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Progress in Natural Science:Materials International 2022年第3期32卷 304-313页

作者： Zhengrong Zhou Rongjin Huang Huiming Liu Yalin Zhao Zhicong Miao Zhixiong Wu Wanyin Zhao Chuanjun Huang Laifeng Li State Key Laboratory of Technologies in Space Cryogenic Propellants Technical Institute of Physics and Chemistry Chinese Academy of Sciences Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences

In a superconducting magnet, the thermal properties of the insulating material at low temperatures is an important technical index to ensure the normal operation of a superconducting coil. Herein, a low-temperature thermal conductivity testing device with a tiny uncertainty was developed to measure the composites. Furthermore, Si C/epoxy and Al N/epoxy composites were prepared and their properties were tested at low temperatures.The results showed that the composites have a better thermal conductivity at low temperatures than pure epoxy.In addition, the Al N/epoxy and Si C/epoxy composites have excellent dynamic mechanical properties and low coefficient of thermal expansion. Due to the fair thermal and dynamic mechanical properties, the composites will have potential application in the superconducting magnet.

关键词： Thermal properties epoxy composites Low temperatures

Fiber-reinforced Three-dimensional Graphene Aerogels for Electrically Conductive epoxy composites with Enhanced Mechanical Properties

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Chinese Journal of Polymer Science 2017年第11期35卷 1381-1390页

作者： Fang-Lan Guan Fei An Jing Yang 李晓锋 Xing-Hua Li 于中振 Beijing Key Laboratory of Advanced Functional Polymer composites Beijing University of Chemical Technology Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology

To enhance the mechanical properties of three-dimensional graphene aerogels with aramid fibers, graphene/organic fiber aerogels are prepared by chemical reduction of graphene oxide in the presence of organic fibers of poly（p-phenylene terephthalamide）（PPTA） and followed by freeze-drying. Thermal annealing of the composite aerogels at 1300℃ is adopted not only to restore the conductivity of the reduced graphene oxide component but also to convert the insulating PPTA organic fibers to conductive carbon fibers by the carbonization. The resultant graphene/carbon fiber aerogels （GCFAs） exhibit high electrical conductivities and enhanced compressive properties, which are highly efficient in improving both mechanical and electrical performances of epoxy composites. Compared to those of neat epoxy, the compressive modulus, compressive strength and energy absorption of the electrically conductive GCFA/epoxy composite are significantly increased by 60%, 59% and 131%, respectively.

关键词： Electrical conductivity Mechanical properties Graphene aerogels epoxy composites Thermal annealing

Construction of 3D interconnected boron nitride/carbon nanofiber hybrid network within polymer composite for thermal conductivity improvement

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Journal of Materials Science & Technology 2023年第16期147卷 165-175页

作者： Yexiang Cui Fei Xu Di Bao Yueyang Gao Jianwen Peng Dan Lin Haolei Geng Xiaosong Shen Yanji Zhu Huaiyuan Wang School of Chemical Engineering and Technology and State Key Laboratory for Chemical Engineering Tianjin UniversityTianjin 300350China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin Key Laboratory of Chemical Process Safety and Equipment TechnologyTianjin UniversityTianjin 300350China College of Chemistry and Chemical Engineering Northeast Petroleum UniversityDaqing 163318China School of Materials Science and Engineering Tianjin UniversityTianjin 300350China

With the increasing power density and integration of electronic devices,polymeric composites with high thermal conductivity(TC)are in urgent demand for solving heat accumulation issues.However,the direct introduction of inorganic fillers into a polymer matrix at low filler content usually leads to low TC enhancement.In this work,an interconnected three-dimensional(3D)polysulfone/hexagonal boron nitride-carbon nanofiber(PSF/BN-CNF)skeleton was prepared via the salt templated method to address this issue.After embedding into the epoxy(EP),the EP/PSF/BN-CNF composite presents a high TC of 2.18 W m^(−1) K^(−1) at a low filler loading of 28.61 wt%,corresponding to a TC enhancement of 990%compared to the neat epoxy.The enhanced TC is mainly attributed to the fabricated 3D interconnected structure and the efficient synergistic effect of BN and CNF.In addition,the TC of the epoxy composites can be further increased to 2.85 W m^(−1) K^(−1) at the same filler loading through a post-heat treatment of the PSF/BN-CNF skeletons.After carbonization at 1500°C,the adhesive PSF was converted into carbonaceous layers,which could serve as a thermally conductive glue to connect the filler network,further decreasing the interfacial thermal resistance and promoting phonon transport.Besides,the good heat dissipation performance of the EP/C/BN-CNF composites was directly confirmed by thermal infrared imaging,indicating a bright and broad application in the thermal management of modern electronics and energy fields.

关键词： Thermal conductivity Boron nitride Carbon nanofiber 3D network epoxy composites

Wear Displayed by the Scratch of epoxy composites Filled by Metallic Particles under the Influence of Magnetic Field

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Materials Sciences and Applications 2016年第2期7卷 119-127页

作者： F. I. El-Zahraa G. T. Abdel-Jaber M. I. Khashaba W. Y. Ali Faculty of Engineering Qena South Valley University Qena Egypt Faculty of Engineering Minia University El-Minia Egypt Faculty of Engineering Taif University Al-Taif Saudi Arabia

The tribological performance of the sliding bearings which are probably made of polymers, which is subjected to magnetic field, is of great intense. The wear of epoxy composites filled by metallic particles such as iron, copper and aluminum scratched by steel indenter is investigated. The wear scar width of the scratch was measured by an optical microscope. It was found that wear displayed by the scratch of epoxy filled by the metallic filling materials such as iron, copper and aluminum increased with increasing applied load. As the content of the metallic filling materials increased, wear slightly increased due to the reduction in cohesive stress inside the matrix as well as the epoxy transfer into the indenter surface might be responsible for that behavior. For epoxy filled by iron, when the magnetic field was applied to the contact area wear significantly decreased. Increasing the intensity of the magnetic field showed slight wear increase. Wear displayed by the scratch of epoxy filled by copper showed higher values than that observed for copper filled epoxy. Presence of the magnetic field might generate electric current at the contact area leading to an increase in the intensity of the electric static charge. Moreover, wear of epoxy filled by aluminum showed lower values than that observed for epoxy composites filled by copper and higher than that displayed by iron filled epoxy composites. Under the effect of magnetic field, wear significantly increased. This behavior could explained on the basis that the presence of magnetic field accompanied by the movement of the indenter in the epoxy composites generated electric current passing through the steel indenter which caused softening of the epoxy composites. In that condition removal of epoxy from the wear track was easier and epoxy transfer into the steel indenter was accelerated.

关键词： Wear epoxy composites Iron Copper Aluminum Magnetic Field Scratch

Particle packing theory guided multiscale alumina filled epoxy resin with excellent thermal and dielectric performances

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Journal of Materiomics 2022年第5期8卷 1058-1066页

作者： Qi-Kun Feng Chang Liu Dong-Li Zhang Yan-Hui Song Kai Sun Hai-Ping Xu Zhi-Min Dang State Key Laboratory of Power System Department of Electrical EngineeringTsinghua UniversityBeijing100084China School of Chemistry and Chemical Engineering Xi'an University of Science and TechnologyXi'an710054China Shanghai Engineering Research Center of Advanced Thermal Functional Materials Shanghai Polytechnic UniversityShanghai201209China

Polymers and composites with high thermal conductivity are promising yet challenging for the growing demand of thermal management in electrical and electronic equipment.Guided by the closest packing model,a multiscale filling Al_(2)O_(3) strategy was designed and incorporated with epoxy resin(EP)to form high thermal conductive composites in this work.epoxy composites with single filler loading were also prepared.The microstructures,thermal,rheological,and dielectric characteristics of the multiscale filling Al_(2)O_(3)/EP composites have been investigated.Compared with single-scale Al_(2)O_(3) filled epoxy based composites,it is found that the multiscale filling Al_(2)O_(3)/EP composites exhibit higher thermal conductivity under the same filler loading of 50 vol%,which is attributed to the efficient heat conduction paths formed by appropriate multiscale fillers.Particularly,a remarkably improved thermal conductivity of 2.707 W m^(-1) K^(-1) was acquired in Al_(2)O_(3)/EP composites at filler loading of 50 vol%(5 mm Al_(2)O_(3)(26.67 vol%),30 mm Al_(2)O_(3)(27.41 vol%)and 70 mm Al_(2)O_(3)(45.92 vol%)),which is about 1300%higher than that of the pure epoxy resin.In addition,the dielectric constant of the Al_(2)O_(3)/EP composites were significantly improved while keeping the dielectric loss almost unchanged.The finite element simulation further verified the effectiveness of improving the thermal conductivity of materials in the heat dissipation of electrical equipment.Therefore,this research provides a simple strategy for manufacturing high thermal conductive composite materials with a wide range of potential applications as packaging materials.

关键词： Closest packing model epoxy composites Alumina Thermal conductivity Dielectric property

3D Lamellar-Structured Graphene Aerogels for Thermal Interface composites with High Through-Plane Thermal Conductivity and Fracture Toughness

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Nano-Micro Letters 2021年第2期13卷 13-27页

作者： Pengfei Liu Xiaofeng Li Peng Min Xiyuan Chang Chao Shu Yun Ding Zhong-Zhen Yu Beijing Key Laboratory of Advanced Functional Polymer composites Beijing University of Chemical TechnologyBeijing 100029People’s Republic of China State Key Laboratory of Organic-Inorganic composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029People’s Republic of China Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100029People’s Republic of China

Although thermally conductive graphene sheets are efficient in enhancing in-plane thermal conductivities of polymers,the resulting nanocomposites usually exhibit low through-plane thermal conductivities,limiting their application as thermal interface materials.Herein,lamellarstructured polyamic acid salt/graphene oxide(PAAS/GO)hybrid aerogels are constructed by bidirectional freezing of PAAS/GO suspension followed by lyophilization.Subsequently,PAAS monomers are polymerized to polyimide(PI),while GO is converted to thermally reduced graphene oxide(RGO)during thermal annealing at 300℃.Final graphitization at 2800℃ converts PI to graphitized carbon with the inductive effect of RGO,and simultaneously,RGO is thermally reduced and healed to high-quality graphene.Consequently,lamellar-structured graphene aerogels with superior through-plane thermal conduction capacity are fabricated for the first time,and its superior through-plane thermal conduction capacity results from its vertically aligned and closely stacked high-quality graphene lamellae.After vacuum-assisted impregnation with epoxy,the resultant epoxy composite with 2.30 vol% of graphene exhibits an outstanding through-plane thermal conductivity of as high as 20.0 W m^−1 K^−1,100 times of that of epoxy,with a record-high specific thermal conductivity enhancement of 4310%.Furthermore,the lamellar-structured graphene aerogel endows epoxy with a high fracture toughness,~1.71 times of that of epoxy.

关键词： Anisotropic aerogels Graphene Thermal conductivity epoxy composites Fracture toughness

Tribological response of an epoxy matrix filled with graphite and/or carbon nanotubes

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Friction 2017年第2期5卷 171-182页

作者： M.M.SAKKA Z.ANTAR K.ELLEUCH J.F.FELLER Laboratoire de Génie des Matériaux et Environnement ENIS Université de Sfax Sfax BP.1173-3038 Tunisia Smart Plastics Group European University of Brittany(UEB) LIMATB-UBS Lorient 56321 France

Reinforced polymer–matrix composites are widely used under sliding contact conditions in various boating and automotive applications. In this paper, the friction and wear of bulk epoxy and carbon filler reinforced epoxy composites have been investigated using a pin-on-disc tribometer. The effect of different fillers on the tribological behavior of an epoxy has been studied using treated and untreated carbon nanotubes, graphite, and a mixture of graphite and carbon nanotubes. Filler addition greatly enhances the tribological properties of the epoxy resin, by reducing the friction coefficient and the wear rate. In addition, it was found that the treated carbon nanotubes/epoxy composites have the best tribological behavior. Moreover, a correlation between contact temperature and friction coefficient is reported. Finally, the wear mechanisms were determined by scanning electronic microscopy.

关键词： epoxy composites carbon nanotubes wear friction temperature