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Author: Vannessa Goodship
Publisher: iSmithers Rapra Publishing
ISBN: 9781859574942
Category : Science
Languages : en
Pages : 152
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Book Description
SCFs are currently the subjects of intense research and commercial interest. Applications such as the RESS (rapid expansion of supercritical fluid solutions) process are part of standard industrial practice. In view of their ever-growing importance in the polymer industry there is a need to fully comprehend how supercritical fluids interrelate with polymeric materials to realise the potential that can be gained from their use. The authors review the basic principles of SCFs and their application within the polymer industry: characteristics and properties, extraction of unwanted residual products, polymerisation solvents, and polymer impregnation. Processing applications such as plasticisation, foaming and blending are also considered. There is discussion of the potential within the polymer recycling industry for use of SCFs as cleaning agents or within supercritical oxidation processes. Around 400 references with abstracts from recent global literature accompany this review, sourced from the Polymer Library, to facilitate further reading. A subject index and a company index are included.
Author: Vannessa Goodship
Publisher: iSmithers Rapra Publishing
ISBN: 9781859574942
Category : Science
Languages : en
Pages : 152
Get Book Here
Book Description
SCFs are currently the subjects of intense research and commercial interest. Applications such as the RESS (rapid expansion of supercritical fluid solutions) process are part of standard industrial practice. In view of their ever-growing importance in the polymer industry there is a need to fully comprehend how supercritical fluids interrelate with polymeric materials to realise the potential that can be gained from their use. The authors review the basic principles of SCFs and their application within the polymer industry: characteristics and properties, extraction of unwanted residual products, polymerisation solvents, and polymer impregnation. Processing applications such as plasticisation, foaming and blending are also considered. There is discussion of the potential within the polymer recycling industry for use of SCFs as cleaning agents or within supercritical oxidation processes. Around 400 references with abstracts from recent global literature accompany this review, sourced from the Polymer Library, to facilitate further reading. A subject index and a company index are included.
Author: Maartje F. Kemmere
Publisher: John Wiley & Sons
ISBN: 3527607056
Category : Technology & Engineering
Languages : en
Pages : 358
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Book Description
Recently, supercritical fluids have emerged as more sustainable alternatives for the organic solvents often used in polymer processes. This is the first book emphasizing the potential of supercritical carbon dioxide for polymer processes from an engineering point of view. It develops a state-of-the-art overview on polymer fundamentals, polymerization reactions and polymer processing in supercritical carbon dioxide. The book covers topics in a multidisciplinary approach starting from polymer chemistry and thermodynamics, going through monitoring, polymerization processes and ending with polymer shaping and post-processing. The authors are internationally recognized experts from different fields in polymer reaction engineering in supercritical fluids. The book was initiated by the Working Party on Polymer Reaction Engineering of the European Federation of Chemical Engineering and further renowned international experts.
Author: E. Kiran
Publisher: Springer Science & Business Media
ISBN: 9401139296
Category : Science
Languages : en
Pages : 602
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Book Description
Supercritical fluids are neither gas nor liquid, but can be compressed gradually from low to high density and they are therefore interesting and important as tunable solvents and reaction media in the chemical process industry. By adjusting the density the properties of these fluids can be customised and manipulated for a given process - physical or chemical transformation. Separation and processing using supercritical solvents such as CO2 are currently on-line commercially in the food, essential oils and polymer industries. Many agencies and industries are considering the use of supercritical water for waste remediation. Supercritical fluid chromatography represents another, major analytical application. Significant advances have recently been made in materials processing, ranging from particle formation to the creation of porous materials. The chapters in this book provide tutorial accounts of topical areas centred around: (1) phase equilibria, thermodynamics and equations of state; (2) critical behaviour, crossover effects; (3) transport and interfacial properties; (4) molecular modelling, computer simulation; (5) reactions, spectroscopy; (6) phase separation kinetics; (7) extractions; (8) applications to polymers, pharmaceuticals, natural materials and chromatography; (9) process scale-up.
Author: Elena Aionicesei
Publisher:
ISBN:
Category :
Languages : en
Pages : 183
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Book Description
The traditional methods for polymer processing use environmentally hazardous volatile organic solvents and chlorofluorocarbons. Due to the increase of hazardous solvent emission and generation of aqueous waste streams, there is an obvious need of finding new and cleaner methods for the processing of polymers. Supercritical carbon dioxide (scCO2) has attracted particular attention for these applications due to its tremendous potential as a plasticizer in polymer processing. A particular interest is shown to the use of supercritical fluids for processing polymers destined for biomedical applications (as microspheres, microcapsules, foams, membranes, polymer/drug composites). The method offers important advantages related to the absence of harmful organic solvents or, when necessary, the efficient extraction of solvents and impurities, the mild processing conditions and the control of particle and foams morphology by simple variation of pressure and temperature. Despite the huge potential of scCO2 as a ʺgreenʺ solvent for processing biocompatible and biodegradable polymers, the phase equilibrium data, essential for process design, are quite scarce. Optimum processing techniques and parameters (pressure, temperature) still need consideration andstudy. The data are especially scarce regarding the scCO2 processing of polymer/ceramic composites for biomedical applications. On this basis, this thesis is aimed to open new perspectives over the use of scCO2 as a ʺgreenʺ solvent for the processing of biodegradable polymers and composites used as biomaterials. Two biodegradable polymers were chosen for this study, poly(L-lactide) (PLLA) and poly(D,L-lactide-co-glycolide) (PLGA). Their composite with a bioactive ceramic powder, hydroxyapatite (HA), was also studied. The main idea followed by this thesis was the obtaining of porous polymeric or composite material scaffolds suitable for tissue engineering under mild temperature conditions and without the use of additional organic solvents. The behavior of the two polymers under dense CO2 had been studied and explained. More data about the polymer-gas phase equilibrium, necessary for understanding and optimizing the effect of processing parameters, were obtained by determining the solubility and diffusion coefficients of CO2 in the polymers for certain values of temperature and pressure. The solubility ofCO2 was measured for each polymer for three different temperatures (308, 313and 323 K) in the pressure range 10 - 30 MPa. The temperatures were chosen higher than the critical temperature for CO2, but still low enough so as not to affect the bioactivity of any drugs or proteins that could be introduced in the system during processing. The same range of temperature and pressure was employed for all tests involving the studied polymers or their composite materials. The efficiency of mixing in the presence of scCO2 for obtaining composite materials from PLLA and HA and respectively PLGA and HA was studied by comparison with coprecipitation. The solubility and diffusion coefficient of CO2 in the composite materials were afterward determined, and the results were compared with the ones obtained for the polymer alone in order to determine the effect of the ceramic filler on the gas uptake. The possibility of obtaining porous scaffolds was assessed by using a pressure quench technique using dense CO2 as blowing agent, with and without the presence of aporogen. The effect of pressure, temperature, depressurization rate and porogen on the final porous structure was investigated. The experimental results were compared with literature data and with data obtained by mathematical modeling, employing equations of state commonly used for polymersor polymer/solvent systems. The results indicate that gas foaming of biodegradable polymers represents a promising technique for obtaining tissue engineering scaffolds with the desired structure. Still the processing parameters need to be studied and optimized, according to the nature of the substrate and of the aimed final product.
Author: Ernesto Di Maio
Publisher: Elsevier
ISBN: 0444637362
Category : Science
Languages : en
Pages : 486
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Book Description
Foaming with Supercritical Fluids, Volume Nine provides a comprehensive description of the use of supercritical fluids as blowing agents in polymer foaming. To this aim, the fundamental issues on which the proper design and control of this process are rooted are discussed in detail, with specific attention devoted to the theoretical and experimental aspects of sorption thermodynamics of a blowing agent within a polymer, the effect of the absorbed blowing agent on the thermal, interfacial and rheological properties of the expanding matter, and the phase separation of the gaseous phase, and of the related bubble nucleation and growth phenomena. Several foaming technologies based on the use of supercritical blowing agents are then described, addressing the main issues in the light of the underlying chemical-physical phenomena. Offers strong fundamentals on polymer properties important on foaming Outlines the use of supercritical fluids for foaming Covers theoretical points-of-view, including foam formation of the polymer/gas solution to the setting of the final foam Discusses the several processing technologies and applications
Author: Joseph Robert Royer
Publisher:
ISBN:
Category :
Languages : en
Pages : 272
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Book Description
Keywords: Supercrtical fluids, Viscosity reduction, CO2-induced plasticization.
Author: Mark McHugh
Publisher: Elsevier
ISBN: 0080518176
Category : Technology & Engineering
Languages : en
Pages : 523
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Book Description
Supercritical Fluid Extraction is a technique in which CO2 is used under extremely high pressure to separate solution (e.g., removing caffeine from coffee). Separations is basic to all process industries and supercritical fluid extraction is a specific type which is receiving a high level of attention. The book will combine basic fundamentals with industrial applications. The second edition has been expanded and updated and includes new chapters on chromatography and food processing. "...this is an excellent book which is both instructive and amusing to read. Its true value is neatly summarised in one of the closing sentences: 'We have supplied you with the guidelines and criteria which you can now apply when considering supercritical fluids for your own needs.'' - Chemistry in Britain, February 1995
Author: Željko Knez
Publisher: Springer Nature
ISBN: 303134636X
Category : Science
Languages : en
Pages : 262
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Book Description
This book describes cutting edge technology using supercritical fluids for the production of foodstuffs, medicals, and polymers. It illustrates the importance and use of basic data for design and operation at industrial scale units. The book's authors have several decades of experience of applied research on how to develop large scale industrial units. It provides readers complete insight in design and operation of industrial high pressure process plants. The book is written so it may be understood for people (with?) little or no background on high pressure process technology. It will provide information on how some foodstuffs, medicals, polymers are produced using high pressure technologies. The book demonstrates the importance of fundamental data, how to measure them and how to apply them to design industrial plants. At the same time, it also serves as a textbook for students.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The use of supercritical carbon dioxide, scCO is a gas under atmospheric conditions, it can be used as a processing aid and then easily removed from a polymer through evaporation to obtain the original physical properties of the unplasticized polymer matrix. In addition, CO has been shown to be more environmentally friendly in comparison to many of the traditional organic plasticizers. However, the biggest challenge hindering the widespread use of CO as a plasticizer involves a lack of understanding of and data quantifying its effect on polymer swelling and the concomitant reduction in material viscosity. In this work, a three-step approach is used to investigate and quantify the physical phenomena associated with CO-induced plasticization of polymer melts. First, a novel experimental apparatus was designed and constructed to measure equilibrium swelling, swelling kinetics and diffusion of CO into a polymer melt. It was found that diffusion of CO pressure had a negligible effect on the diffusion coefficient; however, the system temperature directly affected the diffusion coefficient. Increased pressure was found to enhance the extent of swelling whereas a maximum was observed with increasing temperature, at pressures above 15 MPa. The Sanchez-Lacombe equation of state was found to be in good agreement with the experimentally calculated variables, and thus, can be used as a predictive tool to obtain physical properties of the CO-PDMS system. Secondly, a high pressure extrusion slit die rheometer was constructed to measure the viscosity of polymer melts plasticized with low concentrations of CO. Polystyrene, poly(methyl methacrylate), polypropylene, low density polyethylene, and poly(vinylidene fluoride) were all investigated. CO was found to be an efficient plasticizer for all of these polymer materials, generally lowering the viscosity of the melt 30-80%, depending on processing conditions. Predictive viscoelastic scaling models based on free-volume principles and a p.
Author: Siti Machmudah
Publisher: Penerbit Andi
ISBN: 6238493666
Category : Technology & Engineering
Languages : en
Pages : 450
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Book Description
This book explores the range and the utility of supercritical fluid system in a variety of diverse chemical applications. The book highlighted the green process and served the necessary background and details about separation, material processing, and reaction regarding technique, mechanism, protocol, and potential applications; hence it can appeal to academics and industrialists. Both from a chemical as well as engineering scene, the book updates the recent advances in supercritical fluid technology and other pressurized-solvent system (subcritical water technology). The most wide-spread use of supercritical CO2 as a solvent has been in supercritical fluid extraction and fractionation processes. Other applications are recrystallization of pharmaceuticals, metal nanoparticles generation, and polymer processing. Sub or supercritical water is a unique green solvent which can serve a high solubility for many weakly-polar organics and light inorganic gases. This solvent denotes very high reactivity for biomass processing.
