Maria Calhoun, Ph.D. (2009)

Effect of Environmental Aging on the Thermal and Mechanical Performance of Neat and Nanostructured Polymeric Systems
Major Professor:  Dr. Heshmat Aglan, Professor of Mechanical Engineering & Associate Dean, College of Engineering
M.S.:  Mechanical  Engineering, Tuskegee University
Employment:  Assistant Professor of Mechanical Engineering, Tuskegee University

Dissertation Abstract:

The durability of polymeric systems and their composites under various environmental conditions is a major concern for scientists and engineers, in that they ultimately determine the suitability of a material for specific applications.  Understanding the degradation mechanisms for these systems under various challenging environmental conditions are extremely important in the determination of service life. These environmental challenges include ultraviolet radiation, thermal events, moisture and corrosion, among others. Though aging studies of unfilled polymeric materials and conventional composites have been widely reported in the literature, there has not been much consideration toward the investigation of aging of accompanies. In this work, the effects of severe prolonged environmental conditions on neat and macrostructure thermosetting epoxy and polyurethane (PU) polymeric systems are studied.  Various loading levels of multi-walled carbon inanities (MWCNT) or manically (NC) were used to manufacture the polymer accompanies.  The neat and the endoscopes specimens were subjected to one or more of the following aging conditions: UV exposure, hydrothermal cycling, corrosive environments and pulse laser.  The aged materials were evaluated on the basis of changes in mechanical and thermal properties, molecular structure, surface morphology and/or electrochemical impedance versus their unaged constituents.