Numerical Simulation of Fiber Orientation and Dispersion for Fiber-Filled Polymer Melts

This paper describes the numerical simulation of the fiber orientation and dispersion for fiber-filled polymer melts in entry and exit flows. First we calculated the viscoelastic flow field of matrix fluids. The higher elastic fluid shows the larger normal stress difference in a die and swells more after extrusion. The velocity profile in the die depends on the shear viscosity, and the shear-thinning viscosity makes the swell smaller. Next we calculated the fiber orientation and dispersion using the velocity fields of the matrix fluids. The fibers tend to array along the streamlines in acceleration flow and perpendicularly to the flow direction in deceleration flow. In the shear flow, the long fibers array along the streamline and the short fibers rotate. The fiber orientation state is less affected by the flow field with increasing interaction between fibers. The fiber dispersion state depends on the inlet boundary of the flow field.