The role of dislocations for the plastic deformation of semicrystalline polymers as investigated by multireflection X-ray line profile analysis

Wide angle X-ray experiments evaluated by recent developments of X-ray line profile analysis allow for the detection of the presence of dislocations as well as to determine their density in crystalline materials. The application to semicrystalline polymers not only provides information on the crystal size and the dislocations but-in combination with in situ deformation-also information on the evolution of these microstructural parameters. Investigations on cold rolled and on uniaxially compressed samples of α-phase isotactic polypropylene (α-iPP) as well as poly(3-hydroxybutyrate) (P3HB) are presented. The synchrotron experiments reveal a dislocation governed deformation process in α-iPP. P3HB, however, deforms by a process not including dislocation generation. Here, microcracking and strain localization in the amorphous phase seem to be the predominant deformation mechanisms.