Thermal Analysis (TA) has become an indispensable family of analytical techniques in the polymer research. The increased importance of these techniques can be seen as the result of three more or less parallel developments: & bull; a tempestuous development of TA measuring techniques in combination with a high degree of automation, & bull; the strongly increased understanding of the underlaying theory and, & bull; the increasing knowledge of the relation between the polymers' chemical structure and their physical properties. These areas are still in their developmental stages, especially the third area. The increasing knowledge of the dependence of physical properties on chemical structure just accentuated more and more the need for accurate thermoanalytical measurements, and this knowledge is very important for the first stages of the development of new polymeric systems. Besides, the contribution of TA remains necessary for the technical and commercial development of such a new polymer system. The use of the various TA techniques in these processes is described in this book in nine chapters, while chapter ten illustrates the information obtained about different polymers during special case studies. This book illustrates in this way, applications of a wide variety of TA techniques whilst it is written from a materials characterisation rather than from a TA point of view with attention being paid to the chemical structure/physical properties correlations.