Technology & Engineering

Developments in Polymer Stabilisation—8

Author: G. Scott

Publisher: Springer Science & Business Media

ISBN:

Category: Technology & Engineering

Page: 296

View: 488

The purpose of the present series of publications is two-fold. In the first place it is intended to review progress in the development of practical stabilising systems for a wide range of polymers and applications. A complementary and ultimately more important objec tive is to accommodate these practical developments within the framework of antioxidant theory, since there can be little question that further major advances in the practice of stabilisation technology will only be possible on the basis of a firm mechanistic foundation. Research into the role of 'stable' free radicals as antioxidants and stabilisers for polymers has intensified in recent years. Nitroxyl radicals (nitroxides) were the earliest long-lived radicals to be investi gated in detail and Maslov and Zaikov review the developments that have taken place in understanding their reaction mechanisms from the time when they were first investigated in liquid hydrocarbon systems to the present day when their outstanding performance as light stabilisers has been the object of much scientific research. Although some features of their reactivity remain obscure, the authors approach the problem kinetically and indicate the factors limiting their effectiveness.
Technology & Engineering

Handbook of Polymer Degradation

Author: S. Halim Hamid

Publisher: CRC Press

ISBN:

Category: Technology & Engineering

Page: 800

View: 262

"Covers recent advances in polymer degradation and stabilization. Focuses on the basics of photo- and bio-degradability. Delineates special and general environmental parameters such as solar irradiation, temperature, and agrochemical exposure. Surveys plastic waste disposal strategies such as recycling, incineration, chemical recovery by pyrolysis,
Science

Atmospheric Oxidation and Antioxidants

Author: Gerard Meurant

Publisher: Elsevier

ISBN:

Category: Science

Page: 556

View: 391

This volume examines the oxidation chemistry of carbon-based materials in more detail with emphasis on the technological phenomena that result from the attack of oxygen and the practical procedures developed to prevent them.
Technology & Engineering

Antioxidants in Science, Technology, Medicine and Nutrition

Author: G. Scott

Publisher: Elsevier

ISBN:

Category: Technology & Engineering

Page: 348

View: 659

The use of antioxidants is widespread throughout the rubber, plastics, food, oil and pharmaceutical industries. This book brings together information generated from research in quite separate fields of biochemical science and technology, and integrates it on a basis of the common mechanisms of peroxidation and antioxidant action. It applies present knowledge of antioxidants to our understanding of their role in preventing and treating common diseases, including cardiovascular disease, cancer, rheumatoid arthritis, ischemia, pancreatitis, hemochromatosis, kwashiorkor, disorders of prematurity and disease of old age. Antioxidants deactivate certain harmful effects of free radicals in the human body due to biological peroxidation, and thus prevent protection against cell damage. The book is of considerable interest to scientists working in the materials and foodstuff industries, and to researchers seeking information on the connection between diet and health, and to those developing new drugs to combat diseases associated with oxidative stress. It is important also throughout the non-medical world, especially to the work force within the affected industries. Examines research in separate fields of biochemical science and technology and integrates it on a basis of the common mechanisms of peroxidation and antioxidant action Applies present knowledge of antioxidants to our understanding of their role in preventing and treating common diseases, including cardiovascular disease, cancer, rheumatoid arthritis and others
Chlorure de polyvinyle - Recyclage

Recycling of PVC and Mixed Plastic Waste

Author: Francesco Paolo La Mantia

Publisher: ChemTec Publishing

ISBN:

Category: Chlorure de polyvinyle - Recyclage

Page: 199

View: 972

This book, on recycling of PVC and mixed plastic wastes, has been compiled from contributions from an array of scientists from several countries who are playing a leading role in plastic recycling. They offer practical solutions to many difficult problems in this field. Anyone involved in production of materials from virgin polymers who is concerned with their recyclability should read this book. The ideas and data presented will help the process of planning future recycling efforts and help to bring the recycling process from a costly nuisance to a profitable industry.
Science

Photostabilization of Polymers

Author: J.F. Rabek

Publisher: Springer Science & Business Media

ISBN:

Category: Science

Page: 596

View: 930

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.
Science

Reactive Modifiers for Polymers

Author: S. Al-Malaika

Publisher: Springer Science & Business Media

ISBN:

Category: Science

Page: 400

View: 273

Chemical modification of polymers by reactive modifiers is no longer an academic curiosity but a commercial reality that has delivered a diverse range of speciality materials for niche markets: reactively grafted styrenic alloys, maleated polyolefins, super-tough nylons, silane modified and moisture-cured polyolefins, and thermoplastic elastomers, are but few exam ples of commercial successes. Although the approach of reactive modification of polymers has been largely achieved either in solution or in the solid state (through in situ reactions in polymer melts), it is the latter route that has attracted most attention in the last two decades owing to its flexibility and cost-effective ness. This route, referred to as reactive processing, focuses on the use of suitable reactive modifier(s) and the adoption of conventional polymer processing machinery, an extruder or a mixer, as a chemical reactor, to perform in situ targeted reactions for chemical modification of preformed polymers. This relatively simple, though scientifically highly challenging, approach to reactive modification offers unique opportunities in exploiting various reactive modifiers for the purpose of altering and transforming in a controlled manner the properties of preformed commercial polymers into new/speciality materials with tailor-made properties and custom-designed performance for target applications. Such an economically attractive route constitutes a radical diversion away from the traditional practices of manufacturing new polymers from monomers which involves massive in vestments in sophisticated technologies and chemical plants.
Science

Polymer Degradation and Stabilisation

Author: Norman Grassie

Publisher: CUP Archive

ISBN:

Category: Science

Page: 232

View: 775

The study of polymer degradation and stabilisation is of considerable practical importance as the industrial uses of polymeric materials continue to expand. In this book, the authors lucidly relate technological phenomena to the chemistry and physics of degradation and stabilisation processes. Degradation embraces a variety of technologically important phenomena ranging from relatively low temperature processes such as 'weathering' of plastics, 'fatigue' of rubbers through the processing of polymers in shearing mixers to very high temperature processes such as flammability and ablation. All these technological phenomena have in common certain basic chemical reactions. Thus 'weathering' has its roots in photo-oxidation, 'fatigue' and melt-degradation in mechano-oxidation and flammability, and ablation in ablation in pyrolysis and vapour phase oxidation.