Divided into four parts. Chapters 1 and 2 deal with current theories of friction and wear, and include discussion of various hypotheses based upon experimental studies. Chapter 3 details experiments designed to improve tribological performance via polymer blending and composite production, whilst Chapter 4 explains how the data obtained from these experiemnts can be applied to sliding machine parts. The work will prove useful in the design of plastic materials and components and will also provide a stepping-stone toward future innovations in this field.