Local Chain Dynamics and Dynamic Heterogeneity in Cross-Linked Epoxy in the Vicinity of Glass Transition.
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| Title: | Local Chain Dynamics and Dynamic Heterogeneity in Cross-Linked Epoxy in the Vicinity of Glass Transition. |
|---|---|
| Authors: | Po-Han Lin1, Rajesh Khare1 |
| Source: | Macromolecules. Aug2010, Vol. 43 Issue 15, p6505-6510. 6p. |
| Subjects: | Molecular dynamics, Crosslinked polymers, Epoxy compounds, Glass transition temperature, Simulation methods & models, Autocorrelation (Statistics) |
| Abstract: | We studied the local chain dynamics as well as the dynamic heterogeneity in highly cross-linked epoxy near glass transition by molecular dynamics simulation. In previous work (Lin and Khare in Macromolecules2009, 42, 4319), we had reported creation of fully relaxed atomistic structures of cross-linked epoxy; the glass transition temperature of these structures was also determined from volume−temperature behavior. The local chain dynamics in these structures is characterized by using molecular dynamics simulation in this work. Local translational mobility of cross-linked epoxy as measured by mean-squared displacement of atoms exhibited two subdiffusive regimes within the simulation time of 200 ns. Local orientational mobility was determined by monitoring the autocorrelation function (ACF) of a vector associated with the epoxy monomer. Time dependence of an order parameter based on this ACF showed that there was almost no orientational relaxation when the temperature was near or below glass transition temperature and the system cannot completely relax orientationally even at temperatures that are 120 K higher than the glass transition temperature. Furthermore, a time scale for the identification of glass transition in simulations was determined using the kinetic interpretation of glass transition. Dynamic heterogeneity was studied by identifying the mobile and immobile atoms in the system. Simulation results confirmed the existence of dynamic heterogeneity in the cross-linked system with the fraction of the immobile domains in the structures showing a rapid increase as the temperature dropped below the glass transition temperature. Results are also presented for the probability of percolation of the system by the immobile domains in the vicinity of glass transition. [ABSTRACT FROM AUTHOR] |
| Copyright of Macromolecules is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 52878392 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Local Chain Dynamics and Dynamic Heterogeneity in Cross-Linked Epoxy in the Vicinity of Glass Transition. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Po-Han+Lin%22">Po-Han Lin</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Rajesh+Khare%22">Rajesh Khare</searchLink><relatesTo>1</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Macromolecules%22">Macromolecules</searchLink>. Aug2010, Vol. 43 Issue 15, p6505-6510. 6p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Molecular+dynamics%22">Molecular dynamics</searchLink><br /><searchLink fieldCode="DE" term="%22Crosslinked+polymers%22">Crosslinked polymers</searchLink><br /><searchLink fieldCode="DE" term="%22Epoxy+compounds%22">Epoxy compounds</searchLink><br /><searchLink fieldCode="DE" term="%22Glass+transition+temperature%22">Glass transition temperature</searchLink><br /><searchLink fieldCode="DE" term="%22Simulation+methods+%26+models%22">Simulation methods & models</searchLink><br /><searchLink fieldCode="DE" term="%22Autocorrelation+%28Statistics%29%22">Autocorrelation (Statistics)</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: We studied the local chain dynamics as well as the dynamic heterogeneity in highly cross-linked epoxy near glass transition by molecular dynamics simulation. In previous work (Lin and Khare in Macromolecules2009, 42, 4319), we had reported creation of fully relaxed atomistic structures of cross-linked epoxy; the glass transition temperature of these structures was also determined from volume−temperature behavior. The local chain dynamics in these structures is characterized by using molecular dynamics simulation in this work. Local translational mobility of cross-linked epoxy as measured by mean-squared displacement of atoms exhibited two subdiffusive regimes within the simulation time of 200 ns. Local orientational mobility was determined by monitoring the autocorrelation function (ACF) of a vector associated with the epoxy monomer. Time dependence of an order parameter based on this ACF showed that there was almost no orientational relaxation when the temperature was near or below glass transition temperature and the system cannot completely relax orientationally even at temperatures that are 120 K higher than the glass transition temperature. Furthermore, a time scale for the identification of glass transition in simulations was determined using the kinetic interpretation of glass transition. Dynamic heterogeneity was studied by identifying the mobile and immobile atoms in the system. Simulation results confirmed the existence of dynamic heterogeneity in the cross-linked system with the fraction of the immobile domains in the structures showing a rapid increase as the temperature dropped below the glass transition temperature. Results are also presented for the probability of percolation of the system by the immobile domains in the vicinity of glass transition. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Macromolecules is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1021/ma100752c Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 6 StartPage: 6505 Subjects: – SubjectFull: Molecular dynamics Type: general – SubjectFull: Crosslinked polymers Type: general – SubjectFull: Epoxy compounds Type: general – SubjectFull: Glass transition temperature Type: general – SubjectFull: Simulation methods & models Type: general – SubjectFull: Autocorrelation (Statistics) Type: general Titles: – TitleFull: Local Chain Dynamics and Dynamic Heterogeneity in Cross-Linked Epoxy in the Vicinity of Glass Transition. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Po-Han Lin – PersonEntity: Name: NameFull: Rajesh Khare IsPartOfRelationships: – BibEntity: Dates: – D: 10 M: 08 Text: Aug2010 Type: published Y: 2010 Identifiers: – Type: issn-print Value: 00249297 Numbering: – Type: volume Value: 43 – Type: issue Value: 15 Titles: – TitleFull: Macromolecules Type: main |
| ResultId | 1 |
