[19] He worked as a laboratory technician for the Linen Thread Company developing foamed plastic boat bumpers the summer before college.
[11][18] He wrote a senior thesis under William R. Schowalter on normal stress measurements and worked at the Dupont Engineering Research Laboratory[9][2] during the summers of 1960[citation needed] and 1961.
He pursued his PhD in chemical engineering at the University of Minnesota between 1961 and 1964 and wrote his dissertation, "The Optimization by Complex Processes," under the supervision of Rutherford Aris.
[1][2][9][11] After finishing his degree, he spent one year as a postdoctoral fellow in the University of Delaware's Chemical Engineering department, studying Non-Newtonian fluid mechanics with Arthur B.
[10][2][1] Denn joined the faculty at the University of Delaware in 1965 as an assistant professor of computer science; only a quarter of his academic appointment at this time was in chemical engineering.
In 2001, he became the Albert Einstein Professor of Science and Engineering[1][9] and was appointed the third[citation needed] director of the Benjamin Levich Institute for Physicochemical Hydrodynamics, a role he held until 2015.