Fabrication of graphene/epoxy resin composites with much enhanced thermal conductivity via ball milling technique

Ball milling is selected to prepare composites of graphene nanoplatelets (GNPs) and epoxy. Much enhanced thermal conductivity was recorded with higher GNP loading, which varied between 5 and 25 wt %. A maximum thermal conductivity of 2.67 W/m·K was found. The prepared composites were characterized by scanning electron microscopy, transmission electron microscopy, and Raman. It was found that KNG180, a commercially available kind of natural graphite, with a thickness of 30 ～ 80 nm were mainly exfoliated into GNPs (<10 layers) with high quality, which were in turn uniformly dispersed in the composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40565.     

球磨时间对石墨烯复合材料电化学性能的影响

采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和电化学工作站等手段研究了球磨时间（0~60 min）对石墨烯/La₁₅Fe₂Ni₇₁Mn₆B₂Al₂复合材料微观结构和电化学性能的影响。结果表明,球磨时间为0~60 min制备的石墨烯复合储氢合金都主要由La₃Ni₁₃B₂、（Fe,Ni）、LaNi₅相组成,其中LaNi₅相的晶胞体积会随着球磨时间的增加而减小。随着球磨时间从0 min增加至60 min,石墨烯复合储氢合金的电荷转移电阻先减小后增大、交换电流密度先增大后减小、氢扩散系数和荷电保持率先增加后减小,在球磨时间为40 min时取得电荷转移电阻最小值,交换电流密度、氢扩散系数和荷电保持率最大值。此外,在相同循环次数下球磨时间为40 min制备的石墨烯复合储氢合金具有相对较高的放电比容量。适宜的石墨烯/La₁₅Fe₂Ni₇₁Mn₆B₂Al₂复合材料的球磨时间为40 min,此时氢扩散系数和荷电保持率分别为1.259×10^-8 cm²/s和97.62%,具有较好的电化学性能,这主要与此时复合材料粉末颗粒较为细小、均匀且结晶度较高等有关。     

石墨烯/导电聚合物复合防腐蚀材料制备及应用研究进展

石墨烯/导电聚合物复合材料不仅具有石墨烯优异的屏蔽性能和导电聚合物良好的氧化还原特性,还能协同发挥二者的功能,在金属防腐蚀领域有着巨大的应用潜力。本文综述了石墨烯/导电聚合物复合防腐蚀材料的制备方法,包括电化学方法、化学氧化法、分散液混合法和化学气相沉积法（CVD）;并全面总结了石墨烯/导电聚合物复合材料在防腐蚀涂层中的应用及性能。制备的石墨烯/导电聚合物复合材料可以通过电化学方法、溶剂挥发法制成石墨烯/导电聚合物防腐蚀薄膜涂层,还可以混入成膜物树脂中制备树脂复合防护涂层。讨论了石墨烯/导电聚合物在制备过程、薄膜涂层和树脂复合涂层应用中的优势与不足,提出了构建结构可控、综合性能好的复合防腐涂层是石墨烯/导电聚合物复合防腐蚀材料的未来主要发展趋势。     

High-yield water-phase exfoliated few-defect graphene for high performance polymer nanocomposites

Application of graphene requires a high-yield, low-cost, scalable production method, but it remains highly challenging. We here report a water-phase technique to produce few-defect graphene nanosheets (FGS) with a high exfoliation yield (92%), based on the chemically expanded graphite with ultrahigh specific surface areas, and demonstrate the application in graphene-polymer nanocomposites. The exfoliated FGS has low degree of oxidation and preserves good mechanical and electrical properties, revealing promising potential for improving comprehensive properties of polymer composites. When 0.5 wt% FGS was incorporated to poly(methyl methacrylate) (PMMA), the 5% weight loss temperature and storage modulus increase by 87°C and 21%, respectively, relative to the neat polymer. With increasing the content of FGS to 4.6 wt%, the glass transition temperature of the composite increases by 25°C. In addition, the composites show a percolation threshold as low as 0.25 vol% and excellent electrical conductivity (50 S/m for 2.7 vol% FGS-PMMA composite).     

石墨烯/聚合物纳米复合材料制备与微波吸收性能研究进展

二维片状的石墨烯不仅具有优异的力学、热学和电学性能,而且还具有较好的微波吸收特性。自它被发现以来,一直受到科学界的广泛关注,目前已有学者将其与聚合物复合,制备了石墨烯/聚合物纳米复合材料,这种新型微波吸收材料不仅吸波效果好而且密度小、易加工。目前石墨烯/聚合物纳米复合材料用于微波吸收的报道还比较少,该研究基本处于起步阶段。本文首先概述了石墨烯独特的物理结构和优异的力学、热学、电学性能,然后综述了石墨烯/聚合物纳米复合材料的制备方法,并分析了其微波吸收机理,最后结合国内外研究现状展望了石墨烯/聚合物纳米复合材料制备与微波吸收性能研究的发展方向,指出调控复合材料的微观形貌,对石墨烯进行磁性掺杂,探索石墨烯与聚合物微波吸收的协同效应将成为今后研究的重点和热点。     

石墨烯/聚合物复合材料的研究进展

介绍了石墨烯的制备与改性方法,概述了石墨烯/聚合物复合材料的制备工艺,主要有熔融共混法、原位聚合法、溶液混合法及乳液混合法,并总结了石墨烯对聚合物导电性能、导热性能、耐热性能、物理机械性能和气体阻隔性能的影响.     

Effect of high energy ball milling on strengthening of Cu-ZrO2 nanocomposites

In this paper, copper matrix nanocomposites reinforced by 5 and 10?wt% ZrO₂ particles were produced by mechanical milling technique at different milling times. The produced nanocomposite powders were investigated by X-ray diffraction technique and transmission electron microscopy. The effect of high energy ball milling on the morphology, microstructure and microhardness of the produced composites has been investigated. After that cold compaction was applied to the prepared powders under a pressure of 700?MPa and sintered at 950?°C for 2?h in hydrogen atmosphere. The results showed that increasing milling time improves microhardness of the prepared nanocomposites. The microhardness of Cu-10%ZrO₂ after 20?h milling is 3.76 times larger than pure Cu. This improvement is attributed firstly to the presence of ZrO₂ nanoparticles in addition to the improvement coming from the grain refinement and crystallite size reduction occurred due to mechanical alloying. So, in spite of the crystallite size of Cu-10%ZrO₂ nanocomposite is reduced to 10.75?nm compared to 105.5?nm for pure Cu, the presence of ZrO₂ nanoparticles plays a major role on mechanical properties improvement.     

石墨烯/聚合物纳米复合材料研究进展

近年来,石墨烯以其完美的二维结构和众多优异的性能,引起了科学家的极大兴趣,成为纳米材料领域的一大研究热点。在众多研究中,基于石墨烯的聚合物纳米复合材料的研究是一个重要方向。本文在简要介绍石墨烯结构、性质和制备以及石墨烯的改性方法的基础上,重点总结了石墨烯基聚合物纳米复合材料的常用制备方法、结构及性能,进而得出大规模制备结构完整、尺寸和层数可控的高质量石墨烯及其衍生物是未来的研究热点,而改进石墨烯聚合物基复合材料合成方法,有效模拟石墨烯结构特征对复合材料的热、力、电、光等性能的影响则是该领域的重点发展方向。     

Properties and structural characterization of oxide starch/chitosan/graphene oxide biodegradable nanocomposites

Novel chitosan (CS)/oxidized starch (OST)/graphene oxide (GO) nanocomposites (COST/GO‐n) films are prepared in a casting and solvent evaporation method. Fourier transform infrared spectroscopy, X‐ray diffractions, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis, tensile testing, and moisture uptake are used to study the structure and properties of these nanocomposites. To indicate the effect of carboxyl groups of OST, some results of the properties of CS/starch/GO nanocomposite (CST/GO‐n) were selected for control experimentation. Compared with the control CST/GO‐n series, COST/GO‐n films, which have the same component ration showed higher tensile strength (σ_b) and lower elongation at break (ε_b). Additionally, in the COST/GO‐n series, the σ_b increased with an increase of GO loading. However, higher proportion of GO could result in aggregations of GO nanosheets and deterioration of the film properties. Compared with the COST/GO‐0, the values of σ_b and water resistance of the COST/GO‐4 containing 2.0 wt % of GO were improved by 57.7 and 20.1%, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

聚合物/石墨烯复合材料制备与性能研究进展

首先综述了聚合物/石墨烯复合材料的制备方法,重点介绍了两种近些年新开发的制备方法;之后综述了聚合物/石墨烯复合材料的结构设计与性能;最后对聚合物/石墨烯复合材料的研究前景进行了展望。     

Epoxy/clay nanocomposites: further exfoliation of newly modified clay induced by shearing force of ball milling

To induce montmorillonite (MMT) to be further exfoliated and homogeneously dispersed in epoxy matrix (diglycidyl ether of bisphenol A) curing in the presence of diaminodiphenyl sulfone and obtain improved mechanical properties, a promising new method has been developed to prepare highly reinforced epoxy/MMT nanocomposites through exerting shearing force on epoxy/MMT solution by ball milling. Modifying agents, being combined with dodecylbenzyldimethylammonium chloride and meta‐xylylenediamine, were used to organically modify the clay (MMTII). Different resultant products were characterized by Fourier‐transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, etc, and the fracture surface of the mechanically tested specimens was also observed by scanning electronic microscopy. Results show that the novel MMTII possess a reactive interaction surface with the epoxy matrix. Exfoliation of the retained sandwich structure (being intercalated) or large agglomerates (undispersed MMTII) can be promoted by external shearing force of ball milling, and homogeneously dispersed MMTII nano‐sheets in epoxy matrix nanocomposites are typically observed. Mechanical properties, especially impact toughness, can be increasingly enhanced by the newly structured MMTII and ball milling. Impact strength is increased up to 48.1 kJ m^?2 from 32.1 kJ m^?2 at 3 wt% MMTII content, which is about 50 % higher than that of pristine matrix, and the flexural strength can also be enhanced by about 8 % higher. Copyright © 2004 Society of Chemical Industry     

乳液聚合法制备聚合物/石墨烯复合材料研究进展

综述了近些年来使用乳液聚合法制备聚合物/石墨烯复合材料的国内外研究现状,详细阐述了制备聚合物/石墨烯复合材料的乳液聚合方法,总结了乳液聚合法中聚合物的种类和石墨烯的改性方法以及复合材料的性能改善,并对乳液聚合法制备聚合物/石墨烯复合材料的应用领域和研究方向进行了展望。     

Enhanced mechanical and thermal properties of polyurethane/functionalised graphene oxide composites by in situ polymerisation

ABSTRACT

Isocyanate-functionalised graphene (iGO) was prepared and incorporated into a thermoplastic polyurethane via an in situ polymerisation. Firstly, graphene oxide was successfully modified using a mixture of isocyanate- and diisocyanate-containing compounds, leading to the formation of good dispersions of resulting functional graphene oxide in organic solvents, such as N,N-dimethylacetamide and N,N-dimethylformamide. The addition of iGO into polyurethane matrix improved both mechanical and thermal properties in the polyurethane/iGO composites relative to neat polyurethane. An addition of only 0.03?wt-% of functionalised graphene into the polyurethane increased Young’s modulus by 1.4 times and tensile strength by two times. Meanwhile, the elongation at break was similar to that of the neat polymer. In addition, dynamic mechanical analysis also confirmed the improvement in storage modulus of the polymer composites especially at high-temperature range. We believe that the developed modification approach for graphene oxide and polyurethane/graphene composites presented herein could be useful in polymer/graphene composite development.     

高能球磨法制备铈锆铝复合氧化物的工艺

采用高能球磨法制备铈锆铝复合氧化物,运用XRD、SEM等方法研究CeO₂-ZrO₂-Al₂O₃复合催化材料分别在不同球磨时间、不同成分含量、不同焙烧温度和不同球磨工艺路线下的组织结构和稳定性能。结果表明：①随球磨时间的延长,各组元晶粒细化效果越来越明显,球磨30h,CeO₂晶粒约20nm,颗粒约200nm,但复合粉末一直未发生机械合金化。②经30h球磨的复合粉体,在1000℃以下具有良好的稳定性能,高温下有少量的ZrO₂溶入CeO₂中形成固溶体,CeO₂-ZrO₂和Al₂O₃之间表现出一定的协同稳定效应,而在1000℃以上相结构变化明显。③质量分数为18%的CeO₂和6%的ZrO₂的复合粉体颗粒比较细小,分布比较均匀,对γ-Al₂O₃的稳定化效果比较理想。④采用先将CeO₂和ZrO₂球磨30h,再添加Al₂O₃并继续球磨30h的高能球磨工艺,可制备出含大量CeO₂-ZrO₂固溶体的复合粉体,CeO₂-ZrO₂与γ-Al₂O₃相互改性作用更加理想。     

结构有序的Si/void/C/graphene纳米复合结构的制备及储锂性能

采用简单的超声、冷冻干燥和热还原相结合的自组装方法,设计和构建了纳米硅核/间隙/无定形碳壳层/石墨烯（Si/void/C/graphene） 三维有序纳米复合结构。在该结构中,纳米硅核与碳壳层之间的空隙有效避免了硅的巨大体积膨胀对碳层的破坏,大幅度提高了锂离子电池的循环稳定性;将Si/void/C纳米结构嵌入在石墨烯层与层之间,利用石墨烯卓越的导电性和柔韧性,进一步缓冲了硅材料的体积效应和提高了复合材料的导电性能。该复合材料在4200 mA·h·g^-1（1 C）电流密度下循环1000次后比容量仍高达1603 mA·h·g^-1;在67 A·g^-1（16 C）的高倍率下,比容量仍有310 mA·h·g^-1,显示出了在锂离子电池负极材料领域的巨大应用潜力。     

Enhanced mechanical properties of nanocomposites at low graphene content based on in situ ball milling

In this study, epoxy‐based nanocomposites with low content mechanically exfoliated graphene were successfully prepared via one‐step in situ ball milling method. The effect of graphene on mechanical properties of the nanocomposites was investigated. The results showed that samples with loadings less than 0.1% weight of mechanically exfoliated graphene increased by 160% in tensile strength and 65% in Young's modulus. The experimental value of Young's modulus was also compared with the predictions of the well‐established Halpin‐Tsai model. In addition, the adding of graphene did not decrease the impact strength of epoxy. The microstructural results showed that the as‐prepared graphenes were single‐ and few‐layer graphene sheets and preserved perfect structure. Thus enhancements of mechanical properties in the nanocomposites could be ascribed to the strong interfacial interaction between the stiff graphene nanosheets and the epoxy matrix. POLYM. COMPOS. 37:1190–1197, 2016. © 2014 Society of Plastics Engineers     

Effects of high-energy ball milling and reactive spark plasma sintering on the densification of HfC-SiC composites

The combined effects of high-energy ball milling (HEBM) and reactive spark plasma sintering (R-SPS) of HfSi₂ and C powder mixture on the densification and microstructure of nanostructured HfC-SiC composites were investigated. HEBM significantly promoted the densification and improved the microstructure of the HfC-SiC composites. In contrast, the reactions between HfSi₂ and C did not directly promote the densification of the HfC-SiC composites. While the reaction was mostly completed at 1300 °C, the onset temperature of significant densification was 1610 °C. Fine and homogeneously distributed HfC and SiC particles formed by HEBM and R-SPS were the key factors for promoting the densification of the HfC-SiC composites. The fine particles had high surface energy, which provided enough driving force for densification. In addition, the homogeneously distributed SiC particles effectively suppressed the growth of HfC matrix grains during densification.     

聚合物/高岭石嵌入纳米复合材料研究进展

介绍了聚合物/高岭石嵌入纳米复合材料的制备方法，对嵌入过程的热力学和动力学分析进行了总结。展望了聚合物/高岭石嵌入纳米复合材料的应用前景。     

In situ polymerization of bio‐based thermosetting polyurethane/graphene oxide nanocomposites

Novel bio‐based polyurethane/graphene oxide (GO) nanocomposites have been successfully synthesized from biorenewable epoxidized soybean‐castor oil fatty acid‐based polyols with considerable improvement in mechanical and thermal properties. The GO was synthesized via a modified pressurized oxidation method, and was investigated using Raman spectra, AFM and XPS, respectively. The toughening mechanism of GO in the bio‐based polyurethane matrix was explored. The elongation at break and toughness of polyurethane were increased by 1.3 and 0.8 times with incorporation of 0.4 wt % GO, respectively. However, insignificant changes in both mechanical strength and modulus were observed by adding GO. The results from thermal analysis indicated that the GO acts as new secondary soft segments in the polyurethane which lead to a considerable decrease in the glass transition temperature and crosslink density. The SEM morphology of the fracture surface after tensile testing showed a considerable aggregation of graphene oxide at concentrations above 0.4 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41751.