Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene
Using a realistic united-atom force field, molecular dynamics simulations were performed to study homogeneous nucleation of the crystal phase at about 30% supercooling from the melts of n-pentacontahectane (C150) and a linear polyethylene (C1000), both of which are long enough to exhibit the chain f...
| Main Authors: | , , |
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| Format: | Article |
| Language: | en_US |
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American Chemical Society (ACS)
2014
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| Online Access: | http://hdl.handle.net/1721.1/92420 https://orcid.org/0000-0001-8137-1732 |
| _version_ | 1811090775212032000 |
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| author | Yi, Peng Locker, C. Rebecca Rutledge, Gregory C. |
| author2 | Massachusetts Institute of Technology. Department of Chemical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Chemical Engineering Yi, Peng Locker, C. Rebecca Rutledge, Gregory C. |
| author_sort | Yi, Peng |
| collection | MIT |
| description | Using a realistic united-atom force field, molecular dynamics simulations were performed to study homogeneous nucleation of the crystal phase at about 30% supercooling from the melts of n-pentacontahectane (C150) and a linear polyethylene (C1000), both of which are long enough to exhibit the chain folding that is characteristic of polymer crystallization. The nucleation rate was calculated and the critical nuclei were identified using a mean first-passage time analysis. The nucleation rate was found to be insensitive to the chain length in this range of molecular weight. The critical nucleus contains about 150 carbons on average and is significantly smaller than the radius of gyration of the chains, at this supercooling. A cylinder model was used to characterize the shape of the crystal nuclei and to calculate the interfacial free energies. A chain segment analysis was performed to characterize the topology of the crystal surface in terms of loops (including folds) and tails. The length distribution of loops is broad, supporting the “switchboard model” for the early stage crystals formed at deep supercooling. Using the survival probability method, the critical nucleus size was determined as a function of temperature. The interfacial free energies were found to be temperature-dependent. The free energy barrier and nucleation rate as functions of temperature were also calculated and compare favorably with experiments. |
| first_indexed | 2024-09-23T14:51:45Z |
| format | Article |
| id | mit-1721.1/92420 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:51:45Z |
| publishDate | 2014 |
| publisher | American Chemical Society (ACS) |
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| spelling | mit-1721.1/924202022-09-29T11:02:23Z Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene Yi, Peng Locker, C. Rebecca Rutledge, Gregory C. Massachusetts Institute of Technology. Department of Chemical Engineering Massachusetts Institute of Technology. Department of Physics Rutledge, Gregory C. Yi, Peng Rutledge, Gregory C. Using a realistic united-atom force field, molecular dynamics simulations were performed to study homogeneous nucleation of the crystal phase at about 30% supercooling from the melts of n-pentacontahectane (C150) and a linear polyethylene (C1000), both of which are long enough to exhibit the chain folding that is characteristic of polymer crystallization. The nucleation rate was calculated and the critical nuclei were identified using a mean first-passage time analysis. The nucleation rate was found to be insensitive to the chain length in this range of molecular weight. The critical nucleus contains about 150 carbons on average and is significantly smaller than the radius of gyration of the chains, at this supercooling. A cylinder model was used to characterize the shape of the crystal nuclei and to calculate the interfacial free energies. A chain segment analysis was performed to characterize the topology of the crystal surface in terms of loops (including folds) and tails. The length distribution of loops is broad, supporting the “switchboard model” for the early stage crystals formed at deep supercooling. Using the survival probability method, the critical nucleus size was determined as a function of temperature. The interfacial free energies were found to be temperature-dependent. The free energy barrier and nucleation rate as functions of temperature were also calculated and compare favorably with experiments. Exxon Mobil Corporation 2014-12-19T20:36:15Z 2014-12-19T20:36:15Z 2013-05 2013-05 Article http://purl.org/eprint/type/JournalArticle 0024-9297 1520-5835 http://hdl.handle.net/1721.1/92420 Yi, Peng, C. Rebecca Locker, and Gregory C. Rutledge. “Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene.” Macromolecules 46, no. 11 (June 11, 2013): 4723–4733. https://orcid.org/0000-0001-8137-1732 en_US http://dx.doi.org/10.1021/ma4004659 Macromolecules Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) Prof. Rutledge via Erja Kajosalo |
| spellingShingle | Yi, Peng Locker, C. Rebecca Rutledge, Gregory C. Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene |
| title | Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene |
| title_full | Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene |
| title_fullStr | Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene |
| title_full_unstemmed | Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene |
| title_short | Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene |
| title_sort | molecular dynamics simulation of homogeneous crystal nucleation in polyethylene |
| url | http://hdl.handle.net/1721.1/92420 https://orcid.org/0000-0001-8137-1732 |
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