Supercritical Carbon Dioxide Processing Of Nano - Clays And Polymer/clay Nanocomposites

SUPERCRITICAL CARBON DIOXIDE PROCESSING OF NANO CLAYS ANDPOLYMER/CLAY NANOCOMPOSITESbyMIHAI MANITIUAugust 2010Advisor: Rangaramanujam KannanCo-Advisor: Esin GulariMajor: Chemical EngineeringDegree: Doctor of Philosophy Effective dispersion of the fillers in a polymer matrix and improvement of polymer clayinteractions are two key challenges in the field of nanocomposites. A novel processing methodthat utilizes the unique properties of supercritical carbon dioxide (scCO2) to disperse nano clayand prepare a series of polymer/clay nanocomposites with enhanced properties was explored.Significant dispersion was achieved using the scCO2 process with Cloisite 10A withoutthe presence of an organic phase as evident by the absence of the diffraction peak in WAXD andthe presence of individual tactoids that lost their parallel registry. The expanded flexible structureof the scCO2 processed clay exposes more of the available surface area allowing for morecontact between the polymer and clay surface, and the platelets should be easier to disperse intoa polymer matrix than the “as received” clay.Enhanced nano clay dispersion and improved properties were achieved in the scCO2processed polystyrene/clay nanocomposites compared to melt compounding and solutionblended benchmarks. There was a three-fold reduction in the number of tactoids in the scCO2