共混顺序对石墨烯微片在PP/PA6/SEBS共混物中的选择性分布和迁移的影响

研究了聚丙烯(PP)/聚酰胺6(PA6)/氢化苯乙烯-丁二烯嵌段共聚物(SEBS)/石墨烯微片(GNPs)纳米复合材料在不同共混顺序下的微观形貌、导电及导热性能,分析了GNPs在复合体系中的选择性分布和迁移及其对复合材料性能的影响.结果表明,在PP/PA6/SEBS/GNPs共混体系中,GNPs在界面张力的作用下趋向于...     

聚乙二醇/石墨烯纳米片复合相变材料的制备及其性能研究

以聚乙二醇(PEG)作为相变工作物质,以具有优异导热性能的石墨烯纳米片(GNPs)作为导热填料,通过熔融共混法制备出一系列不同GNPs含量的PEG/GNPs复合相变材料。采用激光导热仪、差示扫描量热仪、扫描电子显微镜、X射线衍射仪、红外光谱仪等测试PEG/GNPs复合相变材料的导热性能、热物性、微观形貌、结晶性能及化学组成。结果表明,GNPs均匀分散于PEG基体中,形成能够加快热量传递的导热通路,复合材料体系的导热系数得以显著提高,而相变焓仅仅略微下降,当GNPs含量为2%时,复合材料体系的导热系数是PEG的249.7%,而相变焓损失率却仅为3.9%;PEG与GNPs二者间仅是物理吸附,并未发生化学反应,复合材料体系的结晶性能良好;PEG与GNPs复合相变材料的热响应速度更快,能源利用率因而更高。     

聚乙二醇/石墨烯纳米片复合相变材料的制备及其性能研究

以聚乙二醇(PEG)作为相变工作物质,以具有优异导热性能的石墨烯纳米片(GNPs)作为导热填料,通过熔融共混法制备出一系列不同GNPs含量的PEG/GNPs复合相变材料。采用激光导热仪、差示扫描量热仪、扫描电子显微镜、X射线衍射仪、红外光谱仪等测试PEG/GNPs复合相变材料的导热性能、热物性、微观形貌、结晶性能及化学组成。结果表明,GNPs均匀分散于PEG基体中,形成能够加快热量传递的导热通路,复合材料体系的导热系数得以显著提高,而相变焓仅仅略微下降,当GNPs含量为2%时,复合材料体系的导热系数是PEG的249.7%,而相变焓损失率却仅为3.9%;PEG与GNPs二者间仅是物理吸附,并未发生化学反应,复合材料体系的结晶性能良好;PEG与GNPs复合相变材料的热响应速度更快,能源利用率因而更高。     

拉伸力场对聚丙烯/石墨烯微片纳米复合材料形态和性能的影响

设计了2种挤出机头以产生不同加工力场,研究了聚丙烯（PP）/石墨烯微片（GNPs）纳米复合材料的微观形态、导电及导热性能,分析GNPs在PP基体中的分布形态对复合材料的性能影响。结果表明,收敛流道产生的拉伸力场对GNPs有剥离分散作用,减少GNPs团聚;加入静态混合器后产生的混沌混炼力场能进一步提高GNPs在PP中的分散均匀性,有利于构建导电导热网络,从而提高复合材料的导电导热性能;当GNPs含量为6 %(质量分数,下同)时,相比于无静态混合器的拉伸机头,在带静态混合器的拉伸机头挤出下,电导率增大了5个数量级,热导率提高了24.1 %。     

石墨烯填充高导热塑料研究进展

阐述了石墨烯和石墨烯填充高导热塑料的制备方法及导热性能,并对几种石墨烯/聚合物复合材料的制备方法进行了对比。分析了影响石墨烯填充高导热塑料导热性能的因素,并对石墨烯及其填充高导热复合材料的研究方向及发展前景进行了展望。     

超声辅助真空作用下石墨烯/PBS复合材料的制备及热性能

以石墨烯纳米片(GNPs)和聚丁二酸丁二醇酯(PBS)为原料,利用自制的超声辅助真空实验装置进行熔融混合,通过调控超声振荡-真空灌注工艺制备了一系列GNPs/PBS复合材料。分别采用扫描电子显微镜(SEM)、差示扫描量热仪(DSC)、热重分析仪(TG)、维卡软化温度(VST)和Hot disk导热仪研究了PBS基复合材料的界面形态、结晶性能、热稳定性能、抗热变形性能和导热性能。结果表明:与纯PBS相比,当GNPs添加量达到0.5%、超声功率300 W时,GNPs/PBS复合材料的玻璃化转变温度、最大热分解温度、维卡软化点与导热系数分别提高了5.4℃、5.3℃、12.7℃与1 107.8%,而结晶度出现轻微降低。同时,对比超声功率研究结果发现,提高超声功率可以明显改善GNPs/PBS复合材料的热稳定性、抗热变形性和热导率,这是因为高功率的超声振荡提高了GNPs在PBS基体中的分散性。     

中科院纳米所开发出超高热导率石墨烯-聚合物复合材料

作为近来纳米科学领域的研究热点，新兴的石墨烯由于具有独特的二维结构、高比表面积和优异的热学性能[导热系数可高达3000～6000 W／(m · K)]，受到了广泛关注。石墨烯／聚合物导热复合材料有望在电子器件、光电子器件、消费电子及导热聚合物材料中得到重要应用。目前，石墨烯的添加一定程度上改善了聚合物复合体系的导热性能，尽管能使聚合物的导热系数提高一个数量级，但有限石墨烯添加量、无序结构以及石墨烯／聚合物高界面热阻致使石墨烯-聚合物复合体系的热导率无法实现更高突破，阻碍了其在未来热管理中的广泛应用。     

石墨烯/聚丙烯复合材料制备及性能研究

以石墨烯(GNPs)为填料对聚丙烯(PP)进行改性,通过球磨和熔融挤出共混的方法制备了一系列不同GNPs含量的GNPs/PP复合材料。用X射线衍射、扫描电子显微镜、电导率测试及拉伸测试等手段对复合材料的结构和性能进行表征分析,研究GNPs含量对复合材料性能的影响。结果表明:随着GNPs含量的增加,复合材料的电导率逐渐增大;当GNPs质量分数为15%时,复合材料的电导率达到0. 127 S/cm;复合材料的电阻逾渗阈值在GNPs质量分数为5%～8%之间。在力学性能方面,随着GNPs含量的增加,复合材料的拉伸强度呈现出先增加后降低的趋势;当GNPs质量分数为3%时,复合材料的拉伸强度达到最大,为35. 658 MPa,比纯PP提高了21. 04%;复合材料的弹性模量随着GNPs含量的增加而增加,在GNPs质量分数为15%时,复合材料的弹性模量比纯PP提高了89. 6%,达到2 068. 54 MPa。本文对制备高导电和高强度的导电聚合物或者导电纤维母粒可以提供一定的参考价值。     

石墨烯/聚合物复合材料的制备与研究进展

对石墨烯及石墨烯/聚合物复合材料制备的进展进行了综述。主要介绍了石墨烯与石墨烯/聚合物复合材料的制备工艺、结构、性能及应用情况,并结合石墨烯/聚合物复合材料的研究现状,展望了其今后的发展方向。     

聚合物基石墨烯纳米复合材料的研究进展

聚合物基石墨烯纳米复合材料是近年来开发的新型聚合物基复合材料,将具有独特结构和优异性能的石墨烯添加到聚合物中,可以显著提高聚合物基体的导电导热能力和力学性能。首先简要介绍石墨烯的结构、性能和制备方法,然后重点综述聚合物基石墨烯纳米复合材料的制备以及其在导电导热性能和力学性能等方面的最新研究进展。     

石墨烯导热高分子复合材料的制备、性能与机理

石墨烯是一种具有超大的比表面积、良好的热和化学稳定性、超高的热导率以及易于化学修饰的蜂窝状单层碳材料,已作为填料广泛应用于导热高分子复合材料领域。近年来石墨烯导热高分子材料的研究重点是改善石墨烯在聚合物基体中的界面相容性和分散性能。阐述了近年来石墨烯导热高分子复合材料的制备方法及其热性能,并重点对石墨烯导热高分子复合材料的导热机理进行综述,同时结合研究现状对石墨烯导热高分子复合材料的研究方向进行展望。     

Recent Progress on Fabrication and Performance of Polymer Composites with Highly Thermal Conductivity

The rise of miniaturized, integrated, and functional electronic devices has intensified the need for heat dissipation. To address this challenge, it is necessary to develop novel thermally conductive polymer composites as packaging materials. In this paper, a number of factors for the construction and design of thermally conductive polymers are concluded. Special attention is focused on the analysis and comparison of the thermally conductive composites prepared by various fillers or strategies to provide guidelines and references for future design of composite materials. The current commonly used preparation strategies of thermally conductive polymer are summarized, such as using a variety of fillers, vacuum filtration, template method, and so on. The challenges of thermally conductive polymer composites are finally sketched. This review can inspire the design of polymer composites with brilliant thermal conductivity.     

High thermally conductive PLA based composites with tailored hybrid network of hexagonal boron nitride and graphene nanoplatelets

Bio‐based polymers and multifunctional polymeric composites are promising for the development of new environmentally sustainable materials and are becoming increasingly popular compared to their oil based counterparts. This research aims to develop new multifunctional bio‐based polymer composites with improved thermal conductivity and tailored electrical properties to be used as heat management materials in the electronics industry. A series of parametric studies were conducted to clarify the science behind the hybrid composites' behavior and their structure‐to‐property relationships. Using bio‐based polymers [e.g., polylactic acid (PLA)] as the matrix, heat transfer networks were developed and structured by embedding hexagonal boron nitride (hBN) and graphene nanoplatelets (GNP) in a PLA matrix. The effects of random uniform thermal hybrid networks of hBN‐GNP on improving the effective thermal conductivity (k_eff) of produced composites were studied and compared. Composites were characterized with respect to physical, thermal, electrical, and mechanical properties for practical application in the electronics industry. The use of high thermally conductive hybrid filler systems, with optimized filler content, was found to promote the composites' effective thermal conductivity to more than 12 times over neat PLA. The thermally conductive composite is expected to provide unique opportunities to injection mold three‐dimensional, net‐shape, lightweight, and eco‐friendly microelectronic enclosures with superior heat dissipation performance. POLYM. COMPOS., 37:2196–2205, 2016. © 2015 Society of Plastics Engineers     

Electrical conductivity of thermally reduced graphene oxide/polymer composites with a segregated structure

A simple method to prepare thermally reduced graphene oxide/polymer composites was developed to enhance the electrical conductivity of the polymer. Graphene oxide sheets were coated onto the surfaces of poly(vinylidene fluoride) powders and then hot pressed at 200 °C to form composites with a segregated structure. After hot-pressing, the thermally reduced graphene oxide sheets were located in the interstices among the polymer domains and formed a two-dimensional conductive network. The resulting composites exhibited excellent electrical conductivity and a low percolation threshold (0.105 vol.%).     

聚合物/新型导热填料复合电介质的研究进展

综述了非常规新型导热粒子如纳米金刚石、碳化物、铁电陶瓷及其他无机功能粒子及其填充聚合物电介质的最新研究进展,重点探讨了新型导热粒子的含量、表面改性、加工方式等对聚合物复合材料的导热及介电性能的影响。介绍和分析了基于有机分子晶体为连续声子传递通路改性聚合物导热性能的研究及机理;在基体树脂内利用无机导热粒子及有机分子晶体可构筑连续的声子导热通路,从而达到降低界面热阻、提高体系热导率的目的。相比传统导热粒子,新型导热粒子在提高绝缘聚合物热导率的同时,还赋予体系其他物理性能如磁性、优良介电性能及储能等性能。     

锂硫电池石墨烯/纳米硫复合正极材料的制备及电化学性能

利用热解还原将Hummers法制得的氧化石墨烯还原为石墨烯,并采用化学沉淀法将纳米硫成功负载到石墨烯片层上,获得石墨烯/纳米硫（RGO/nano-S）正极复合材料。利用FT-IR、XRD、SEM、TEM和Raman对所制备复合材料的微观结构、形貌等进行表征,采用恒流充放电、循环伏安法和交流阻抗法对复合材料的电化学性能进行研究。研究结果表明,热还原所得石墨烯褶皱的表面形成容纳硫及多硫离子的空间,有助于缓解活性物质溶解和抑制多硫离子迁移;同时,均匀分布的纳米硫能更好地与电解液接触,在石墨烯的导电网络上增大了电化学反应面积,进而改善了该材料作为锂硫电池的实际放比电容量和倍率循环性能。     

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.     

Thermal conductivity of polymer-based composites: Fundamentals and applications

Thermal management is critical to the performance, lifetime, and reliability of electronic devices. With the miniaturization, integration and functionalization of electronics and the emergence of new applications such as light emitting diodes, thermal dissipation becomes a challenging problem. Addressing this challenge requires the development of novel polymer-based composite materials with enhanced thermal conductivity. In this review, the fundamental design principles of highly thermally conductive composites were discussed. The key factors influencing the thermal conductivity of polymers, such as chain structure, crystallinity, crystal form, orientation of polymer chains, and orientation of ordered domains in both thermoplastics and thermosets were addressed. The properties of thermally conductive fillers (carbon nanotubes, metal particles, and ceramic particles such as boron nitride or aluminum oxide) are summarized at length. The dependence of thermal conductivity of composites on the filler loading, filler aggregate morphology and overall composite structure is also discussed. Special attention is paid to recent advances in controlling the microstructure of polymer composites to achieve high thermal conductivity (novel approaches to control filler orientation, special design of filler agglomerates, formation of continuous filler network by self-assembly process, double percolation approach, etc.). The review also summarizes some emerging applications of thermally conductive polymer composites. Finally, we outline the challenges and outlook for thermally conductive polymer composites.     

Hybrid modification of high‐density polyethylene with hyperbranched polyethylene‐functionalized multiwalled carbon nanotubes and few‐layered graphene

Herein, a facile method has been reported to efficiently prepare debundled multiwalled carbon nanotubes (MWCNT) and few‐layered graphene using a hyperbranched polyethylene (HBPE), and as hybrid fillers, their modification effects on high‐density polyethylene (HDPE) are well demonstrated. Stable dispersions of debundled MWCNT and graphene in chloroform were respectively obtained by sonication using the HBPE as stabilizer, and MWCNT/graphene/HDPE ternary nanocomposites were then fabricated by solution‐assisted premixing and subsequent melt mixing, at a fixed mass ratio of MWCNT/graphene of 3:1 and serially changed filler loadings. It is found that the MWCNT and graphene have good dispersibility in the composites, and as hybrid fillers, they can effectively form composite net‐like structure, which makes them show better modification effects on both the electrically and thermally conductive properties of HDPE, as compared to the single MWCNT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44848.     

Preparation and electrical conductivity of graphene/ultrahigh molecular weight polyethylene composites with a segregated structure

Graphene-coated ultrahigh molecular weight polyethylene (UHMWPE) powders were prepared by a two-step process. The first step is to coat UHMWPE polymers with graphene oxide (GO) sheets. The second step is to reduce GO on the powders to graphene. The two-step process can effectively prevent the aggregation of graphene during reduction. The resultant graphene/UHMWPE mixtures were hot pressed at 200 °C to obtain the composites with a segregated structure. The composites exhibit high electrical conductivity at a very low percolation threshold (0.028 vol.%). Our method provides a new route for preparing electrical conductive graphene/polymer composites with low percolation threshold.