Abstract
Within the field of polymer research, the investigation of crystalline polymers has proved to be useful from both a practical and a more fundamental point of view. Concerning the practical point, crystallinity strongly influences such mechanical properties of polymers as density, elastic modulus, tensile strength, and impact resistance. Concerning the more fundamental viewpoint, crystallinity and in particular the crystallization process seem to be not totally understood, and these topics have therefore been the subject of many theoretical considerations and speculations.