Continuous Precipitation Polymerization of Acrylic Acid in Supercritical Carbon Dioxide
Continuous Precipitation Polymerization of Acrylic Acid in Supercritical Carbon Dioxide

Author:

Publisher:

Published: 2004

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

The precipitation polymerization of acrylic acid in supercritical carbon dioxide (scCO2) was carried out in a continuous stirred tank reactor. The product polymer was a white, dry, fine powder that dissolved in water. A wide range of polymer molecular weights (5 to 200 kg/mol) was obtained. The effect of the operating variables on the polymerization rate and on the polymer molecular weight was evaluated. The polymerization showed distinct deviations from the normal solution polymerization. By assuming that chain initiation occurs in the solution phase, but chain propagation and chain termination occur in the polymer phase, a 'surface polymerization model' and a 'particle polymerization model' both described the polymerization well. Scanning electron micrographs showed that three types of polymer particles were obtained: agglomerates of primary particles of about 100 nanometers in size, irregular particles of 5--20 micrometers, and spheres of 10--100 micrometers. It is speculated that the agglomerates were produced when the polymerization temperature (TP) was below the polymer glass transition temperature (Tg), the irregular particles were obtained when TP was close to Tg, and the spheres were prepared when TP was above Tg. The CO2 absorption into poly(acrylic acid) (PAA) was measured with a quartz crystal microbalance. The Tg depression by scCO2 was calculated with the Chow's equation. The calculated results lent strong support to the proposed particle formation mechanism. Cross-linking polymerization of acrylic acid in scCO2 was studied in a batch reactor at 50°C and 207 bar. All products were white, dry, fine powders. By adjusting the cross-linker concentration, water-soluble and water-insoluble PAAs were synthesized. The water-insoluble PAA was neutralized by ammonia gas and sodium hydroxide alcohol solution to make superabsorbent polymers.

Polymerizations in Supercritical Carbon Dioxide Medium
Polymerizations in Supercritical Carbon Dioxide Medium

Author: Isha Ruhulla Kamrupi

Publisher: LAP Lambert Academic Publishing

Published: 2011-09

Total Pages: 192

ISBN-13: 9783846512234

DOWNLOAD EBOOK

Polymers have become an inextricable part of our daily life. Not only the synthesis but also the processing of polymers has been given a major attention. Most of the commercial methods use environmentally hazardous volatile organic solvents (VOC)and chlorofluorocarbons (CFC) for processing and synthesis of polymers. Due to the enormous increment of VOC/CFC emissions and also the generation of aqueous waste streams, chemical engineers and chemists have already been looking for new and cleaner alternatives. One of these methods is the use of supercritical fluids as a processing solvent. An intense research activity concentrated in the last decade has demonstrated that dense carbon dioxide is an attractive solvent for polymer synthesis as it is environmentally benign, inexpensive, with tunable physico-chemical properties and substantially inert towards chain transfer reactions. We have briefly described the synthesis of different polymers and their nanocomposites with metal nanoparticles in supercritical carbon dioxide in this book.

Polymer Processing with Supercritical Fluids
Polymer Processing with Supercritical Fluids

Author: Vannessa Goodship

Publisher: iSmithers Rapra Publishing

Published: 2005

Total Pages: 152

ISBN-13: 9781859574942

DOWNLOAD EBOOK

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.

Carbon Dioxide Recovery and Utilization
Carbon Dioxide Recovery and Utilization

Author: M. Aresta

Publisher: Springer Science & Business Media

Published: 2013-06-29

Total Pages: 422

ISBN-13: 9401702454

DOWNLOAD EBOOK

Carbon Dioxide Recovery and Utilization is a complete and informative resource on the carbon dioxide sources and market at the European Union level, with reference to the world situation. The book covers the following themes: - Sources of carbon dioxide and their purity, - Market of carbon dioxide and its uses, - Separation techniques of carbon dioxide from flue gases, - Analysis of the potential of each technique and application, - Basic science and technology of supercritical CO2, - Reactions in supercritical CO2 and its use as reactive solvent, - Utilization of CO2 in the synthesis of chemicals with low energy input, - Conversion of CO2 into fuels: existing techniques, - Dry reforming of methane, - Assessment of the use of carbon dioxide for the synthesis of methanol. This book is unique in providing integrated information and a perspective on innovative technologies for the use of carbon dioxide. The book is suitable for use as a textbook for courses in chemical engineering and chemistry. It is also of great interest as a general reference for those involved with technologies for avoiding carbon dioxide production and for economists. This is an invaluable reference for specialists on synthetic chemistry, gas separation, supercritical fluids, carbon dioxide marketing, renewable energy and sustainable development. In addition, it will be useful for those working in the chemical industry and for policy makers for carbon dioxide mitigation, innovative technologies, carbon recycling, and power generation.

Green Chemistry and Technologies
Green Chemistry and Technologies

Author: Long Zhang

Publisher: Walter de Gruyter GmbH & Co KG

Published: 2018-09-24

Total Pages: 534

ISBN-13: 3110479311

DOWNLOAD EBOOK

The book gives a systematic introduction to green chemistry principles and technologies in inorganic and organic chemistry, polymer sciences and pharmaceutical industry. It also discusses the use of biomass and marine resources for synthesis as well as renewable energy utilization and the concepts and evaluation of recycling economy and eco-industrial parks.

Fundamentals of Polymerization
Fundamentals of Polymerization

Author: Broja Mohan Mandal

Publisher: World Scientific

Published: 2013

Total Pages: 468

ISBN-13: 9814322466

DOWNLOAD EBOOK

Over the last twenty years, the field of the chemistry of polymerization witnessed enormous growth through the development of new concepts, catalysts, processes etc. Examples are: non classical living polymerizations (group transfer polymerization, living carbocationic polymerization, living radical polymerization and living ring-opening metathesis polymerization (ROMP)); new catalysts (metallocenes and late transition metal catalysts for stereospecific polymerization, Schrock and Grubbs catalyst for ROMP among others) and new processes such as miniemulsion, microemulsion polymerization and dispersion polymerization (in polar solvents). Apart from the developments in the chemistry of polymerization, methods have been developed for the evaluation of highly reliable rate constants of propagation in radical as well as cationic polymerization. All these have revolutionized the field of synthetic polymer chemistry. In the book, fundamentals of both the new and old polymerization chemistry have been dealt with. The new chemistry has been given nearly equal space along with the old.