Foaming With Supercritical Fluids

Foam Extrusion: Principles and Practice combines the science of foam with the engineering of extrusion processes in one comprehensive volume, joining scientific principles and engineering practice. Starting with the fundamentals and then moving to phase separation, the text lays the scientific foundation in such a manner that the microscopic transition from a nucleus to a void (nucleation) and macroscopic movement from a void to an object (formation) are plausibly addressed. The last section of the book presents interesting foam extrusion developments, demonstrating how scientific findings can be applied to the engineering field, from principles to batch experimentation and continuous foaming. Each chapter concludes with a section of references for further study, and most include a nomenclature section and/or summary section as well. Drawing from the experience of the editor and the authors, Foam Extrusion: Principles and Practice captures the interesting evolution of foam extrusion, and offers a solid foundation for future developments. It is an informative guide for anyone involved with this field.

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

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.

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.

Polymers are widely used in everyday life due to their properties as toughness, viscoelasticity, and the possibility to form glasses and semicrystalline structures. For that reason, it is used in mostly drug delivery systems and tissue engineering and in pharmaceutical and biomedical investigations. Foaming process allows creating porous structure into the polymer leading to scaffolds. Scaffolds are the focus of many investigations as prolonged drug delivery systems and implants or injections which are used to deliver cells, drugs, and genes into the body. Particulate leaching, freeze-drying, thermally induced phase separation, rapid prototyping, powder compaction, sol,Äìgel, and melt molding are the main techniques in front of supercritical fluid technology to prepare scaffolds. Supercritical foaming process using CO2 presents advantages as a high dissolution in polymers and a green process because CO2 is nontoxic, inexpensive, and reusable. Moreover, supercritical technology allows to do an impregnation with an active substance together with the foaming at the same time. Thus active substances entrapped into scaffolds could be fabricated in a one-step green process.

Keywords: polymer surfactants, polymer blends, high pressure rheology, controlled foam nucleation, carbon dioxide, nanoporous polymers, microcellular foam, supercritical fluids.

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.

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.