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Developments Series books overcome these disadvantages by bringing together within one cover papers dealing with the latest trends and developments in a specific field of study and publishing them within six months of their being written.
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PREFACE
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 objective 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.
The stabilisation of PVC has traditionally been an empirical procedure which has led to the development of synergistic systems of great complexity. The precise role of each component has been largely a matter of conjecture and recent studies have recognised that a better understanding of the molecular basis of the degradation process is a primary pre-requisite to the design of improved stabilisation systems. This has prompted intensive investigations into the role of impurities present in the polymer on its subsequent degradation under the influence of heat and light. Two aspects of this are considered in the present volume. The first is the presence in the commercial polymer of defects, particularly unsaturation, arising from its manufacture. This has assumed increasing importance in recent years as a result of the necessity to reduce the vinyl chloride monomer concentration in the polymer during manufacture to a level acceptable to the converting industries. The influence of some of the main classes of PVC stabiliser on these defects is considered. In Chapter 1, Ayrey and Poller review the chemistry of the organotin stabilisers and in Chapter 3, Guyot and Michel examine the role of the metal soaps.
The second problem area is the processing operation itself which not only
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introduces further unsaturation with evolution of HC1, but also causes partial pre-oxidation of the polymer due to the severe mechanochemical processes occurring under the influence of shear. The more specific interaction of organotin stabilisers with hydrogen chloride, unsaturation and hydroperoxides under these conditions is examined by Cooray and Scott in Chapter 2. The stabilisation chemistry of the phosphite esters in both polyolefins and PVC is considered in Chapter 4 by Pobedimskii, Mukmeneva and Kirpichnikov. This is a particularly valuable summary of recent work carried out in the USSR since much of the information has not previously been available in English. Finally, in Chapter 5, Luston reviews the extensive data available from recent studies on the importance of physical factors in determining the effectiveness of antioxidants and stabilisers in polymers.
GERALD SCOTT
CONTENTS
v Preface . • •'........
List of Contributors.........lx
1. Organotin Stabilisers for Polyvinyl Chloride ... 1
G. AYREY and R. C. POLLER
2. The Role of Tin Stabilisers on the Processing and Service Performance of PVC........53
B. BOYD COORAY and GERALD SCOTT
3. Stabilisation of Polyvinyl Chloride with Metal Soaps and Organic Compounds........°"
ALAIN GUYOT and ALAIN MICHEL
4. Organophosphorus Stabilisers: Efficiency and Mechanisms of Action..........125
D. G. POBEDIMSKII, N. A. MUKMENEVA and P. A. KIRPICHNIKOV
5. Physical Loss of Stabilisers from Polymers . . . . 185
JOZEF LUSTON
