Authority on the flow properties of molten polymers; their measurement and use in polymer science and plastics engineering
Dealy is a leader in the science of rheology, and on how it can be used to understand polymer performance. Rheology is the study of the deformation and flow of matter, and is intrinsic to the industrial development of plastics.
Dealy's contributions to the science of rheology include inventing experimental techniques and building innovative new equipment, such as the shear stress transducer, a significant development in the measurement of non-linear viscoelasticity in concentrated polymer solutions and melts. His careful and innovative work on measuring die swell of molten polymers flowing through diverging and converging annular dies is classic literature.
Dealy is also a master communicator on a complex topic. According to colleagues, he is
"...a fine scholar [and] master teacher who makes rheology understandable and logical. Many of his manuscripts and his two books on rheology demonstrate this. In particular, his last book with Kurt Wissbrun, Melt Rheology and its Role in Plastics Processing, is a model of clarity. His tutorial lectures in scientific meetings are considered amongst the best delivered papers. This is mainly due to his abilities to communicate complicated concepts in an incisive and simple way."
Dealy served as President of the Society of Rheology between 1988 and 1989 and was Dean of Engineering at McGill University from 1996 to 1999. He is author or co-author of three books, Rheometers For Molten Plastics (1981), Rheology in Plastics Quality Control (1999), and Melt Rheology and Its Role in Plastics Processing (1990, re-released in paperback, 1999). In 1998, he was honoured with the Society of Rheology's highest award, the Bingham Medal, awarded to a North American or member of The Society who has made an outstanding contribution to the science of rheology.