Because of the sheer size of the plastics industry, the title Developments in Plastics Technology now covers an incredibly wide range of subjects or topics. No single volume can survey the whole field in any depth and so what follows is therefore a series of chapters on selected topics. The topics were selected by us, the editors, because of their immediate relevance to the plastics industry. When one considers the materials produced and used by the modern plastics industry, there is a tendency to think of the commodity thermoplastics (such as poly(vinyl chloride) or polyethylene); the thermosetting materials are largely ignored. Because of this attitude we are very pleased to include in this volume a chapter which deals with the processing of a thermosetting material, i.e. the pultrusion of glass reinforced polyester. The extrusion of plastics is, of course, a very important subject but an aspect which is often overlooked is the need to remove volatile matter during processing: for this reason we have included a chapter on devolatilisation. Current industrial practice is towards materials modification and this attitude is reflected in the chapters on the transformation of ethylene vinyl acetate polymers and the use of wollastonite in two important thermoplastics. When assessing the performance of materials, there is a tendency to concentrate on short-term mechanical tests and ignore such topics as fatigue and longer-term testing. We are therefore very pleased to include a chapter on this subject.