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Title Experimental Study of Nucleation in Polystyrene/CO2 System
URL
Publication Date
Degree PhD
Discipline/Department Chemical and Biomolecular Engineering
Degree Level doctoral
University/Publisher The Ohio State University
Abstract Polymer foams have many applications, e.g., being used as insulation material, sound-adsorbing material, and packaging material, due to their features and enhanced performance, compared to the counterpart, namely pure polymers. Therefore, both industrial and academic communities have put much effort to investigate polymer foams from exploring new applications to enhancing the performance. Although progress has been made on those paths; one challenge remains, i.e., poor control of morphology of polymer foams. In order to fully address this challenge, fundamental understanding of morphology evolution is needed.Additionally, the traditional blowing agents for polymer foams, i.e., chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), are banned from the market according to the Montreal protocol as these chemicals cause ozone depletion. Therefore, it is necessary to find a replacement for CFCs and HCFCs as blowing agents. Among all the promising alternatives, CO2 has attracted much interest due to being environmentally benign and it's relative ease of use, compared to other candidates, e.g., water and N2. In present study, nucleation, an important stage of morphology evolution in the polymer foaming process, is experimentally studied in the polystyrene/CO2 system. Specifically, nucleation experiments are conducted on different polystyrene/CO2 systems where polystyrene has different molecular weights. Then, based on the information extracted from nucleation experiments, a scaling curve in terms of free energy barrier of nucleation is constructed for the purpose of providing insight into the connection between phase equilibrium boundaries and nucleation phenomena. The result shows that the scaling curve is practically independent of molecular weight, indicating that the same scaling curve could be applied to different polystyrene/CO2 systems where polystyrene has different molecular weights for the prediction of free energy barrier of nucleation. Further, the finding that the scaling curve is practically independent of molecular weight of polystyrene partially confirms the claim that scaling curve is practically independent of intermolecular potentials.
Subjects/Keywords Chemical Engineering; Polystyrene; Carbon dioxide; nucleation; foaming; free energy barrier
Contributors Tomasko, David (Committee Chair)
Language en
Rights unrestricted ; This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
Country of Publication us
Format application/pdf
Record ID oai:etd.ohiolink.edu:osu1330866154
Repository ohiolink
Date Indexed 2021-01-29
Grantor The Ohio State University

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