I am pleased to present the Fifth Edition of the Plastics Engineering Handbook. Last published in 1976, this version of the standard industry reference on plastics processing incorporates the numerous revisions and additions necessitated by 14 years of activity in a dynamic industry. At that last printing, then-SPI President Ralph L. Harding, Jr. anticipated that plastics pro­ duction would top 26 billion pounds in 1976 (up from 1.25 billion in 1947, when the First Edition of this book was issued). As I write, plastics production in the United States had reached almost 60 billion pounds annually. Indeed, the story of the U.S. plastics industry always has