Book excerpt: This book is unique in its focus on micromechanical processes of polymers and their role to improve the properties of polymeric materials. It combines the detailed knowledge of structure and morphology of polymers with the explanation and theoretical interpretation of micro- and nanoscopic processes and mechanisms in different polymers. Thus, it offers a better understanding of correlations between structure and property of nearly all polymers used in industrial applications. The knowledge of these correlations is a key for successful development of polymers with improved properties.