  The development of the crystallinity and of the crystallographic orientation
of isotactic polypropylene (iPP) during rolling deformation and subsequent heat
treatment is studied. The experiments are conducted by using X-ray diffraction
with an area detector. The evolution of crystallographic orientation is tracked
by calculating the pole figures and by applying a quantitative 3D texture
component fit method. The rolling orientation after a true strain of -1.5
mainly consists of the (010)[001], (130)[001], and [001]//RD fiber components
(RD: rolling direction). The results reveal that the crystallinity drastically
decreases during rolling. We suggest that decrystallization (disaggregation) is
a deformation mechanism which takes place as a microscopic alternative to
crystallographic intralamellar shear depending on the orientation of the
lamellae relative to the imposed deformation tensor. Heat treatment after
rolling leads to the recrystallization of amorphous material and to a strong
enhancement of the fiber orientation component. The recrystallization
orientation is explained in terms of an oriented nucleation mechanism where
amorphous material aligns along existing crystalline lamellae blocks which
prevailed during the preceding deformation.
