The Polymer Society of Korea

Abstract

Extensional rheology of polymer solutions governs processes such as fiber spinning, coating, and microscale flow-driven deformation, yet is difficult to measure for low-viscosity, non-polar systems under volume-limited conditions. We report a study of non-polar wet-capillary-thinning (WCT) in epoxy microchannels to characterize the extensional behavior of polystyrene (PS) solutions. Stable, fully lubricated polymer threads were formed under converging extensional flow, enabling reproducible filament thinning without gas-liquid contact. The thinning dynamics depend systematically on polymer molecular weight and concentration, with extensional viscosity scaling consistent with linear viscoelastic predictions in dilute and semi-dilute regimes. Elastocapillary thinning highlights the dominant role of polymer elasticity and relaxation. These results establish non-polar WCT as a robust microfluidic platform for probing polymer extensional rheology beyond conventional methods.