Download Free From Linear To Long Chain Branched Polyethylene Terephthalate Reactive Extrusion Rheology And Molecular Characterization Book in PDF and EPUB Free Download. You can read online From Linear To Long Chain Branched Polyethylene Terephthalate Reactive Extrusion Rheology And Molecular Characterization and write the review.

Poly(ethylene terephthalate) is one of the most widely used polymers in packaging industry, due to its high mechanical strength, chemical resistance, and barrier functions. However, its processing is determined by degradation and low viscosity. In particular, foaming and film blowing is restricted by the linear structure of the molecule and low melt strength. The stability of three linear commercial PET grades produced by different synthesis routes with different molar masses is analyzed in regards of processing at industrial scale. Subsequently, reactive processing with three multi-functional chain extenders (pyromellitic dianhydride, PMDA, tetraglycidyl diamino diphenyl methane, TGDDM, and triphenyl phosphite, TPP) is conducted to create large and long-chain branched (LCB) molecules. The mechanical and molecular properties in melt state are analyzed by linear and non-linear viscoelastic rheology, modeling by the molecular stress function (MSF) theory and size-exclusion chromatography (SEC) with light scattering measurements. Thermal stability measurements in the linear viscoelastic regime revealed degradation and a reduction of the storage modulus in air atmosphere, and, besides thermal degradation, an enhancement of the modulus in nitrogen atmosphere, due to polycondensation [Kruse et al., 2013]. Fitting by an exponential function leads to the reconstruction of the initial state of the sample at zero-loading time and to a time constant, which reveals clear relations between stability and molar mass for all three PET grades in both atmospheres. High molar mass PET is more stable in nitrogen and less stable in air environment, and vice versa, depending on OH end group concentration and synthesis route. The analysis by means of time-resolved mechanical spectroscopy allows the observations of moduli and complex viscosity at a fixed time, a wide range of angular frequencies, and at different atmospheres, and revealed: (i) a plasticizer effect induced by small molecules from thermal and thermo-oxidative degradation, (ii) cross-linking leading to yield stress, (iii) diffusion influencing polycondensation reaction, (iv) slipping due to deposition of side products, and (v) an enhanced shear thinning regime [Kruse and Wagner, 2016]. The extrusion of neat PET with a twin-screw extruder at industrial scale leads to strong reduction of viscosity mainly due to shearing. The impact of thermo-oxidative degradation is comparably small. The reactive processing of the three PET grades with the three chain extenders leads to the conclusion that the tri-functional TPP is not a useful chain extender due to rapid degradation and toxicity. The two tetra-functional chain extenders, PMDA and the epoxy-based TGDDM, lead to strong viscosity increase, increasing strain hardening effect, and increasing thermal stability with increasing chain extender concentration as confirmed by loss- and storage modulus, phase angle, activation energy of flow, and elongational viscosity. The MSF model predictions show good agreement with data measured, and allowed a quantitative analysis of the branching structure and of the stretch of the molecules by both non-linear MSF parameters. In comparison to the high molar mass PET with an apparent comb-like structure at high PMDA concentrations, the two initially low molar mass grades show a higher molar mass after processing with PMDA and seem to have a tree-like structure, which can be explained by the hydroxyl end group concentration of these two PET grades. The extensive use of TGDDM leads to a hyperbranched and gel-like structure. The fracture analysis from uniaxial elongation experiments reveals a limiting stress value for high PMDA concentrations and a limiting strain value for high TGDDM concentrations due to formation of a covalent network. The molecular analysis by SEC with triple detection of the high molar mass PET, which was reacted with PMDA and TGDDM, shows a strong increase of the average molar masses, polydispersity, radius of gyration, and hydrodynamic radius and confirms the molar mass increase observed by the rheological measurements. The branching was confirmed by a decreasing Mark-Houwink exponent with increasing chain extender concentration. Further, the analysis of the contraction of the molecule revealed a more star-like structure at low concentrations for both chain extenders. With increasing concentration, the structure changed to more comb-like for PMDA and random tree-like or hyperbranched for TGDDM as was also observed by non-linear viscoelastic measurements. PMDA revealed to be an excellent coupling agent which induces reproducibly either a star-like, comb-like, or tree-like structures depending on the concentration of coupling agent added and the hydroxyl concentration of the PET employed. Polyethylenterephthalat (PET) zeichnet sich durch hervorragende mechanische Eigenschaften, sowie chemische Beständigkeit und Barriereeigenschaften aus und findet insbesondere in der Verpackungsindustrie Verwendung. Die Neigung zur Degradation und die wegen der linearen Kettenmoleküle geringe Viskosität schränken jedoch die Verarbeitbarkeit von PET wie beispielsweise das Schäumen und Folienblasen erheblich ein. In der vorliegenden Arbeit wird der Einfluss der thermischen Stabilität während der Verarbeitung von drei linearen industriellen PET-Typen untersucht, die sich durch Molmasse und Herstellungsverfahren unterscheiden. Des Weiteren wird langkettenverzweigtes PET (LCBPET) durch reaktive Verarbeitung mit drei verschiedenen multifunktionalen Kettenverlängerern, Pyromellitsäuredianhydrid (PMDA), Tetra- glycidyl-Diamino-Diphenyl-Methan (TGDDM) und Triphenylphosphit (TPP), hergestellt und charakterisiert. Durch die experimentelle Bestimmung der linearen und nichtlinearen rheologischen Eigenschaften der Schmelze und ihre Beschreibung mit Hilfe des sogenannten "Molecular Stress Function" (MSF) Modells gelingt eine quantitative Analyse des Materialverhaltens. Die molekulare Analyse wird zusätzlich durch die Ergebnisse von Gelpermeationschromatographie (GPC bzw. SEC) in Verbindung mit Lichtstreumessung gestützt. Die Untersuchungen der thermischen Stabilität von linearem PET im linear-viskoelastischen Bereich zeigen einen abnehmenden Speichermodul und somit ein thermo-oxidatives Degradationsverhalten in Luftatmosphäre. In inerter Stickstoffatmosphäre tritt hingegen nur thermische Degradation auf, gleichzeitig führt jedoch eine Polykondensationsreaktion zu einem Anstiegen des Moduls [Kruse et al., 2013]. Mit einem exponentiellen Regressionsansatz kann der anfängliche Zustand des Moduls in beiden Atmosphären zum Zeitpunkt Null, der dem Einbringen der Probe in das Rheometer entspricht, rekonstruiert werden. Die sich aus diesem Ansatz ergebende Zeitkonstante erlaubt es, quantitative Zusammenhänge zwischen der thermischen Stabilität der drei PET-Sorten und deren Molmasse sowie dem Herstellungsverfahren der PET-Typen aufzuzeigen. So weist hochmolekulares PET eine höhere Stabilität in Stickstoff und eine geringere Stabilität in Luft auf und umgekehrt. Hauptursache für dieses Verhalten ist die unterschiedliche Konzentration an Hydroxylendgruppen, die je nach Molmasse und Herstellungsmethode der jeweiligen PET-Typen variiert. Mit Hilfe der "Time-Resolved Mechnical Sprectroscopy" konnte die sich ändernde Viskosität über ein weites Frequenzspektrum und zu einer beliebigen Messzeit in beiden Atmosphären bestimmt werden. Wesentliche Ergebnisse dieser Untersuchung sind der Nachweis des Auftretens von (i) einem Weichmachereffekt bedingt durch die thermische und thermo-oxidative Degradation und den daraus resultierenden Oligomeren, (ii) dreidimensionaler Vernetzung mit der Ausbildung einer Fließgrenze, (iii) Diffusionsprozessen, die Einfluss auf die Polykondensationsreaktion haben, (iv) Wandgleiten, bedingt durch die Ablagerung von Nebenprodukten auf den Platten des Rheometers und (v) einem verbreiterten Scherverdünnungbereich [Kruse and Wagner, 2016]. Die Extrusion von linearem PET mit einem Doppelschneckenextruder unter industriellen Bedingungen führt zu einer starken Abnahme der Viskosität, die hauptsächlich durch Scherung und weniger durch thermo-oxidativen Abbau verursacht wird. Bei der reaktiven Verarbeitung der drei PET-Typen mit den drei verschiedenen Kettenverlängerern erwies sich das dreifunktionale TPP auf Grund von Toxizität und Lagerinstabilitäten als unbrauchbar. Die Verarbeitung der beiden vierfunktionalen Kettenverlängerer, PMDA und das epoxidhaltige TGDDM, führt zu erhöhter Viskosität, erhöhter Dehnverfestigung und erhöhter thermischer Stabilität mit zunehmender Konzentration des jeweiligen Kettenverlängerers. Das beschriebene Verhalten zeigt sich sowohl am Speicher- und Verlustmodul und dem daraus abgeleiteten Verlustwinkel, als auch an der Fließaktivierungsenergie und der Dehnviskosität. Dabei lassen sich die gemessenen Dehnviskositäten sehr präzise mit dem MSF-Modell beschreiben und die beiden nichtlinearen Modelparameter, β und f_max^2 ermöglichen eine quantitative Analyse der Verzweigungsstruktur und der Molekülstreckung. So zeigt die Modifiziereng von hohen PMDA-Konzentrationen und dem hochmolekularen PET eine mehr kammartige Struktur im Vergleich zu den beiden niedermolekularen PET-Typen, die eine baumartige Molekülstruktur und eine höhere Molmasse nach der reaktiven Extrusion aufweisen. Beide Effekte können mit der höheren OH-Endgruppenkonzentration der beiden niedermolekularen PET-Typen erklärt werden. Zu hohe Zusätze von TGDDM führen zu einem hochverzweigten und gelartigen Polymer. Das Bruchverhalten bei der uniaxialen Dehnung von mit einem hohen Zusatz von PMDA hergestellten langkettenverzweigten PET wird von einer limitierenden Bruchspannung bestimmt. Demgegenüber bestimmt eine maximale Dehnung das Bruchverhalten des mit einem hohen TGDDM-Zusatz hergestellten LCB-PET, verursacht durch ein kovalent gebundenes Polymernetzwerk. Die GPC Messungen mit drei Detektoren wurden an LCB-PET durchgeführt, das auf Basis der hochmolekularen PET-Type hergestellt wurde. Die molekulare Analyse der mit PMDA und TGDDM modifizierten Proben zeigt eine deutliche Zunahme der mittleren Molmassen, Molmassenverteilungsbreite, des Gyrationsradius und des hydrodynamischen Radius und bestätigt somit die rheologischen Ergebnisse. Das Auftreten von Verzweigungen wird außerdem durch den abnehmenden Mark-Houwink-Exponenten bei zunehmender Additivkonzentration verdeutlicht. Eine genauere Betrachtung weist auf eine sternartige Molekülstruktur bei geringer Zugabe beider Kettenverlängerer hin. Bei erhöhter Zugabe hingegen tritt eine kammartige Struktur bei PMDA und eine baumartige oder hochverzweigte Struktur bei TGDDM auf, wie auch aus den nichtlinearen viskoelastischen Messungen zu schließen ist. Insbesondere PMDA erweist sich als hervorragender Kettenverlängerer, der bei reaktiver Extrusion reproduzierbar eine sternartige, kammartige oder baumartige Molekülstruktur in Abhängigkeit von der verwendeten PET-Type und der PMDA-Konzentration ermöglicht und so das Verarbeitungsspektrum von PET auf neue Anwendungsgebiete erweitert.
Additives are essential components of plastic formulations providing maintenance and modification of polymer properties, performance and long-term use. The book provides information on the many different plastic ingredients and their purpose with market information, theoretical background such as mechanisms, state-of-the-art technical solutions, applications and examples, synergisms and antagonisms, risk and future trends covering plastics recycling and biobased products.
Understanding the elastic properties of polymer melts is necessary for ensuring successful polymer processing and thus producing high-quality plastic parts. This unique book is the first to focus on this important topic. Starting with the molecular origin of elastic behavior and an explanation of the physical quantities involved, experimental methods and the dependence of elastic behavior on experimental parameters are then presented. Elastic properties of filled and unfilled systems are compared directly, and polymer blends are also considered. Elastic effects in various applications are included, such as in extrudate swell, internal stresses, and shrink films, to illustrate the importance of this field in the plastics processing industry.
The most current guide to solid state polymerization Solid State Polymerization (SSP)is an indispensable tool in the design, manufacture, and study of polymers, plastics, and fibers. SSP presents significant advantages over other polymerization techniques due to low operating temperatures, inexpensive equipment, and simple and environmentally sound procedures. Combining fundamentals of polymer science, chemistry, physical chemistry, and engineering, SSP also offers many research applications for a wide range of students and investigators. Gathering and filtering the latest literature on SSP, Solid Solid State Polymerization offers a unique, one-stop resource on this important process. With chapters contributed by leaders in the field, this text summarizes SSP, and provides essential coverage that includes: An introduction to SSP, with chemical and physical steps, apparatus, advantages, and parameters SSP physical chemistry and mechanisms Kinetic aspects of polyesters and polyamides SSP Catalysis in SSP processes Application of SSP under high pressure conditions in the laboratory Engineering aspects regarding process modeling and industrial application Recent developments and future possibilities Solid State Polymerization provides the most up-to-date coverage of this constantly developing field to academic and industry professionals, as well as graduate and postgraduate-level students in chemical engineering, materials science and engineering, polymer chemistry, polymer processing and polymer engineering.
Explore polymer rheology from an industrial standpoint Presenting state-of-the-art polymer rheology as observed by well-recognized authors, Applied Polymer Rheology: Polymeric Fluids with Industrial Applications is designed to help readers understand the relationship between molecular structure and the flow behavior of polymers. In particular, it focuses on polymeric systems that elicit special attention from industry. Providing a comprehensive overview of the rheological characteristics of polymeric fluids, the book bridges the gap between theory and practice/application, enabling readers to see the connection between molecular structure and the behavior of the polymers studied. Beginning with a discussion of the properties, processability, and processing aids of specific polymers, later chapters examine filled polymers and composites, and the theoretical framework upon which their analysis is based. Various systems containing microstructure are presented subsequently, with the final chapter introducing paste extrusion of polytetrafluoroethylene paste. An invaluable reference guide that covers the literature and vast array of technical approaches to polymer rheology, Applied Polymer Rheology's coverage of polymeric fluids of interest to industry make it an essential resource for plastics, polymer, and chemical engineers, materials scientists, polymer chemists, and polymer physicists to use when interpreting findings and planning experiments.
This handbook provides an exhaustive description of polyethylene. The 50+ chapters are written by some of the most experienced and prominent authors in the field, providing a truly unique view of polyethylene. The book starts with a historical discussion on how low density polyethylene was discovered and how it provided unique opportunities in the early days. New catalysts are presented and show how they created an expansion in available products including linear low density polyethylene, high density polyethylene, copolymers, and polyethylene produced from metallocene catalysts. With these different catalysts systems a wide range of structures are possible with an equally wide range of physical properties. Numerous types of additives are presented that include additives for the protection of the resin from the environment and processing, fillers, processing aids, anti-fogging agents, pigments, and flame retardants. Common processing methods including extrusion, blown film, cast film, injection molding, and thermoforming are presented along with some of the more specialized processing techniques such as rotational molding, fiber processing, pipe extrusion, reactive extrusion, wire and cable, and foaming processes. The business of polyethylene including markets, world capacity, and future prospects are detailed. This handbook provides the most current and complete technology assessments and business practices for polyethylene resins.
Multiphase Polylactide Blends: Toward a Sustainable and Green Environment guides the reader through fundamentals, science, preparation, and key areas of innovation in polylactide (PLA) blends. Bio-based polymers, and notably PLA, have not only gained increasing interest as a more sustainable alternative but also bring challenges in terms of mechanical, rheological, thermal and physical properties, processability, shapability, and foamability. The use of blends looks to address these, with the development of new types of economically viable and environmentally friendly systems. This is a valuable book for academic researchers, scientists, and graduate students across bio-based polymers, polymer science, chemistry, and materials science, as well as engineers, R&D professionals, and all those in industry with interest in PLA-based blends, biopolymers, and sustainable materials and products. More specifically, the first three chapters of this book overview the fundamentals of thermoplastic polymers, polymer blends, and structure and properties of PLA. These chapters could technically be used as a valuable textbook on the noted topics. The rest of the chapters inclusively study the fundamentals, investigations, and achievements in PLA-based blends with various types of polymers. These include miscible blends of poly L-lactide and poly D-lactide, binary immiscible/miscible blends of PLA with other thermoplastics and elastomers, PLA-based ternary blends and blend nanocomposites, as well as PLA-based blend foams. Overall, this book provides a thorough and critical overview of the state of the art in PLA-based blends, including significant past and recent advances, with the aim of supporting and shaping further research and industrial application of these materials for the development of a green and sustainable future. - Overviews the fundamentals of thermoplastic polymers, polymer blends, and the structure and properties of PLA. - Provides detailed coverage of the fundamentals and science of PLA blends, including phase miscibility, thermal and mechanical properties, interface and rheological properties, the use of compatibilizers, and phase morphological analysis. - Offers a thorough critical overview of the state of the art in processing and development of PLA-based blends, addressing key challenges and future perspectives. - Covers the latest advances, including PLA-based ternary blends, blend nanocomposites, and PLA-based blend microcellular foams.
In recent years, we have assisted the remarkable growth in the use of functional polyesters. This book gathers novel research works dealing with the manufacturing and characterization of polyesters that have been functionalized by synthesis, copolymerization, additives (at micro- and nanoscale), surface modification, among other methodologies, to tailor desired properties in terms of mechanical, chemical, thermal, and barrier properties, biodegradation, and biocompatibility. Thus, Advances in Manufacturing and Characterization of Functional Polyesters will serve to guide a diverse audience of polymer scientists and engineers and provides an update of the “state-of-the-art” knowledge on functional polyesters.
Polymers are used in everything from nylon stockings to commercial aircraft to artificial heart valves, and they have a key role in addressing international competitiveness and other national issues. Polymer Science and Engineering explores the universe of polymers, describing their properties and wide-ranging potential, and presents the state of the science, with a hard look at downward trends in research support. Leading experts offer findings, recommendations, and research directions. Lively vignettes provide snapshots of polymers in everyday applications. The volume includes an overview of the use of polymers in such fields as medicine and biotechnology, information and communication, housing and construction, energy and transportation, national defense, and environmental protection. The committee looks at the various classes of polymersâ€"plastics, fibers, composites, and other materials, as well as polymers used as membranes and coatingsâ€"and how their composition and specific methods of processing result in unparalleled usefulness. The reader can also learn the science behind the technology, including efforts to model polymer synthesis after nature's methods, and breakthroughs in characterizing polymer properties needed for twenty-first-century applications. This informative volume will be important to chemists, engineers, materials scientists, researchers, industrialists, and policymakers interested in the role of polymers, as well as to science and engineering educators and students.