Molecular dynamics simulation of H2 in amorphous polyethylene system: H2 diffusion in various PE matrices and bubbling during rapid depressurization

Zhao, Jiawei; Wang, Xingguo; Yang, Qingquan; Yin, Hua; Zhao, Bo; Zhang, Shijun; Wu, Changjiang

doi:10.1016/j.ijhydene.2022.09.124

Cited by 5 publications

(5 citation statements)

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“…The visualization of the simulation results discussed above highlights the possibility of long hops, which we found to occur in correspondence with the areas of aligned PE chains. Of note, Zhao recently noted that the orientation of branched polyethylene–graphene systems may contribute to the overall directional trajectory of small diatomic molecules such as hydrogen …”

Section: Resultsmentioning

confidence: 99%

“…Of note, Zhao recently noted that the orientation of branched polyethylene–graphene systems may contribute to the overall directional trajectory of small diatomic molecules such as hydrogen. 28 …”

Section: Resultsmentioning

confidence: 99%

“…Of note, Zhao recently noted that the orientation of branched polyethylene−graphene systems may contribute to the overall directional trajectory of small diatomic molecules such as hydrogen. 28 To answer this fundamental question, model PE ordered domains were created in our system by rapid cooling a PE melt. 82 The initial 100 chain C 50 H 102 system was cooled from 600 to 200 K over 500 ps, before heating it to 350 K for 30 ns, and then cooling it slowly to the desired temperatures over a further 10 ns of simulations.…”

Section: Relation Between Polymer Structure and Guest Gas Diffusionmentioning

confidence: 99%

“…In addition, a hopping mechanism was observed . Zhao et al found that linear PE was best for containment, as branched and LDPE allowed for an increased likelihood of H 2 diffusion through the polymer matrix …”

Section: Introductionmentioning

confidence: 99%

“…27 Zhao et al found that linear PE was best for containment, as branched and LDPE allowed for an increased likelihood of H 2 diffusion through the polymer matrix. 28 This work aims to complement the existing literature and expand our collective mechanistic understanding of the diffusion of H 2 through PE. A suitable PE model was first developed ensuring that thermodynamic and structural properties are comparable to experimental ones.…”

Section: Introductionmentioning

confidence: 99%

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Hop, Skip, and Jump: Hydrogen Molecular Transport through Amorphous Polyethylene Matrices Studied via Molecular Dynamics Simulations

Divine-Ayela,

Perez,

Striolo

2023

Ind. Eng. Chem. Res.

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In the pursuit of advancing and diversifying energy technologies for a more sustainable future, the possibilities of hydrogen (H 2 ) usage will broaden, as will our understanding of its containment materials. Polyethylene (PE) has a vast assortment of uses and applications, which are growing with demands for alternative energy possibilities. One use of PE liner is as a prime candidate for nonmetallic piping and pressurized type IV storage devices. Such applications require PE to effectively prevent H 2 transport through containment systems. To study the molecular transport mechanism of hydrogen through polymeric barriers, a system containing hydrogen molecules absorbed within amorphous PE is modeled here using molecular dynamics simulations. The simulations are conducted within a range of temperatures that span the glass transition temperature of amorphous PE. The simulated PE displays bulk density, radius of gyration, and self-diffusion coefficient that are consistent with experimental data. The simulated trajectories are interrogated to study the movement of the guest gas molecules. The results show that the diffusion coefficients increase with temperature, as expected. However, the mobility of the PE chains is found to affect the mobility of absorbed H 2 molecules to a much lower extent than it affects that of CH 4 molecules because of the much smaller size of the former than of the latter guest. From a molecular perspective, a "hopping" mechanism is observed, according to which H 2 molecules hop between one vacant free volume space to another within the polymer matrix, in combination with longer, straight, undisturbed "jumps" or "skips" along directions aligned with regions of ordered PE chains. This suggests that the orientation of the crystallites within the semicrystalline PE matrix affects the H 2 containment. Implications of these findings toward PE usage as containment material are discussed.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%