Acoustophoretic Liquefaction For 3D Printing Ultrahigh Viscosity Nanoparticle Suspensions.

2021 
An acoustic liquefaction approach to enhance the flow of yield stress fluids during digital light processing (DLP) based 3D printing is reported. This enhanced flow enables processing of ultrahigh viscosity resins (μapp > 3700 Pa·s at shear rates γ = 0.01 s-1 ) based on silica particles in a silicone photopolymer. Numerical simulations of the acousto-mechanical coupling in the DLP resin feed system at different agitation frequencies predicts local resin flow velocities exceeding 100 mm·s-1 at acoustic transduction frequencies of 110 s-1 . Under these conditions, highly loaded particle suspensions (weight fractions, f = 0.23) can be printed successfully in complex geometries. Such mechanically reinforced composites possess a tensile toughness 2000% greater than the neat photopolymer. Beyond an increase in processible viscosities, acoustophoretic liquefaction DLP (AL-DLP) creates a transient reduction in apparent viscosity that promotes resin recirculation and decreases viscous adhesion. As a result, AL-DLP improves the printed feature resolution by more than 25%, increases printable object sizes by over 50 times, and can build parts > 3 × faster when compared to conventional methodologies. This article is protected by copyright. All rights reserved.
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