石墨烯气凝胶/环氧树脂复合材料的制备及导电性能

以氧化石墨烯为前驱体,通过溶胶-凝胶法制备了石墨烯气凝胶（GA）,然后通过超声混合的方式将GA与环氧树脂（EP）复合,制备了GA/EP复合材料。利用扫描电镜、N₂吸附测试、X射线光电子能谱和X射线衍射对GA的结构进行了表征,并研究了添加不同质量分数的GA对GA/EP 复合材料的热性能和导电性能的影响。结果表明,GA具有丰富的孔结构,其骨架是由石墨烯无规则堆积在一起形成的三维网格结构。经过高温热还原处理后,GA的比表面积增加到731.84 m²·g^-1,组成其骨架的石墨烯的层间距缩小至0.347 nm,且绝大部分的含氧基团已经被除去。DMA和电导率测试结果表明,随着GA质量分数的增加,GA/EP复合材料的玻璃化转变温度呈现先升高后降低的变化趋势,而其电导率则呈现逐渐增加的趋势,逾渗阈值在0.05%~0.3%之间。     

石墨烯/环氧树脂复合材料的介电性能研究

通过Staudenmaier法制备了完全氧化的氧化石墨(GO),并通过高温热膨胀制备了单层石墨烯(graphene)。用FT-IR和TG对GO的氧化程度、含氧官能团进行了表征,用SEM和TEM对天然石墨(NG)、GO和graphene的微观结构进行了分析。利用超声共混法制备了graphene/环氧树脂介电纳米复合材料,介电性能的测试表明,graphene的加入使环氧树脂介电常数大幅提高,当graphene添加量为0.25%(质量分数)时,材料介电常数达到25,是纯环氧树脂的4倍,介电损耗0.11。这为石墨烯在介电储能方面的应用和低成本介电复合材料的制备提供了新思路。     

Mechanical properties of epoxy composites filled with silane-functionalized graphene oxide

In this work, the effects of as-produced GO and silane functionalized GO (silane-f-GO) loading and silane functionalization on the mechanical properties of epoxy composites are investigated and compared. Such silane functionalization containing epoxy ended-groups is found to effectively improve the compatibility between the silane-f-GO and the epoxy matrix. Increased storage modulus, glass transition temperature, thermal stability, tensile and flexural properties and fracture toughness of epoxy composites filled with the silane-f-GO sheets are observed compared with those of the neat epoxy and GO/epoxy composites. These findings confirm the improved dispersion and interfacial interaction in the composites arising from covalent bonds between the silane-f-GO and the epoxy matrix. Moreover, several possible fracture mechanisms, i.e. crack pinning/deflection, crack bridging, and matrix plastic deformation initiated by the debonding/delamination of GO sheets, were identified and evaluated.     

Carbon black/graphite nanoplatelet/rubbery epoxy hybrid composites for thermal interface applications

Hybrid composites were developed by dispersing carbon black (CB) nanoparticles and graphite nanoplatelets (GNPs) at 4–6 and 12–14 wt%, respectively, into rubbery epoxy resin. SEM analysis showed that CB particles improved the dispersion of GNPs in the hybrid composite. The thermal conductivity of 4 wt% CB/14 wt% GNP-15/rubbery epoxy hybrid composite, 0.81 W/m K, is ca. four times higher than that of rubbery epoxy. When silane-functionalised, the fillers reduced the viscosity of the hybrid dispersion and made the hybrid composite highly electrically insulating. Nevertheless, filler functionalisation decreased the composite’s thermal conductivity by only 16.6%. Compression testing showed that the hybrid fillers increased the compressive modulus and strength of rubbery epoxy by nearly two and three times, respectively. Overall, the hybrid composites with their thermal paste-type morphology, low viscosity, high compliance, improved thermal conductivity and, when fillers are functionalised, low electrical conductivity makes them promising materials as thermal interface adhesives.     

改性凹凸棒土-氧化石墨烯/环氧树脂复合材料的力学性能和热电性能

分别用硅烷偶联剂KH560改性凹凸棒土(Attapulgite，ATP)和氧化石墨烯(Graphene oxide，GO)，并将其复合制备ATP-GO复合物。以环氧树脂(Epoxy，EP)为基体，采用原位聚合法制备ATP-GO/EP复合材料。采用SEM和FTIR对ATP-GO复合物的形貌和化学结构进行表征。结果表明:ATP与GO成功键合并附着在GO表面；ATP-GO的加入，提高了EP的冲击强度、弯曲强度和热稳定性，降低了其介电常数和介电损耗。3wt%ATP-0.5wt%GO/EP复合材料的弯曲强度和冲击强度分别为138.58 MPa和20.80 kJ/m2，比纯EP分别提高了75.5%和351.6%，而其介电常数和介电损耗分别低至3.36和0.0118，比纯EP降低了7.7%和27.3%。      

氧化石墨烯纳米片/环氧树脂复合材料的制备与性能

氧化石墨烯(GO)是石墨烯重要的衍生物之一,通过氧化和超声波分散制备了GO纳米片/环氧树脂复合材料。采用XRD、拉曼光谱、FTIR和TEM表征了GO纳米片的结构与形貌,研究了GO纳米片用量对GO纳米片/环氧树脂复合材料热稳定性、力学性能及介电性能的影响。结果表明:GO纳米片的加入提高了GO纳米片/环氧树脂复合材料失热稳定性;随着GO纳米片填充量的增加,GO纳米片/环氧树脂复合材料的冲击强度和抗弯性能先提高后降低,其介电常数和介电损耗则先减小后增加。GO纳米片填充量为0.3wt%的GO纳米片/环氧树脂复合材料的失重5%时的热分解温度由纯环氧树脂的400.2℃提高到424.5℃,而冲击强度和弯曲强度分别在GO纳米片填充量为0.2wt%和0.3wt%时达到最大,冲击强度由纯环氧树脂的10.5kJ/m2提高到19.7kJ/m2,弯曲强度由80.5 MPa提高到104.0 MPa。     

石墨烯纳米片/环氧树脂复合材料的制备与介电性能研究

以天然鳞片石墨为原料,通过Hummers法制备氧化石墨,微波热解剥离制备出少层数的石墨烯纳米片。以硅烷偶联剂KH-560为改性剂,超声共混制备石墨烯纳米片/环氧树脂复合材料。采用FT-IR和SEM分析样品的微观结构和形貌,测试其介电性能。结果表明,随着石墨烯纳米片添加量的增加,复合材料介电常数呈现先增大后减小的趋势,当石墨烯纳米片含量为0.3%(质量分数)时,介电常数达到最大;石墨烯纳米片对复合材料介电损耗的影响与之相反;偶联改性使复合材料的介电常数增大,介电损耗减小。     

BN纤维对石墨烯微片/聚丙烯复合材料导热绝缘性能的影响

采用熔融共混法制备BN纤维-石墨烯微片/聚丙烯（BN纤维-GNP/PP）高导热绝缘复合材料,结合有限元模拟、SEM、XRD、导热导电测试结果,探究了BN纤维含量和长度对BN纤维-GNP/PP复合材料导热绝缘性能的影响。结果表明:BN纤维-GNP/PP复合材料中BN纤维含量和长度的增加可增大GNP分布范围,增大BN纤维与GNP的接触概率;在GNP含量为7wt%、100 μm BN纤维含量为20wt%时BN纤维-GNP/PP复合材料的热导率较PP提高了4.2倍,同时电绝缘性略有提高。模拟结果表明,高含量100 μm BN纤维的加入使BN纤维-GNP/PP复合材料导热网络的构建趋于完整,局部热通量较低的区域减少。片状GNP与纤维状BN二相填料的"协同效应",使GNP和BN纤维分别作为"岛"和"桥"形成了一种特殊的"双网络"结构,BN纤维作为高导热"桥"阻隔了相邻GNP间导电通路的形成,从而提高了BN纤维-GNP/PP复合材料的导热绝缘性能。      

Effect of processing technique on the transport and mechanical properties of graphite nanoplatelet/rubbery epoxy composites for thermal interface applications

Graphite nanoplatelet (GNP)/rubbery epoxy composites were fabricated by mechanical mixer (MM) and dual asymmetric centrifuge speed mixer (SM). The properties of the GNP/rubbery epoxy were compared with GNP/glassy epoxy composites. The thermal conductivity of GNP/rubbery epoxy composite (25 wt.% GNP, particle size 15 μm) reached 2.35 W m⁻¹ K⁻¹ compared to 0.1795 W m⁻¹ K⁻¹ for rubbery epoxy. Compared with GNP/rubbery epoxy composite, at 20 wt.%, GNP/glassy epoxy composite has a slightly lower thermal conductivity but an electrical conductivity that is 3 orders of magnitude higher. The viscosity of rubbery epoxy is 4 times lower than that of glassy epoxy and thus allows higher loading. The thermal and electrical conductivities of composites produced by MM are slightly higher than those produced by SM due to greater shearing of GNPs in MM, which results in better dispersed GNPs. Compression and hardness testing showed that GNPs increase the compressive strength of rubbery epoxy ∼2 times without significantly affecting the compressive strain and hardness. The GNP/glassy epoxy composites are 40 times stiffer than the GNP/rubbery epoxy composites. GNP/rubbery epoxy composites with their high thermal conductivity, low electrical conductivity, low viscosity before curing and high conformability are promising thermal interface materials.     

Electromagnetic interference shielding properties of nitrogen-doped graphene/epoxy composites

Journal of Materials Science: Materials in Electronics - Nitrogen-doped graphene (N-GP) containing 8.5 at% N and 0.5–5 μm wide was synthesized using chemical vapor deposition...     

Mechanical properties of carbon fiber/fullerene-dispersed epoxy composites

This study examined the effect of fullerene dispersion on the mechanical properties of carbon-fiber reinforced epoxy matrix composites (CFRPs). Mechanical properties such as tension, compression, open-hole compression, comparession after impact (CAI), binding, short beam shear, and interlaminar fracture toughness were evaluated for [0]₈, [90]₁₆, [45/0/?45/90]_2S laminates. Tension and compression strengths increased 2–12% by dispersing 0.5% of fullerene into the matrix resin. Furthermore, interlaminar fracture toughness of the composite was improved by about 60%. It was revealed that a small amount of fullerene (0.1–1 wt.%) increased the failure strain of epoxy resin itself, thereby improving the CFRP strength.     

Mechanical properties of multi-walled carbon nanotube/epoxy composites

Untreated and acid-treated multi-walled carbon nanotubes (MWNT) were used to fabricate MWNT/epoxy composite samples by sonication technique. The effect of MWNT addition and their surface modification on the mechanical properties were investigated. Modified Halpin–Tasi equation was used to evaluate the Young’s modulus and tensile strength of the MWNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. There was a good correlation between the experimentally obtained Young’s modulus and tensile strength values and the modified Halpin–Tsai theory. The fracture surfaces of MWNT/epoxy composite samples were analyzed by scanning electron microscope.     

三维网状石墨烯/环氧树脂热界面复合材料的制备和热性能

三维网状石墨烯/环氧树脂热界面复合材料由于具有良好的热导性能和力学性能,而被广泛应用于微电子器件领域。但是通过化学剥离-还原法制备石墨烯,在填加石墨烯质量分数相同的条件下,石墨烯/环氧树脂热界面复合材料的热导率差别仍然很大。研究发现这主要是由于石墨烯表面官能团含量不同所导致的,因此很难建立统一的标准评估石墨烯作为导热填料的作用效果。为了避免表面官能团对石墨烯/环氧树脂复合物热导率的影响,本研究小组采用化学气相沉积法制备的三维网状石墨烯作为导热填料,对环氧树脂进行修饰,制备了一系列石墨烯/环氧树脂材料。通过研究三维网状石墨烯含量对石墨烯/环氧树脂材料热导率、力学性能及热导率在高温条件下稳定性的影响,有助于完善石墨烯修饰的环氧树脂热界面复合材料的研究,并建立石墨烯作为导热填料的评价体系。     

氧化石墨烯/密胺树脂复合材料的制备及其热性能研究

首先采用Hummers法制备出氧化石墨烯(GO),然后与三聚氰胺、甲醛进行原位聚合,制备出GO/密胺树脂(MF)复合材料,并用傅里叶红外光谱仪(FT-IR)、原子力显微镜(AFM)、扫描电镜(SEM)分析和观察了氧化石墨烯及复合材料的分子结构及形貌,通过导热系数测试仪、热重分析仪(TG)对复合材料的热性能进行了表征。研究发现,随着氧化石墨烯(GO)添加量的增加,复合材料导热系数增加先快后慢,当GO添加量为0.84%时,复合材料导热系数提高32.0%,GO的添加提高复合材料低温下的热稳定性。     

高温热还原石墨烯气凝胶/环氧树脂电磁屏蔽复合材料

以氧化石墨烯(GO)水分散液为原料采用简单的一步水热还原法制备了石墨烯水凝胶,通过定向冷冻和常规冷冻两种冷冻方法,冷冻干燥后制得了两种不同结构的石墨烯气凝胶,在不同温度下进行热退火处理,采用真空辅助浸渍回填法制备了不同结构热退火石墨烯气凝胶/环氧树脂复合材料.研究结果表明,在石墨烯含量仅为0.16％(质量分数)下,16...     

纳米HA/PU复合材料的力学性能和热性能

以4 , 4′-亚甲基二环己基二异氰酸酯( H₁₂MDI) 、聚乙二醇、蓖麻油、1 , 4-丁二醇和具有生物活性的纳米羟基磷灰石(n-HA) 为原料, 采用预聚法制备了纳米羟基磷灰石/ 聚氨酯( HA/PU) 复合材料, 并对其力学性能和热性能进行了研究。结果表明: 复合材料的拉伸强度和断裂伸长率随n-HA 含量的增加而提高。当n-HA 的质量百分数为30 %时, 复合材料的综合力学性能达到最佳, 与纯PU 相比, 拉伸强度和断裂伸长率分别提高了186 %和107 %。动态力学分析得出复合材料的储能模量随n-HA 质量百分含量的增加而显著上升。TGA 试验表明HA/PU 纳米复合材料的热稳定性能随n2 HA 的添加得到改善, 而DSC 分析显示n-HA 的加入在一定程度上降低了PU 软段的结晶度。这些结果均表明该n-HA/PU 是一种有应用前景的组织工程材料。      

氧化石墨烯改性不同表面性质的碳纤维/环氧树脂复合材料的微观形貌与动态热力学性能

通过模压成型，采用氧化石墨烯(GO)对四种碳纤维(CCF300、T700、CCF800、CCM40J)织物/环氧树脂(CF/EP)复合材料进行改性，通过复合材料的微观形貌、动态热力学性能等研究了GO对四种不同表面性质的CF/EP复合材料的改性效果。研究表明，添加GO后，GO/EP对四种CF的浸润性均比EP明显提高，纤维与GO/EP间的界面黏接比与EP基体间的黏接明显改善；CF/EP复合材料的破坏主要发生在CF与EP的界面，而GO的存在使GO-CF/EP复合材料的破坏由CF与EP基体的界面向GO/EP区域过渡。CF表面的氧碳比和沟槽均显著影响复合材料的玻璃化转变温度(T_g)，具有最高表面氧碳比的GO-CCF300/EP复合材料表现出最高的T_g，但沟槽更丰富的CCM40J和CCF300碳纤维对CF/EP复合材料的T_g表现出更好的GO改性效果。      

Mechanical and morphological properties of fly ash/epoxy composites using conventional thermal and microwave curing methods

Conventional thermal and microwave curing methods were utilized to cure fly ash/epoxy composites, and the mechanical and morphological properties of the composites were evaluated. The conventional thermal curing was performed at 70 °C for 80 min while microwave curing was carried out at 240 W for 18 min in order to achieve the optimum cure of the composites, determined using Differential Scanning Calorimeter. The results suggested that the tensile and flexural moduli of the composites increased with increasing fly ash content while the effect became opposite for tensile, flexural and impact strengths, and tensile strain at break. Improved mechanical properties of the composite could be obtained by addition of N-2(aminoethyl)-3-aminopropyltrimethoxysilane coupling agent, the contents of 0.5 wt% being recommended for the optimum mechanical properties. Beyond these recommended contents, the mechanical properties greatly reduced, except for the flexural modulus. The comparative results indicated that the composites by the microwave cure consumed shorter cure time and had higher ultimate strengths (especially impact strength), and strain at break than those by the conventional thermal cure. The composites with higher tensile and flexural moduli could be obtained by the conventional thermal cure.     

Mechanical properties and toughness of carbon aerogel/epoxy polymer composites

Journal of Materials Science - Because of their nanoporous structure and large surface area, carbon aerogels have high potential for improving the material properties of polymer-based composites....     

Magnetic-aligned,magnetite-filled epoxy composites with enhanced thermal conductivity

This paper investigates the influence of magnetic field-assisted filler alignment technology on the morphology and the thermal conductivity of magnetite-filled epoxy composites. A magnetic field was applied during the solidification of the composite in order to change the position of the filler and its distribution in the polymer matrix. It is shown that the applied procedure leads to the filler being oriented along the direction of the magnetic field, and as a result, the thermal conductivity is improved by up to 120 % compared to a composite with randomly oriented filler obtained without the assistance of a magnetic field. This positive effect is caused by the appearance of conductive paths at a much lower content of the filler when the composite solidification is assisted by a magnetic field, relative to an equivalent isotropic sample. These morphological changes were confirmed by microscopic and X-ray microtomography imaging. The temperature dependences of thermal conductivity were also investigated over a broad temperature range for a magnetite-filled epoxy composite sample and compared to the bulk magnetite reference, showing that thermal behaviour of the magnetite-filled composite is stable, which is a promising result when considering the future application of the technology.