Fengyuan Yang (Dr. Kannan/Dr. Cammarata's research group) will present a thesis proposal as part of our Graduate Research Seminar series. The presentation will take place in Maryland Hall 110 at 1:30pm on Wednesday, October 23, 2013. Graduate students are required to attend.
SUPERCRITICAL CARBON DIOXIDE (scCO2) PROCESSING OF DISPERSED POLYMER/CLAY NANO-COMPOSITES: STRUCTURE, BARRIER AND MECHANICAL PROPERTIES
Abstract: Improved polymeric packaging materials have significant economic and environmental impact on food, beverage and other industries. In this dissertation, we develop polymer-clay nanocomposites, by incorporating impermeable layered silicates into polymeric matrix to enhance barrier properties. We utilize the unique properties of super critical carbon dioxide (scCO2) to exfoliate clay layers and improve polymer-clay interactions, which are two key challenges in the field of nanocomposites. A detailed research plan with three successive steps is proposed. Firstly, the scCO2 processing is applied to pre-disperse natural, commercial and customized clays, the effects of chemical and physical properties of clay particles and scCO2 processing on clay pre-dispersion are investigated, and the extent of clay pre-dispersion are assessed by SEM, WAXD and TGA. Second, the pre-dispersed clay particles are compounded with polystyrene (PS), and characterized by WAXD, TEM, rheology and barrier testing, to investigate the effect of scCO2 processing, clay dispersion, modification and fraction and temperature on structure and physical properties of nanocomposites. Structure-barrier property relationship will be assessed based on several phenomenological models. Finally, the concept of scCO2 processing reinforced polymer/clay nanocomposites based on PS matrix is translated to more complex engineering polymers, using polyethylene terephthalate (PET) as matrix. These studies will reveal the processing-structure-property relationships in scCO2-dispersed polymer-clay nanocomposites.