石墨烯/热塑性聚氨酯复合材料的制备及性能研究

采用溶液共混浇铸成膜法,制备了热塑性聚氨酯/石墨烯复合材料,并对其结构和性能进行了研究。结果表明,高温还原得到的石墨烯可大幅度提高热塑性聚氨酯复合材料的储能模量。电学性能测试表明,热塑性聚氨酯/石墨烯复合材料的电性能在质量分数为1%～3%的填料量范围内出现了突变,体积电阻率降低了6个数量级。     

高填充石墨烯纳米片/硅橡胶复合材料的结构与性能

通过机械共混法将石墨烯纳米片分散至30 000 m Pa·s乙烯基封端的聚二甲基硅氧烷中,并制备了石墨烯纳米片/硅橡胶复合材料。对其微观形貌进行了表征,并考察了复合材料的性能。结果发现,随石墨烯纳米片用量的增加,复合材料的熔点逐渐下降,结晶度呈现先升后降的趋势。当石墨烯纳米片填充量达30份时,复合材料的导热和导电性能明显提升,当填充80份时,石墨烯纳米片/硅橡胶复合材料的热导率和体积电阻率分别达到2. 648 W/(m·K)和0. 156Ω·cm。     

石墨烯/PVC抗静电复合材料性能的研究

以石墨烯母料的形式,采用共混法制备了石墨烯/PVC抗静电复合材料,测试了其流变性能、电学性能和力学性能。结果表明:石墨烯的加入能明显促进PVC物料的塑化,显著降低复合材料的表面电阻率,且对拉伸强度影响不大。     

导热聚氨酯复合材料的制备及性能研究

聚氨酯弹性体应用广泛，但其导热性能较差，在特殊灌封领域限制其发展与应用。主要对聚氨酯弹性体导热性能进行研究，分别考察导热剂种类、添加量及粒径比对弹性体性能的影响。研究结果表明：在复合材料制备过程中选取经济的导热剂Al₂O₃,且导热剂Al₂O₃添加量为55%,粒径40μm搭配10μm复配使用时，得到的复合材料物化性能最优，黏度较小，导热系数可达0.7 W·m^-1·K^-1,可较好的满足新能源灌封领域特殊产品灌封，成本低廉且便于施工操作。     

石墨烯/硅橡胶导电复合材料的制备及性能研究

以甲基乙烯基硅橡胶(MVQ)为主体材料、石墨烯为导电填料,制备石墨烯/MVQ导电复合材料,研究石墨烯品种和用量对复合材料物理性能和导电性能的影响。结果表明:石墨烯LKR6963的剥离程度较高、片层较薄、缺陷较少,易在硅橡胶基体中形成导电网络,提高复合材料的导电性能;随着石墨烯LKR6963用量的增大,复合材料的硬度和拉伸强度明显增大,体积电阻率逐渐减小。     

石墨烯/橡胶复合材料的制备及研究进展

介绍石墨烯/橡胶复合材料的制备方法及应用研究进展。石墨烯/橡胶复合材料的制备方法主要包括机械共混法、溶液共混法、乳液共混法、熔融混合法以及多种方法联用。与未添加石墨烯的胶料相比,石墨烯/橡胶复合材料的导电性能、导热性能、物理性能和液体/气体阻隔性能等明显提高,综合性能优异。石墨烯/橡胶复合材料的研发工作重点为创新制备方法,提高制备的经济性和环保性,加大基础研究与应用研究的力度,加快科研成果转化。     

水性聚氨酯/石墨烯柔性导电复合材料制备及性能

针对石墨烯在与聚合物基体复合中出现的难以均匀分散、易出现团聚的问题,通过采用不同的分散剂对石墨烯进行非共价键功能化改性,选取最佳分散剂,以制备稳定的石墨烯分散液。通过溶液共混法和流延浇铸法将石墨烯均匀分散在水性聚氨酯（WPU）基体中,制备了WPU/石墨烯柔性导电复合材料。溶剂分散效果及吸光度测试结果显示,聚乙烯醇（PVAL）水溶液对石墨烯的分散能力强,制备的石墨烯分散液较为稳定,且PVAL水溶液的最佳质量分数是15%,其吸光度达到2.943;导电性能测试结果发现,石墨烯含量为WPU质量的2%时,WPU/石墨烯柔性导电复合材料综合性能较好,其电导率为2.6×10^-7 S/m,并在此基础上,考察发现WPU∶PVAL水溶液质量比为80∶20时,复合材料的拉伸强度较未加分散剂的增加了116%,电导率为4.5×10^-5 S/m,较未加分散剂的增加了5个等级;扫描电子显微镜结果表明,加入PVAL水溶液后,石墨烯能均匀地分散在WPU基体中,表明PVAL水溶液对石墨烯具有良好的分散作用。     

石墨烯/炭黑/天然橡胶复合材料的制备与性能研究

采用硅烷偶联剂KH570改性氧化石墨烯,并还原制备石墨烯。用机械共混的方法制备石墨烯/炭黑/天然橡胶复合材料,研究了石墨烯/炭黑/天然橡胶复合材料的力学性能、导热性能、磨耗性能以及复合材料的微观结构,并与炭黑/天然橡胶复合材料性能对比。结果表明,石墨烯添加1 phr石墨烯,石墨烯/炭黑/天然橡胶复合材料的裤形撕裂强度提升显著,提高了40%。老化前磨耗降低17.1%,老化后磨耗降低10.2%。添加了1.5 phr石墨烯,石墨烯/炭黑/天然橡胶复合材料导热系数提高了17%左右。     

石墨烯微片的尺寸和形态对聚丙烯基纳米复合材料导电导热性能的影响

通过熔融共混法制备了5种不同石墨烯微片（GNP）的聚丙烯（PP）/GNP纳米复合材料,采用电子和光学显微镜等仪器和导电导热等性能测试研究了GNP的尺寸和含量对PP基纳米复合材料导电导热性能的影响。结果表明,同一厚度的GNP片径越大,片层间的接触面积也越大,复合材料导电导热性能越好;同一片径的GNP,片层薄的在PP基体中的剥离程度和分散程度好,相应的PP/GNP纳米复合材料的导电导热性能好;而且GNP含量的改变对PG-100、PG-030和PG-G5导电导热性能的影响是不同的;其中PG 030导电网络最先形成,渗流阈值最低,而PG-G5在高含量时导电和导热率最高。     

石墨烯基聚氨酯复合膜的电及热性能研究

以热塑性聚氨酯为基材,商业石墨烯为导电填料,采用共混法制备柔性复合膜。系统地研究了复合膜的电性能、热性能及红外光热响应和电热响应性能。实验结果表明,复合膜电性能和热性能与热塑性聚氨酯初始质量分数、石墨烯质量分数等密切相关。当TPU初始质量分数为20%且复合膜中石墨烯质量分数为5%时,复合膜的电阻率约为2. 7×10-3Ω·cm,导热系数为0. 298 W/(m·K)。随着复合膜中石墨烯含量增加,复合膜的导电性逐渐增加,但导热系数先增加而后下降。复合膜具有较强的红外光热响应特性,含有石墨烯0. 3%的复合膜在红外光热处理60 s后,膜温升至123. 4℃,明显高于纯聚氨酯膜温度的75. 6℃,但是膜温的变化与石墨烯含量间关系不大。TPU初始质量分数为20%且石墨烯含量分别为3%、4%、5%的复合膜,在0. 3 A电流作用下,50 s内薄膜温度分别可达114、90、68℃,说明复合膜具有较快的电热响应特性。     

石墨烯对聚四氟乙烯导热和摩擦磨损性能的影响

针对聚四氟乙烯(PTFE)导热性能和耐磨损性能较差的问题,将石墨烯经过氧化氢预处理后,再用硅烷偶联剂KH550对其进行表面改性,然后采用冷压烧结法制备了PTFE/石墨烯复合材料,研究了不同用量下改性和未改性石墨烯对复合材料电性能、导热性能和摩擦磨损性能的影响。结果表明,随着石墨烯用量增加,复合材料的体积电阻率逐渐下降,但在石墨烯质量分数为0%~2%时,复合材料体积电阻率基本处于同一数量级,仍为绝缘材料;当石墨烯质量分数由0%增加至2%时,复合材料的导热系数明显提高,磨损量明显降低,而摩擦系数先升高后降低,但变化幅度较小。与未改性石墨烯相比,KH550改性石墨烯填充的复合材料具有更高的导热性能和摩擦磨损性能。     

Experiments and modeling of thermal conductivity of flake graphite/polymer composites affected by adding carbon-based nano-fillers

Enhancement of thermal conductivity of natural flake graphite/polymer (NFG/polymer) composite sheets, prepared with tape casting method, was studied by adding carbon-based nano-fillers including carbon black, carbon nanotube (CNT) and graphene. The in-plane thermal conductivities of the composites, i.e., the thermal conductivities along the tape casting plane, were measured. The improvement of thermal conductivities of the composites was observed to be up to 24% by adding CNT and 31% by adding graphene at 10 wt.%. Micro-structures of the NFG/polymer composites were revealed by X-ray diffraction patterns and field emission scanning electron microscopy images to delineate the mechanism of thermal conductance in the composites. From the observed structure, a new thermal conductivity model for the composites with CNT and graphene additives was constructed based on a bridging mechanism. The new model applies well to the measured thermal conductivities of the as-prepared samples. It is expected that the model could also be applied well to composites added with other homologous materials for bridging thermal contacts.     

Low percolation threshold of graphene/polymer composites prepared by solvothermal reduction of graphene oxide in the polymer solution

Graphene/polyvinylidene fluoride (PVDF) composites were prepared using in-situ solvothermal reduction of graphene oxide in the PVDF solution. The electrical conductivity of the composites was greatly improved by doping with graphene sheets. The percolation threshold of such composite was determined to be 0.31 vol.%, being much smaller than that of the composites prepared via blending reduced graphene sheets with polymer matrix. This is attributed to the large aspect ratio of the SRG sheets and their uniform dispersion in the polymer matrix. The dielectric constant of PVDF showed a marked increase from 7 to about 105 with only 0.5 vol.% loading of SRG content. Like the other conductor-insulator systems, the AC conductivity of the system also obeyed the universal dynamic response. In addition, the SRG/PVDF composite shows a much stronger nonlinear conduction behavior than carbon nanotube/nanofiber based polymer composite, owing to intense Zener tunneling between the SRG sheets. The strong electrical nonlinearity provides further support for a homogeneous dispersion of SRG sheets in the polymer matrix.     

Synergistic enhancement of thermal conductivity by addition of graphene nanoplatelets to three-dimensional boron nitride scaffolds for polyamide 6 composites

Three-dimensional boron nitride/graphene nanoplatelets (3D-BN-GNP) scaffolds were fabricated using an ice-templating method and polyamide 6 (PA6)-based composites were prepared by vacuum impregnation of caprolactam monomers into the scaffolds, followed by polymerization. The BN sheets in the PA6/3D-BN and PA6/3D-BN-GNP composites display a predominant parallel alignment along the ice-crystal formation constructing thermally conductive paths. The addition of few GNPs assists the dispersion of BN sheets in the PA6/3D-BN-GNP composites and repair the broken thermal paths caused by local agglomeration of the BN sheets. Consequently, GNPs play a morphology-promoted synergistic role in the enhancement of the thermal conductivity of the PA6/3D-BN-GNP composites. The PA6/3D-BN-GNP composite prepared with 23.40 wt% BN sheets and 2.60 wt% GNPs exhibits the highest thermal conductivity of 2.80 W m⁻¹ K⁻¹, which is 833% and 33% higher than the values recorded for the pure PA6 and the PA6/3D-BN composite at BN loading of 26.18 wt%, respectively. Infrared imaging analysis revealed that the surface of the PA6/3D-BN-GNP composite has a fast response to heating and cooling, suggesting the potential of the composites in thermal management applications.     

Cobalt/graphene oxide nanocomposites: Electro-synthesis,structural, magnetic,and electrical properties

In this research, different samples of cobalt/graphene oxide nanocomposites were successfully synthesized electrochemically by applying different voltages. Their structure, magnetization and electrical properties were studied using X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), atomic force microscope (AFM), fourier transformation infrared (FT-IR), vibrating sample magnetometer (VSM), two point probe electrical conductivity meter, galvanostat/potentiostat, and universal testing machine. The results of structural characterization confirmed the formation of cobalt/graphene oxide nanocomposites. The FESEM images showed the porous flower-like structure of particles deposited on the graphene oxide sheets. The AFM images clearly showed the surface roughness and the dispersion of nanoparticles on graphene oxide sheets. Room-temperature magnetization values range from 18 emu g^?1 to 167 emu g^?1, depending on the applied voltage. In order to study the electrical properties of the nanocomposites, the volumetric resistivity and volumetric conductivity under different pressures and the current-voltage characteristic curves were measured. Based on the results, the nanocomposites synthesized by applying 8 V and 23 V show ohmic behavior and have the highest volumetric conductivity. The volumetric conductivity increases with increasing the pressure. The nanocomposite prepared by applying 23 V presents good structural, magnetic, and electrical properties.     

室温硫化硅橡胶／石墨烯复合材料的制备与性能

采用溶液共混法制备了以石墨烯和氧化石墨为填料的室温硫化硅橡胶复合材料,并对其导电性能和力学性能进行了研究。结果表明,当石墨烯质量分数为3％时,复合材料的拉伸强度提高200％左右;体积电导率提高了9个数量级,复合材料中石墨烯的逾渗阈值为1％。利用原位热还原法处理氧化石墨／硅橡胶复合材料,当处理时间为30min时,其体积电导率提高了3个数量级。     

聚丙烯基石墨烯改性复合材料的导电及热稳定性

以邻二氯苯（O-DCB）为溶剂,将超声预分散的石墨烯纳米微片（GNS）混入聚丙烯（PP）基材,再经塑化、热压成型获得GNS/PP复合材料。采用扫描电镜观察其微观形态变化,高阻计测量其电阻并计算出体积电阻率,同步热分析仪测试其在空气中的热稳定性能。结果表明,GNS在PP基材中分散均匀,并相互连接构成网络结构;GNS/PP复合材料的导电性能相较PP有了显著提升,当GNS质量含量为1%~2%时,复合材料出现明显的导电渗流现象,其体积电阻率降幅达6个数量级;当空气温度高于324℃时,在相同温度下,1% GNS/PP复合材料相较PP的失量更少,且整个失量阶段的温度跨度较PP提高40℃,但GNS的存在也导致GNS/PP复合材料的起始失量温度较PP提前30~40℃,并出现使材料完全失量的终点温度,且GNS质量含量越高,该终点温度越低。将低成本的GNS均匀掺入PP中能够获得导电性能优异并具备一定程度热稳定性的功能型复合材料。     

聚丙烯/石墨烯微片/碳化硅复合材料微观形态与导电导热性能研究

采用熔融共混法制备聚丙烯/石墨烯微片/碳化硅(PP/GNP/SiC)复合材料,研究了SiC用量对PP/GNP/SiC复合材料的微观形态、结晶度和导电导热性能的影响。SEM与XRD测试结果表明,SiC粒子有助于提高拉伸力场对GNP的剥离效果以及GNP在PP基体中的分散程度,随着SiC粒子用量的增加,GNP的片径尺寸和片层厚度均减小,并与SiC粒子相互搭接。导电导热分析结果表明,随着SiC粒子用量的增加,PP/GNP/SiC复合材料的电导率先升高后降低,热导率逐渐提高。SiC用量为5%时,复合材料的电导率最高;SiC用量为20%时,复合材料的热导率最高。     

Graphene/nanosized silicon composites for lithium battery anodes with improved cycling stability

Graphene/nanosized silicon composites were prepared and used for lithium battery anodes. Two types of graphene samples were used and their composites with nanosized silicon were prepared in different ways. In the first method, graphene oxide (GO) and nanosized silicon particles were homogeneously mixed in aqueous solution and then the dry samples were annealed at 500 °C to give thermally reduced GO and nanosized silicon composites. In the second method, the graphene sample was prepared by fast heat treatment of expandable graphite at 1050 °C and the graphene/nanosized silicon composites were then prepared by mechanical blending. In both cases, homogeneous composites were formed and the presence of graphene in the composites has been proved to effectively enhance the cycling stability of silicon anode in the lithium-ion batteries. The significant enhancement on cycling stability could be ascribed to the high conductivity of the graphene materials and absorption of volume changes of silicon by graphene sheets during the lithiation/delithiation process. In particular, the composites using thermally expanded graphite exhibited not only more excellent cycling performance, but also higher specific capacity of 2753 mAh/g because the graphene sheets prepared by this method have fewer structural defects than thermally reduced GO.