Michael Mackay

Michael Mackay

Distinguished Professor

Department of Materials Science and Engineering
Department of Chemical and Biomolecular Engineering

Email : mem@udel.edu
Phone : (302) 831-6194
205 DuPont Hall

Biosketch

Research in Dr. Mackay’s group concerns materials processing and the structures developed from processing effects. Most of his research centers on processing polymers using fused filament fabrication (FFF), sometimes called fused deposition modeling® or 3D printing. Our goal is to develop new materials and processing technologies to make strong products with this new polymer processing technology

We use sophisticated characterization tools such as small angle neutron scattering (SANS), a technique we have many years of experience using, to understand the structure – property relation. This technique requires us to use deuterated polymers to measure the radius of gyration. Deuterated polystyrene is blended with protonated polystyrene using a twin screw extruder and we make the filament for FFF. After FFF we determine the radius of gyration using SANS with the aim of determining how oriented the molecules are in the product and then relate this to its strength. We are interested in generating highly oriented polymers using FFF to improve the product strength. To do this we make new polymers and polymer blends for FFF and optimize the “hot end” of our Taz 3D printers.

The weld strength between filaments is another aspect of FFF that dictates printed product strength. We have developed heat transfer models to predict the temperature of deposited filaments, relate this to molecular diffusion at the filaments’ interface and subsequently to the weld strength.

In summary, we are using sophisticated techniques to optimize a new processing technique to make the strongest products possible in the shortest amount of processing time.

We also use FFF for other uses than pure research. We use printing of lithophanes as a way to test our skills. A lithophane uses thickness to generate light and dark regions of a photograph. The figure on the left is the as-printed lithophane that shows its picture when back-lit by placing it on a window pane as shown on the right. The interplay of processing conditions and polymer properties dictates the lithophane’s contrast and sharpness.

A movie of the polymer being extruded from the hot end of a 3D printer. It is slowed down after a couple of seconds to see the gross melt fracture which is undesirable and limits the processing speed of FFF. We are devising blends and processing conditions to minimize gross melt fracture.

Research Interests

  • Nanotechnology
  • Coating and surface behavior
  • Rheology and processing of polymer solutions and melts and suspensions
  • Polymer Crystallization
  • Self-assembly and solar cells
  • Additive Manufacture (Fused Deposition Modelling or 3D printing)

Representative Publications

Mackay, M. E., Z. R. Swain, C. R. Banbury, D. D. Phan and D. A. Edwards. “The performance of the hot end in a plasticating 3D printer,” Journal of Rheology 61 (2017) 229-236.

Kleine, T. S., N. A. Nguyen, L. E. Anderson, S. Namnabat, E. A. LaVilla, S. A. Showghi, P. T. Dirlam, C. B. Arrington, M. S. Manchester, J. Schwiegerling, R. S. Glass, K. Char, R. A. Norwood, M. E. Mackay and J. Pyun. “High Refractive Index Copolymers with Improved Thermomechanical Properties via the Inverse Vulcanization of Sulfur and 1,3,5-Triisopropenylbenzene,” ACS Macro Letters 5 (2016) 1152-1156.

Mackay, M. E. (2015). Solar energy: An introduction. New York, Oxford University Press.

Shen, H., N. E. Valadez-Perez, B. Guralnick, Y. Liu and M. E. Mackay. “Performance enhancement of polymer-based solar cells by induced phase-separation with silica particles,” Journal of Materials Chemistry C 2 (2014) 10087-10100.