Thermal conductivity of cross-linked polyethylene from molecular dynamics simulation

Xiong, Xue; Yang, Ming; Liu, Changlin; Li, Xiaobo; Tang, Dawei

doi:10.1063/1.4994797

Cited by 40 publications

(34 citation statements)

References 25 publications

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“…To test the AIREBO potential for thermal conductivity of PE, we calculate the thermal conductivity of bulk PE, which is found to be 0.34 W m À1 K À1 at room temperature. This result falls in the range of 0.22-0.37 W m À1 K À1 reported by the literature study [35][36][37] for the bulk PE. Furthermore, the nal structures for different LAPE samples with varying lengths have a similar density about 0.70 g cm À3 aer NPT relaxation (Table 1), which is in good agreement with the reported density 0.68-0.73 g cm À3 at ambient condition.…”

Section: Effective Thermal Conductivitysupporting

confidence: 71%

Effect of boundary chain folding on thermal conductivity of lamellar amorphous polyethylene

Ouyang

Zhang

et al. 2019

RSC Adv.

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Section: Effective Thermal Conductivitysupporting

confidence: 71%

Effect of boundary chain folding on thermal conductivity of lamellar amorphous polyethylene

Ouyang

Zhang

et al. 2019

RSC Adv.

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“…Crosslinks can form efficient heat conduction pathways and networks by connecting polymer chains with strong covalent bonds. It is natural to expect that the thermal conductivity would increase with the increasing number of crosslinks in the polymer network [62,63]. For example, Tonpheng et al [64] experimentally achieved a 50 % enhancement of the thermal conductivity for the PE polymer at a higher cross-linking densities.…”

Section: Crosslinkmentioning

confidence: 99%

Thermal conductivity of polymers and polymer nanocomposites

Huang

Qian

Yang

2018

Materials Science and Engineering: R: Reports

636

391

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Polymers are widely used in industry and in our daily life because of their diverse functionality, light weight, low cost and excellent chemical stability. However, on some applications such as heat exchangers and electronic packaging, the low thermal conductivity of polymers is one of the major technological barriers. Enhancing the thermal conductivity of polymers is important for these applications and has become a very active research topic over the past two decades. In this review article, we aim to: 1). systematically summarize the molecular level understanding on the thermal transport mechanisms in polymers in terms of polymer morphology, chain structure and inter-chain coupling; 2). highlight the rationales in the recent efforts in enhancing the thermal conductivity of nanostructured polymers and polymer nanocomposites. Finally, we outline the main advances, challenges and outlooks for highly thermal-conductive polymer and polymer nanocomposites. the inter-chain coupling. Fig. 1 Schematic diagrams of a polymer: (a) the morphology of a polymer consisting of crystalline and amorphous domains; (b) structure of a polymer chain.In addition to engineering the morphology of polymer chains, another common method to enhance the thermal conductivity of polymers is to blend polymers with highly thermal conductive fillers. The progress of nanotechnology over the last two decades not only provides more diverse high thermal conductivity fillers of different material types and topological shapes but also advances the understanding at the nanoscale. Fig. 2 shows a sketch of a polymer nanocomposite to illustrate the thermal transport mechanisms. In general, there are two types of polymer nanocomposites depending on whether nano-fillers form a network or not. When the filler concentration is low, no inter-filler networks could be formed, as shown in Fig. 2(a). The thermal conductivity is essentially determined by the filler-matrix coupling, i.e, interfacial thermal resistance, and the concentration and the geometric shapes of fillers. When the filler concentration is large enough, high conductivity fillers might form thermally conductive networks, as shown in Fig. 2(b). Although nanocomposites with filler network could possess a higher thermal conductivity than that without a network, their thermal conductivity could still be low due to the large inter-filler thermal contact resistance. Recently, three-dimensional fillers, such as carbon and graphene foams, have drawn a lot of attention. The fundamental thermal transport mechanisms and recent synthesis efforts in both types of nanocomposites are reviewed.This review article is organized as follows. In Section 2, we introduce the experimental progress on the enhancement of thermal conductivity by aligning polymer chains, and then review the methods to further tune the thermal conductivity by engineering chain structure and inter-chain coupling, as illustrated in Fig. 3(a). In Section 3, we discuss the thermal conductivity of polymer nanocomposites both with and without inter...

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“…While rigid formulation has been put forward for both obtaining local pressure [8,9] and handling many-body interactions [5,[10][11][12], approximations using atomic stress have also been applied with acceptable accuracy and a much greater ease of implementation [13][14][15], which is also the case for the widely used molecular dynamics package LAMMPS [16]. Owing to the similarity of pressure and heat flux formulation, the same atomic stress approximation has been applied to computing heat flux and thermal conductivity without any rigid validation for either molecular dynamics systems containing simple many-body interactions such as angle, torsion, or improper [17][18][19][20][21][22][23][24][25][26], or for more complex ones such as Stillinger-Weber, Tersoff, or AIREBO potentials .…”

mentioning

confidence: 99%

Application of atomic stress to compute heat flux via molecular dynamics for systems with many-body interactions

et al. 2019

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Although the computation of heat flux and thermal conductivity either via Fourier's law or the Green-Kubo relation has become a common task in molecular dynamics simulation, contributions of three-body and larger many-body interactions have always proved problematic to compute. In recent years, due to the success when applying to pressure tensor computation, atomic stress approximation has been widely used to calculate heat flux, where the LAMMPS molecular dynamics package is the most prominent propagator. We demonstrated that the atomic stress approximation, while adequate for obtaining pressure, produces erroneous results in the case of heat flux when applied to systems with many-body interactions, such as angle, torsion, or improper potentials. This also produces incorrect thermal conductivity values. To remedy this deficiency, by starting from a strict formulation of heat flux with many-body interactions, we reworked the atomic stress definition which resulted in only a simple modification. We modified the LAMMPS package accordingly to demonstrate that the new atomic stress approximation produces excellent results close to that of a rigid formulation.

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Thermal conductivity of cross-linked polyethylene from molecular dynamics simulation

Cited by 40 publications

References 25 publications

Effect of boundary chain folding on thermal conductivity of lamellar amorphous polyethylene

Effect of boundary chain folding on thermal conductivity of lamellar amorphous polyethylene

Thermal conductivity of polymers and polymer nanocomposites

Application of atomic stress to compute heat flux via molecular dynamics for systems with many-body interactions

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