DOCSLIB.ORG

Development of Expanded Thermoplastic Polyurethane Bead Foams and Their Sintering Mechanism

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Development of Expanded Thermoplastic Polyurethane Bead Foams and Their Sintering Mechanism Development of Expanded Thermoplastic Polyurethane Bead Foams and Their Sintering Mechanism by Nemat Hossieny A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Mechanical and Industrial Engineering University of Toronto © Copyright by Nemat Hossieny 2014 Development of Expanded Thermoplastic Polyurethane Bead Foams and Their Sintering Mechanism Nemat Hossieny Degree of Doctor of Philosophy Department of Mechanical and Industrial Engineering University of Toronto 2014 Abstract Polymer bead foaming technology represents a breakthrough in the production of low density plastic foamed components that have a complex geometrical structure and has helped to expand the market for plastic foams by broadening their applications. In this research, the unique microstructure of thermoplastic polyurethane (TPU) consisting of phase-separated hard segment (HS) domains dispersed in the soft segment (SS) matrix has been utilized to develop expanded TPU (E-TPU) bead foam with microcellular morphologies and also to create inter-bead sintering into three dimensional products using steam-chest molding machine. The phase-separation and crystallization behavior of the HS chains in the TPU microstructure was systematically studied in the presence of dissolved gases and also by changing the microstructure of TPU by melt- processing and addition of nano-/micro-sized additives. It was observed that the presence of gas improved the phase separation (i.e. crystallization) of HSs and increased the overall crystallinity of the TPU. It was also shown that by utilizing the HS crystalline domains, the overall foaming behavior of TPU (i.e. cell nucleation and expansion ratio) can be significantly improved. Moreover, the HS crystalline domains can be effective for both sintering of the beads as well strengthening the individual beads to improve the property of the moulded part. It was also observed that unlike other polymer bead foaming technologies, the E-TPU bead foaming ii sintering does not require formation of double melting-peak. The original broad melting peak existing in the TPU microstructure due to the wide size distribution of HS crystallites can be effectively utilized for the purpose of sintering as well as maintenance of the overall dimensional stability of the moulded part. iii Acknowledgments I would like to express my sincere gratitude and appreciation to my supervisor, Professor Chul B. Park for providing me with the continuous guidance, enthusiasm and encouragement to assist me in conducting a successful research. His visions, insights and suggestions have an everlasting influence on my personal and professional growth. I feel extremely honored and fortunate to have such a supportive mentor. I would like to thank my Ph.D. committee members, Professor Hani Naguib and Professor Glenn D. Hibbard for their valuable comments and suggestions offered during the course of my Ph.D. research. Also, I am grateful for Professor Anup Ghosh and Professor Lidan You for their valuable feedback in my Ph.D. final oral examination. I am grateful of the financial support and scholarships from Ontario Graduate Scholarship (OGS), Consortium of Cellular and Micro-Cellular Plastics (CCMCP), and Natural Sciences and Engineering Research Council of Canada (NSERC) funding for Network for Innovative Plastics Materials and Manufacturing Processes (NIPMMP). My special thanks goes to Kara Kim for her kind assistance. I would like to extend my acknowledgment to my colleagues and other members of Microcellular Plastic Manufacturing Laboratory. Their advice, assistance and friendship have contributed to the successful completion of my research. Special thanks goes to Dr. Changwei Zhu, Dr. Saleh Amani, Hasan Mahmood, Dr. Reza Barzegari, Dr. Reza Nofar, Dr. Amir Ameli, Alireza Tabatabaei, Mehdi Saniei, Vahid Shaayegan, Lun Howe Mark, Weidan Ding, Davoud Jahani, Ali Rizvi, Mo Xu, Sai Wang, Raymond Chu, Dr. Peter Jung, Dr. Anson Wong, Hui Wang, Anne Zhao as well as everyone else who helped me in my Ph.D. studies. I am also grateful for the many undergraduate students who have assisted me during the course of my research. Also, to the administrative staff in our department: Konstantine, Brenda, Ceaser and Jho: thank you for your kind assistance on the various administrative matters. Finally, my special thanks go to my family members in India and Canada for their support, encouragement and patience throughout the course of this Ph.D. research. iv Table of Contents Acknowledgments .......................................................................................................................... iv Table of Contents ............................................................................................................................ v List of Tables .................................................................................................................................. x List of Figures ................................................................................................................................ xi List of Symbols ............................................................................................................................ xix Chapter 1 Introduction .................................................................................................................... 1 1.1 Thermoplastic Foams .......................................................................................................... 1 1.2 Classification of Thermoplastic Foams .............................................................................. 1 1.3 Bead Foam Technology ...................................................................................................... 2 1.4 Research Motivation ........................................................................................................... 2 1.5 Objective of Thesis ............................................................................................................. 3 1.6 Organization of Thesis ........................................................................................................ 4 1.7 References ........................................................................................................................... 5 Chapter 2 Literature Review ........................................................................................................... 7 2 Literature Review ....................................................................................................................... 7 2.1 Basic and General Principles of Foaming ........................................................................... 7 2.1.1 Polymeric foams and foaming process ................................................................... 7 2.1.2 Polymeric foams and foaming process ................................................................... 8 2.1.3 Supercritical CO2 (scCO2) foaming ...................................................................... 11 2.2 Extrusion Foaming Technology ........................................................................................ 17 2.3 Injection Foam Molding Technology ............................................................................... 19 2.3.1 Conventional foam injection molding and microcellular injection molding technologies .......................................................................................................... 19 2.3.2 Low-pressure and high-pressure foam injection molding technologies ............... 20 2.4 Rotational Foam Molding Technology ............................................................................. 22 v 2.5 Bead Foam Molding Technology ..................................................................................... 24 2.5.1 Bead fabrication .................................................................................................... 25 2.5.2 Bead bonding ........................................................................................................ 26 2.5.3 Bead foam materials ............................................................................................. 33 2.6 Thermoplastic polyurethane .............................................................................................. 40 2.7 References ......................................................................................................................... 42 Chapter 3 Phase Separation and Crystallization of TPU in the Presence of Dissolved Gas:- Effects of Processing, Nano-/Micron-Sized Additives and Gas Types ................................... 57 3 Phase Separation and Crystallization of TPU in the Presence of Dissolved Gas .................... 57 3.1 Introduction ....................................................................................................................... 57 3.2 Experimental Procedure .................................................................................................... 59 3.2.1 Materials ............................................................................................................... 59 3.2.2 Sample preparation ............................................................................................... 59 3.2.3 Rheological analysis ............................................................................................. 60 3.2.4 Atomic force microscopy ...................................................................................... 61 3.2.5 Crystallization
Load more

Recommended publications
  • Polymers and Supercritical
    Polymers and Supercritical CO2 - An invention to new polymer processing technologies - On-line Number 5017 Masahiro Ohshima Department of Chemical Engineering, Kyoto University, Nishikyo-ku, Kyoto, 615-8510, Japan E-mail: [email protected] ABSTRACT Supercritical CO2 (sc-CO2) is being utilized for various polymers processing such as polymer blending, additive impregnation and plastic foaming. When CO2 dissolves into polymers, the polymer chain mobility is enhanced and rheological and thermal properties of the polymer are changed. In this talk, the solubility and the diffusivity of CO2 in the polymer as well as the CO2-induced polymer property (i.e., plasticization effects), such as reduction of glass transition temperature and viscosity, are shown with experimental data. Then, CO2 microcellular polymeric foaming, a CO2 aided additive infusion and polymer surface modification schemes are introduced to illustrate the potential of CO2 creating new polymer processing techniques. KEYWORDS Super critical fluid, carbon dioxide, plasticization effect, polymer, foams, and surface modification INTRODUCTION Carbon dioxide (CO2) becomes supercritical at pressures and temperatures above 7.38 MPa and o 31.1 C. At the supercritical condition, the CO2 has a higher diffusion coefficient and a lower viscosity than liquids and the surface tension becomes absent, which allows a rapid penetration of molecule into the pores of heterogeneous matrices. Taking advantage of these characteristics together with its nontoxicity, nonflammability and inexpensiveness, CO2 has been used in a variety of industries, i.e., food, pharmaceutical, fiber, chemical and plastic industries (Berens et al, 1992; Schnitzler et al, 1999). At the beginning of the research on the supercritical fluids, the focus was mainly on extraction and separation of small molecules by the fluids.
    [Show full text]
  • Processing and Characterization of Polycarbonate Foams with Supercritical
    PROCESSING AND CHARACTERIZATION OF POLYCARBONATE FOAMS WITH SUPERCRITICAL CO2 AND 5-PHENYL-1H-TETRAZOLE Thomas Cloarec, B.S. Thesis Prepared for the Degree of MASTER OF SCIENCE UNIVERSITY OF NORTH TEXAS May 2015 APPROVED: Witold Brostow, Major Professor Samir Aouadi, Committee Member Nandika A. D’Souza, Committee Member Richard F. Reidy, Committee Member Cloarec, Thomas. Processing and Characterization of Polycarbonate Foams with Supercritical Co2 and 5-Phenyl-1h-Tetrazole. Master of Science (Materials Science and Engineering), May 2015, 100 pp., 11 tables, 59 figures, references, 5 titles. Since their discovery in the 1930s, polymeric foams have been widely used in the industry for a variety of applications such as acoustical and thermal insulation, filters, absorbents etc. The reason for this ascending trend can be attributed to factors such as cost, ease of processing and a high strength to weight ratio compared to non-foamed polymers. The purpose of this project was to develop an “indestructible” material made of polycarbonate (PC) for industrial applications. Due to the high price of polycarbonate, two foaming methods were investigated to reduce the amount of material used. Samples were foamed physically in supercritical CO2 or chemically with 5-phenyl-1H-tetrazole. After thermal characterization of the foams in differential scanning calorimetry (DSC), we saw that none of the foaming methods had an influence on the glass transition of polycarbonate. Micrographs taken in scanning electron microscopy (SEM) showed that foams obtained in physical and chemical foaming had different structures. Indeed, samples foamed in supercritical CO2 exhibited a microcellular opened-cell structure with a high cell density and a homogeneous cell distribution.
    [Show full text]
  • FY 1992 Budget Summary Table for DOE Materials Activities
    Is a.:. S A * A A 0 0 - 0@ E a a A - a 5 0O I.. - 0 - 0 S -. -. C S -. :. -. B S S --. - This report has been reproduced directly from the best available copy. Available to DOE and DOE contractors from the Office of Scientific and Technical Informa- tion, P.O. Box 62, Oak Ridge, TN 37831; prices available from (615) 576-8401, Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161. 0 Printed with soy ink on recycled paper DOE/ER-0589 ENERGY MATERIALS COORDINATING COMMITTEE (EMaCC) Fiscal Year 1992 May 1993 Annual Technical Report U.S. Department of Energy Office of Energy Research Office of Basic Energy Sciences Division of Materials Sciences Washington, D.C. 20585 Table of Contents TABLE OF CONTENTS Page Introduction ........................................................ 1 Membership List .................................................... 2 FY 1992 Budget Summary Table for DOE Materials Activities .................. 6 Program Descriptions OFFICE OF ENERGY EFFICIENCY AND RENEWABLE ENERGY ......... 9 Office of Building Technologies ................................... 13 Office of Building Energy Research .............................. 14 Buildings Systems and Materials Division ........................ 15 Office of Industrial Technologies .................................. 17 Office of Waste Reduction Technologies ........................... 21 Industrial Energy Efficiency Division ............................ 21 Waste Material Management Division
    [Show full text]
  • (12) United States Patent (10) Patent No.: US 8,827,197 B2 Powers (45) Date of Patent: Sep
    USOO8827 197B2 (12) United States Patent (10) Patent No.: US 8,827,197 B2 POWers (45) Date of Patent: Sep. 9, 2014 (54) APPARATUS AND METHOD FOR (56) References Cited INTERLEAVING POLYMERIC ROLL FOR GAS IMPREGNATION AND SOLD-STATE U.S. PATENT DOCUMENTS FOAMI PROCESSING 1948,568 A 2f1934 Faber 2,224,997 A * 12/1940 Weisse ....................... 242/.530.2 (75) Inventor: Steven Ray Powers, Everett, WA (US) (Continued) (73) Assignee: MicroGREEN Polymers Inc, Arlington, WA (US) FOREIGN PATENT DOCUMENTS (*) Notice: Subject to any disclaimer, the term of this E. 36 A1 8.8 patent is extended or adjusted under 35 U.S.C. 154(b) by 1305 days. (Continued) OTHER PUBLICATIONS (21) Appl. No.: 12/612,652 Wang, "Solvent-free Fabrication of Porous Polymer for Tissue Engi (22) Filed: Nov. 4, 2009 neering Applications.” University of Washington, Dept. of Mechani cal Engineering (dissertation), 2007. (65) Prior Publication Data US 2010/01 12301A1 May 6, 2010 (Continued) Related U.S. Application Data Primary Examiner — William A Rivera (60) Provisional application No. 61/111.298, filed on Nov. R Attorney, Agent, or Firm — John M Janeway; Janeway atent Law PLLC 4, 2008. (51) Int. Cl. (57) ABSTRACT B65H (8/08 (2006.01) The present invention relates to apparatuses and methods for B32B 37/00 (2006.01) making interleaved cylindrical rolls from a polymer roll and a B65H 39/6 (2006.01) porous roll. The interleaved rolls disclosed herein are useful B32B I/08 (2006.01) for Subsequent high pressure gas impregnation and solid-state B32B 27/2 (2006.01) foam processing.
    [Show full text]
  • Development of High Strength Microcellular
    DEVELOPMENT OF HIGH STRENGTH MICROCELLULAR FOAMS USING POLYETHER BLOCK AMIDE ………………….. KUN LIN ………………….. M.Eng. PROJECT REPORT DEPARTMENT OF MECHANICAL AND INDUSTRIAL ENGINEERING UNIVERSITY OF TORONTO 2010 DEVELOPMENT OF HIGH STRENGTH MICROCELLULAR FOAMS USING POLYETHER BLOCK AMIDE by KUN LIN A thesis submitted in conformity with the requirements for the degree of Masters of Engineering Graduate Department of Mechanical and Industrial Engineering University of Toronto © Copyright by Kun Lin (2010) Development of High Strength Microcellular Foams Using Polyether Block Amide M.Eng. 2010-09-15 Kun Lin Department of Mechanical & Industrial Engineering University of Toronto Abstract This report presents a successful development of batch foaming techniques of the engineering elastomer. The polyether block amide (PEBAX) was investigated as an engineering elastomer by using batch foaming techniques. The Pebax provide a unique combination of mechanical and chemical properties. Understanding the effect of the different parameter in batch foaming process allows obtaining the high quality foamed product of the engineering elastomer. Temperature has been considered as an important parameter in the batch foaming process. It was shown that the density of foamed product was decreasing by the temperature increasing under its melting temperature. Both temperature and pressure have to reach the minimum requirement to obtain the fine foamed product. As an experiment result, it indicates that there is an optimal portfolio of foaming parameter for the different Pebax resin. Acknowledgements I would like to thank my supervisor Professor Chul B. Park, who provided me this opportunity and resources to complete this research project. I would like to thank my co- supervisor Nan Chen for his guidance, supports and encouragements during my research.
    [Show full text]
  • Flame Retardants for ABS and ABS-Matrix Wood-Plastic Composites
    Graduate Theses, Dissertations, and Problem Reports 2008 Flame Retardants for ABS and ABS-matrix Wood-Plastic Composites Tze-Wei Liu West Virginia University Follow this and additional works at: https://researchrepository.wvu.edu/etd Recommended Citation Liu, Tze-Wei, "Flame Retardants for ABS and ABS-matrix Wood-Plastic Composites" (2008). Graduate Theses, Dissertations, and Problem Reports. 4397. https://researchrepository.wvu.edu/etd/4397 This Dissertation is protected by copyright and/or related rights. It has been brought to you by the The Research Repository @ WVU with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you must obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Dissertation has been accepted for inclusion in WVU Graduate Theses, Dissertations, and Problem Reports collection by an authorized administrator of The Research Repository @ WVU. For more information, please contact [email protected]. Flame Retardants for ABS and ABS-matrix Wood-Plastic Composites Tze-Wei Liu Dissertation submitted to the College of Engineering and Mineral Resources At West Virginia University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemical Engineering Rakesh K. Gupta, Ph.D. Eung H. Cho, Ph.D. Caulton Irwin, Ph.D. Edwin L. Kugler, Ph.D. John Zondlo, Ph.D. Department of Chemical Engineering West Virginia University Morgantown, West Virginia 2008 Keywords: flame retardants, non-halogenated flame retardants, polymer recycling, acrylonitrile-butadiene-styrene, wood plastic composites, char formation, FTIR, flammability, thermal degradation.
    [Show full text]
  • Effective Use of Filling Simulations to Balance Hot
    Society of Plastics Engineers 6666tthh AAnnnnuuaall TTeecchhnniiccaall CCoonnffeerreennccee ooff tthhee SSoocciieettyy ooff PPllaassttiiccss EEnnggiinneeeerrss Plastics Encounter at ANTEC 2008 May 4 – 8, 2008 Milwaukee, Wisconsin, USA Volume 1 of 4 Printed from e-media with permission by: Curran Associates, Inc. 57 Morehouse Lane Red Hook, NY 12571 www.proceedings.com ISBN: 978-1-60560-320-9 Some format issues inherent in the e-media version may also appear in this print version. COPYRIGHTED © 2008 BY THE SOCIETY OF PLASTICS ENGINEERS. PO BOX 403, BROOKFIELD, CONNECTICUT 06804-0403 REPRODUCTION IN WHOLE OR IN PART WITH OUT WRITTEN PERMISSION IS PROHIBITED. Society of Plastics Engineers 66th Annual Technical Conference of the Society of Plastics Engineers 2008 TABLE OF CONTENTS VOLUME 1 AUTOMOTIVE – D31 AUTOMOTIVE DIVISION INTERACTIVE SESSION POLYMER FLOW ANALYSIS ON AN AUTOMOTIVE INSTRUMENT PANEL.................................. 1 Bhagat, Harsh COMPOSITES – D39 COMPOSITE PROCESSING AND APPLICATION SELF-REINFORCING THERMOPLASTIC COMPOSITES ................................................................. 6 Lesser, Alan; McCarthy, Thomas; Yoon, Joonsung HYDROXYAPATITE- POLYLACTIDE COMPOSITE FOR BONE REPAIR...................................... 11 Olson, James; Shaw, Montgomery; Sun, Shih-Po; Wei, Mei STRUCTURAL REINFORCED INJECTION MOLDING OF FIBERGLASS AND POLYDICYCLOPENTADIENE........................................................................................................... 14 Hoekstra, Nicole; Lao, Edward IMPROVING WATER RESISTANCE
    [Show full text]
  • Development of Innovative Gas- Assisted Foam Injection Molding
    Development of Innovative Gas- Assisted Foam Injection Molding Technology By Peter Ungyeong Jung A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Mechanical and Industrial Engineering University of Toronto © Copyright by Peter Ungyeong Jung 2013 Development of Innovative Gas-Assisted Foam Injection Molding Technology Peter Ungyeong Jung Degree of Doctor of Philosophy, 2013 Department of Mechanical and Industrial Engineering University of Toronto ABSTRACT Injection molding technology is utilized for a wide range of applications from mobile phone covers to bumper fascia of automotive vehicles. Foam injection molding (FIM) is a branched manufacturing process of conventional injection molding, but it was designed to take advantage of existing foaming technology, including material cost saving and weight reduction, and to provide additional benefits such as improvement in dimensional stability, faster cycle time, and so on. Gas-assisted injection molding (GAIM) is another supplemental technology of injection molding and offers several advantages as well. This thesis study takes the next step and develops innovative gas-assisted foam injection molding (GAFIM) technology, which is the result of a synergistic combination of two existing manufacturing technologies, FIM and GAIM, in order to produce a unique thermoplastic foam structure with proficient acoustic properties. The foam structure manufactured by GAFIM consists of a solid skin layer, a foam layer, and a hollow core; and its 6.4-mm thick sample outperformed the conventional 22-mm thick polyurethane foam in terms of the acoustic absorption coefficient. With respect to ii foaming technology, GAFIM was able to achieve a highly uniform foam morphology by completely decoupling the filling and foaming phases.
    [Show full text]
  • Pla) and Pla Nanocomposite Foams in Injection Molding for Automotive Applications
    UNIVERSITÉ DE MONTRÉAL DEVELOPMENT OF POLYLACTIDE (PLA) AND PLA NANOCOMPOSITE FOAMS IN INJECTION MOLDING FOR AUTOMOTIVE APPLICATIONS NAQI NAJAFI CHALOUPLI DÉPARTEMENT DE GÉNIE MÉCANIQUE ÉCOLE POLYTECHNIQUE DE MONTRÉAL THÈSE PRÉSENTÉE EN VUE DE L’OBTENTION DU DIPLÔME DE PHILOSOPHIAE DOCTOR (GÉNIE MÉCANIQUE) AOÛT 2015 © Naqi Najafi Chaloupli, 2015. UNIVERSITÉ DE MONTRÉAL ÉCOLE POLYTECHNIQUE DE MONTRÉAL Cette thèse intitulée : DEVELOPMENT OF POLYLACTIDE (PLA) AND PLA NANOCOMPOSITE FOAMS IN INJECTION MOLDING FOR AUTOMOTIVE APPLICATIONS présentée par : NAJAFI CHALOUPLI Naqi en vue de l’obtention du diplôme de : Philosophiae Doctor a été dûment acceptée par le jury d’examen constitué de : M. AJJI Abdellah, Ph. D., président M. THERRIAULT Daniel, Ph. D., membre et directeur de recherche Mme HEUZEY Marie-Claude, Ph. D., membre et codirectrice de recherche M. CARREAU Pierre, Ph. D., membre et codirecteur de recherche M. BATAILLY Alain, Ph. D., membre M. RODRIGUE Denis, Ph. D., membre externe III DEDICATION To my lovely wife, cheerful daughter, and beloved parent. IV ACKNOWLEDGEMENTS I wish to express my deep gratitude to my advisors, professor Marie-Claude Heuzey, professor Pierre Carreau, and professor Daniel Therriault for the trust they placed in me and for all their supports throughout the period of this research. My sincere appreciation goes to prof. Heuzey for her availability, patience, enthusiasm toward scientific research, and productive discussions. I owe my sincere gratitude to prof. Carreau for the thing I learnt from him; not only the scientific matters, but also lots of knowledge which are helpful in all aspects of my life. I also acknowledge all the efforts made by prof.
    [Show full text]
  • Increasing Void Fraction of the Polypropylene Foams Blown with Chemical Blowing Agents in High Temperature Extrusion
    Increasing Void Fraction of the Polypropylene Foams Blown with Chemical Blowing Agents in High Temperature Extrusion By K.M. Zamil Andalib A thesis submitted in conformity with the requirements For the degree of Master of Applied Science Department of Mechanical and Industrial Engineering University of Toronto © Copyright by K.M. Zamil Andalib 2015 Increasing Void Fraction of the Polypropylene Foams Blown with Chemical Blowing Agents in High Temperature Extrusion K.M. Zamil Andalib Master of Applied Science Department of Mechanical and Industrial Engineering University of Toronto 2015 ABSTRACT The global demand for the polymeric foams especially Polypropylene (PP) foams is increasing rapidly. Some industrial processing of the PP foam need high processing temperature. But, there are only a few research has been done on high temperature processing as the quality of foam deteriorates in that condition. Moreover, Physical Blowing Agents (PBA) need additional accessories to process the foam. But usually industries are reluctant to change their existing system to get foamed output initially. This thesis develops an approach to manufacture PP foams with Chemical Blowing Agents (CBA) in high temperature extrusion. In the first step, a series of fundamental studies have been carried out by investigating the effect of different chemical blowing agent and content, pressure drop rate and residence time on the foaming behavior of polypropylene. And then, optimized parameters are applied and the combination effect of CBA-PBA and the effect of nucleating agents has been examined. II To my beloved wife, Prova For all the sacrifices, love and support during my journey to MASc degree. III ACKNOWLEDGMENT Words are not good enough for the acknowledgment to those people who helped me through my academic life in University of Toronto.
    [Show full text]
  • Surface Tension Measurement of Polystyrenes in Supercritical Fluids
    Surface Tension Measurement of Polystyrenes in Supercritical Fluids by Hyuk Sang Park A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Doctor of Philosophy in Chemical Engineering Waterloo, Ontario, Canada, 2007 © Hyuk Sang Park 2007 AUTHOR’S DECLARATION I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Abstract Interfacial tension provides valuable information about polymer processes such as foaming, particle (pigment) suspension, wetting, and blending. Among the methods commonly used to measure surface tension, drop shape methods entail several advantages such as simplicity and versatility. The profile of the drop, which is determined by the balance between gravity and surface forces, is easily defined. The surface tension is obtained from the profile of the drop. Recent progress in image analysis and data acquisition systems makes it possible to digitalize drop images directly using a video frame grabber with a digital camera. The digital signals are easily analyzed using different algorithms to determine the surface/interfacial tension from the drop profile. This study concentrates on one of the drop methods, the pendant drop method, which involves the determination of a drop profile of one dense liquid suspended in another liquid at mechanical equilibrium. Despite theoretical simplicity of using sessile and pendant drops for determining the surface tension of polymer melts, research in this area is limited because of the experimental difficulty associated with maintaining equilibrium of highly viscous melts.
    [Show full text]