Extensional rheology of all-polystyrene nanocomposites.

This article investigates the nonlinear extensional rheology of all-polystyrene (all-PS) nanocomposites composed of a polystyrene matrix and polystyrene-based nanoparticles (NPs) with varying rigidity and weight fractions. Despite prior confirmation of homogeneous nanoparticle dispersion in equilibrium, the study reveals that flow-induced phase separation occurs during extensional deformation, particularly in nanocomposites containing higher fractions of harder, highly crosslinked NPs. This phase separation correlates with a reduction in strain hardening behavior, which may impact the processing and mechanical performance of these materials. The findings highlight the need for further research into the mechanisms driving phase separation under flow and the influence of nanoparticle characteristics on nonlinear rheological properties.