gamma orthorhombic isotactic polypropylene transcrystallinity nucleated on aramid fibers under high pressure was investigated by synchrotron X-ray diffraction and by scanning electron microscopy. It was determined that the c axes of the lamellae (the growth axes) are distributed radially about the fiber and that the lamellar ab face is randomly oriented on the fiber surface. This finding is consistent with the apparent absence of an epitaxial relationship between the crystal structure of the surface of the Kevlar aramid fiber and the lattice of gamma iPP crystals.