Polymers are materials composed of long molecular chains that are well-accepted for a wide variety of applications. This book explores polymeric materials in terms of their chemical composition, associated properties and processes of manufacture from petrochemicals. The book also shows a range of products in which polymers are used and explains why they are chosen in preference to many conventional materials. After studying this book, the reader should be able to : isolate the key design features of a product which relate directly to the material(s) used in its construction; indicate how the properties of polymeric materials can be exploited by a product designer; describe the role of rubber-toughening in improving the mechanical properties of polymers; identify the repeat units of particular polymers and specify the isomeric structures which can exist for those repeat units; and estimate the number- and weight-average molecular masses of polymer samples given the degree of polymerisation and mass fraction of chains present.