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Information to Users INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrougb, substandard margins, and improper alignment can adversely afreet reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. • Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. A Bell & Howell Information Company 300 North Z e e b Road. Ann Arbor. Ml 48106-1346 USA 313/761-4700 800/521-0600 ANALYSIS OF MORPHOLOGY, CRYSTALLIZATION KINETICS, AND PROPERTIES OF HEAT AFFECTED ZONE IN HOT PLATE WELDING OF POLYPROPYLENE DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree of Philosophy in the Graduate School of The Ohio State University By Jenn-Yeu Nieh, B.S., M.S. The Ohio State University 1995 Dissertation Committee Approved by L. J. Lee K. Koelling A. Benatar Adviser Department of chemical engineering UHI Number: 9612251 UMI Microform 9612251 Copyright 1996, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 To My Lovely Wife and Two Children ACKNOWLEDGEMENTS I wish to express my sincere appreciation to Dr. James L. Lee for his guidance and insight through the study. Under his influnence, I have learned not only how to handle the project, but also how to sell the ideas. Thanks go to the other members of my advisory committee, Dr. A. Benatar and Dr. K. Koelling, for their suggestions and comments. I would like to thank Edison Welding Institute for providing technical and financial supportsiii. I also would like to thank my dear fellow members in polymer group for the discussion and help, especially Dr. C.S. Wu and Dr. J. H. Tsai. Dr. Wu gave me lots of help while I am developing the computer code. Dr. Tsai walked me through some tough time in the Lab. Gratitude is expressed to Mr. M. Kukalar for his technical assistance. To my wife, Lillian, it is almost impossible for me to express my appreciation for your encouragement and for all the efforts you made to prepare a warm home for a tired and frustrated heart. At last I would like to thank my Bible study group members in Columbus Chinese Christian Church for their praying support At last I would like to thank God for giving me the opportunity to study, learn, and grow in OSU. VITA Octobor 12,1963 ----------------------------------Bom, Kaohsiung, Taiwan Republic of China 1985 -------------------------------------------------- B.S., National Cheng Kung University Tainan 1985-1987 ----------------------------------------- - Military service 1988-1990 -------------------------------------------Research Associate, Fluidization Lab. The Department of Chemical Engineering The Ohio State University Columbus, Ohio 1990-Present---------------------------------------- Research Associate, Polymer Lab. The Department of Chemical Engineering The Ohio State University Columbus, Ohio FIELDS OF STUDY Chemical Engineering Polymer Characterization and Processing LIST OF FIGURES FIGURES PAGE 1.1 The schematics of pressure and displacement control of the hot plate welding process ....................................................................................3 1.2 The diagram showing the relationship between weld quality and welding factors ....................................................................................... 7 1.3 Block diagram of methodology ................................................................................ 8 2.1 The schematics of joint design .............................................................................. 11 2.2 Schematics of different types of misalignment at pipe butt joints .................................................................................................................... 22 2.3 Schematic illustration of three major types of crack causing failure............................................................................................................23 2.4 Schematic diagram of the weld with distinctive regions of different microstructres ....................................................................................... 27 2.5 Disengangement of a chain from its initial tube ................................................. 37 2.6 Conformation of two chains at the interface before and after diffusion ............................................................................................................39 2.7 (a) Average shape and size of a chain’s most probable envelope at the interface before and after healing, (b) Segment density of the chain in (a) before and after healing .........................................................................................................................39 2.8 The morphology of skin-core zone in an injection molded part ................................................................................................................45 2.9 A Hoffman and Week plot to determine the equilibrium melting temperature, T ^ ..........................................................................................46 v 2.10 The effects of shear rate on the half time crystallization based on Janeschitz-Kriegl model ....................................... 59 3.1 Micrographies of type I III and IV spherulites ....................................................66 3.2 The DSC heat flux responses during melting and crystallization under different cooling rates ..........................................................69 3.3 The temperature dependent apparent heat capacity of PP ................................................................................................................................ 72 3.4 The isothermal crystallization curve under different crystallization temperatures by DSC ......................................................................75 3.5 The crystallization peak times under various isothermal conditions ................................................................................................................... 76 3.6 The DSC results of heating to different temperature and then cooling to room temperature to complete the crystallization ........................................................................................................... 77 3.7 The schematic of crystal structure as temperature increases ..................................................................................................................... 79 3.8 The DSC results of heating to different temperature zones and holding for 60 min and then cooling at constant rate to complete the crystallization ......................................................... 81 3.9 The setup for microstructure examination during crystallization .............................................................................................................82 3.10 The morphological change during melting and crystallization along the DSC curve, case 1, completely melted ..........................................................................................................................84 3.11 The morphological change during melting and crystallization along the DSC curve, case 2, partially melted ..........................................................................................................................87 3.12 The Avrami plot for determining the spherulite growth rate constant and Avrami exponent ........................................................................ 93 3.13 The Lauritzen and Hoffman plot for determining KSg parameters.................................................................................................................. 94 3.14(A) The comparison of rate constants from model calculation and experimental results under different crystallization temperatures .................................................................................... 96 vi 3.14(B) The comparison of rate constants from model calculation and experimental results under different crystallization temperatures ....................................................................................97 3.15 The comparison of model prediction and DSC result of crystallization from zone EU .................................................................................. 100 3.16 The comparison of model prediction and DSC result of crystallization from zone I .................................................................................... 101 3.17 The simulated crystallization
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