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Migration and community in Bronze Age Orkney: innovation and continuity at the Links of Noltland
- Hazel Moore, Graeme Wilson, Mairead Ni Challanain, Maeve McCormick, Peter D. Marshall, Katharina Dulias, M. George B. Foody, Pierre Justeau, Maria Pala, Martin B. Richards, Ceiridwen J. Edwards
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The remarkable archaeological record of Neolithic Orkney has ensured that these islands play a prominent role in narratives of European late prehistory, yet knowledge of the subsequent Bronze Age is comparatively poor. The Bronze Age settlement and cemetery at the Links of Noltland, on the island of Westray, offers new evidence, including aDNA, that points to a substantial population replacement between the Late Neolithic and Bronze Age. Focusing on funerary practice, the authors argue for interconnecting identities centred on household and community, patrilocality and inheritance. The findings prompt a reconsideration of the Orcadian Bronze Age, with wider implications for population movement and the uptake of cultural innovations more widely across prehistoric north-western Europe.
Correlates of long-term land-cover change and protected area performance at priority conservation sites in Africa
- ALISON E. BERESFORD, GRAEME M. BUCHANAN, BEN PHALAN, GEORGE W. ESHIAMWATA, ANDREW BALMFORD, ANDREAS B. BRINK, LINCOLN D.C. FISHPOOL, PAUL F. DONALD
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- Environmental Conservation / Volume 45 / Issue 1 / March 2018
- Published online by Cambridge University Press:
- 28 March 2017, pp. 49-57
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The loss of natural habitats is a major threat to biodiversity, and protected area designation is one of the standard responses to this threat. However, greater understanding of the drivers of habitat loss and of the circumstances under which protected areas succeed or fail is still needed. We use visual assessment of satellite images to quantify land-cover change over periods of up to 30 years in and around a matched sample of protected and unprotected Important Bird and Biodiversity Areas (IBAs) in Africa. We modelled the annual survival of forests and other natural land covers as a function of a range of environmental and anthropic predictors of plausible drivers. The best-supported model indicated that survival rates of natural land cover were highest in steeper areas, at higher altitudes, in areas with lower human population densities and in areas where the cover of natural habitats was already higher at the start of the period. Survival rates of natural land cover in protected areas were, on average, around twice those in unprotected areas, but the differences between them varied along different environmental gradients. The overall survival rates of both protected and unprotected forests were significantly lower than those of other natural land-cover types, but the net benefit of protection, in terms of the absolute difference in rates of loss between protected and unprotected sites, was higher in forests. Interaction terms indicated that as slope and altitude increased, the natural protection offered by topography increasingly nullified the additional benefits of legislative protection. Furthermore, protected area designation offered reduced additional benefits to the survival of natural land cover in areas where rates of conversion were higher at the start of the observation period. Variation in the impacts of protected area status along different environmental gradients indicates that targets to improve the world's protected area network, such as Aichi Target 11 of the Convention on Biological Diversity, need to look beyond simple area-based metrics. Our methods and results contribute to the development of a protocol for prioritizing places where protection is likely to have the greatest effect.
Contributors
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- By Mitchell Aboulafia, Frederick Adams, Marilyn McCord Adams, Robert M. Adams, Laird Addis, James W. Allard, David Allison, William P. Alston, Karl Ameriks, C. Anthony Anderson, David Leech Anderson, Lanier Anderson, Roger Ariew, David Armstrong, Denis G. Arnold, E. J. Ashworth, Margaret Atherton, Robin Attfield, Bruce Aune, Edward Wilson Averill, Jody Azzouni, Kent Bach, Andrew Bailey, Lynne Rudder Baker, Thomas R. Baldwin, Jon Barwise, George Bealer, William Bechtel, Lawrence C. Becker, Mark A. Bedau, Ernst Behler, José A. Benardete, Ermanno Bencivenga, Jan Berg, Michael Bergmann, Robert L. Bernasconi, Sven Bernecker, Bernard Berofsky, Rod Bertolet, Charles J. Beyer, Christian Beyer, Joseph Bien, Joseph Bien, Peg Birmingham, Ivan Boh, James Bohman, Daniel Bonevac, Laurence BonJour, William J. Bouwsma, Raymond D. Bradley, Myles Brand, Richard B. Brandt, Michael E. Bratman, Stephen E. Braude, Daniel Breazeale, Angela Breitenbach, Jason Bridges, David O. Brink, Gordon G. Brittan, Justin Broackes, Dan W. Brock, Aaron Bronfman, Jeffrey E. Brower, Bartosz Brozek, Anthony Brueckner, Jeffrey Bub, Lara Buchak, Otavio Bueno, Ann E. Bumpus, Robert W. Burch, John Burgess, Arthur W. Burks, Panayot Butchvarov, Robert E. Butts, Marina Bykova, Patrick Byrne, David Carr, Noël Carroll, Edward S. Casey, Victor Caston, Victor Caston, Albert Casullo, Robert L. Causey, Alan K. L. Chan, Ruth Chang, Deen K. Chatterjee, Andrew Chignell, Roderick M. Chisholm, Kelly J. Clark, E. J. Coffman, Robin Collins, Brian P. Copenhaver, John Corcoran, John Cottingham, Roger Crisp, Frederick J. Crosson, Antonio S. Cua, Phillip D. Cummins, Martin Curd, Adam Cureton, Andrew Cutrofello, Stephen Darwall, Paul Sheldon Davies, Wayne A. Davis, Timothy Joseph Day, Claudio de Almeida, Mario De Caro, Mario De Caro, John Deigh, C. F. Delaney, Daniel C. Dennett, Michael R. DePaul, Michael Detlefsen, Daniel Trent Devereux, Philip E. Devine, John M. Dillon, Martin C. Dillon, Robert DiSalle, Mary Domski, Alan Donagan, Paul Draper, Fred Dretske, Mircea Dumitru, Wilhelm Dupré, Gerald Dworkin, John Earman, Ellery Eells, Catherine Z. Elgin, Berent Enç, Ronald P. Endicott, Edward Erwin, John Etchemendy, C. Stephen Evans, Susan L. Feagin, Solomon Feferman, Richard Feldman, Arthur Fine, Maurice A. Finocchiaro, William FitzPatrick, Richard E. Flathman, Gvozden Flego, Richard Foley, Graeme Forbes, Rainer Forst, Malcolm R. Forster, Daniel Fouke, Patrick Francken, Samuel Freeman, Elizabeth Fricker, Miranda Fricker, Michael Friedman, Michael Fuerstein, Richard A. Fumerton, Alan Gabbey, Pieranna Garavaso, Daniel Garber, Jorge L. A. Garcia, Robert K. Garcia, Don Garrett, Philip Gasper, Gerald Gaus, Berys Gaut, Bernard Gert, Roger F. Gibson, Cody Gilmore, Carl Ginet, Alan H. Goldman, Alvin I. Goldman, Alfonso Gömez-Lobo, Lenn E. Goodman, Robert M. Gordon, Stefan Gosepath, Jorge J. E. Gracia, Daniel W. Graham, George A. Graham, Peter J. Graham, Richard E. Grandy, I. Grattan-Guinness, John Greco, Philip T. Grier, Nicholas Griffin, Nicholas Griffin, David A. Griffiths, Paul J. Griffiths, Stephen R. Grimm, Charles L. Griswold, Charles B. Guignon, Pete A. Y. Gunter, Dimitri Gutas, Gary Gutting, Paul Guyer, Kwame Gyekye, Oscar A. Haac, Raul Hakli, Raul Hakli, Michael Hallett, Edward C. Halper, Jean Hampton, R. James Hankinson, K. R. Hanley, Russell Hardin, Robert M. Harnish, William Harper, David Harrah, Kevin Hart, Ali Hasan, William Hasker, John Haugeland, Roger Hausheer, William Heald, Peter Heath, Richard Heck, John F. Heil, Vincent F. Hendricks, Stephen Hetherington, Francis Heylighen, Kathleen Marie Higgins, Risto Hilpinen, Harold T. Hodes, Joshua Hoffman, Alan Holland, Robert L. Holmes, Richard Holton, Brad W. Hooker, Terence E. Horgan, Tamara Horowitz, Paul Horwich, Vittorio Hösle, Paul Hoβfeld, Daniel Howard-Snyder, Frances Howard-Snyder, Anne Hudson, Deal W. Hudson, Carl A. Huffman, David L. Hull, Patricia Huntington, Thomas Hurka, Paul Hurley, Rosalind Hursthouse, Guillermo Hurtado, Ronald E. Hustwit, Sarah Hutton, Jonathan Jenkins Ichikawa, Harry A. Ide, David Ingram, Philip J. Ivanhoe, Alfred L. Ivry, Frank Jackson, Dale Jacquette, Joseph Jedwab, Richard Jeffrey, David Alan Johnson, Edward Johnson, Mark D. Jordan, Richard Joyce, Hwa Yol Jung, Robert Hillary Kane, Tomis Kapitan, Jacquelyn Ann K. Kegley, James A. Keller, Ralph Kennedy, Sergei Khoruzhii, Jaegwon Kim, Yersu Kim, Nathan L. King, Patricia Kitcher, Peter D. Klein, E. D. Klemke, Virginia Klenk, George L. Kline, Christian Klotz, Simo Knuuttila, Joseph J. Kockelmans, Konstantin Kolenda, Sebastian Tomasz Kołodziejczyk, Isaac Kramnick, Richard Kraut, Fred Kroon, Manfred Kuehn, Steven T. Kuhn, Henry E. Kyburg, John Lachs, Jennifer Lackey, Stephen E. Lahey, Andrea Lavazza, Thomas H. Leahey, Joo Heung Lee, Keith Lehrer, Dorothy Leland, Noah M. Lemos, Ernest LePore, Sarah-Jane Leslie, Isaac Levi, Andrew Levine, Alan E. Lewis, Daniel E. Little, Shu-hsien Liu, Shu-hsien Liu, Alan K. L. Chan, Brian Loar, Lawrence B. Lombard, John Longeway, Dominic McIver Lopes, Michael J. Loux, E. J. Lowe, Steven Luper, Eugene C. Luschei, William G. Lycan, David Lyons, David Macarthur, Danielle Macbeth, Scott MacDonald, Jacob L. Mackey, Louis H. Mackey, Penelope Mackie, Edward H. Madden, Penelope Maddy, G. B. Madison, Bernd Magnus, Pekka Mäkelä, Rudolf A. Makkreel, David Manley, William E. Mann (W.E.M.), Vladimir Marchenkov, Peter Markie, Jean-Pierre Marquis, Ausonio Marras, Mike W. Martin, A. P. Martinich, William L. McBride, David McCabe, Storrs McCall, Hugh J. McCann, Robert N. McCauley, John J. McDermott, Sarah McGrath, Ralph McInerny, Daniel J. McKaughan, Thomas McKay, Michael McKinsey, Brian P. McLaughlin, Ernan McMullin, Anthonie Meijers, Jack W. Meiland, William Jason Melanson, Alfred R. Mele, Joseph R. Mendola, Christopher Menzel, Michael J. Meyer, Christian B. Miller, David W. Miller, Peter Millican, Robert N. Minor, Phillip Mitsis, James A. Montmarquet, Michael S. Moore, Tim Moore, Benjamin Morison, Donald R. Morrison, Stephen J. Morse, Paul K. Moser, Alexander P. D. Mourelatos, Ian Mueller, James Bernard Murphy, Mark C. Murphy, Steven Nadler, Jan Narveson, Alan Nelson, Jerome Neu, Samuel Newlands, Kai Nielsen, Ilkka Niiniluoto, Carlos G. Noreña, Calvin G. Normore, David Fate Norton, Nikolaj Nottelmann, Donald Nute, David S. Oderberg, Steve Odin, Michael O’Rourke, Willard G. Oxtoby, Heinz Paetzold, George S. Pappas, Anthony J. Parel, Lydia Patton, R. P. Peerenboom, Francis Jeffry Pelletier, Adriaan T. Peperzak, Derk Pereboom, Jaroslav Peregrin, Glen Pettigrove, Philip Pettit, Edmund L. Pincoffs, Andrew Pinsent, Robert B. Pippin, Alvin Plantinga, Louis P. Pojman, Richard H. Popkin, John F. Post, Carl J. Posy, William J. Prior, Richard Purtill, Michael Quante, Philip L. Quinn, Philip L. Quinn, Elizabeth S. Radcliffe, Diana Raffman, Gerard Raulet, Stephen L. Read, Andrews Reath, Andrew Reisner, Nicholas Rescher, Henry S. Richardson, Robert C. Richardson, Thomas Ricketts, Wayne D. Riggs, Mark Roberts, Robert C. Roberts, Luke Robinson, Alexander Rosenberg, Gary Rosenkranz, Bernice Glatzer Rosenthal, Adina L. Roskies, William L. Rowe, T. M. Rudavsky, Michael Ruse, Bruce Russell, Lilly-Marlene Russow, Dan Ryder, R. M. Sainsbury, Joseph Salerno, Nathan Salmon, Wesley C. Salmon, Constantine Sandis, David H. Sanford, Marco Santambrogio, David Sapire, Ruth A. Saunders, Geoffrey Sayre-McCord, Charles Sayward, James P. Scanlan, Richard Schacht, Tamar Schapiro, Frederick F. Schmitt, Jerome B. Schneewind, Calvin O. Schrag, Alan D. Schrift, George F. Schumm, Jean-Loup Seban, David N. Sedley, Kenneth Seeskin, Krister Segerberg, Charlene Haddock Seigfried, Dennis M. Senchuk, James F. Sennett, William Lad Sessions, Stewart Shapiro, Tommie Shelby, Donald W. Sherburne, Christopher Shields, Roger A. Shiner, Sydney Shoemaker, Robert K. Shope, Kwong-loi Shun, Wilfried Sieg, A. John Simmons, Robert L. Simon, Marcus G. Singer, Georgette Sinkler, Walter Sinnott-Armstrong, Matti T. Sintonen, Lawrence Sklar, Brian Skyrms, Robert C. Sleigh, Michael Anthony Slote, Hans Sluga, Barry Smith, Michael Smith, Robin Smith, Robert Sokolowski, Robert C. Solomon, Marta Soniewicka, Philip Soper, Ernest Sosa, Nicholas Southwood, Paul Vincent Spade, T. L. S. Sprigge, Eric O. Springsted, George J. Stack, Rebecca Stangl, Jason Stanley, Florian Steinberger, Sören Stenlund, Christopher Stephens, James P. Sterba, Josef Stern, Matthias Steup, M. A. Stewart, Leopold Stubenberg, Edith Dudley Sulla, Frederick Suppe, Jere Paul Surber, David George Sussman, Sigrún Svavarsdóttir, Zeno G. Swijtink, Richard Swinburne, Charles C. Taliaferro, Robert B. Talisse, John Tasioulas, Paul Teller, Larry S. Temkin, Mark Textor, H. S. Thayer, Peter Thielke, Alan Thomas, Amie L. Thomasson, Katherine Thomson-Jones, Joshua C. Thurow, Vzalerie Tiberius, Terrence N. Tice, Paul Tidman, Mark C. Timmons, William Tolhurst, James E. Tomberlin, Rosemarie Tong, Lawrence Torcello, Kelly Trogdon, J. D. Trout, Robert E. Tully, Raimo Tuomela, John Turri, Martin M. Tweedale, Thomas Uebel, Jennifer Uleman, James Van Cleve, Harry van der Linden, Peter van Inwagen, Bryan W. Van Norden, René van Woudenberg, Donald Phillip Verene, Samantha Vice, Thomas Vinci, Donald Wayne Viney, Barbara Von Eckardt, Peter B. M. Vranas, Steven J. Wagner, William J. Wainwright, Paul E. Walker, Robert E. Wall, Craig Walton, Douglas Walton, Eric Watkins, Richard A. Watson, Michael V. Wedin, Rudolph H. Weingartner, Paul Weirich, Paul J. Weithman, Carl Wellman, Howard Wettstein, Samuel C. Wheeler, Stephen A. White, Jennifer Whiting, Edward R. Wierenga, Michael Williams, Fred Wilson, W. Kent Wilson, Kenneth P. Winkler, John F. Wippel, Jan Woleński, Allan B. Wolter, Nicholas P. Wolterstorff, Rega Wood, W. Jay Wood, Paul Woodruff, Alison Wylie, Gideon Yaffe, Takashi Yagisawa, Yutaka Yamamoto, Keith E. Yandell, Xiaomei Yang, Dean Zimmerman, Günter Zoller, Catherine Zuckert, Michael Zuckert, Jack A. Zupko (J.A.Z.)
- Edited by Robert Audi, University of Notre Dame, Indiana
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- The Cambridge Dictionary of Philosophy
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- 05 August 2015
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- 27 April 2015, pp ix-xxx
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Control of an Outbreak of Carbapenem-Resistant Acinetobacter baumannii in Australia after Introduction of Environmental Cleaning with a Commercial Oxidizing Disinfectant
- Michelle Doidge, Anthony M. Allworth, Marion Woods, Penelope Marshall, Michael Terry, Kathryn O'Brien, Hwee Mian Goh, Narelle George, Graeme R. Nimmo, Mark A. Schembri, Jeffrey Lipman, David L. Paterson
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- Infection Control & Hospital Epidemiology / Volume 31 / Issue 4 / April 2010
- Published online by Cambridge University Press:
- 02 January 2015, pp. 418-420
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- April 2010
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In the midst of an outbreak, carbapenem-resistant Acinetobacter baumannii was grown from samples of multiple environmental sites in an intensive care unit. A commercial oxidizing disinfectant (potassium peroxomonosulphate 50%, sodium alkyl benzene sulphonate 15%, and sulphamic acid 5%) was introduced throughout the intensive care unit, and its use coincided with cessation of the outbreak.
6 - Industrial technologies, chemorheological modelling and process modelling for processing reactive polymers
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp 375-434
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Summary
Introduction
The aim of this chapter is to describe a range of industrial processing technologies for reactive polymer systems, and specifically to
characterise the process and highlight important processing-quality-control tests, process variables and typical systems used,
highlight applications of chemorheology in the process and
examine the use of chemorheology in modelling of the production process.
In this way we will be bringing the concepts and understanding from all subsequent chapters into practical processing applications in order to aid acquisition of deeper understanding of these processes.
Casting
Process diagram and description
Casting is a relatively simple process (Figure 6.1) involving the pouring of a thermosetting liquid into a mould, where the liquid hardens into a solid, dimensionally-stable shape.
Examples of products include rod stocks, spheres, gears, bushings and complex moulded items. In casting applications structural properties such as hardness, toughness, dimensional stability and machinability are of most interest.
Quality-control tests and important process variables
Important process variables include
cost
viscosity
reaction exotherm
shrinkage
pot life
Cost is typically reduced by minimizing the amount of resin used (either via incorporation of fillers or modifiers, or by foaming). Viscosity is critical for casting operations, in which requirements concerning ease of processibility and large loadings of fillers need to be optimized. Exotherms typically pose processing problems for large casting masses since the cure reaction evolves >100 kJ/mol (Section 3.2.2), which may be reduced by incorporation of fillers, modifiers and the correct curing agent at an optimum concentration.
Index
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 28 May 2009, pp 440-443
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3 - Chemical and physical analyses for reactive polymers
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp 195-320
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Summary
Monitoring physical and chemical changes during reactive processing
Reactive processing involves the production of a novel polymer as a result of chemical reactions that occur during the processing operation. These changes may be deliberate, as in functionalization, or inadvertent, as in chain scission due to undesired thermo- or mechano-chemistry. Section 1.4 gave the chemical changes to be expected when a thermoplastic polymer is subjected to elevated temperature for a period of minutes in the presence or absence of an oxidative atmosphere (Scott, 1993, Zweifel, 1998). For example, there will be the appearance of higher oxidation states of carbon such as in ether, alcohol, ketone and acid groups. These often accompany chain scission, which occurs during the free-radical-initiated oxidation chain reaction. In addition, there may be other chemical changes, such as grafting and functionalization, in which new chemical species are added to the polymer backbone in the course of the processing operation. The initiation of the oxidation, grafting or functionalization reactions will be through added initiator such as an organic peroxide and the novel chemistry will involve a monomer or other grafting agent, neither of which will necessarily be totally consumed during the reaction sequence. The measurement of the concentration profiles of these reagents as a function of time and, if possible, position in the reaction zone is crucial to the development of an understanding of the link between the chemical and rheological changes of the novel polymer system during processing.
Glossary of commonly used terms
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp 435-439
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Preface
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp ix-x
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Summary
Plastics are the most diverse materials in use in our society and the way that they are processed controls their structure and properties. The increasing reliance on plastics for high-value and high-performance applications necessitates the investment in new ways of manufacturing polymers. One way of achieving this is through reactive processing. However, the dynamics of reactive processes places new demands on characterization, monitoring the systems and controlling the complete manufacturing process.
This book provides an in-depth examination of reactive polymers and processing, firstly by examining the necessary fundamentals of polymer chemistry and physics. Polymer characterization tools related to reactive polymer systems are then presented in detail with emphasis on techniques that can be adapted to real-time process monitoring. The core of the book then focuses on understanding and modelling of the flow behaviour of reactive polymers (chemorheology). Chemorheology is complex because it involves the changing chemistry, rheology and physical properties of reactive polymers and the complex interplay among these properties. The final chapter then examines a range of industrial reactive polymer processes, and gives an insight into current chemorheological models and tools used to describe and control each process.
This book differs from many other texts on reactive polymers due to its
breadth across thermoset and reactive polymers in-depth consideration of fundamentals of polymer chemistry and physics focus on chemorheological characterization and modelling extension to practical industrial processes
The book has been aimed at chemists, chemical engineers and polymer process engineers at the advanced-undergraduate, post-graduate coursework and research levels as well as industrial practitioners wishing to move into reactive polymer systems.
4 - Chemorheological techniques for reactive polymers
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp 321-350
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Summary
Introduction
This chapter highlights the importance of chemorheology in determining cure properties of reactive systems. A brief introduction to experimental rheology has been provided in Chapter 3 to provide a baseline knowledge of experimental rheology. In this chapter we examine a description of chemorheology in terms of basic chemorheology, chemoviscosity, gelation and vitrification transitions and ultimate properties. Finally, examples of chemorheological analysis will be discussed. (We will briefly summarize chemorheological data and models in this chapter, but only for reference to chemorheological testing. A more extensive examination of chemorheology and modelling of systems will be presented in Chapter 5.)
Chemorheology
The definition of chemorheology (in this text) is the study of the deformation properties of reactive polymer systems. Figure 4.1 shows a schematic representation of the structural development during thermoset cure.
Step (a) shows unreacted monomers, and cure proceeds to step (b), at which there is the formation of some branched molecules. By step (c) the cure has progressed to the gel point, such that an infinite network is formed across the whole structure. Further cure can occur to point (d), at which the material becomes fully cured and vitrification is reached.
The essential elements of a chemorheological study are
fundamental chemorheology
chemoviscosity profiles
gelation
vitrification
ultimate chemorheological properties
modelling
We shall focus on modelling in Chapter 5.
1 - Chemistry and structure of reactive polymers
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp 1-168
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Summary
The purpose of this chapter is to provide the background principles from polymer physics and chemistry which are essential to understanding the role which chemorheology plays in guiding the design and production of novel thermoplastic polymers as well as the complex changes which occur during processing. The focus is on high-molar-mass synthetic polymers and their modification through chemical reaction and blending, as well as degradation reactions. While some consideration is given to the chemistry of multifunctional systems, Chapter 2 focuses on the physical changes and time—temperature-transformation properties of network polymers and thermosets that are formed by reactions during processing.
The attention paid to the polymer solid state is minimized in favour of the melt and in this chapter the static properties of the polymer are considered, i.e. properties in the absence of an external stress as is required for a consideration of the rheological properties. This is addressed in detail in Chapter 3. The treatment of the melt as the basic system for processing introduces a simplification both in the physics and in the chemistry of the system. In the treatment of melts, the polymer chain experiences a mean field of other nearby chains. This is not the situation in dilute or semi-dilute solutions, where density fluctuations in expanded chains must be addressed. In a similar way the chemical reactions which occur on processing in the melt may be treated through a set of homogeneous reactions, unlike the highly heterogeneous and diffusion-controlled chemical reactions in the solid state.
Contents
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp v-viii
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5 - Chemorheology and chemorheological modelling
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp 351-374
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Summary
Introduction
Chapters 3 and 4 presented chemical, physical and chemorheological techniques useful for characterizing various reactive polymer systems. This chapter will now focus on a review of chemorheological analyses for a variety of polymer systems, including detailed experimental findings and chemorheological modeling.
Chemoviscosity and chemorheological models
Chemorheology is defined as the study of the viscoelastic behaviour of reacting polymer systems. This involves examining the effects on chemoviscosity of chemical reactions (cure conversion, cure kinetics) and processing conditions (temperatures, shear rates), as well as gelation and vitrification. In Chapter 4 we briefly summarized chemoviscosity models that highlight effects of cure (ηc=ηc(Τ, α)), shear rate (ηsr=ηsr(γ, Τ)) and filler (ηf=ηf(F, Τ, t)) in Tables 4.4–4.6. This chapter will examine the development of chemorheology and chemorheological modelling in more detail by examining the chemorheology and chemoviscosity models of unfilled reactive systems, overviewing the effects of fillers on chemoviscosity and then presenting chemoviscosity data and models for filled systems. It is hoped that, by presenting the data and models in more depth, a better understanding of the chemorheology of systems will be obtained.
Neat systems
Chemorheological models for neat (unfilled) curing systems can be grouped into the following categories:
simple empirical models
Arrhenius models
structural and free-volume models
probability-based and molecular models
Simple empirical models
Malkin and Kulichikin (1991) initially reviewed the rheokinetics of cured polymers and highlighted the first empirical chemorheological models.
Chemorheology of Polymers
- From Fundamental Principles to Reactive Processing
- Peter J. Halley, Graeme A. George
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- Published online:
- 14 August 2009
- Print publication:
- 28 May 2009
-
Understanding the dynamics of reactive polymer processes allows scientists to create new, high value, high performance polymers. Chemorheology of Polymers provides an indispensable resource for researchers and practitioners working in this area, describing theoretical and industrial approaches to characterising the flow and gelation of reactive polymers. Beginning with an in-depth treatment of the chemistry and physics of thermoplastics, thermoset and reactive polymers, the core of the book focuses on fundamental characterization of reactive polymers, rheological (flow characterization) techniques and the kinetic and chemorheological models of these systems. Uniquely, the coverage extends to a complete review of the practical industrial processes used for these polymers and an insight into the current chemorheological models and tools used to describe and control each process. This book will appeal to polymer scientists working on reactive polymers within materials science, chemistry and chemical engineering departments as well as polymer process engineers in industry.
2 - Physics and dynamics of reactive polymers
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp 169-194
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Summary
Chapter rationale
This chapter focusses on the physical properties and models of network and reactively modified polymers. Understanding changes in physical properties during curing, in tandem with changes in chemical properties (Chapter 1), and chemorheological properties (Chapter 4), is essential to fully characterizing network and reactively modified polymer systems. This chapter will first give a brief introduction to polymer physics and dynamics before focussing on redefining network and reactively modified polymer systems. Then it will focus on defining the key changes in physical properties during cure. Finally this chapter will focus on key experimental techniques for describing changes in physical properties during cure.
Polymer physics and dynamics
Chapter 1 has already introduced basic concepts of polymers relating to their physical nature, such as crystalline and amorphous regions, molar mass, glass transition and rubbery regions. This section will focus on developing further basic polymer-physics and polymer-dynamics concepts that will be pertinent to reactive polymer systems. Specifically we will be interested in examining the physics behind polymer dynamics — to understand how to characterize the dynamics and stress behaviour of polymers under deformation and flow. This will be essential background for the chemorheology of polymer systems.
Polymer physics and motion — early models
Polymer chains consist of large molecules (macromolecules), which are composed of multiple repetition of one or more species of atoms or groups of atoms that are interlinked.
Frontmatter
- Peter J. Halley, Graeme A. George
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- Chemorheology of Polymers
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- 14 August 2009
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- 28 May 2009, pp i-iv
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Characterizing the Dopant Behavior of Functionalized Carbon Nanotubes in Conducting Polymers
- Mark Hughe, Graeme A. Snook, George Z. Chen, Milo S. P. Shaffer, Derek J. Fray, Alan H. Windle
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- Journal:
- MRS Online Proceedings Library Archive / Volume 788 / 2003
- Published online by Cambridge University Press:
- 01 February 2011, L12.11
- Print publication:
- 2003
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The electrochemical polymerization of conducting polymers, such as polypyrrole, generally requires the incorporation of an anionic dopant to balance the positive charge on the oxidized conducting polymer chains. The susceptibility of multiwalled carbon nanotube (MWNT) surfaces to functionalization makes them exciting candidates for a new class of dopant for conducting polymers. In this work, the doping of polypyrrole with functionalized MWNTs is investigated using a combination of electrochemical impedance spectroscopy, scanning electron microscopy, and quartz crystal microbalance work. The findings described here are particularly relevant in light of recent reports indicating that carbon nanotube-conducting polymer composites hold great promise for use in electrochemical capacitors, also known as supercapacitors [1,2].
Discussion
- Murase, Cohen, Taijudo, Yokota, Graeme Bush, George Pappas
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- Journal:
- Proceedings of the ASIL Annual Meeting / Volume 69 / 1975
- Published online by Cambridge University Press:
- 28 February 2017, pp. 81-87
- Print publication:
- 1975
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- Article
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