频率扫描中才出现峰值.     

聚甲基丙烯酸甲酯改性碳纳米管及其在聚合物中的应用

本文利用引发剂偶氮二异丁腈(AIBN)在碳纳米管(CNTs)表面引发甲基丙烯酸甲酯(MMA)聚合,使CNTS表面接枝聚甲基丙烯酸甲酯(PMMA),提高CNTs与基体的界面粘结力,改善CNTs在基体中的分散状态。通过熔融共混法制备PVDF/CNTs和PVDF/CNTs-PMMA复合材料。结果表明改性后的CNTs在PVDF中的分散更好,PVDF/CNTs复合材料的导电逾渗阈值为0.7 vol%,PVDF/CNTs-PMMA复合材料的导电逾渗阈值为0.28 vol%,降低了60%。这表明通过对填料化学改性是一种降低复合材料逾渗阈值的有效方法。     

具有隔离结构的聚丙烯/碳纳米管复合材料的制备及电磁屏蔽性能

通过共挤出包覆-热压法制备了具有隔离结构的聚丙烯(PP)/碳纳米管(CNTs)电磁屏蔽复合材料。 其中,CNTs随机分布于PP基体中形成导电相,该导电复合物作为包覆层包敷在纯PP颗粒表面,形成包覆复合粒子,经热压后形成隔离导电网络。 结果表明,所制备的隔离结构复合材料呈现良好的导电性能,可获得较低的导电逾渗值0.28%(体积分数);在CNTs质量分数为5.6%时,该复合材料电磁屏蔽性能达到25.6 dB,同时具有良好的力学性能。 本文结果表明,共挤出包覆-热压法制备隔离结构导电复合材料方法简单可控、绿色环保,对开发高性能电磁屏蔽复合材料具有重要指导意义。     

导电炭黑在聚丙烯/极性聚合物体系中的选择性分散及其对导电性能的影响

以聚丙烯(PP)和极性聚合物的共混物为基体材料,以导电炭黑为填料,通过熔融共混制备导电复合材料。探讨了导电炭黑在两相基体中的分散情况以及双基体各组分比例对复合体系结构形态和导电性能的影响。SEM测试结果表明:炭黑粒子选择性地分散在极性乙烯-丙烯酸共聚物(EAA)树脂或尼龙6(PA6)中。EAA相在PP基体中呈棒状伸长结构,且随着EAA树脂含量的增大,在PP基体中形成更多更为连续的棒状伸长结构,使体积电阻率迅速下降。当在体系中加入PA6,mPP/mPA6=80/20时,PA6在PP基体中形成相互连接的纤维状分散结构,显著降低了复合体系的体积电阻率。电性能测试结果表明:材料在相同导电炭黑含量下的体积电阻率相对单基体体系可降低3~7个数量级。     

MWCNTs与疏水纳米SiO_2填充PMMA/PS共混物的导电与动态流变行为

以多壁碳纳米管(MWCNTs)为导电填料、疏水纳米二氧化硅(SiO2)为非导电填料,填充不相容聚甲基丙烯酸甲酯(PMMA)/聚苯乙烯(PS)(1/1,V/V)共混物,制备(PMMA/SiO2)/(PS/MWCNTs)四元导电高分子复合材料(CPC),研究其导电逾渗与动态流变行为,并与PMMA/(PS/MWCNTs)三元CPC进行对比.发现三元、四元CPC具有类似的导电逾渗行为,且逾渗阈值显著低于PS/MWCNTs二元CPC.在四元CPC中,SiO2粒子可细化相区尺寸,提高熔体模量,但不影响熔体热处理过程中的依时性动态导电逾渗行为.MWCNTs与SiO2均显著影响熔体热处理中的依时性模量逾渗行为,分别缩短、延长四元CPC相粗化起始时间,但均延长相粗化时间区间.     

高分子基导电复合材料气敏响应机理研究

高分子基气敏导电材料是近年来发展起来的一种新型功能高分子复合材料.本文介绍了以炭黑(CB)为导电填充剂的复合传感材料的气敏响应机理的体积膨胀模型、结晶模型和氢键模型,并讨论了逾渗阀值、CB及聚合物微观结构与性能、以及CB与聚合物和溶剂三者之间相互作用等因素对该类材料气敏响应性的影响.     

炭黑的“impurity-free”改性及其在聚酰亚胺薄膜中的分散特性研究

利用聚酰胺酸(PAA)在研磨过程形成炭黑(CB)的"impurity-free"分散剂制备纳米CB填充聚酰亚胺(PI)高性能复合薄膜.球磨CB和PAA/N-甲基-2-吡咯烷酮(NMP)溶液的混合液,PAA在研磨过程中降解形成活性分子,原位生成与CB表面具有反应活性和强烈物理吸附能力的"impurity-free"分散剂.拉曼、红外以及紫外-可见光吸收光谱证实了降解PAA分子对CB的改性作用.经改性的CB与PAA溶液共混,涂覆固化制备PI/CB复合薄膜.TEM照片表明该分散剂可以显著促进CB粒子在PI基体中的均匀分散,分散粒径约为200nm.力学性能测试和导电性能测试表明PI/CB复合薄膜的断裂伸长率大幅提高,电阻率(ρ)重复性浮动范围从2个数量级降到1个数量级.进一步研究发现,研磨过程中添加高分子量PAA更有利于CB在PI基体中的均匀分散.     

电响应聚合物薄膜的表面图案化

研究了炭黑(CB)和石墨(GP)填充高密度聚乙烯(HDPE)复合体系的动态流变行为.发现高填料含量时出现似固体行为,并认为它归因于无机粒子网络逾渗结构的形成.在相同聚合物基体条件下,粒子种类和粒子几何参数(粒子形状、大小、粒径分布)对低频区域流变行为、流变参数的逾渗行为和逾渗阈值(φc)有决定性影响,且种类的影响相比于粒子几何参数更为显著.此外,高表面活性及高比表面积(大径厚比、小尺寸)粒子填充体系具有较低的φc.     

Electrical properties and conductive mechanisms of immiscible polypropylene/Novolac blends filled with carbon black

Carbon black (CB)-filled immisicible thermoplastic/thermosetting polymer blends consisting of polypropylene (PP) and Novolac resin were reported in this paper. The PP/Novolac/CB blends with varied compositions and different processing sequences were prepared by melt-mixing method. The CB distribution, conductive mechanism and the relationship between morphology and electrical properties of the PP/Novolac/CB blends were investigated. Scanning electron microscopy (SEM), optical microscopy and extraction experiment results showed that in PP/Novolac blends CB particles preferentially localized in the Novolac phase, indicating CB has a good affinity with Novolac resin. The incorporation of CB changed the spherical particles of the dispersed Novolac phase into elongated structure. With increasing Novolac content, the elongation deformation of Novolac phase became more obvious and eventually the blends developed into co-continuous structure, which form double percolation and decrease the percolation threshold. When CB was initially blended with PP and followed by the addition of Novolac resin, the partial migration of CB from PP to the Novolac phase was possibly occurred. The addition of Novolac to PP evidently increases the storage modulus G′, loss modulus G″ and complex viscosity η^∗. The addition of CB to PP/Novolac blends further increase η^∗, and it increases with increasing CB loading, which was related to the change of composite morphology.     

Sensing of liquids by electrically conductive immiscible polypropylene/thermoplastic polyurethane blends containing carbon black

Immiscible polymer blends based on polypropylene/thermoplastic polyurethane (PP/TPU) are interesting host multiphase systems for the incorporation of low concentrations of conductive carbon black (CB) particles. The enhancement of conductivity (and the lower critical CB content for percolation) in the PP/TPU blend is achieved via double percolation, that is, structural and electrical. The CB particles form chainlike network structures within the TPU phase, which exhibit phase continuity of elongated particles within the PP matrix. Moreover, scanning electron microscopy and dynamic mechanical thermal analysis studies indicated that the incorporation of CB particles into the PP/TPU blend has a “compatibilizing” effect, resulting in an enhanced interaction between the two polymers. Extruded PP/TPU/CB filaments produced by a capillary rheometer process at various shear rates were examined as sensing materials for a homologous series of alcohols, that is, methanol, ethanol, and 1‐propanol. All filaments displayed increasing resistance upon exposure to the various alcohols combined with excellent reproducibility and recovery behavior. An attempt is made to identify the dominant mechanisms controlling the sensing process in a CB‐containing immiscible polymer blend characterized by a double‐continuity structure. The interphase region, its quantity, and continuity played a significant role in the liquid‐transport process. Blend composition, filaments' extrusion temperature, and production shear rate level were considered as significant parameters determining the structure and the resultant sensing properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1428–1440, 2003     

高均一性聚丙烯/炭黑薄膜的制备及炭黑分散性的定量表征

采用熔融共混-母粒稀释技术,辅以高效动态混合器制备了炭黑含量为2.2%与3.3%的两种聚丙烯/炭黑薄膜.基于扫描电镜(SEM)与光学显微镜(OM)图像,首次利用Image J图像分析软件定量表征了炭黑在薄膜中的分散与分布.SEM分析结果表明,炭黑含量为2.2%的膜中粒子的平均面积为0.220 μm2,且面积严格服从指数...     

Simultaneous enhancement of electrical conductivity and impact strength via formation of carbon black‐filler network in PP/EPDM Blends

The electrical conductivity and impact strength of polypropylene(PP)/EPDM/carbon black ternary composites were investigated in this paper. Two processing methods were employed to prepare these ternary composites. One was called one‐step processing method, in which the elastomer and the filler directly melt blended with PP matrix. Another one was called two‐step processing method, in which the elastomer and the filler were mixed first, and then melt blended with pure PP. To get an optimal phase morphology that favors the electrical conductivity and impact strength, controlling the distribution of CB in PP/EPDM blend was a crucial factor. Thus the interfacial tension and the work of adhesion were first calculated based on the measurement of contact angle, and the results showed that CB tended to be accumulated around EPDM phases to form filler‐network structure. Expectably, the filler‐network structure was observed in PP/EPDM/CB(80/20/3) composite prepared by two‐step processing method. The formation of this filler‐network structure decreased the percolation threshold of CB particles in polymer matrix, and the electrical conductivity as well as Izod impact strength of the composite increased dramatically. This work provided a new way to prepare polymer composites with both improved conductivity and impact strength. Copyright © 2009 John Wiley & Sons, Ltd.     

Temperature-resistivity characteristics of a segregated conductive CB/PP/UHMWPE composite

A carbon black (CB)/polypropylene (PP)/ultrahigh-molecular-weight polyethylene (UHMWPE) composite with a segregated structure was fabricated by using binary polymer granules as matrices. In preparation, an ethanol-assisted dispersion method was employed to disperse CB particles on the surface of the two polymer granules. The segregated conductive network was then constructed by hot compaction based on the volume exclusion effect of the polymer matrices. The conductive composite shows an ultralow percolation threshold of 0.34 vol.%. In temperature-resistivity test, a double positive temperature coefficient (PTC) effect was observed. In addition, the negative temperature coefficient (NTC) effect was eliminated significantly. These interesting temperature-resistivity behaviors were ascribed to the introduction of the binary polymer matrices and the mobility limitation of CB particles located at the PP/UHMWPE interface. These characteristics were probed by in situ morphology observation in heating process. The present paper provides a novel route for preparing conductive composites with an ultralow percolation threshold, a wider PTC region, and a zero NTC effect.     

Nanostructured carbon black filled polypropylene/polystyrene blends containing styrene-butadiene-styrene copolymer: Influence of morphology on electrical resistivity

This paper is part of a comprehensive study on using selective localization of carbon black (CB) at the interface of immiscible polymer blends in order to reduce the percolation threshold concentration and enhance the conductivity of the blends. CB was successfully localized at the interface of polypropylene/polystyrene (PP/PS) blend by introducing styrene-butadiene-styrene (SBS) tri-block copolymer to the blend. In CB-PP/PS/SBS blends, CB has higher affinity for the polybutadiene (PBD) section of the SBS copolymer, whereas in CB-PP/PS blends, CB prefers the PS phase. PP/PS interface is one of the preferred locations for the SBS copolymer in the (PP/PS) blend; at which the PBD section of the SBS copolymer forms a few nanometers thick layer able to accommodate the CB nano-particles. The influence of SBS addition on the morphology and electrical properties of various PP/PS blends filled with 1 vol% CB were studied. SBS influence on the conductivity of PP/PS blends was found to be a function of the PP/PS volume ratio and SBS loading. The most dramatic increase in conductivity was found in the (60/40) and (70/30) PP/PS blends upon the addition of 5 vol% SBS. 5 vol% SBS was found to be the optimum loading for most blends. Using 10 vol% of SBS was reported to deteriorate electrical conductivity of the conductive co-continuous PP/PS blends. For all blends studied, SBS addition was found to compatibilize the blends. Finer morphologies were obtained by increasing SBS loading.     

Synthesis of crystallizable sydiotactic-atactic stereoblock polypropylene using a living polymerization system

Propylene polymerizations were conducted by [t-BuNSiMe₂(3,6-t-Bu₂Flu)]TiMe₂ using dried modified methyaluminoxane as a cocatalyst in heptane, chlorobenzene (CB), and a mixture of heptane/CB (1:1 in volume) at 0°C. Postpolymerizations testified that the propylene polymerization proceeded in a living manner regardless of the solvent used. The heptane system gave highly syndiotactic crystalline polypropylene (PP), whereas the CB and heptane/CB mixture systems gave amorphous PP. After the first polymerization in heptane had been completed, the same amounts of propylene and CB were added for the second polymerization. This procedure gave the syndiotactic-atactic stereoblock PP with a melting point of 119°C. The text was submitted by the authors in English.     

Effect of nanosized carbon black on thermal stability and flame retardancy of polypropylene/carbon nanotubes nanocomposites

Nanosized carbon black (CB) was introduced into polypropylene/carbon nanotubes (PP/CNTs) nanocomposites to investigate the effect of multi‐component nanofillers on the thermal stability and flammability properties of PP. The obtained ternary nanocomposites displayed dramatically improved thermal stability compared with neat PP and PP/CNTs nanocomposites. Moreover, the flame retardancy of resultant nanocomposites was greatly improved with a significant reduction in peak heat release rate and increase of limited oxygen index value, and it was strongly dependent on the content of CB. This enhanced effect was attributed mainly to the formation of good carbon protective layers by CB and CNTs during combustion. Rheological properties further confirmed that CB played an important role on promoting the formation of crosslink network on the base of PP/CNTs system, which were also responsible for the improved thermal stability and flame retardancy of PP. Copyright © 2013 John Wiley & Sons, Ltd.     

Surface modification of carbon black by thiol-ene click reaction for improving dispersibility in aqueous phase

Carbon black (CB) particles were firstly encapsulated by γ-Methacryloxypropyltrimethoxysilane (MEMO) using a sol-gel method and then grafted with sodium 3-Mercapto-1-propanesulfonate (MPS) via thiol-ene click reaction. Morphology characterization reveals that modified CB particles have a core-shell structure. Element composition and chemical status derived from X-ray photoelectron spectroscopy (XPS) results prove the grafting of MPS molecules. Moreover, the crystal structure and thermal behavior of modified CB particles were characterized by Raman spectra and Thermogravimetric analysis (TGA) curves, respectively. The modified CB particles exhibit excellent self-dispersing ability in aqueous media and the dispersion has high thermal and centrifugal stability. This research provides a new insight into the preparation of inkjet printing ink with excellent stability.     

Ethylene–acrylic acid copolymer induced electrical conductivity improvements and dynamic rheological behavior changes of polypropylene/carbon black composites

The experimental data reveal that the addition of ethylene–acrylic acid copolymer (EAA) into carbon black (CB)/polypropylene (PP) composites can improve the electrical conductivity of CB/PP composites by two to six orders of magnitude at a comparatively low CB content (φ), and when φ = 2.5 vol %, 60/40 of PP/EAA is an optimum for electrical conductivity improvement. The dynamic rheological data show that with increasing φ there are apparent rheological percolations for CB/PP composites. A modified Kerner–Nielson equation can be used to describe the correlation between electrical percolation and dynamic viscoelastic percolation. The addition of EAA into CB/PP composites leads to apparent changes in dynamic rheological behaviors. When φ = 2.5 vol %, a rheological percolation appears in CB/PP/EAA (CPE) composites with increasing EAA content. The similar rheological behaviors correspond to the similar morphological structures for CPE composites with φ = 5.0 vol %. The appearance of bumps in the van‐Gurp–Palmen plots corresponds to the formation of network structure in CB/PP and CPE composites, and the more perfect the networks, the higher the amplitude of the bumps. All data indicate that the van‐Gurp–Palmen plot is sensitive to the formation of filler particle networks or cocontinuous phase which spans the whole composite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1762–1771, 2009