This book continues the tradition of the first two editions of the late W. S. Penn's original PVC Technology, and the extensively revised third (1971) edition prepared by myself and B. J. Lanham. In the present edition the original general format, and the arrange­ ment of chapters, have been largely preserved, but virtually nothing now remains of Penn's own text: a part of the contents is based on material from the 1971 TitowlLanham version (revised, updated and mainly rewritten): the rest is new, including, inter alia, several chapters specially contributed by experts from the plastics industry in the UK and Europe. The section listing international (ISO) and national (BS, ASTM and DIN) standards relevant to PVC, which was first intro­ duced (as Appendix 1) in the 1971 edition, proved a popularfeature: it has now been brought up to date and considerably extended. Two further appendices provide, respectively, comprehensive unit conver­ sion"tables (with additional information on some ofthe mostfrequently encountered units, and the SI units), and a list of many properties of interest in PVC materials, with definitions, typical numerical values, and references~to relevant standard test methods. For various reasons, work on this edition involved more than the usual quota of problems: I am truly grateful to the Publisher's Manag­ ing Editor, Mr G. B. Olley, for his understanding, patience, unfailing courtesy and friendly encouragement.