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

We report for the first time details of the morphology of alpha isotactic p olypropylene transcrystallinity induced by aramid fibers as determined by h igh spatial resolution X-ray diffraction. We suggest that the parent lamell ae nucleate at the fiber surface with the crystallite a*-axes parallel to t he fiber axis, twist one quarter turn about the parent a axis within an app roximate distance of 25 mu -m and then continue to grow without further twi sting. This result is unexpected since lamellar twisting has never been obs erved in pure a spherulitic polypropylene. (C) 2001 Elsevier Science Ltd. A ll rights reserved.