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Microcellular Foams Prepared From Demixed Polymer Solutions
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Book Synopsis Microcellular Foams Prepared from Demixed Polymer Solutions by :
Download or read book Microcellular Foams Prepared from Demixed Polymer Solutions written by and published by . This book was released on 1990 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-density, microcellular polymer foams have numerous applications as structural supports in high-energy physics experiments, in catalysis, ion exchange, and filtration, and for a variety of biomedical uses. A versatile method to prepare such foams is by thermally-induced phase separation (TIPS) of polymer solutions. Demixed solutions can be transformed into a foam by freezing the demixed solution and removing the solvent by freeze-drying. The morphology of these foams is determined by the the thermodynamics and kinetics of phase separation. A model of both the early and late stage structure development for demixed polymer solutions will be presented. For semi-crystalline polymers, gels can be prepared by crystallizing the polymer from solution, either a homogeneous solution or a demixed solution. Foams can be prepared from these gels by the supercritical extraction of the solvent. By understanding and utilizing the phase separation behavior of polymer solutions, engineered microcellular foams can be prepared. To design the foams for any application one must be able to characterize their morphology. Results will be presented on the morphological characterization of these foams and the relationship of the morphology to their processing history. 14 refs., 12 figs.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mechanical Properties of Porous and Cellular Materials by : Karl Sieradzki
Download or read book Mechanical Properties of Porous and Cellular Materials written by Karl Sieradzki and published by . This book was released on 1991 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1986 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Book Synopsis Government Reports Announcements & Index by :
Download or read book Government Reports Announcements & Index written by and published by . This book was released on 1991 with total page 618 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Microcellular Foams from Some High-performance Thermoplastics and Their Composites by :
Download or read book Microcellular Foams from Some High-performance Thermoplastics and Their Composites written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Microcellular foams were successfully processed from several high-performance thermoplastics by a two-stage batch process using CO 2 as foaming agent. These microcellular foams had well-defined closed-cell structures with average cell sizes in the range 2 - 15?m, and cell densities on the order of 10 9 - 10 12 cells/cm 3 . Compression and tension tests were performed on these foams to evaluate their mechanical properties. In order to improve the thermal stabilities and mechanical properties of these foams, composites were prepared by incorporation of rigid-rod polymers or nano-dispersed clay layers in the thermoplastics to form molecular composites, or nanocomposites. These composites were also processed into microcellular foams. The foaming behavior and morphologies of the resulting composite foams were much more complicated than those of the pure polymers. The thermal stabilities and some mechanical properties of the composite foams were significantly enhanced relative to those of the pure matrix polymers. These improvements could be due to nanoscale or even molecular dispersions of the rigid-rod chains in the polymer matrices, including having these chains aligned along the foam struts or within the foam walls in unique reinforcing arrangements.
Download or read book SPE/ANTEC 1997 Proceedings written by Spe and published by CRC Press. This book was released on 1997-04-22 with total page 1504 pages. Available in PDF, EPUB and Kindle. Book excerpt: First published in 1997. Routledge is an imprint of Taylor & Francis, an informa company.
Book Synopsis Handbook of Polymer Foams by : David Eaves
Download or read book Handbook of Polymer Foams written by David Eaves and published by iSmithers Rapra Publishing. This book was released on 2004 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Handbook reviews the chemistry, manufacturing methods, properties and applications of the synthetic polymer foams used in most applications. In addition, a chapter is included on the fundamental principles, which apply to all polymer foams. There is also a chapter on the blowing agents used to expand polymers and a chapter is on microcellular foams - a relatively new development where applications are still being explored.
Book Synopsis Low Density Microcellular Foams by :
Download or read book Low Density Microcellular Foams written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the resultant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Means for subjecting such a solvent to one-dimensional cooling are also provided. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 .mu.m and a volume such that the foams have a length greater than 1 cm are provided.
Book Synopsis Advances in Preparing and Characterizing Low Density Pan-carbon Microcellular Foam by :
Download or read book Advances in Preparing and Characterizing Low Density Pan-carbon Microcellular Foam written by and published by . This book was released on 1993 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents an improved preparation of low density microcellular carbon as well as characterization of spatial homogeneity. The report also documents the process for preparing the nficrocellular carbon from poly(acrylonitrile) raw material. A microcellular polymer precursor (0.025 g/cc) is first prepared via a solution-based process and then pyrolyzed to produce the microcellular carbon in a monolithic form (0.05 g/cc). The process improvement developed in this study permits the pore structure of the n-ficrocellular polymer precursor and the microcellular carbon to be reproduced consistently in different laboratories. Pore structure is affected by the completeness of dissolution of the polymer raw material, which variable can be adjusted via dissolution temperature or particle size of the raw material. The second topic in this report involves determining the spatial fluctuation in mass density caused by periodic, millimeter-scale bands, known as 'tree rings' visible on machined surfaces of the carbon monoliths. To measure the fluctuations, we developed a high precision, spatially resolved X-ray transmission technique. The periodic bands caused less than "2% variation of mass density in a microcellular carbon having average density 0.041 g/cc.
Book Synopsis System Development in Control of Polymer/gas Solution Formation for Molding Microcellular Foams by : Dong B. Wang
Download or read book System Development in Control of Polymer/gas Solution Formation for Molding Microcellular Foams written by Dong B. Wang and published by . This book was released on 2002 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advances in Regenerative Medicine by : Sabine Wislet
Download or read book Advances in Regenerative Medicine written by Sabine Wislet and published by BoD – Books on Demand. This book was released on 2011-11-21 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Even if the origins of regenerative medicine can be found in Greek mythology, as attested by the story of Prometheus, the Greek god whose immortal liver was feasted on day after day by Zeus' eagle; many challenges persist in order to successfully regenerate lost cells, tissues or organs and rebuild all connections and functions. In this book, we will cover a few aspects of regenerative medicine highlighting major advances and remaining challenges in cellular therapy and tissue/organ engineering.
Book Synopsis Structural Foams of Improved Strength and Thermal Stability From Random-Coil and Rigid-Rod Polymers by :
Download or read book Structural Foams of Improved Strength and Thermal Stability From Random-Coil and Rigid-Rod Polymers written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most significant accomplishments were determining the conditions for preparing microcellular structural foams from high-temperature polymers of interest to the US Air Force. The primary system was rodlike polybenzobisthiazole blended with poly(etherketoneketone) with 5% rod content. This gave microcellular foams with densities about 0.92 g/cc, and a yield strength about 9.4 ksi. A modified foaming technique gave foams with high porosity, a density of 0.65 g/cc, and pore sizes from 10 to 40 micrometers. Also, some sulfonated poly(p-phenylenebenzobismidazole)/poly(2-vinylpyidine) molecular composites gave foams of uniform microstructures and a cell size less than 10 micrometers, but with some brittleness. Molecular composites based on polysulfone (PSF) and polybenzimidazole (PBI) were also successfully prepared. PSF and PBI are immiscible, but introduction of functional groups into the PSF or PBI resulted in miscible polymer blends. Very homogeneous microcellular foams were obtained from them, and their thermal behavior and mechanical properties were encouraging.
Book Synopsis Low Density Microcellular Carbon Foams and Method of Preparation by :
Download or read book Low Density Microcellular Carbon Foams and Method of Preparation written by and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A low density, open-celled microcellular carbon foam is disclosed which is prepared by dissolving a carbonizable polymer or copolymer in a solvent, pouring the solution into a mold, cooling the solution, removing the solvent, and then carbonizing the polymer or copolymer in a high temperature oven to produce the foam. If desired, an additive can be introduced in order to produce a doped carbon foam, and the foams can be made isotropic by selection of a suitable solvent. The low density, microcellular foams produced by this process are particularly useful in the fabrication of inertial confinement fusion targets, but can also be used as catalysts, absorbents, and electrodes.
Book Synopsis Government reports annual index by :
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Projects Within the Center for Advanced Materials, 1990-1991 by :
Download or read book Projects Within the Center for Advanced Materials, 1990-1991 written by and published by . This book was released on 1992 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Microcellular Foams from Rigid-Rod Polymers in Solutions: Effect of Aggregation Characteristics on Foam Properties by :
Download or read book Microcellular Foams from Rigid-Rod Polymers in Solutions: Effect of Aggregation Characteristics on Foam Properties written by and published by . This book was released on 1989 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Upon cooling, solutions of rigid-rod macromolecules often form gels . These can be further processed to form microcellular materials with very regular structure. A two -stage melting of the precursor gels has been tentatively associated with a bimodal structure found in the microcellular materials. Microcellular foams, PBLG, Rigid-rod polymers.
