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EXPERIMENTAL APPROACH FOR ANALYZING SURFACE AND INTERFACIAL PROPERTIES OF POLYMERS
The surface and interfacial properties of polymers are of great importance for many applications, such as coatings, thin films, abrasives, fillers, and adhesives. The molecular structure at surfaces and interfaces are different from those in the bulk, which can lead to an abnormal phenomenon in a certain environmental condition. When implementing newly developed materials into industrial systems, it is crucial to characterize the materials’ properties to determine the materials’ lifespan and avoid any safety problems, especially for applications requiring long-term working conditions.
Mechanical and chemical factors primarily influence the mechanical and chemical performance of materials at surfaces or the interfaces. A variety of testing tools have been developed over decades to characterize the mechanical and chemical properties of polymers. However, as industry needs grow and new technology facilitates various forms of materials advancement, understanding surface and interfacial properties of the materials becomes more challenging. Additionally, although some materials have been commonly utilized in industry or our daily lives for a long time, standardized evaluation protocols have not been developed yet. Thus, the work in this dissertation investigates the surface or interfacial properties of various materials already being used or potentially used in many applications using various experimental approaches.
The first study examines the mechanical properties of glassy-rubbery polymer blend thin films under uniaxial strain. A recently developed mechanical characterization technique utilizing buckling instabilities was employed to analyze how the blend thin films deform and fail as a function of the ratios of blend polymers used. The second study discusses how the intrinsic properties of thermoplastic pavement marking materials (PPMs) affect adhesion on road surfaces in various environmental conditions. In order to investigate the interfacial performance of PPMs on asphalt, a shear adhesion test is developed. The third study investigates a model of thermal interface materials (TIMs) in thermal cycling and aging conditions. A computational method was also utilized to define a potential thermal degradation mechanism. Lastly, the fourth study measures surface damages on general polymeric materials from simulated routine disinfectant processes. By using various spectroscopic and microscopic characterization tools, the effect of surface damages on bacterial activity is analyzed.