John Douglass Ferry

John D. Ferry is known as the leading figure in the history of polymer science on the subject of viscoelasticity. He graduated from Stanford University at the age of 19, as noted above. For his doctoral work with George Parks he studied the properties of polyisobutylene as a function of temperature. He found the glass transition temperature and characterized the viscoelastic properties (Fig. 5.6). 

Ferry went to Harvard University in 1937 and worked there in a variety of posts, including as a Junior Fellow, until he joined the University of Wisconsin in 1946. He was promoted to Full Professor in 1947 His extensive measurements of the temperature dependence of the dynamic mechanical properties of polymers led to the concept of reduced variables in rheology. His demonstration that time-temperature superposition applied to many systems is the basis for the rational description of polymer rheology. He measured the dynamic response over a very wide range of frequency. One of the fruits of this work is the Williams-Landel-Ferry (WLF) equation for time-temperature shift factors. 

Ferry also made seminal measurements on dilute solutions, using a precision shear wave apparatus. The Rouse-Zimm theory of chain dynamics was explored in great detail. 

When the molecular chain length is long enough, polymeric systems display a rubbery plateau in the creep compliance. Ferry and his collaborators made shear creep measurements on a wide range of polymers. The asymptotic behavior of the shear viscosity was established. 

The pubhcation of his monograph. Viscoelastic Properties of Polymers, in 1961 provided a solid basis for all future work, and a key guide to all previous work [7]. It ranks with Flory s Principles of Polymer Chemistry as an essential record of the paradigm of polymer science. 

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