2026-04-28T04:46:02Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/52542021-11-02T12:04:46Zcom_10259_4201com_10259_5086com_10259_2604col_10259_4505

Nieto Simavilla, David 391 500 0000-0001-5389-4827 Sgouros, Aristotelis P. 8cf6b7aa-c83d-44ea-835e-b08769e82140 500 Vogiatzis, Georgios G. bff6ce70-ca4c-4faa-b52f-738e538a3337 500 Tzoumanekas, Christos dd647a14-b500-4b3c-bc54-fcdf392c1f5f 500 Georgilas, Vasilis 31a6925d-3571-4b0e-b066-9a4e3349ceb0 500 Verbeeten, Wilco M.H. 573 500 0000-0001-7026-1642 Theodorou, Doros N. 96ba3a41-7e12-410a-9e95-6c8a8fd38aa3 500 2020-04-03T11:57:52Z 2020-04-03T11:57:52Z 2020-02 http://hdl.handle.net/10259/5254 Anisotropic thermal transport induced by deformation and the linear relation between the thermal conductivity and stress tensors, also known as the stress-thermal rule (STR), are tested via molecular dynamics simulations in well-entangled linear polyethylene (PE) and polystyrene (PS) melts subjected to extensional flow. We propose a method to determine the stress in deformed molecular melts, a key component missing in prior simulation studies on thermal transport in polymers that prevented verification of the STR. We compare our results with available data from previous experimental and simulation studies. Thermal conductivity (TC) is found to increase (decrease) in the direction parallel (perpendicular) to the imposed stretch. We find that the STR is valid for both PE and PS over a wide range of deformation rates and stress levels. In direct agreement with experimental evidence and the STR, we observe that for a given strain, the anisotropy in TC increases with the strain rate. Surprisingly, our results for PE question the universal behavior with respect to polymer chemistry suggested by experiments by showing a significantly higher proportionality constant (the stress-thermal coefficient) between stress and anisotropy in TC. We argue that this discrepancy can be explained by the high degree of entanglement interactions in PE affecting the transport of energy at the molecular level. Our conjecture is tested by studying an entangled linear PS melt, a polymer with a much lower entanglement plateau, for which thermal transport experimental results are available. For PS, the normalized stress-thermal coefficient is found to be commensurate with the experimental value. Finally, we test the fundamental molecular hypothesis of preferential energy transport along the backbone of polymer chains used to formulate the STR, which was prompted by early experimental evidence showing an increase in TC with chain length. We are able to establish that the increase in TC with chain length in PE melts fades as the system becomes entangled (i.e., TC remains constant beyond the critical entanglement chain length that marks the transition to entanglement-dominated rheological behavior). Our findings are of key importance in developing robust molecular-to-continuum methodologies for the study of nonisothermal macroscopic flows that are extremely relevant to polymer manufacturing processes. European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie IF MTCIATTP 750985. application/pdf eng American Chemical Society Macromolecules. 2020, V. 53, p. 789-802 info:eu-repo/grantAgreement/EC/H2020/750985 Attribution-NonCommercial-NoDerivatives 4.0 Internacional http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Stress Thermal conductivity Deformation Magnetic properties Polyethylene Materiales Materials Molecular Dynamics Test of the Stress-Thermal Rule in Polyethylene and Polystyrene Entangled Melts info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion ORIGINAL Nieto-macromolecules_2020.pdf Nieto-macromolecules_2020.pdf application/pdf 4173493 https://riubu.ubu.es/bitstream/10259/5254/1/Nieto-macromolecules_2020.pdf e4c9b0707a45955ca4473380288fe016 MD5 1 CC-LICENSE license_rdf license_rdf application/rdf+xml; charset=utf-8 805 https://riubu.ubu.es/bitstream/10259/5254/2/license_rdf 4460e5956bc1d1639be9ae6146a50347 MD5 2 LICENSE license.txt license.txt text/plain; charset=utf-8 999 https://riubu.ubu.es/bitstream/10259/5254/3/license.txt b295bcbce42e2caabeb0c623d3860c06 MD5 3 THUMBNAIL Nieto-macromolecules_2020.pdf.jpg Nieto-macromolecules_2020.pdf.jpg IM Thumbnail image/jpeg 5282 https://riubu.ubu.es/bitstream/10259/5254/4/Nieto-macromolecules_2020.pdf.jpg f42f551f0445519c06c6456a457008e3 MD5 4 TEXT Nieto-macromolecules_2020.pdf.txt Nieto-macromolecules_2020.pdf.txt Extracted text text/plain 82676 https://riubu.ubu.es/bitstream/10259/5254/5/Nieto-macromolecules_2020.pdf.txt 72736d321eee762b4762f21a07bb9fdb MD5 5 10259/5254 oai:riubu.ubu.es:10259/5254 2021-11-02 13:04:46.305 Repositorio Institucional de la Universidad de Burgos bubrep@ubu.es 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