Abstract

Ever since a synthetic cis-1,4-polyisoprene with the structure and properties of natural rubber was prepared in 1954 with the then newly discovered Ziegler catalyst, synthetic polyisoprene has been an important elastomer. Various catalysts have been used for synthesizing polyisoprenes, and the two commercially important systems are Ziegler-Natta and anionic. The manufacture of cis-1,4-polyisoprene and its compounding into formulations useful in making finished goods and articles are discussed. World plant capacities and estimated production figures for cis-1,4-polyisoprene are given, along with current polymer cost. trans-1,4-Polyisoprene is produced commercially only in Japan. Some of the specifications for cis-1,4-polyisoprene (Natsyn) made by The Goodyear Tire & Rubber Co., the sole United States producer, include volatile matter, extractables, ash, and Mooney viscosity. The principal use for cis-1,4-polyisoprene is in tires and tire products, and for trans-1,4-polyisoprene is in golf ball covers and orthopedic devices.