Nonlinear behavior of polyethylene/layered double hydroxide nanocomposites under shear flow

The structural evolution of filler clusters in polyethylene/layered double hydroxide-based nanocomposites is investigated under application of a simple shear flow and is described in the framework of a modified Wagner model. Overall, the structural behavior of these polymer-clay nanocomposites is found to be similar to the behavior of filled elastomers for which breakdown of filler clusters at increasing strain and their reaggregation at decreasing strain were observed under oscillatory shear (Payne effect). Similar to the filled elastomers and other jammed systems, the polymer-clay nanocomposites demonstrate an asymmetric behavior upon approaching the steady state depending on whether the system was initially at higher or lower shear strain. In particular, the reaggregation time of filler structure in the quiescent state is found to be about one order of magnitude larger than the characteristic breakage time in the nonlinear shear regime.