Strain effects on the anisotropic thermal transport in crystalline polyethylene
Autor: | Jun Liu, Jixiong He, Yangchao Wang, Kyunghoon Kim |
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Rok vydání: | 2018 |
Předmět: |
chemistry.chemical_classification
Materials science Physics and Astronomy (miscellaneous) Condensed matter physics Mean free path Phonon 02 engineering and technology Polymer Polyethylene 021001 nanoscience & nanotechnology 01 natural sciences Condensed Matter::Soft Condensed Matter Condensed Matter::Materials Science chemistry.chemical_compound symbols.namesake Thermal conductivity chemistry 0103 physical sciences symbols Group velocity van der Waals force 010306 general physics 0210 nano-technology Anisotropy |
Zdroj: | Applied Physics Letters. 112:051907 |
ISSN: | 1077-3118 0003-6951 |
Popis: | Thermal transport in the axial direction of polymers has been extensively studied, while the strain effect on the thermal conductivity, especially in the radial direction, remains unknown. In this work, we calculated the thermal conductivity in the radial direction of a crystalline polyethylene model and simulated the uniaxial strain effect on the thermal conductivity tensor by molecular dynamics simulations. We found a strong size effect of the thermal transport in the radial direction and estimated that the phonon mean free path can be much larger than the prediction from the classic kinetic theory. We also found that the thermal conductivity in the axial direction increases dramatically with strain, while the thermal conductivity in the radial direction decreases with uniaxial strain. We attribute the reduction of thermal conductivity in the radial direction to the decreases in inter-chain van der Waals forces with strains. The facts that the chains in the crystalline polyethylene became stiffer and more ordered along the chain direction could be the reasons for the increasing thermal conductivity in the axial direction during stretching. Besides, we observed longer phonon lifetime in acoustic branches and higher group velocity in optical branches after uniaxial stretching. Our work provides fundamental understandings on the phonon transport in crystalline polymers, the structure-property relationship in crystalline polymers, and the strain effect in highly anisotropic materials. |
Databáze: | OpenAIRE |
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