Thermal Conductivity of Amorphous Polystyrene in Supercritical Carbon Dioxide Studiedby Reverse Nonequilibrium Molecular Dynamics Simulations

摘要

The thermal conductivity of amorphous atactic polystyrene (PS) swollen in supercritical carbon dioxide (scCO2) has been investigated over wide temperature, pressure, and concentration ranges. Nonequilibriummolecular dynamics simulations with a full atomistic force field have been used to calculate the thermalconductivity of neat PS and sc CO2 as well as of the binary system at different compositions. An analyticalinterpolation formula for the thermal conductivity of the binary mixture on the basis of PS and CO2 data hasbeen obtained. Particular attention has been paid to the implications of the quasi-degeneracy and finite-sizeeffects in the simulated polymer system. It has been found that, in addition to the degrees of freedom pervolume, the orientation of the carbon—carbon bonds in the backbone relative to the direction of the temperaturegradient is important for the heat transport in PS.