Latent heat and thermal conductivity enhancements in polyethylene glycol/polyethylene glycol-grafted graphene oxide composites

Tu, Junyang; Li, Hairong; Zhang, Jingjing; Hu, Die; Cai, Ziqing; Yin, Xianze; Dong, Lijie; Huang, Leping; Xiong, Chuanxi; Jiang, Ming

doi:10.1007/s42114-019-00083-x

Cited by 65 publications

(26 citation statements)

References 31 publications

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“…The result is mainly attributed to the interfacial thermal resistance between fillers and fillers in polymer composite system, which limits the transportation of heat flow during healing process. The maximum value of thermal conductivity in the composites with hybrid nanoparticles is up to 1.65 Wm −1 K −1 which is about six times than pure polymer matrix; meanwhile, it can be found that the thermal conductivity of the CNT‐DAPU composites is only improved two times in comparison with pure polymer matrix, and its thermal conductivity values are less than that of the former, which is mainly attributed to the interfacial contact probability in increase between CNTs due to the existence of nano Ag on the surface of CNTs as well as the sufficient dispersion, resulting in an increase of the phonon mean free path for the films 62‐65 . To further verify the fact that the existence of Ag is helpful to improve thermal conductivity in the composites, the thermal conductivity data of all films is fitted, as shown in Figure 9A,B, based on effective medium theory (EMT) model proposed by Foygel et al, 66 the fitted Equation (1) as follows 67 :

K - K_{m} = k_{0} {[\frac{v - v_{c}}{1 - v_{c}}]}^{α}

where V c is the critical volume fraction at the thermal percolation threshold, k 0 is a pre‐exponential factor contributed by the thermal conductivity of the filler alone, and α is a conductivity exponent that is dependent on the aspect ratio ( δ ) of CNTs.…”

Section: Resultsmentioning

confidence: 94%

Promoting healing progress in polymer composites based on Diels‐Alder reaction by constructing silver bridges

Ding

Zhang

Zhou

et al. 2020

Polymers for Advanced Techs

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Polymer composites with self‐healing ability are highly desired for applications in advanced modern devices. Here, we report on self‐healing polymer composites consisting of silver deposited‐carbon nanotubes hybrid nanoparticles (CNT‐Ag) as fillers and self‐healable polyurethane (DAPU) as a matrix based on thermally reversible Diels‐Alder reaction. The results indicated that as the hybrid filler loading is 1 wt%, the composites not only obtained a high‐strength (~15.97 MPa) and high healing efficiency (~90.1%) by increasing filler loading after healing, but also enhance thermal conductivity (~1.65 Wm−1 K−1) and obviously shorten its healing progress in comparison with other composites in the case of the same healing time. Given that Ag_NPs deposited on the surfaces of the CNTs act as bridges to link the adjacent CNTs and reduce interfacial thermal resistance, which can effectively explain the reasons for the obtained high mechanical strength and healing efficiency and promoting healing progress in the polymer composites. This work may offer a novel strategy for balancing relation between mechanical property, healing ability and healing progress in the field of self‐healing materials application.

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K - K_{m} = k_{0} {[\frac{v - v_{c}}{1 - v_{c}}]}^{α}

Section: Resultsmentioning

confidence: 94%

Promoting healing progress in polymer composites based on Diels‐Alder reaction by constructing silver bridges

Ding

Zhang

Zhou

et al. 2020

Polymers for Advanced Techs

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“…As seen from these data, especially the LHC values of the composites including CNTs- g -FA (grafting ratio: 1:3) were 6.5–8.9% higher than that of the composites including CNTs due to the LHC contribution of the CNTs-g-FA additive. On the other hand, when compared the LHC of the FA/CNTs- g -FA composite PCMs with those of different kinds of organic PCMs doped with carbon based fillers 14 – 20 , 22 , 26 , 29 , 36 , it was observed that the FA/CNTs-g-FA composite PCMs prepared in this work had relatively higher LHC than most of them. This boosted in the LHC value of the FA/CNTs-FA composite PCMs was due to the fact that the CNTs- g -FA used as doping agents had LHC of in the range of 25–93 J g −1 .…”

Section: Resultsmentioning

confidence: 72%

“…On the other hand, the improvement (%) of TC values of CA/CNTs (5 wt%), PA/CNTs (5 wt%) and SA/CNTs (5 wt%) composite PCMs was calculated as 37.5, 70.6 and 68.4% compared to that of pure CA, PA and SA, respectively. In comparison to pure FAs or FA/CNTs composites, a higher degree of TC enhancement was observed from the FA/CNTs- g -FA composite PCMs, which was attributed to their increased interfacial compatibility/or interfacial contact area between the grafted CNTs and FA 23 , 29 . Relatively better miscibility and affinity between the covalent functionalized CNTs and FAs allowed improving interfacial thermal transport and thus remarkably enriching their TC values 22 , 26 , 30 , 31 .…”

Section: Resultsmentioning

confidence: 95%

Thermal energy storage and thermal conductivity properties of fatty acid/fatty acid-grafted-CNTs and fatty acid/CNTs as novel composite phase change materials

Al‐Ahmed

Sarı

Mazumder

et al. 2020

Sci Rep

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In recent year, fatty acids (FAs) are heavily studied for heat storage applications and they have shown promising advantages over other organic phase change materials (PCMs). Among the FAs; capric, palmitic and stearic acids are the most studied PCMs. Several researchers have investigated these FAs and tried to improve their thermal properties, mainly by adding different high conducting fillers, such as graphite, metal foams, CNTs, graphene etc. In most cases, these fillers improved the thermal conductivity and heat transfer property but reduce the heat storage capacity considerably. These composites also lose the mixing uniformity during the charging and discharging process. To overcome these issues, selected FAs were grafted on the functionalized CNT surfaces and used as conductive fillers to prepare FA based composite PCMs. This process significantly contributed to prevent the drastic reduction of the overall heat storage capacity and also showed better dispersion in both solid and liquid state. Thermal cycling test showed the variations in the thermal energy storage values of all composite PCMs, however, within the tolerable grade and they had appreciable phase change stability and good chemical stability even after 2,000 cycles.

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“…Nanomaterial-based thin films are widely studied in several engineering fields owing to their excellent material properties and diverse potential applications [1][2][3][4][5][6][7]. Several fabrication methods have been used to develop such nanomaterials-based thin films, including solvent casting, painting, spray processing, printing, spin coating, the floating technique, pulsed laser deposition technique, and the layer-by-layer (LbL) method [8][9][10][11][12][13][14][15][16][17]. Among these thin films, graphene oxide (GO)-based thin films, which are synthesized via the LbL method, are noteworthy as they can be used to fabricate multifunctional engineering products [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of graphene oxide–silk fibroin bionanofilms via nanoindentation experiments and finite element analysis

Cho

Hwang

et al. 2021

Friction

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Understanding the mechanical properties of bionanofilms is important in terms of identifying their durability. The primary focus of this study is to examine the effect of water vapor annealed silk fibroin on the indentation modulus and hardness of graphene oxide–silk fibroin (GO–SF) bionanofilms through nanoindentation experiments and finite element analysis (FEA). The GO–SF bionanofilms were fabricated using the layer-by-layer technique. The water vapor annealing process was employed to enhance the interfacial properties between the GO and SF layers, and the mechanical properties of the GO–SF bionanofilms were found to be affected by this process. By employing water vapor annealing, the indentation modulus and hardness of the GO–SF bionanofilms can be improved. Furthermore, the FEA models of the GO–SF bionanofilms were developed to simulate the details of the mechanical behaviors of the GO–SF bionanofilms. The difference in the stress and strain distribution inside the GO–SF bionanofilms before and after annealing was analyzed. In addition, the load-displacement curves that were obtained by the developed FEA model conformed well with the results from the nanoindentation tests. In summary, this study presents the mechanism of improving the indentation modulus and hardness of the GO–SF bionanofilms through the water vapor annealing process, which is established with the FEA simulation models.

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Latent heat and thermal conductivity enhancements in polyethylene glycol/polyethylene glycol-grafted graphene oxide composites

Cited by 65 publications

References 31 publications

Promoting healing progress in polymer composites based on Diels‐Alder reaction by constructing silver bridges

Promoting healing progress in polymer composites based on Diels‐Alder reaction by constructing silver bridges

Thermal energy storage and thermal conductivity properties of fatty acid/fatty acid-grafted-CNTs and fatty acid/CNTs as novel composite phase change materials

Mechanical properties of graphene oxide–silk fibroin bionanofilms via nanoindentation experiments and finite element analysis

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