镀银纳米石墨微片/丙烯酸酯导电压敏胶的研究

以天然EG(膨胀石墨)为原料,采用超声分散法制得NanoG(纳米石墨微片);然后采用化学镀法制备导电填料Ag-NanoG(镀银纳米石墨微片);最后采用溶液共混法制备丙烯酸酯类Ag-NanoG/PSA(镀银纳米石墨微片/导电压敏胶)。研究结果表明:NanoG表面镀上了一层均匀紧凑的金属Ag,Ag层厚度为250 nm左右,其质量分数为50.04%;导电填料Ag-NanoG已均匀分散在丙烯酸酯PSA基体中,并形成了导电网络;当w(Ag-NanoG)=40%时,Ag-NanoG/PSA的综合性能相对最好,其180°剥离强度为0.25 kN/m,剪切强度为0.133 MPa且电导率为2.5×10-2S/cm。     

聚吡咯/镀银纳米石墨微片复合材料的制备与表征

以氧化石墨为原料,制备膨胀石墨,在超声波的作用下,膨胀石墨的片层结构发生剥离得到纳米石墨微片,对纳米石墨微片进行化学镀银,制备镀银纳米石墨微片,然后采用原位聚合法制备了聚吡咯/镀银纳米石墨微片复合材料。结果表明,纳米石墨微片的厚度为30～90nm,直径为1～20μm,具有相当大的径厚比(平均为200),该结构对纳米石墨微片在聚合物基体中形成导电网络极为有利;镀银纳米石墨微片的厚度为200～250nm,被聚吡咯完全包覆,并以纳米级尺寸均匀分散在聚吡咯基体中;聚吡咯/镀银纳米石墨微片复合材料的耐热性能和导电性能较纯聚吡咯均有所提高。     

炭系导电涂料的研究进展

综述了炭系导电涂料的导电机理,以石墨、炭黑为导电填料,以醇酸树脂、丙烯酸树脂及氯醚树脂为基料的炭系导电涂料的研究进展,并介绍了新型纳米石墨微片填料及其应用研究进展。     

纳米石墨片/炭黑/氯醋树脂复合导电膜的制备及性能研究

以氯醋树脂P(VC-Co-VAc)为基体,采用原位还原萃取分散技术制备了纳米石墨片复合导电膜,通过与炭黑填料的对比,考察了导电填料的几何形状以及两相导电填料之间的协同作用对复合膜导电性能的影响.结果表明:纳米石墨片在基体中分散良好,其复合膜的导电性能明显优于炭黑导电膜;当纳米石墨片和炭黑的体积比为4:6时,二者的协同作用最佳,其导电性明显优于相同含量下的单相填料复合导电膜.     

纳米石墨片/环氧树脂复合材料的制备及性能

分别采用低温固化剂和高温固化剂制备了纳米石墨片/环氧树脂复合材料。通过电阻测试仪和材料试验机研究了纳米石墨片的含量对复合材料导电性能和力学性能的影响规律,并将溶液混合法与直接混合法制备的复合材料的性能进行对比,同时比较了纳米复合材料的性能与微粉石墨/环氧树脂复合材料的性能。结果表明,溶液混合法制备的复合材料逾渗阈值更低,可得到填料质量分数达60%、体积电阻率为0.0085 Ω·cm的纳米复合材料。当填料质量分数高于4%时,纳米复合材料的力学性能低于微粉复合材料。     

聚丙烯酸酯基导电压敏胶的制备与研究

利用不同形貌填料间的架桥、插层等"协同"效应,将一定比例的碳黑、短切碳纤维、碳纳米管、纳米石墨微片复合作为导电填料,加入到聚丙烯酸酯压敏胶中,采用溶液共混法超声分散,得到导电填料添加量少、导电性能和力学性能良好的导电压敏胶。     

超高分子量聚乙烯/石墨包覆纳米铜复合导电材料研究

在NaBH4/EDA体系中还原CuCl2石墨层间化合物合成了石墨包覆纳米铜复合填料(GECNP).以GECNP为导电填料,采用球磨共混-热压成型工艺制备了超高分子量聚乙烯(UHMWPE)基复合材料.UHMWPE/GECNP复合材料的X射线衍射(XRD)分析表明:在制备过程中无新相生成;扫描电镜(SEM)观察发现:其微观结构均匀,GECNP以纳米片状分散于基体中,构成导电网络;有关导电性的研究表明:复合材料导电机制符合聚合物基复合材料的导电渗滤理论,渗滤阈值为8.766%,低于常规碳系填料.当GECNP体积浓度为12.8%时,体系电导率最高,为7.55S/cm,高于石墨纳米片填料.     

导电胶用纳米石墨微片的表面化学镀Cu及其表征

采用无钯化学镀Cu法对纳米石墨微片表面进行处理,并对其制备工艺进行了探究,旨在得到一种导电胶用新型导电填料。研究结果表明:当改性剂浓度为3 g/L、AgNO3浓度为3 g/L、氨水浓度为40 g/L、m(无水乙醇)∶m(水)=9∶1、活化温度为50℃和活化时间为1.5 h时,纳米石墨微片表面镀上了一层致密而均匀的金属Cu层,Cu层的厚度约为100 nm,Cu沉积量超过60%(相对于纳米石墨微片质量而言)。     

导电聚氨酯泡沫材料研究进展

从使用不同导电填料（炭黑、碳纳米管、石墨、金属、有机填料等）制备导电聚氨酯泡沫（PUF）材料的角度进行分析,总结了添加不同导电填料的复合泡沫制备方法以及对泡沫材料性能的影响,并论述了导电PUF材料在压阻材料、吸波材料、电磁屏蔽材料以及电极材料等领域的应用。分析表明,通过添加导电填料,可以改善PUF的静电现象,提高防静电、导电等性能并拓宽PUF材料的应用领域。     

聚乙烯/纳米石墨微片导电复合材料的制备与性能研究

采用纳米石墨微片(GNP)为导电填料与线形低密度聚乙烯（PE-LLD）共混来制备导电复合材料,研究了改变GNP、表面处理剂十二烷基苯磺酸钠（SDBS）和分散剂聚乙二醇(PEG)的添加量对导电复合材料的力学性能、导电性能和热性能的影响。结果表明,GNP添加量为40份时,材料会形成导电网络,体积电阻率达到8.95×10^8 Ω·cm,继续增加GNP的添加量对材料的导电性能和力学性能影响不大;导电复合材料的最佳配方为:100份PE-LLD、40份GNP、SDBS和PEG均为GNP质量的10 %。     

Preparation of polystyrene/graphite nanosheet composite

A new process for the dispersion of graphite in the form of nanosheets in a polymer matrix was developed via in situ polymerization of monomer at the presence of sonicated expanded graphite during sonication. Graphite nanosheets prepared via powdering the expanded graphite had a thickness ranging 30-80 nm and a diameter ranging 0.5-20 μm and was an excellent nanofiller for the fabrication of polymer/graphite conducting nanocomposite. The process fabricated electrically conducting polystyrene/graphite nanosheet nanocomposite films with much lower percolation threshold and much higher conductivities than those of composites made by conventional methods.     

Preparation of polystyrene–graphite conducting nanocomposites via intercalation polymerization

In situ polymerization of styrene was conducted in the presence of expanded graphite obtained by rapid heating of a graphite intercalation compound (GIC), to form a polystyrene–expanded graphite conducting composite. The composite showed excellent electrically conducting properties even though the graphite content was much lower than in normal composites. The transition of the composite from an electrical insulator to an electrical semiconductor occurred when the graphite content was 1.8 wt%, which is much lower than that of conventional conducting polymer composites. TEM, SEM and other studies suggest that the graphite was dispersed in the form of nanosheets in a polymer matrix with a thickness of 10–30 nm, without modification of the space between carbon layers and the structure of the graphite crystallites. The composite exhibited high electrical conductivity of 10^?2 S cm^?1 when the graphite content was 2.8–3.0 wt%. This great improvement of conductivity could be attributed to the high aspect ratio (width‐to‐thickness) of the graphite nanosheets. The rolling process strongly affected the conductivity and the mechanical properties of the composite. © 2001 Society of Chemical Industry     

Preparation and characterization of graphite nanosheets from ultrasonic powdering technique

Natural flake graphite was exfoliated into exfoliated graphite via an acid intercalation procedure. The resulting exfoliated graphite was a worm-like particle composed of graphite sheets with thickness in the nanometer scale. Subjecting it to ultrasonic irradiation, the exfoliated graphite was effectively further foliated into isolated graphite nanosheets. SEM, TEM, SAD, laser counting, and BET measurements revealed that the graphite nanosheets prepared with 10 h irradiation were about 52 nm in thickness and 13 μm in diameter. FTIR examination showed that there were oxygen-containing groups presented on the surface of the exfoliated graphite. This result substantiated the statement reported in the literature that acid treatment could result in oxidization of carbon bonds on graphite surface.     

聚苯胺/纳米石墨复合材料的原位制备与导电性能研究

采用原位聚合法制备了聚苯胺/纳米石墨微片（PANI/NanoG）导电复合材料。结果表明,NanoG的直径约为1~20 μm,厚度为30~90 nm,径厚比为300~500;PANI均匀覆盖在NanoG表面;当NanoG体积含量为2.30 %时,复合材料电导率达到5.16 S/cm,其渗滤阈值达到2.30 %,NanoG的高比表面积及在PANI中的分散造就了复合材料良好的导电性能。     

Dispersion of graphite nanosheets in a polymer matrix and the conducting property of the nanocomposites

Poly(methyl methacrylate)(PMMA)/expanded graphite composite has been made via an in situ polymerization of methyl methacrylate(MMA) in the presence of expanded graphite obtained by rapid heating of the graphite intercalation compound (GIC). The composite was then blended with poly(vinyl chloride) (PVC) to form an electrically conducting composite. SEM, TEM and XRD showed that the graphite had been dispersed throughout the polymer matrix in the form of nanosheets with thicknesses of about 20 nm. The resulting composite showed excellent electrical conductivity despite a low concentration of graphite. The transition from an electrical insulator to an electrical semiconductor for the composite occurred when the graphite content was 3.5 wt%, much lower than that of conventional conducting polymer composites. Conductivity reached a maximum of 10^?4 s/cm at a graphite concentration of 5.0 wt%. This improvement of conductivity could be attributed to the high aspect ration (width‐to‐thickness) of the graphite nanosheets dispersed in the polymer matrix.     

Silicone rubber/graphite nanosheet electrically conducting nanocomposite with a low percolation threshold

A novel electrically conductive nanocomposite was successfully fabricated by dispersing homogeneously conductive graphite nanosheets (GN) in an insulating silicone rubber (SR) matrix. GN were prepared by powdering expanded graphite with sonication in aqueous alcoholic solution. The particular geometry of GN 30–80 nm in thickness with high aspect ratio contributes to the advantage of forming the conducting network, so that the percolation threshold of SR/GN nanocomposite is about 0.009, much lower than that of composites with conventional graphite. The SR/GN nanocomposite presents a remarkable piezoresistive behavior under much low pressure, related to the low elastic modulus of the composite. The elastic modulus of the nanocomposite with various GN content and at the different speed of compression was discussed. POLYM. COMPOS., 28:493–498, 2007. © 2007 Society of Plastics Engineers     

Fabrication of polyethylene/graphite nanocomposite from modified expanded graphite

A novel process was employed to fabricate a polymer/expanded graphite nanocomposite by modifying the conducting filler expanded graphite (EG) with unsaturated polyester resin (UPR). The modified expanded graphite (MEG) was prepared from EG in which the graphite nanosheets, already present in EG, were wrapped and isolated by the UPR during processing. The as‐prepared MEG was reduced to powder form to improve its dispersion in the matrix. MEG powders were embedded into a high‐density polyethylene (HDPE) matrix via melt‐extrusion in a single‐screw extruder to prepare the conducting composite. The as‐prepared HDPE/EG conducting composite exhibited a low percolation threshold of ～5.7 wt% due to the high aspect ratio of graphite nanosheets. Mechanical properties such as the tensile and impact strength were also studied. Scanning electron microscopy was used to characterize the microstructure of EG, MEG powder and the resulting nanocomposites. Copyright © 2006 Society of Chemical Industry     

Effect of dispersion on graphite nanosheet composites

By intercalating and exfoliating natural graphite flakes, expanded graphite was obtained and used as the additive for making composites. The expanded graphite was composed of partly connected graphite nanosheets. Three types of composites were made, representing three levels of dispersing the graphite nanosheets. The first was the impregnation of epoxy resin to the expanded graphite by resin transfer molding. No dispersion was applied, and the expanded graphite can retain its original shape. The second was the use of a high‐power sonication to break apart the expanded graphite. The thickness of the sonicated expanded graphite was reduced to about 100 times. The third method was to use a high‐shear strain rate to separate the graphite nanosheets from the expanded graphite and to disperse them into the resin. The thickness range of the graphite nanosheets was 20–50 nm, about 100 times thinner than the sonicated ones. Compression and impact tests were conducted. The influence of dispersion on the material behavior was studied. Some fracture modes associated with the layered microstructures of the graphite nanosheets were observed. A simple model was used to study the stress transfer and frictional energy consumption of the pullout of the nanosheet. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Preparation and characterization of a PMMA/Ce(OH)3, Pr2O3/graphite nanosheet composite

An easy process for the synthesis of poly(methyl methacrylate)/Ce(OH)₃, Pr₂O₃/graphite nanosheet (PMMA/Ce(OH)₃, Pr₂O₃/NanoG) composite was developed. Graphite nanosheets (NanoG) were prepared by treating the expanded graphite with sonication in aqueous alcohol solution. The PMMA/Ce(OH)₃, Pr₂O₃/NanoG composites were prepared via in situ polymerization of MMA monomer in the presence of graphite nanosheets and Ce(OH)₃, Pr₂O₃ through reverse micelle template, in which the methyl methacrylate was designated as the oily phase. The composites were then dispersed with chloroform and coated on glass slides to form films. Scanning and transmission electron microscopy were used to characterize the structure and dispersion of the graphite nanosheets and the composites. The results showed that the high-aspect-ratio structure of the nanosheets played an important role in forming a conducting network in the PMMA matrix. From thermogravimetric analysis, the introduction of graphite nanosheets and inorganic nanopartices exhibited a beneficial effect on the thermal stability of PMMA.     

Preparation of polymer/graphite conducting nanocomposite by intercalation polymerization

An in situ polymerization was conducted in the presence of expanded graphite obtained by rapid heating of the graphite intercalation compound (GIC) to form a polymer/expanded graphite conducting composite. Study showed that the graphite was dispersed in the form of nanosheets in the polymer matrix. The transition from an electrical insulator to an electrical semiconductor for the composite occurred when the expanded graphite content was 1.8 wt %, which was much lower than that of conventional conducting polymer composite. The composite exhibited high electrical conductivity of 10⁻² S/cm when the graphite content was 3.0 wt %. This great improvement of conductivity could be attributed to the high aspect ratio (width-to-thickness) of the graphite nanosheets. Study suggested that extensive rolling of the blend greatly affected the conductivity of the composite. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2506–2513, 2001