Professor
PhD Graduate Advisor, Associate Head (Research)
Office:
CHBE 243

Research Summary

Rheology of Polymers, Blends and Suspensions, Associating Polymers, Non-Newtonian Fluid Mechanics, Polymer Processing

Education

McGill University, 1991, Ph.D.
University of Toronto, 1988, M.Sc.
Aristotelion University of Thessaloniki, 1984, Diploma (ptychion)

Research interests + projects

The rheology and mechanical properties of associating polymers (ionomers and hydrogen bonding polymers) is of particular interest in our research program. Due to the presence of reversible associations, these polymers exhibit many idiosyncrasies, rich dynamics and unique properties such as self-healing and adhesion. The main thrust of this program is to study their non-linear viscoelasticity and self-healing behaviour using novel rheo-mechanical techniques to explore their potentials in applications such as coatings, packaging, 3D printing and blend compatibilization.

Non-Newtonian fluid mechanics is often distinguished from its Newtonian counterpart by the additional requirement that first a constitutive equation be specified as part of the problem statement and secondly a suitable wall boundary condition other than the no-slip be imposed as a necessary ingredient. The main thrust of this part of the research program is both a theoretical and an experimental study of diverse polymer-wall interfaces under flow.

The interplay between thermodynamics and rheology of polymer blends is of particular interest. During flow of polymer blends, there is a variety of phenomena that may take place such as shear induced mixing and de-mixing. These effects are dramatic as the homogeneous region in their (polymer blends) phase diagram may be shifted or enlarged by several degrees under flow. This part of the research program focuses on the rheological and thermodynamic behavior of polymer blends under flow (shear/extensional), the resulting morphology and its effects on the mechanical properties of final products.

Professor Hatzikiriakos and his students have published over 250 papers. He has edited a book entitled Polymer Processing Instabilities: Understanding and Control. His group is actively collaborating with the University of Crete and the National Technical University of Athens. Professor Hatzikiriakos also serves as an expert witness in polymer patent litigation and dispute and as a consultant to polymer industry.

Selected publications + presentations

A. Abbasi Moud, J. Poisson, Z.M. Hudson and S.G. Hatzikiriakos, “Yield stress and wall slip of kaolinite networks,” Physics of Fluids, 33, 053105 (2021) https://doi.org/10.1063/5.0050541

D. Gilmour, T. Tomkovic, N. Kuanr, M. Perry, H. Gildenast, S.G. Hatzikiriakos and L. Schafer, “Catalytic amine functionalization and polymerization of cyclic alkenes creates adhesive and self-healing materials” ACS Applied Polymer Materials, 3, 2330-2335 (2021) https://doi.org/10.1021/acsapm.1c00158

M. Najm, B. Yavitt and S.G. Hatzikiriakos, “Synergistic ionic interactions in EMAA ionomer blends: A rheological and mechanical property investigation,” J. Rheology, 65, 1373-1389 (2021) https://doi.org/10.1122/8.0000323

M. Najm and S.G. Hatzikiriakos, “Flow-Induced Fractionation Effects on Slip of Polydisperse Polymer Melts,” Physics of Fluids, 32, 073109 (2020) https://doi.org/10.1063/5.0017996

N. Ghahramani, K. Iyer, A.K. Doufas and S.G. Hatzikiriakos, “Rheology of Thermoplastic Vulcanizates (TPVs),” J. Rheology, 64, 1325-1341 (2020) https://doi.org/10.1122/8.0000108