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

Abstract 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.

[1]  H. D. Keith,et al.  Crystallization in Thin Films of Isotactic Polypropylene , 1966 .

[2]  R. Samuels,et al.  Characterization of the structure and organization of β‐form crystals in type III and type IV isotactic polypropylene spherulites , 1972 .

[3]  B. Hsiao,et al.  Matrix molecular orientation in fiber-reinforced polypropylene composites , 1998 .

[4]  H. Wagner,et al.  Morphology and Damage Mechanisms of the Transcrystalline Interphase in Polypropylene , 1995 .

[5]  A. J. Lovinger.  Microstructure and unit‐cell orientation in α‐polypropylene , 1983 .

[6]  B. Hsiao,et al.  The effects of transcrystalline interphase in advanced polymer composites , 1992 .

[7]  Sidney R. Cohen,et al.  Anisotropic nanoindentation of transcrystalline polypropylene by scanning force microscope using blade-like tips , 1999 .

[8]  J. Karger‐Kocsis,et al.  Interfacial morphologies in carbon fibre-reinforced polypropylene microcomposites , 1995 .

[9]  E. Wachtel,et al.  Microstructure of nylon 66 transcrystalline layers in carbon and aramid fibre reinforced composites , 1996 .

[10]  D. Bassett,et al.  On the lamellar morphology of isotactic polypropylene spherulites , 1984 .

[11]  H. D. Keith,et al.  Spherulitic Crystallization in Polypropylene , 1959 .

[12]  G. Marom,et al.  The effect of the transcrystalline layer on the mechanical properties of composite materials in the fibre direction , 1999 .

[13]  H. Wagner,et al.  Microdamage analysis of fibrous composite monolayers under tensile stress , 1989 .

[14]  E. Wachtel,et al.  γ‐Transcrystallization in isotactic polypropylene‐based composites promoted by aramid fibers , 1999 .