Influence of Interfacial Slip on Mechanical Adhesion of Immiscible Polymers

Abstract

The impact of shear flow instability of two-layer incompatible viscous fluids on mechanical adhesion is studied in this work by numerical modeling. The interface shape evolution is tracked with the level set method using the alternating distance function vanishing at the interface between the layers. It is found that the unstable simple shear flow leads to formation of viscous fingers producing mechanical anchoring after solidification of the system. The shape and length of the viscous fingers are shown to strongly depend on layer viscosity and thickness ratio as well as on interface boundary conditions. The apparent interfacial slip is modeled by the thin intermediate layer of low viscosity. This is found to result in an acceleration of extension of viscous fingers in comparison to that revealed at stick boundary conditions. These structures should lead to strengthening of anchoring between layers and thus promote mechanical adhesion between immiscible polymers.

Keywords:

• MECHANICAL ADHESION
• INCOMPATIBLE POLYMERS
• INTERFACIAL INSTABILITY
• SHEAR FLOW
• INTERFACIAL SLIP