Polyvinyl chloride has played a key role in the development of the plastics industry over the past 40 years and continues to be a polymer of major importance. The reasons for its enormous versatility and range of application derive from a combination of the basic structure which gives rise to a relatively tough and rigid material and its ability to accept a range of plasticisers and other additives which can modify its physical characteristics to produce a range of flexible products. Two major problems, however, have tested the skill and ingenuity of PVC technologists since earliest times. One is the thermal instability of the material at the temperatures required for melt processing and fabrication, and the second is the photochemical instability which until recently has limited the potentially large range of outdoor applications. Both problems have been handled in a commercially satisfactory way by the gradual development of a range of stabilisers, lubricants and other processing aids and the high quality material which has resulted has led to massive utilisation of PVC by industry. Totally adequate stabilisation requires a detailed understanding of the mechanisms by which degradation processes are initiated and propagated. Although great advances have been made in this respect in recent years the problem remains incompletely understood. This book presents an account of the present position and the problems which remain to be solved.

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.

In this single handbook, the editors aim to give a diverse audience of readers a complete account of all aspects of PVC--from monomer manufacture to polymerization; the gamut of such additives as stabilizers, lubricants, plasticizers, impact modifiers, fillers and reinforcing agents; blends and alloys; compounding and processing; characterization; combustion resistance and weatherability; product engineering design; applications; environmental and safety; and finally the PVC industry dynamics. This handbook contains both practical formulation information as well as a mechanistic view of why PVC behaves as it does.

The need for a broad development of the production of polymer ma terials has become evident. All these materials are subject to various types of aging (destruction); hence, stabilizers which permit the stor age, reprocessing, and use of polymer materials without any appreci able change in their properties must be introduced into them. In recent years, this problem of stabilizing polymers has attracted the attention of many scientists and technologists, both in the USSR and abroad. The scientific basis of the foreign studies will be found in a number of theo retical premises, but chiefly the theory of chain reactions with un branched chains. In the Soviet Union, the concepts of Academician N. N. Semenov on chain reactions with degenerate branches have become the starting point of theoretical studies of the stabilization and destruction of polymers. Soviet scientists have developed a theory of critical concentrations of antioxidants and have shown that the processes of stabilization have a very complex chemical character. The nature of the polymers them selves greatly affects these processes and consequently, different stabil izers are required for polymers of different structures. In addition, it has been shown that the antioxidants used thus far can not only cause chain termination, but can also initiate oxidation and give rise to de generate branches.

Ever since the beginning of the plastics and rubber industry, it was realized that useful products could be produced only if cer tain additives were incorporated into polymers. With the help of these additives, when physically dispersed in a polymer matrix, it has been possible to improve stability against thermal, oxidative, UV, hydrolytic and biological degradation, mechanical properties, flammability, cost, and processibility of plastics. The enormous growth of the volume of plastics consumed by modern society, and new application areas for plastics, have created a demand for new, better additives and better understanding of their functions in polymer systems. As a result of these trends there is a need for sharing of information on progress achieved in the area of polymer additives among engineers and scientists of the plastics industry and academia. This book is based on expanded and updated papers originally presented at the International Symposium on Polymer Additives, which was held in Las Vegas, Nevada, and was sponsored by the American Chemical Society, Division of Polymeric Materials Science and Engi neering. The book is divided into five parts which cover advances in various areas of polymer additives. The first part is devoted to the progress in understanding of UV degradation and stabilization of various polymers. Oxidation degradation and stabilization of plastic materials is covered in the second part. New developments in the stabilization of PVC are presented in the third part.

This book has its origin in a proposal made a few years ago that I should collaborate with Dr H. J. Stern in the production of a third edition of his well-known text-book entitled Rubber: Natural and Synthetic. The sugges tion was that I should contribute a series of chapters on synthetic rubbers. Although, in the event, it has not proved possible to publish the full book in the form originally planned, it was apparent that, with some restructuring, the material which I had collected would be valuable as an independent summary of the chemistry and technology of synthetic rubbers. It is in this form that the material is now offered. The primary purpose of this book is to provide a brief up-to-date survey of the principal types of synthetic rubber which have been and are currently available. Two classes of material are included which are regarded by some as being thermoplastics rather than rubbers, namely, plasticised polyvinyl chloride and the thermoplastic synthetic rubbers. The topics which are covered for each main family of synthetic rubbers are (i) the sources of the monomers, (ii) polymerisation procedures and the effects of important polymerisation variables upon the rubber produced, (iii) the types of rubber currently available commercially, (iv) interesting aspects of the compounding of the rubbers, with special reference to such matters as vulcanisation, reinforcement, protection against degradation, and (where appropriate) plasticisation, and (v) an indication of applications.