Abstract
We investigate the effect of highly contrasting non-Newtonian liquid properties on the formation of liquid jets with a focused shape. By using two nozzle-free ejection techniques, mechanically impact- and laser-induced, fast jets of a highly elastic (sodium polyacrylate) and weakly elastic (xanthan-gum) diluted polymer solutions are generated. A unique high-speed effect is encountered at the jet ejection onset of the highly elastic solution. Its jet-tip speed is on average 1.4 times faster in comparison to a Newtonian (glycerin/water) and the weakly elastic liquids. We explain this effect occurring as a result of the high viscoelasticity of the sodium polyacrylate solution. Additionally, a ‘bungee jumper’ jet behaviour (Morrison and Harlen in Rheol Acta 49(6):619–632, 2010) is observed in a regime of high speed (10<V_j<40 m/s) and high viscosity (mu >20 mPa s) not previously examined. We additionally characterise the viscoelastic non-breakup jet limit using the Bazilevskii et al. (Fluid Dyn 40(3):376–392, 2005) ejection criterion. Herein, the extensional rheological parameters are measured implementing a novel DoS-CaBER technique (Dinic et al. in Lab Chip 17(3):460–473, 2017). Our findings may influence results of inkjet printing technologies and recent nozzle-free ejection systems for ejecting liquids with non-Newtonian properties.Graphical abstract
Highlights
The generation of highly focused jets of complex liquids is a fundamental phenomenon and crucial for the development of advanced inkjet printing, 2D patterning and 3D additive manufacturing, of particular impact in printed electronics (Bihar et al 2018) and bioprinting (Hölzl et al 2016) applications
We investigate the jet formation of highly viscous Xanthan-gum (XG) and Sodium polyacrylate (SPA) solutions having weakly elastic and highly elastic properties, respectively
We use a mixture of glycerin (Sigma-Aldrich) at 86 wt% and Milli-Q water resulting in constant viscosity of 110 mPa s from shear rate γ ≥ 0.6 s −1 at 25 ◦C, and two polymeric solutions Xanthan-gum 0.35 wt% (Sigma-Aldrich) and Sodium polyacrylate 0.4 wt%
Summary
The generation of highly focused jets of complex liquids is a fundamental phenomenon and crucial for the development of advanced inkjet printing, 2D patterning and 3D additive manufacturing, of particular impact in printed electronics (Bihar et al 2018) and bioprinting (Hölzl et al 2016) applications. Bazilevskii et al (2005), Hoath et al (2009) observed a ‘bungee jumper’ jet behaviour as a secondary effect of drop-on-demand formation where a jet filament stretches and retracts This jet type was numerically predicted by Morrison and Harlen (2010) in the context of inkjet printing technology. The elastic mechanisms influencing the ejection of focused jets are still not well understood To address these challenges, we investigate the jet formation of highly viscous Xanthan-gum (XG) and Sodium polyacrylate (SPA) solutions having weakly elastic and highly elastic properties, respectively. We investigate the jet formation of highly viscous Xanthan-gum (XG) and Sodium polyacrylate (SPA) solutions having weakly elastic and highly elastic properties, respectively Their polymer concentrations are selected to produce the same shear-thinning properties. For the SPA liquid, we observe a non-breakup ‘bungee jumper’ jet behaviour in a regime of high speed (V j > 10 m/s) and high viscosity ( μ > 20 mPa s)
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