reader to reinforce, extend and test his or her knowledge and understand­ ing of specific subjects. In addition to the people and organizations who assisted in the preparation of the First Edition, the authors would like to thank Mrs Susan Brandreth and Mrs Jean Smith for typing the new manuscript. They are also grateful to Dr Frank Heatley, Dr Tony Ryan, Dr John Stanford and Dr Bob Stepto for useful comments on aspects of the new material. Finally, they would like to express their sincere gratitude to their families for the understanding and support they have shown during the writing and preparation of the new edition. ROBERT J. YOUNG PETER A. LOVELL Manchester Materials Science Centre 1990 Preface to the first edition Polymers are a group of materials made up of long covalently-bonded molecules, which include plastics and rubbers. The use of polymeric materials is increasing rapidly year by year and in many applications they are replacing conventional materials such as metals, wood and natural fibres such as cotton and wool. The book is designed principally for undergraduate and postgraduate students of Chemistry, Physics, Materials Science and Engineering who are studying polymers. An increasing number of graduates in these disciplines go on to work in polymer-based industries, often with little grounding in Polymer Science and so the book should also be of use to scientists in industry and research who need to learn about the subject.