Lamellar twisting in α isotactic polypropylene transcrystallinity investigated by synchrotron microbeam X-ray diffraction

We report for the first time details of the morphology of α isotactic polypropylene transcrystallinity induced by aramid fibers as determined by high spatial resolution X-ray diffraction. We suggest that the parent lamellae nucleate at the fiber surface with the crystallite c-axes parallel to the fiber axis, twist one quarter turn about the parent a*-axis within an approximate distance of 25 μm and then continue to grow without further twisting. This result is unexpected since lamellar twisting has never been observed in pure α spherulitic polypropylene.