Paper Number
AM16 

Session
Additive Manufacturing and Composites

Title
Effect of block copolymer micelles on the rheology of 3D printable epoxy inks

Presentation Date and Time
October 24, 2019 (Thursday) 9:05

Track / Room
Track 1 / Room 305A

Authors (Click on name to view author profile)

  1. Krogstad, Daniel V. (University of Illinois at Urbana-Champaign, Applied Research Institute)
  2. Ekbote, Rishabh (University of Illinois at Urbana-Champaign, Applied Research Institute)
  3. Donley, Gavin J. (University of Illinois at Urbana-Champaign, Department of Chemical and Biomolecular Engineering)
  4. Rogers, Simon A. (University of Illinois at Urbana-Champaign, Department of Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Daniel V. Krogstad1, Rishabh Ekbote1, Gavin J. Donley2, and Simon A. Rogers2
1Applied Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL 61820; 2Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801

Speaker / Presenter 
Krogstad, Daniel V.

Text of Abstract
Direct Ink Writing (DIW) is a particularly interesting 3D printing technique due to the versatility of the materials classes that can be printed including thermoplastics, thermosets, hydrogels, nanocomposites and ceramic slurries. Contrary to some other 3D printing techniques, the printability of the materials is directly linked to the rheological properties rather than any thermal properties. However, the required rheological behavior can be very complicated and it is poorly understood. This poster will describe our recent efforts to increase our understanding of the structure-property relationships of nanostructured inks using rheology, small angle x-ray scattering (SAXS) and DIW. Our materials system consists of a base epoxy ink, which uses nanoclay to provide shear thinning properties, and block copolymers, which form micelles in the inks. Our work has shown that flow curves, generated from transient creep testing performed at a variety of stresses, can be used as a strong analog to the flow behavior during the printing process. Using this method, we have identified that the flow of these materials has a strongly time-dependent behavior in which the effective yield stress increases over time. This behavior can lead to large decreases in the material flow during printing over time. Interestingly, when the block copolymer micelles are added to the system, the time-dependent increase in the yield stress is minimized relative to the base ink. These results provide new insights in how we can characterize nanostructured inks and the roles of the various components in our formulations.