Anisotropy of the thermal conductivity in a crystalline polymer: reverse nonequilibrium molecular dynamics simulation of the delta phase of syndiotactic polystyrene.

The thermal conductivity of the crystalline delta phase of syndiotactic polystyrene has been investigated by reverse nonequilibrium molecular dynamics simulations. The results are in the expected range. An anisotropy is found for the thermal conductivity, with the component in chain direction being 2.5-3 larger than perpendicular to it. Any increase in the density causes an increase also in the thermal conductivity, particularly in the perpendicular directions. As side results, the simulations confirm an earlier finding on the force field dependence of the thermal conductivity: The thermal conductivity has a tendency to decrease when the number of active degrees of freedom in the system is reduced by the introduction of constraints. This dependence is, however, weaker and more erratic than previously found for molecular liquids and amorphous polymers.