William W. Graessley

Princeton University

September 10, 1933 – February 18, 2017

Chemical Engineer

Awarded Bingham Medal 1979

Fellow, Elected 2015

William (Bill) W. Graessley was Professor Emeritus at Princeton University and Adjunct Professor at Northwestern University. Professor Graessley received a B.S. in Chemistry and a B.S.E. in Chemical Engineering in 1956, a M.S.E. in Chemical Engineering in 1957, and a Ph.D. in Chemical Engineering in 1960, all from the University of Michigan in Ann Arbor. After earning his Ph.D., Dr. Graessley accepted a position as Senior Chemist and later as Group Leader for Polymer Physics at the Air Reduction Company. In 1963 he took his first faculty appointment as Assistant Professor in both the Department of Chemical Engineering and the Department of Materials Science at Northwestern University. There, his research focused on advancing our molecular understanding of rheology. In 1981 he was named the Walter P. Murphy Professor of Chemical Engineering and Materials Science, in recognition of his high impact scholarship. Dr. Graessley moved back to industry in 1982, as the Senior Scientific Advisor at the newly established Corporate Research Laboratories of Exxon Research & Engineering. Through his work with Exxon, he established strong connections with Princeton’s Department of Chemical Engineering and accepted a full-time position there as Professor of Chemical Engineering in 1987. At Princeton, he developed advanced neutron scattering probe techniques to explore and understand the structure and rheology of polyolefin blends. He moved to emeritus status in 1998.

Dr. Graessley was a strong proponent of using the fundamental ideas of chain entanglement to understand rheological observations in polymer liquids and crosslinked networks. He designed and conducted many experiments to test hypotheses on what entanglements might be and how they controlled rheology. Nowadays, concepts of entanglement are commonplace and accepted as being broadly useful, however, at the time of his research, in the 1960s and 1970s, it was a highly controversial idea. In his extensive 1974 review, "The Entanglement Concept in Polymer Rheology," (Advances in Polymer Science) he presented early theoretical ideas and experimental evidence for entanglement dynamics in polymeric liquids and in crosslinked networks. Simulations done after his work proved that chain entanglements provide a key contribution to the elastic modulus of polymeric liquids. After moving to emeritus status at Princeton, he completed a two book sequence on Polymeric Liquids & Networks. Volume 1, Structures and Properties, was published in 2004 and Volume 2, Dynamics and Rheology, was published in 2008.

For his work, Dr. Graessley has received many awards including the Bingham Medal of The Society of Rheology in 1979 and the Polymer Physics Prize of the American Physical Society in 1990 “for his incisive experimental and theoretical contributions to molecular rheology.” Additionally, Dr. Graessley was elected to the National Academy of Engineering in 1990 “for pioneering research relating the engineering properties of bulk polymers with their molecular architecture.” Dr. Graessley passed away on February 18, 2017.