Deformation patterns in the compression of polypropylene disks: Experiments and simulation

Earlier studies on the molecular orientation developed during the solid‐state compression of cylindrical polypropylene disks revealed a high degree of anisotropy both across the thickness and along the radius of the disk. Tracer deformation experiments reported in the present work suggest that this anisotropy is related to the complex deformation kinematics developed during the disk compression. Finite‐element simulations of the disk compression are also presented, based on a strain‐rate and temperature‐dependent viscosity. Numerical tracking of tracer elements duplicates well the experimentally observed tracer deformation. It is shown that the flow rearrangement (fountain flow) behind the spreading disk front is responsible for the observed deformation patterns.