ゴム・樹脂におけるＣＡＥの進歩 高分子材料におけるメソ領域の計算法とその応用

Abstract

In this paper, we present a particle simulation method (PSM) for particle dispersed materials and a dissipative particle dynamics (DPD) simulation for a polyelectrolyte membrane for a fuel cell. In the PSM, a particle is modeled by using arrays of spheres and each pair of adjacent spheres is connected with three types of springs; stretch, bend, and twist for the deformability of the particle. The motion of the particles in flow is followed by solving the translational and rotational equations of motion for each constituent sphere considering the hydrodynamic interaction. The method was applied to predicting the microstructure of fiber and platelike particle dispersed systems, their rheological properties, and the motion of fillers in an injection molding flow. In the DPD simulation, we studied the mesoscopic structure of a Nafion membrane. Nafion and water are modeled by a coarse-grained method and the Flory-Huggins χ-parameters for these models are then estimated from the mixing energy calculation using an atomistic simulation. As a DPD result, water particles and hydrophilic particles of Nafion side chains spontaneously form aggregates and are embedded in the hydrophobic phase of the Nafion backbone. The cluster size and its dependence on the water content are in good agreement with experimental reports. The atomistic structure of the water channel is then generated based on the obtained mesoscopic structure, and a molecular dynamics simulation is performed.