chapter  20
Properties of plastics
Pages 15

In Chapter 19, we considered a polymer material as consisting of an intertwined mass of giant molecules each containing thousands of atoms. In thermoplastics materials, these molecules are attracted to each other by relatively weak van der Waals forces, whilst in thermosetting plastics they are joined to each other by strong, permanent covalent bonds. This means that whilst thermosetting materials are sometimes stronger than thermoplastics, they are inevitably more rigid and much more brittle. This chapter is about the properties of plastics, their testing, and the methods used to shape them.