Effect of temperature on thermal conductivity of aligned amorphous polyethylene - Molecular Dynamics study

The effects of temperature dependence of the thermal conductivity (k) of chain-oriented amorphous polyethylene (PE) using Molecular Dynamics Simulation. We found that the temperature corresponding to a peak k progressively decreases by increasing the levels of orientation. Un-oriented PE exhibits the peak k at 350K, while aligned PE under an applied strain of 400% shows a maximum at 100K. This transition of peak k to lower temperatures with increasing alignment is explained in terms of a crossover from disorder to anharmonicity dominated phonon transport in aligned polymers. The disorder in the polymer chain is manipulated to support this crossover corresponding to peak k. Disorder is controlled through a change in the dihedral parameters of the potential function, allowing a change in the relative fraction of trans and gauche transformations. The results shed light on the underlying thermal transport processes in aligned polymers and hold importance for low temperature applications of polymer materials in thermal management technologies.