1D-to-3D transition of photon heat conduction in polyethylene using molecular dynamics simulations

Experiments have demonstrated that the mechanical stretching of bulk polyethylene can increase its thermal conductivity by more than two orders of magnitude, from 0.35 W/mK to over 40W/mK, which is comparable to steel. This strong effect is believed to arise from the increased alignment of the constituent polymer chains, which are thought to have very high thermal conductivity. Although it is well established that bulk polymers have low thermal conductivity, these experiments suggest that cheap, high thermal conductivity polymer materials can be engineered. This type of advancement may provide a much cheaper alternative to the conventional metal-based heat transfer materials that are used today. In order to quantify upper limits on the thermal conductivity of polyethylene, we examine the underlying phonon (lattice wave) transport using molecular dynamics simulations. We first show that the thermal conductivity of individual polyethylene chains is high, and can actually diverge (approach infinity) in some cases. We then discuss how the high thermal conductivity of individual chains is reduced by the presence of additional chains, through van der Waals chain-chain interactions. These intermolecular interactions give rise to both a 2D planar lattice structure and a 3D bulk lattice structure, which allows for the observation of an interesting 1D-to-3D transition in phonon transport.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Henry, Asegun Sekou Famake

Advisor dc:contributor.advisor

• Gang Chen.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/49755

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/49755