John M. Dealy

John M. Dealy

McGill University

March 23, 1937 – January 15, 2024

Chemical Engineer
Awarded Bingham Medal 1998
Fellow, Elected 2015

John M. Dealy obtained his B.S. in Chemical Engineering from the University of Kansas in 1958. He continued studying Chemical Engineering at the University of Michigan for his M.Sc. and Ph.D., graduating in 1959 and 1963 respectively. He began teaching at McGill University in 1964, working his way up from Assistant Professor to Professor. During his time at McGill, he also served as Chair of the Department of Chemical Engineering (1993-1994) and Dean of the Faculty of Engineering (1994 to 1999), before becoming Professor Emeritus in 2004.

Dealy has made numerous outstanding contributions to the science of rheology and was a leader among rheologists serving the industrial community. His excellent knowledge and understanding of both rheology and polymer processing operations rank him amongst the most influential rheologists working in the processing of polymer melts. His development of a robust shear stress transducer and its successful incorporation into a sliding plate rheometer is an important contribution to experimental melt rheology. It solved many problems previously encountered in conventional sliding plate rheometers and marked the advent of measurements of non-linear viscoelasticity in concentrated polymer solutions and melts. Dealy popularized the use of Large Amplitude Oscillatory Shear (LAOS) in such systems and was the first to recognize and use exponential shear flow as a strong transient flow and compare it with extensional flows and unsteady shear flows. He also pioneered the development of correlations between rheological measurements and processability and the ways rheology can be used to understand polymer processing performance. His careful and innovative work on measuring die swell of molten polymers flowing through diverging and converging annular dies remains the definitive work on the subject. His work on the wall slip and melt fracture of molten polyethylenes and elastomers is another outstanding contribution. Dealy also developed the pressurized sliding plate rheometer, one of the few rheometer designs that can measure clearly the effects of pressure on the rheological properties and slip velocity of molten polymers and elastomers.

Dealy is a member of the Canadian Society of Chemical Engineering, the Society of Plastics Engineers and the Canadian Society of Rheology. He served as President of The Society of Rheology from 1987 to 1989, is a fellow of the Polymer Processing Society, and was awarded the 1997 S. G. Mason Award from the Canadian Rheology Group and the 1998 Bingham Medal of The Society of Rheology. He is known for teaching rheology in an understandable and logical way, as demonstrated in many of his manuscripts and both his books. His last book with Kurt Wissbrun (1992 Bingham Medalist), Melt Rheology and its Role in Plastics Processing, is a model of clarity, and his tutorial expository lectures in scientific meetings are well-remembered.