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Crystallization of Polymers under the Influence of an External Force Field

We simulated the crystallization and melting behavior of entangled polymer melts using molecular dynamics where each chain is subject to a force dipole acting on its ends. This mimics the deformation of chains in a flow field but represents a well-defined equilibrium system in the melt state. Under...

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Autores principales: Payal, Rajdeep Singh, Sommer, Jens-Uwe
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8272046/
https://www.ncbi.nlm.nih.gov/pubmed/34202647
http://dx.doi.org/10.3390/polym13132078
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author Payal, Rajdeep Singh
Sommer, Jens-Uwe
author_facet Payal, Rajdeep Singh
Sommer, Jens-Uwe
author_sort Payal, Rajdeep Singh
collection PubMed
description We simulated the crystallization and melting behavior of entangled polymer melts using molecular dynamics where each chain is subject to a force dipole acting on its ends. This mimics the deformation of chains in a flow field but represents a well-defined equilibrium system in the melt state. Under weak extension within the linear response of the chains, the mechanical work done on the system is about two orders of magnitude smaller as compared with the heat of fusion. As a consequence, thermodynamic and simple arguments following the secondary nucleation model predict only small changes of the crystalline phase. By contrast, an increase of the stem length up to a factor of two is observed in our simulations. On the other hand, the lamellar thickening induced by the external force is proportional to the increase of the entanglement length in the melt prior to crystallization as measured by the primitive path method. While the mechanical work done on the system is only a small perturbation for thermodynamics of polymer crystallization, the change of the primitive path is large. This suggests that a strong increase in the lamellar thickness induced, by external deformation, a topological rather than a thermodynamic origin.
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spelling pubmed-82720462021-07-11 Crystallization of Polymers under the Influence of an External Force Field Payal, Rajdeep Singh Sommer, Jens-Uwe Polymers (Basel) Article We simulated the crystallization and melting behavior of entangled polymer melts using molecular dynamics where each chain is subject to a force dipole acting on its ends. This mimics the deformation of chains in a flow field but represents a well-defined equilibrium system in the melt state. Under weak extension within the linear response of the chains, the mechanical work done on the system is about two orders of magnitude smaller as compared with the heat of fusion. As a consequence, thermodynamic and simple arguments following the secondary nucleation model predict only small changes of the crystalline phase. By contrast, an increase of the stem length up to a factor of two is observed in our simulations. On the other hand, the lamellar thickening induced by the external force is proportional to the increase of the entanglement length in the melt prior to crystallization as measured by the primitive path method. While the mechanical work done on the system is only a small perturbation for thermodynamics of polymer crystallization, the change of the primitive path is large. This suggests that a strong increase in the lamellar thickness induced, by external deformation, a topological rather than a thermodynamic origin. MDPI 2021-06-24 /pmc/articles/PMC8272046/ /pubmed/34202647 http://dx.doi.org/10.3390/polym13132078 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Payal, Rajdeep Singh
Sommer, Jens-Uwe
Crystallization of Polymers under the Influence of an External Force Field
title Crystallization of Polymers under the Influence of an External Force Field
title_full Crystallization of Polymers under the Influence of an External Force Field
title_fullStr Crystallization of Polymers under the Influence of an External Force Field
title_full_unstemmed Crystallization of Polymers under the Influence of an External Force Field
title_short Crystallization of Polymers under the Influence of an External Force Field
title_sort crystallization of polymers under the influence of an external force field
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8272046/
https://www.ncbi.nlm.nih.gov/pubmed/34202647
http://dx.doi.org/10.3390/polym13132078
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