Download or read book Developing Large Structural Parts for Railway Application Using a Fibre Reinforced Polymer Design written by Jan Prockat and published by Univerlagtuberlin. This book was released on 2005 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Structure and Constitutive Modelling of Polymer Melts written by Victor Hugo Rólon Garrido and published by Univerlagtuberlin. This book was released on 2007 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rheology and Engineering Parameters of Bitumen Modified with Polyolefins Elastomers and Reactive Polymers written by Manuel Navarro González and published by Univerlagtuberlin. This book was released on 2010 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book From linear to long chain branched poly ethylene terephthalate reactive extrusion rheology and molecular characterization written by Kruse, Matthias and published by Universitätsverlag der TU Berlin. This book was released on 2017-07-11 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Thermosets and Composites written by Michel Biron and published by Elsevier. This book was released on 2003-12-18 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: • A succinct source of information for designers and manufacturers.• A decision-making tool for those who need a quick and pragmatic account of thermosets and composites.• A synoptic account of the techno-economics and properties of all the commonly-used thermosets and composites.Designers and manufacturers using thermosets and composites, or those intending to do so, often need a succinct source of information on the economics and properties of these materials. This book provides a synoptic approach.It covers the economic importance of thermosets and composites, a comparison of the properties of the various thermoset categories, monographs on the nine principal families of thermosets, polymer composites and emergent materials and processes. Will enable readers to make informed decisions leading to well designed and made products.

Download or read book Composites for Automotive Applications written by C. D. Rudd and published by iSmithers Rapra Publishing. This book was released on 2000 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Various factors in the automotive sector have combined to create a favourable climate for the development of materials and fabrication techniques for polymer-based composite body panels and structures. The cond104 in which composites are used within the automotive industry has been reviewed in this report and those materials and processes that are used in the fabrication of components and structures are described in detail. For this reason, this report is essential reading for the composites, plastics industries and the land transport/automotive sectors. An additional indexed section containing several hundred abstracts from the Rapra Polymer Library database gives useful references for further reading.

Download or read book Magnesium Technology 2016 written by Alok Singh and published by Springer. This book was released on 2016-12-12 with total page 379 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Magnesium Technology Symposium, the event on which this collection is based, is one of the largest yearly gatherings of magnesium specialists in the world. Papers represent all aspects of the field, ranging from primary production to applications to recycling. Moreover, papers explore everything from basic research findings to industrialization. Magnesium Technology 2016 covers a broad spectrum of current topics, including alloys and their properties; cast products and processing; wrought products and processing; forming, joining, and machining; corrosion and surface finishing; ecology; and structural applications. In addition, there is coverage of new and emerging applications.

Download or read book Lightweight Thermoset Composites written by Peter W. Dufton and published by iSmithers Rapra Publishing. This book was released on 2000 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report reviewed some of the resin systems used for these lightc099 applications, the reinforcements employed and the techniques developed and used to convert them efficiently and as economically as possible into components and structures.

Download or read book Futures in Mechanics of Structures and Materials written by Thiru Aravinthan and published by CRC Press. This book was released on 2008-11-20 with total page 915 pages. Available in PDF, EPUB and Kindle. Book excerpt: Futures in Mechanics of Structures and Materials is a collection of peer-reviewed papers presented at the 20th Australasian Conference on the Mechanics of Structures and Materials (ACMSM20, University of Southern Queensland, Toowoomba, Queensland, Australia, 2 - 5 December 2008) by academics, researchers and practicing engineers mainly from Austral

Download or read book Mechanical Testing of Advanced Fibre Composites written by J M Hodgkinson and published by Elsevier. This book was released on 2000-10-27 with total page 379 pages. Available in PDF, EPUB and Kindle. Book excerpt: Testing of composite materials can present complex problems but is essential in order to ensure the reliable, safe and cost-effective performance of any engineering structure. This essentially practical book, complied from the contributions of leading professionals in the field, describes a wide range of test methods which can be applied to various types of advanced fibre composites. The book focuses on high modulus, high strength fibre/plastic composites and also covers highly anisotrpoic materials such as carbon, aramid and glass.Engineers and designers specifying the use of materials in structures will find this book an invaluable guide to best practice throughout the range of industrial sectors where FRCs are employed.

Download or read book International Polymer Science and Technology written by and published by . This book was released on 1982 with total page 832 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book MECHANICAL ENGINEERING ENERGY SYSTEMS AND SUSTAINABLE DEVELOPMENT Volume I written by Konstantin V. Frolov and published by EOLSS Publications. This book was released on 2009-04-15 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanical Engineering, Energy Systems and Sustainable Development theme is a component of Encyclopedia of Physical Sciences, Engineering and Technology Resources in the global Encyclopedia of Life Support Systems (EOLSS), which is an integrated compendium of twenty one Encyclopedias. The Theme on Mechanical Engineering, Energy Systems and Sustainable Development with contributions from distinguished experts in the field discusses mechanical engineering - the generation and application of heat and mechanical power and the design, production, and use of machines and tools. These five volumes are aimed at the following five major target audiences: University and College Students Educators, Professional Practitioners, Research Personnel and Policy Analysts, Managers, and Decision Makers, NGOs and GOs.

Download or read book Perspectives in Civil Engineering written by Jeffrey S. Russell and published by ASCE Publications. This book was released on 2003-01-01 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report contains 27 papers that serve as a testament to the state-of-the-art of civil engineering at the outset of the 21st century, as well as to commemorate the ASCE's Sesquicentennial. Written by the leading practitioners, educators, and researchers of civil engineering, each of these peer-reviewed papers explores a particular aspect of civil engineering knowledge and practice. Each paper explores the development of a particular civil engineering specialty, including milestones and future barriers, constraints, and opportunities. The papers celebrate the history, heritage, and accomplishments of the profession in all facets of practice, including construction facilities, special structures, engineering mechanics, surveying and mapping, irrigation and water quality, forensics, computing, materials, geotechnical engineering, hydraulic engineering, and transportation engineering. While each paper is unique, collectively they provide a snapshot of the profession while offering thoughtful predictions of likely developments in the years to come. Together the papers illuminate the mounting complexity facing civil engineering stemming from rapid growth in scientific knowledge, technological development, and human populations, especially in the last 50 years. An overarching theme is the need for systems-level approaches and consideration from undergraduate education through advanced engineering materials, processes, technologies, and design methods and tools. These papers speak to the need for civil engineers of all specialties to recognize and embrace the growing interconnectedness of the global infrastructure, economy, society, and the need to work for more sustainable, life-cycle-oriented solutions. While embracing the past and the present, the papers collected here clearly have an eye on the future needs of ASCE and the civil engineering profession.

Download or read book Aging and Durability of FRP Composites and Nanocomposites written by Arya Uthaman and published by Elsevier. This book was released on 2024-02-21 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The usage of composites is a broad and growing area of scientific research, especially in developed and developing countries. These materials are used in a broad range of applications in both structural and civil engineering sectors. In many of these applications FRPs are exposed to one or more environmental influences, so they need to be designed to meet durability requirements to withstand even the harshest of environments. Aging and Durability of FRP Composites and Nanocomposites focuses on the latest developments in durability and long-term ageing studies of composite materials especially for those used in civil and structural engineering applications. The book will be a valuable reference resource for materials scientists and engineers who want to learn more about the long-term service life and durability behaviour of composites under different environmental conditions. - Discusses composites and polymer nanocomposites - Reviews different types of aging processes and degradation mechanisms in composites - Covers different types of accelerated aging tests - Presents theory, modeling, and simulation studies of aged composites and nanocomposites - Looks at recent trends and future possibilities

Download or read book Composites Science and Technology written by R. C. Prasad and published by New Age International. This book was released on 2000 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Advent Of Lightweight, High Strength, Corrosion And Damage Resistant Composites In A Major Breakthrough, Revolutionizing The Use Of Materials In Many High Performance Application. Extensive Scientific Research And Technological Developments Have Resulted In The Production Of Variety Of Composites Vital To Aerospace, Automotive, Medical, Defence, Sporting Goods, Building Materials, Electronic And Marine Applications.Since Composites Are Versatile And Capable Of Being Tailored To Specific Requirements Newer Application Areas Are Opening Up. The Contributions To This Book Have Been Made By Leading Experts Important Topics Covered Include: * Composite Materials Science And Technology * Research And Development In Metal Matrix Composites * Advanced Polymer Composite * Carbon Fibre Composites * Fabrication, Repair And Analysis * Structure And Properties * Environmental Effects.This Book Is A Valuable Resource To Sciencetists And Engineers, Research Establishments And Industries. It Will Also Be Very Helpful To Undergraduate And Post Graduate Students In Enhancing Their Knowledge Of This Interdisciplinary Area.

Download or read book Advances in Potato Chemistry and Technology written by Jaspreet Singh and published by Academic Press. This book was released on 2009-07-22 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developments in potato chemistry, including identification and use of the functional components of potatoes, genetic improvements and modifications that increase their suitability for food and non-food applications, the use of starch chemistry in non-food industry and methods of sensory and objective measurement have led to new and important uses for this crop. Advances in Potato Chemistry and Technology presents the most current information available in one convenient resource.The expert coverage includes details on findings related to potato composition, new methods of quality determination of potato tubers, genetic and agronomic improvements, use of specific potato cultivars and their starches, flours for specific food and non-food applications, and quality measurement methods for potato products. - Covers potato chemistry in detail, providing key understanding of the role of chemical compositions on emerging uses for specific food and non-food applications - Presents coverage of developing areas, related to potato production and processing including genetic modification of potatoes, laboratory and industry scale sophistication, and modern quality measurement techniques to help producers identify appropriate varieties based on anticipated use - Explores novel application uses of potatoes and potato by-products to help producers identify potential areas for development of potato variety and structure

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1969 with total page 736 pages. Available in PDF, EPUB and Kindle. Book excerpt: