2021 年 49 巻 2 号 p. 87-95
We have investigated the flow properties of monodisperse and bidisperse entangled linear polymer melts in a contraction-expansion channel. Unlike conventional macroscopic approaches, where the transport equations are combined with a phenomenological constitutive equation for the stress originating from the polymer dynamics, we use a multiscale simulation (MSS) method, in which a macroscopic simulation model for solving the momentum balance equation is connected to a molecular-based mesoscopic model that can describe the entangled polymer dynamics. In the MSS method, we combine the smoothed particle hydrodynamics method with the dual slip-link model. In this study, we newly investigate the flow properties of a bidisperse entangled linear polymer melt since the polymer melts used in most industrial processes are not monodisperse. Compared with constitutive equations, the slip-link model employed in our MSS is effective at addressing the rheological properties of bidisperse entangled polymer melts. We especially focus on the flow properties of an entangled polymer melt containing a relatively small number of longer polymer chains. The MSS approach enables the relations between the macroscopic complex flows and microscopic states of bidisperse entangled polymer chains to be investigated. As a result of the MSSs, we observe that the flow rate for the bidisperse melt induced by an externally imposed pressure difference is clearly smaller than that for a monodisperse melt because of the high stress originating from the long chains.