Effect of osmotic force on orientational cross-correlation in primitive chain network simulation

Although not frequently discussed, the orientational cross-correlation (OCC) has a non-negligible contribution to the stress relaxation of entangled polymers. The origin of OCC has been conjectured to be a coupling in the chain dynamics through the excluded volume interactions, but it has not been revealed yet. In this study, the OCC contribution was measured in the primitive chain network simulations in which the excluded volume interaction is not explicitly implemented, but the density fluctuation of the system is controlled via the phenomenological osmotic force. It was found that the OCC contribution increases with increasing the intensity of osmotic force. This result suggests the significance of the dynamical constraint among the chains due to incompressibility.