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


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

D.A. Edwards and M.E. Mackay. “Postextrusion Heating in Three-Dimensional Printing,” Journal of Heat Transfer 142 (2020) 052101 (9 pages).

D.D. Phan, J.S. Horner, Z.R. Swain, A.N. Beris and M.E. Mackay. “Computational Fluid Dynamics Simulation of the Melting Process in the Fused Filament Fabrication Additive Manufacturing Technique,” Additive Manufacturing 33 (2020) 101161 (10 pages).

K. Coasey, K.R. Hart, E. Wetzel, D. Edwards and M.E. Mackay. “Nonisothermal Welding in Fused Filament Fabrication,” Additive Manufacturing 33 (2020) 101140 (12 pages)

N.G. Pavlopoulos, K.S. Kang, L. N. Holmen, N.P. Lyons, F. Akhoundi, K.J. Carothers, S.L. Jenkins, T. Lee, T.M. Kochenderfer, A. Phan, D. Phan, M.E. Mackay, I.B. Shim, K. Char, N. Peyghambarian, L.J. LaComb, R.A. Norwood and J. Pyun. “Polymer and magnetic nanoparticle composites with tunable magneto-optical activity: role of nanoparticle dispersion for high verdet constant materials,” Journal of Materials Chemistry C Advance Article (2020) (9 pages).

M. Karayilan, T.S. Kleine, K.J. Carothers, J.J. Griebel, K.M. Frederick, D.A. Loy, R.S. Glass, M.E. Mackay, K. Char, Jeffrey Pyun. “Chalcogenide hybrid inorganic/organic polymer resins: Amine functional prepolymers from elemental sulfur,” Journal of Polymer Science 58 (2020) 35-41.

T.S. Kleine, T Lee, K.J. Carothers, M.O. Hamilton, L.E. Anderson, L. Ruiz Diaz, N.P. Lyons, K.R. Coasey, W.O. Parker Jr., L.Borghi. M.E. Mackay, K. Char, R.S. Glass, D.L. Lichtenberger, R.A. Norwood and J. Pyun. “Infrared Fingerprint Engineering: A Molecular‐Design Approach to Long‐Wave Infrared Transparency with Polymeric Materials,” Angewandte Chemie International Edition 58 (2019) 17656-17660.

D.A. Edwards, M.E. Mackay, Z.R. Swain, C.R. Banbury and D.D. Phan. “Maximal 3D printing extrusion rates,” IMA Journal of Applied Mathematics 84 (2019) 1022-1043.

M.E. Mackay. “The importance of rheological behavior in the additive manufacturing technique material extrusion,” Journal of Rheology 62 (2018) 1549-1561.

D.D. Phan, Z.R. Swain and M.E. Mackay. “Rheological and heat transfer effects in fused filament fabrication,” Journal of Rheology 62 (2018) 1097-1107.

K.F. Shariar, J. Zhang, K. Coasey, M.A. Sufian, R. Remy, J. Qu and M. Mackay. “The effects of ICP dry etching and HF wet etching on the morphology of SiO2 surface,” Materials Research Express 5 (2018) 095903 (8 pages).

K.R. Hart, R.M. Dunn, J.M. Sietins, C.M.H. Mock, M.E. Mackay, E.D. Wetzel. “Increased fracture toughness of additively manufactured amorphous thermoplastics via thermal annealing,” Polymer 144 (2018) 192-204

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