Spreading dynamics of non-Newtonian inkjet drop on solid surface

In this research we investigated the spreading of non-Newtonian inkjet droplets impinged normally on glass surfaces. The wettability of solid substrate was varied by adsorbing a self-assembled monolayer of octadecyltrichloro-silane followed by the exposure to UV-ozone plasma. To understand the effect of non-Newtonian characteristics of fluids on spreading, we chose polyethylene oxide solutions in addition to Newtonian fluid. The concentrations of polyethylene oxide were in the dilute range. We observed that the addition of PEO suppresses the formation of satellite drops during the drop formation. The maximum spreading factor during the transient state was reduced by the added polymer only when the Weber number was large while the equilibrium spreading factor was not affected. The extensional nature of the polymer appears to be responsible for the reduced maximum spreading factor.