Thermal resistance network model for heat conduction of amorphous polymers
Jun Zhou, Qing Xi, Jixiong He, Xiangfan Xu, Tsuneyoshi Nakayama, Yuanyuan Wang, Jun Liu
Abstract
The thermal conductivities (TCs) of the vast majority of amorphous polymers are in a very narrow range, 0.1--0.5 W ${\mathrm{m}}^{\ensuremath{-}1}$ ${\mathrm{K}}^{\ensuremath{-}1}$, although single polymer chains possess TCs of orders of magnitude higher. The chemical structure of polymer chains plays an important role in determining the TC of bulk polymers. We propose a thermal resistance network (TRN) model for the TC in amorphous polymers taking into account the chemical structure of molecular chains. Our model elucidates the physical origin of the low TC universally observed in amorphous polymers with various chemical structures. The empirical formulas of the pressure and temperature dependence of TC can be successfully reproduced not only in solid polymers but also in polymer melts. We further quantitatively explain the anisotropic TC in oriented polymers.