Orientation of Anisometric Layered Silicate Particles in Uncompatibilized and Compatibilized Polymer Melts Under Shear Flow: A Dissipative Particle Dynamics Study

The orientation of a three-layered silicate particle in uncompatibilized and compatibilized polymer melts is studied under shear flows utilizing dissipative particle dynamics (DPD). Based on trajectories, pair distribution functions are calculated in orthogonal planes. Regardless of the applied flow direction, it is shown that the layers rearrange themselves so that their surfaces would be normal to the velocity gradient direction. The maximum shear stress values fall in numerical uncertainties in uncompatibilized systems while they show a characteristic overshoot in compatibilized counterparts. This overshoot is shown to be a result of (i) the large interfaces between the silicate layers and the matrix due to the exfoliation, and (ii) the increased energy dissipation due to friction at the interface.