From linear to long chain branched poly ethylene terephthalate reactive extrusion rheology and molecular characterization

However, its processing is determined by degradation and low viscosity. ... The
stability of three linear commercial PET grades produced by different synthesis
routes with different molar masses is analyzed in regards ... The mechanical and
molecular properties in melt state are analyzed by linear and non-linear
viscoelastic rheology, modeling by the ... The extrusion of neat PET with a twin-
screw extruder at industrial scale leads to strong reduction of viscosity mainly due
to shearing.

Author: Kruse, Matthias

Publisher: Universitätsverlag der TU Berlin

ISBN: 9783798328914

Category: Technology & Engineering

Page: 185

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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.
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Revue Roumaine de Chimie

Ursula Bologa “ Synthesis and Degradation , Rheology and Extrusion ” (
Advances in Polymer Science , vol . 47 ) , Springer - Verlag , Berlin , 1982 , 145
pages , 86 DM ( hard - cover ) . The topic of the first article “ Aromatic
Polybenzimidazoles ...

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ISBN: UCLA:L0064043631

Category: Chemistry

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New Technical Books

Synthesis and degradation . Rheology and extrusion . NY : SpringerVerlag , 1982
. 145 p . $ 37 . ... Some pro blems encountered with degradation mechanisms of
addition polymers . Entangled linear , branched and network polymer systems ...

Author: New York Public Library

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ISBN: UOM:39015036923285

Category: Engineering

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Synthesis Techniques for Polymer Nanocomposites

Covas, J.A., Nóbrega, J.M., and Maia, J.M. (2000) Rheological measurements
along an extruder with an on-line ... L., and O'Shea, M. (2006) Spectroscopic
probes for real-time monitoring of polymer modification and degradation
reactions.

Author: Vikas Mittal

Publisher: John Wiley & Sons

ISBN: 9783527334551

Category: Science

Page: 314

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The book series 'Polymer Nano-, Micro- and Macrocomposites' provides complete and comprehensive information on all important aspects of polymer composite research and development, including, but not limited to synthesis, filler modification, modeling, characterization as well as application and commercialization issues. Each book focuses on a particular topic and gives a balanced in-depth overview of the respective subfield of polymer composite science and its relation to industrial applications. With the books the readers obtain dedicated resources with information relevant to their research, thereby helping to save time and money. Summarizing all the most important synthesis techniques used in the lab as well as in industry, this book is comprehensive in its coverage from chemical, physical and mechanical viewpoints. This book helps readers to choose the correct synthesis route, such as suspension and miniemulsion polymerization, living polymerization, sonication, mechanical methods or the use of radiation, and so achieve the desired composite properties.
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Synthesis Structure and Properties of Poly lactic acid

Polym Degrad Stab 95:116–125 Taubner V, Shishoo R (2001) Influence of
processing parameters on the degradation of ... rheological and mechanical
properties of PLA, PBAT and their blends by reactive extrusion with
functionalized epoxy.

Author: Maria Laura Di Lorenzo

Publisher: Springer

ISBN: 9783319642307

Category: Technology & Engineering

Page: 350

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The series Advances in Polymer Science presents critical reviews of the present and future trends in polymer and biopolymer science. It covers all areas of research in polymer and biopolymer science including chemistry, physical chemistry, physics, material science.The thematic volumes are addressed to scientists, whether at universities or in industry, who wish to keep abreast of the important advances in the covered topics.Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.Review articles for the individual volumes are invited by the volume editors. Single contributions can be specially commissioned.Readership: Polymer scientists, or scientists in related fields interested in polymer and biopolymer science, at universities or in industry, graduate students
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Reactive Polymers Fundamentals and Applications

peroxide-promoted degradation, Polym. ... G. Moad, Corrigendum to “the
synthesis of polyolefin graft opolymers by reactive extrusion” [Prog. ... J.R. Beren,
A.J. de Nicola Jr., Controlled rheology formulations containing high melt strength
polypropylene for extrusion coating, US Patent Application 20 120 199 278,
Assigned to ...

Author: Johannes Karl Fink

Publisher: William Andrew

ISBN: 9781455731589

Category: Technology & Engineering

Page: 576

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The use of reactive polymers enables manufacturers to make chemical changes at a late stage in the production process—these in turn cause changes in performance and properties. Material selection and control of the reaction are essential to acheive optimal performance. The second edition of Reactive Polymers Fundamentals and Applications introduces engineers and scientists to the range of reactive polymers available, explains the reactions that take place, and details applications and performance benefits. Basic principles and industrial processes are described for each class of reactive resin (thermoset), as well as additives, the curing process, and applications and uses. The initial chapters are devoted to individual resin types (e.g. epoxides, cyanacrylates, etc.); followed by more general chapters on topics such as reactive extrusion and dental applications. Material new to this edition includes the most recent developments, applications and commercial products for each chemical class of thermosets, as well as sections on fabrication methods, reactive biopolymers, recycling of reactive polymers, and case studies. Injection molding of reactive polymers, radiation curing, thermosetting elastomers, and reactive extrusion equipment are all covered as well. Most comprehensive source of information about reactive polymers Covers basics as well as most recent developments, including reactive biopolymers, recycling of reactive polymers, nanocomposites, and fluorosilicones Indispensable guide for engineers and advanced students alike—providing extensive literature and patent review
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Polymeric Materials Encyclopedia Twelve Volume Set

Halterman , R . L . “ Synthesis and Applications of Chiral Cyclopentadienyl Metal
Complexes , ” Chem . Rev . ... 2 , 3 Because the MWD largely determines the
rheological properties of polypropylene melts , this parameter must be controlled
to improve the ... Modification of the polypropylene MWD during extrusion can be
generally achieved by thermal degradation or by peroxide - promoted
degradation .

Author: Joseph C. Salamone

Publisher: CRC Press

ISBN: 9781000714111

Category: Science

Page: 9600

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The Polymeric Materials Encyclopedia presents state-of-the-art research and development on the synthesis, properties, and applications of polymeric materials. This groundbreaking work includes the largest number of contributors in the world for a reference publication in polymer science, and examines many fields not covered in any other reference. With multiple articles on many subjects, the encyclopedia offers you a broad-based perspective on a multitude of topics, as well as detailed research information, figures, tables, illustrations, and references. Updates published as new research unfolds will continue to provide you with the latest advances in polymer science, and will keep the encyclopedia at the forefront of the field well into the future. From novices to experienced researchers in the field, anyone and everyone working in polymer science today needs this complete assessment of the state of the art. The entire 12-volume set will be available in your choice of printed or CD-ROM format.
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International Polymer Processing

Rheological Studies on Solutions of Poly - p - phenylene Terephthalamide in
H2SO4 258 State of Dispersion Mechanical Properties ... Rheometry see
Rheology , Testing Roll processor The Synthesis of Polymer Processing
Machines Rolltrusion see Rolling Rubber ... temperature dependence see
Rheology Viscracking see Degradation S Screw extrusion see Extrusion Sheet
molding compound ...

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ISBN: CORNELL:31924056746088

Category: Polymers

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Poly lactic acid

This book describes the synthesis, properties, and processing methods of poly(lactic acid) (PLA), an important family of degradable plastics.

Author: Rafael A. Auras

Publisher: John Wiley & Sons

ISBN: 1118088131

Category: Technology & Engineering

Page: 528

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This book describes the synthesis, properties, and processing methods of poly(lactic acid) (PLA), an important family of degradable plastics. As the need for environmentally-friendly packaging materials increases, consumers and companies are in search for new materials that are largely produced from renewable resources, and are recyclable. To that end, an overall theme of the book is the biodegradability, recycling, and sustainability benefits of PLA. The chapters, from a base of international expert contributors, describe specific processing methods, spectroscopy techniques for PLA analysis, and and applications in medical items, packaging, and environmental use.
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Textile Technology Digest

chemical modification , conference papers , molecular structure , polyethylene
terephthalate 07472 chemistry , developments ( technology ) , extrusion , fiber ...
opening , polymerization , preparation , rings 09046 crystal structure ,
degradation , films , microstructure 00156 crystal ... rheological properties , shear
, stresses , tensile strength , viscosity 07488 dendrimers , molecular structure ,
synthesis 00903 ...

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ISBN: CORNELL:31924063052629

Category: Textile fabrics

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Rheology Abstracts

... 223 Poisson solver , fourth - order , 305 polymerization processes , rheology in
, 535 polyampholytes synthesis and solution viscosity , 240 ... solutions of , shear
degradation in , 47 ultrasonic investigations , 111 viscosity , elongational , 331
viscosity - temperature relations ... properties , 750 die swell , 539 elongational
rheology , 108 , 143 , 546 , 650 extrusion of , 104 , 539 fatigue cracking and
fracture ...

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ISBN: UCAL:B4431812

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Reactive Extrusion Systems

The book succeeds as a three-part surve

Author: Leon P.B.M. Janssen

Publisher: CRC Press

ISBN: 0203014170

Category: Science

Page: 200

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Citing recently realized applications for extruders as polymerization, modification, and degradation reactors and presenting a telling array of new research results and illustrative experimental cases, Reactive Extrusion Systems sheds light on the complex set of interactions underlying reactions in extruders. The book succeeds as a three-part survey of the chemical phenomena behind reactive extrusion, mechanisms operant in particular reactions, and approaches to tackling advanced engineering problems. Written by an accomplished field authority, it works through issues involving scale-up from laboratory to production-size equipment, process stability, and more.
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Starch polycaprolactone Nanocomposites from Reactive Extrusion

... power - law model for biodegradable starch - PCL blends synthesized by
reactive extrusion . Nanoclay loadings , polymer ( starch ) degradation and
crosslinking in these blends affected their mechanical properties and rheological
behavior .

Author: Sathyanarayanan Balasubramanian Kalambur

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ISBN: CORNELL:31924102824541

Category:

Page: 242

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The objectives of this study were to evaluate the mechanical properties of reactively extruded starch-PCL nanocomposite blends, study changes in the morphology of polymer-polymer interface, monitor dispersion of organoclay in the polymer matrix, quantify the effects of reactive extrusion on polymer glass transition, develop a rheological model and scale up the reactive extrusion process from a batch type microextruder to continuous twin-screw extruder.
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Reactive Extrusion

This first comprehensive overview of reactive extrusion technology for over a decade combines the views of contributors from both academia and industry who share their experiences and highlight possible applications and markets.

Author: Günter Beyer

Publisher: John Wiley & Sons

ISBN: 9783527340989

Category: Science

Page: 432

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This first comprehensive overview of reactive extrusion technology for over a decade combines the views of contributors from both academia and industry who share their experiences and highlight possible applications and markets. They also provide updated information on the underlying chemical and physical concepts, summarizing recent developments in terms of the material and machinery used. As a result, readers will find here a compilation of potential applications for reactive extrusion to access new and cost-effective polymeric materials, while using existing compounding machines.
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Handbook of Polyolefins

Functionalized Polyolefins : Synthesis and Application in Blends and Composites
M. Avella , P. Laurienzo , M. ... promoted controlled degradation of PP during melt
extrusion , used for the production of controlled rheology ( CR ) grade resins .

Author: Cornelia Vasile

Publisher: CRC Press

ISBN: 0203908716

Category: Technology & Engineering

Page: 1032

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A handbook on polyolefins. This second edition includes new material on the structure, morphology and properties of polyolefin (PO) synthesis. It focuses on synthetic advances, the use of additives, special coverage of PO blends, composites and fibres, and surface treatments. It also addresses the problem of interfacial and superficial phenomena.
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Processing Fabrication and Manufacturing of Composite Materials 1992

Synthesis and shaping into filament form of polymeric precursors , followed by
pyrolysis under controlled environments ” , “ extrusion of ceramic ... ( i ) controlled
synthesis of precursor polymer with the potential for yielding fluids of spinnable
rheological characteristics and also ... However , infusibility of precursor polymer ,
possible uncontrolled degradation at the melt extrusion temperatures and lack of
( or ...

Author: American Society of Mechanical Engineers. Winter Meeting

Publisher: Amer Society of Mechanical

ISBN: UOM:39015029182485

Category: Technology & Engineering

Page: 265

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