Supercritical carbon dioxide (SC-CO2) is used as a physical blowing agent in the manufacture of plastic foam and as a plasticizer to reduce melt viscosity during processing. Pressure is also an important variable for processing, and the combined effects of dissolved SC-CO 2 and pressure on rheological properties must be known to achieve optimum processing conditions. However, until recently there was no method to measure these effects accurately. A high-pressure sliding plate rheometer in which the shear rate, temperature, pressure, and CO2 concentration are uniform, was used in the present study. The effects of CO2 and pressure on the viscosity, stress growth function, and creep compliance of a high density polyethylene (HDPE) were determined. To separate the effects of pressure and CO2, samples were first pressurized without CO 2, and then pressurized and saturated with CO2. It was possible to use shift factors for pressure and CO2 concentration to obtain a master curve. For the purpose of comparison, the effect of nitrogen on the viscosity is also determine. Another important concern in plastics processing is molecular structure, which has a strong effect on melt flow properties. The effects of long- and short-chain branching and side groups on the pressure sensitivity of viscosity were also determined in this project.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85949 |
| Date | January 2005 |
| Creators | Park, Hee Eon, 1972- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002267662, proquestno: AAINR21686, Theses scanned by UMI/ProQuest. |
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