Biomathematics Seminar: Inkjet printing of dilute polymer solutions
15 November 2011 14:00 in CM105 (Mathematical Sciences)
In inkjet printing the printed drops are formed by surface tension driven break-up of liquid jets. Even at very low concentrations the presence of high molecular weight polymers significantly affects how these jets break-up into drops. The high extension-rates (> 10^4 1/s) and strains involved cause the polymer molecules to become highly extended from their equilibrium configurations, giving rise to elastic stresses that resist break-up. Using numerical simulations of these flows with an appropriate constitutive model for dilute polymer solutions (the FENE dumbbell model) we are able to establish the parameters controlling the break-up length and character of jet break-up, such as the production of small satellite droplets (that are detrimental to inkjet performance). For the case of drop on demand printing, we compare our predictions to experimental measurements on a "model" ink, a dilute solutions of monodisperse polystyrene. By choosing parameter values in the FENE model derived from the molecular structure of the polymer, we are able to demonstrate quantitative agreement between simulations and experiments.
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