The boundary layer effect on viscosity and injection molding studies in radial and unidirectional flows were investigated for liquid crystalline (ethylene terephthalate) using Instron model 3211 capillary rheometer. Two copolyesters of PET modified with 60 and 80 mole percent parahydroxy benzoate were examined. Melt viscosities were measured as a function of temperature and wall shear rates. Mold filling characteristics were investigated by introducing different fluid pigments into the melt before injection. Molecular orientation of the molded parts was studied by measuring the shrinkage of the microtomed samples at various temperatures, injection speeds, and cavity thicknesses for these two molds. For PET/60 mole % PHB, the viscosity was found to be some function of the capillary diameter, showing a marked decrease with decreasing capillary diameter at 275 C; this possible phenomenon is not found in most polymer melts. During mold filling stage, fluid pigments indicated that these liquid crystalline melts flow and split in the core before they approach the flow front. Molecular orientation studies showed that high shrinkage across the flow direction than that measured along the flow direction. Studies also indicated that there existed a relative maximum molecular orientation away from the surface of the parts, corresponding to the shear zone. As the cavity thickness decreases or injection speed increases, this relative maximum peak moves to the surface of the molded parts. / Master of Science

Thesis (M.S.M.E.)--University of Delaware, 2006. / Principal faculty advisor: James Glancey, Dept. of Bioresources Engineering. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 153-159). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 153-159). Also available on the Internet.

The extrusion blow molding process is an important polymer processing operation which involves a complex thermo-mechanical history. / Specimens were obtained from two commercial, blow molding grade, high density polyethylene resins, employing an instrumented Impco reciprocating screw blow molding machine. High speed cinematography was employed in conjunction with a parison pinch-off mold and a transparent blow mold to characterize the dimensional changes of the parison during the parison formation and the clamping and inflation stages. The contact temperature and the heat removal rate were measured during the cooling stage. Numerical methods were employed to investigate the thermal history during various stages. After molding at various operating conditions, the molded specimens were extensively characterized in relation to the distribution of thickness, crystallinity, orientation and impact behavior. / The distributions were analyzed in relation to the data obtained regarding the thermo-mechanical history during the molding process and some theoretical considerations of the relevant flow and heat transfer phenomena.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 134-139). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 134-139). Also available on the Internet.

Thesis (M.S.M.E.)--University of Delaware, 2006. / Principal faculty advisor: Suresh G. Advani, Dept. of Mechanical Engineering. Includes bibliographical references.

No description available.

M.S.