Modeling of Flow-Induced Crystallization of Particle-Filled Polymers

We present a study on flow-induced crystallization of polymers filled with rigid particles. The numerical simulations reveal the interplay between filler particles, the polymer melt, flow and flow-induced crystallization. Both crystallization kinetics and theresulting crystal orientation are affected and they are crucial for the material properties that are created during flow. In the analysis of the problem, First a direct 2D numerical simulation technique for viscoelastic particle suspensions is applied to determine the local molecular conformation during the flow. Subsequently we use this conformation as thedriving force for flow-induced crystallization. Local anisotropic crystalline structures are formed due to high molecular orientation, especially near the particles. Due to the presence of the same particles, regions of the melt are shielded from the flow and, therefore, hardly any effect of the flow is seen in these regions. Both coupled and decoupled simulationswere performed. In the last approximation the flow problem is solved using a generalized Newtonian viscous fluid model and the velocity gradients obtained are plugged into a viscoelastic constitutive model that provides the molecular conformation. It is found thatthe decoupled method gives incorrect results, especially with respect to the molecular andcrystalline structure orientation.