The contents have been divided into sections on physical states of polymers and characterization techniques. Chapters on physical states include discussions of the rubber elastic state, the glassy state, melts and concentrated solutions, the crystalline state, and the mesomorphic state. Characterization techniques described are molecular spectroscopy and scattering techniques.
The contents have been divided into sections on physical states of polymers and characterization techniques. Chapters on physical states include discussions of the rubber elastic state, the glassy state, melts and concentrated solutions, the crystalline state, and the mesomorphic state. Characterization techniques described are molecular spectroscopy and scattering techniques.
Understanding the thermal degradation of polymers is of paramount importance for developing a rational technology of polymer processing and higher-temperature applications. Controlling degradation requires understanding of many different phenomena, including chemical mechanisms, the influence of polymer morphology, the complexities of oxidation chemistry, and the effects of stabilisers, fillers and other additives. This book offers a wealth of information for polymer researchers and processors requiring an understanding of the implications of thermal degradation on material and product performance.
The development of polymers as an important class of material was inhibited at the first by the premature failure of these versatile compounds in many applications. The deterioration of important properties of both natural and synthetic polymers is the result of irreversible changes in composition and structure of polymers molecules. As a result of these reactions, mechanical, electrical and/or aesthetic properties are degraded beyond acceptable limits. It is now generally recognized that stabilization against degradation is necessary if the useful life of polymers is to be extended sufficiently to meet design requirements for long-term applications. Polymers degrade by a wide variety of mechanisms, several of which affect all polymers through to varying degree. This monograph will concentrate on those degradation mechanisms which result from reactions of polymers with oxygen in its various forms and which are accelerated by heat and/or radiation. Those stabilization mechanisms are discussed which are based on an understanding of degradation reaction mechanisms that are reasonably well established. The stabilization of polymers is still undergoing a transition from an art to a science as mechanisms of degradation become more fully developed. A scientific approach to stabilization can only be approached when there is an understanding of the reactions that lead to degradation. Stabilization against biodegradation and burning will not be discussed since there is not a clear understanding of how polymers degrade under these conditions.
Strong bonds form stronger materials. For this reason, the investigation on thermal degradation of materials is a significantly important area in research and development activities. The analysis of thermal stability can be used to assess the behavior of materials in the aggressive environmental conditions, which in turn provides valuable information about the service life span of the materiel. Unlike other books published so far that have focused on either the fundamentals of thermal analysis or the degradation pattern of the materials, this book is specifically on the mechanism of degradation of materials. The mechanism of rapturing of chemical bonds as a result of exposure to high-temperature environment is difficult to study and resulting mechanistic pathway hard to establish. Limited information is available on this subject in the published literatures and difficult to excavate. Chapters in this book are contributed by the experts working on thermal degradation and analysis of the wide variety of advanced and traditional materials. Each chapter discusses the material, its possible application, behavior of chemical entities when exposed to high-temperature environment and mode and the mechanistic route of its decomposition. Such information is crucial while selecting the chemical ingredients during the synthesis or development of new materials technology.
Although plastics are extremely successful commercially, they would never reach acceptable performance standards either in properties or processing without the incorporation of additives. With the inclusion of additives, plastics can be used in a variety of areas competing directly with other materials, but there are still many challenges to overcome. Some additives are severely restricted by legislation, others interfere with each other-in short their effectiveness varies with circumstances. Plastics Additives explains these issues in an alphabetical format making them easily accessible to readers, enabling them to find specific information on a specific topic. Each additive is the subject of one or more articles, providing a suffinct account of each given topic. An international group of experts in additive and polymer science, from many world class companies and institutes, explain the recent rapid changes in additive technology. They cover novel additives (scorch inhibitors, compatibilizers, surface-modified particulates etc.), the established varieties (antioxidants, biocides, antistatic agents, nucleating agents, fillers, fibres, impact modifiers, plasticizers) and many others, the articles also consider environmental concerns, interactions between additives and legislative change. With a quick reference guide and introductory articles that provide the non-specialist and newcomer with relevant information, this reference book is essential reading for anyone concerned with plastics and additives.
Recycling of Polyurethane Foams introduces the main degradation/depolymerization processes and pathways of polyurethane foam materials, focusing on industrial case studies and academic reviews from recent research and development projects. The book can aid practitioners in understanding the basis of polymer degradation and its relationship with industrial processes, which can be of substantial value to industrial complexes the world over. The main pathways of polymer recycling via different routes and industrial schemes are detailed, covering all current techniques, including regrinding, rebinding, adhesive pressing and compression moulding of recovered PU materials that are then compared with depolymerization approaches. The book examines life cycle assessment and cost analysis associated with polyurethane foams waste management, showing the potential of various techniques. This book will help academics and researchers identify and improve on current depolymerization processes, and it will help industry sustainability professionals choose the appropriate approach for their own waste management systems, thus minimizing the costs and environmental impact of their PU-based end products. - Offers a comprehensive review of all polyurethane foam recycling processes, including both chemical and mechanical approaches - Assesses the potential of each recycling process - Helps industry-based practitioners decide which approach to take to minimize the cost and environmental impact of their end product - Enables academics and researchers to identify and improve upon current processes of degradation and depolymerization
During the last two decades, the production of polymers and plastics has been increasing rapidly. In spite of developing new polymers and polymeric materials, only 40-60 are used commercially on a large scale. It has been estimated that half of the annual production of polymers is employed outdoors. Increasing the stability of polymers and plastics towards heat, light, atmospheric oxygen and other environmental agents and weathering conditions has always been a very important problem. The photochemical instability of most of polymers limits them to outdoor application, where they are photo degraded fast over periods ranging from months to a few years. To the despair of technologists and consumers alike, photodegrada tion and environmental ageing of polymers occur much faster than can be expected from knowledge collected in laboratories. In many cases, improved methods of preparation and purification of both monomers and polymers yield products of better quality and higher resistance to heat and light. However, without stabilization of polymers by applica tion of antioxidants (to decrease thermal oxidative degradation) and photostabilizers (to decrease photo-oxidative degradation) it would be impossible to employ polymers and plastics in everyday use.
This volume offers a comprehensive guide on the theory and practice of amorphous solid dispersions (ASD) for handling challenges associated with poorly soluble drugs. In twenty-three inclusive chapters, the book examines thermodynamics and kinetics of the amorphous state and amorphous solid dispersions, ASD technologies, excipients for stabilizing amorphous solid dispersions such as polymers, and ASD manufacturing technologies, including spray drying, hot melt extrusion, fluid bed layering and solvent-controlled micro-precipitation technology (MBP). Each technology is illustrated by specific case studies. In addition, dedicated sections cover analytical tools and technologies for characterization of amorphous solid dispersions, the prediction of long-term stability, and the development of suitable dissolution methods and regulatory aspects. The book also highlights future technologies on the horizon, such as supercritical fluid processing, mesoporous silica, KinetiSol®, and the use of non-salt-forming organic acids and amino acids for the stabilization of amorphous systems. Amorphous Solid Dispersions: Theory and Practice is a valuable reference to pharmaceutical scientists interested in developing bioavailable and therapeutically effective formulations of poorly soluble molecules in order to advance these technologies and develop better medicines for the future.
