Dewetting of a thin polymer film under shear

The objective of this work is to give new insight into the stability of thin polymer films under shear, in order to pave the way to a better control of the nanolayer coextrusion process. To do so, a finite-difference numerical scheme for the resolution of the thin film equation was set up taking into account capillary and van der Waals (vdW) forces. This method was validated by comparing the dynamics obtained from an initial harmonic perturbation to established theoretical predictions. With the addition of shear, three regimes have then been evidenced as a function of the shear rate. In the case of low shear rates the rupture is delayed when compared to the no-shear problem, while at higher shear rates it is even suppressed: the perturbed interface goes back to its unperturbed state over time. In between these two limiting regimes, a transient one in which shear and vdW forces balance each other, leading to a non-monotonic temporal evolution of the perturbed interface, has been identified. While a linear analysis is sufficient to describe the rupture time in the absence of shear, the nonlinearities appear to be essential otherwise.

Automated summary

This paper provides new insights into the stability of thin polymer films under shear, demonstrating the impact of shear rate on the rupture behavior, with findings of delayed rupture at low shear rates, suppressed rupture at high shear rates, and a transient state where shear and van der Waals forces balance each other. Linear analysis suffices to describe rupture time in the absence of shear, while nonlinearities are crucial in the presence of shear.