Thermal conductivity of amorphous polymers and its dependence on molecular weight

Document Type

Article

Publication Date

7-16-2021

Abstract

Thermal conductivity is an important transport property governing the performance of polymers in non-isothermal conditions. Nevertheless, its dependence on molecular weight M has not been the subject of as much attention as other properties of polymeric materials. We determine the thermal conductivity of polystyrene and polyisobutylene for a wide range of molecular weight by measuring the density, heat capacity and thermal diffusivity. Using coarse-graining and reverse mapping methods, we were able to produce molecular melts to study the thermal conductivity of polystyrene using molecular dynamics simulations over a similar range of molecular weight. We find satisfactory agreement between the experimental and simulation results. However, all of our results show that thermal conductivity depends only slightly on molecular weight up the entanglement limit and it is independent thereafter. Our results put into question the few previous experimental studies on this topic by showing that the previously accepted proportionality to M does not hold. Our findings could have significant implications for the understanding of complex phenomena such as anisotropic thermal conductivity in polymers subjected to flow.

Identifier

85107139522 (Scopus)

Publication Title

Polymer

External Full Text Location

https://doi.org/10.1016/j.polymer.2021.123881

ISSN

00323861

Volume

228

Grant

750985

Fund Ref

European Commission

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