Dye Effects on Droplet Pinch-Off Dynamics

The degradation of irradiated polymers such as aqueous Poly(ethylene oxide) (PEO) when in contact with various dyes potentially alters the molecular structure of the polymer. Dripping-onto-substrate experimental method was used to determine the variable extensional relaxation time and extensional viscosity of several polymer-dye solution pairs irradiated by a white light source. First, the pinch-off dynamics of aqueous PEO was validated. Second, various concentrations of cationic and anionic dyes were added to fixed concentrations of PEO. Third, the solutions were irradiated for 24 hours and tested again. The experimental results demonstrated a clear difference in the elasto-capillary regime of the neck-thinning dynamics from the polymer solution alone versus with the added dye and irradiation.