We report an unusual shear-induced smectic phase of high-molecular-mass isotactic polypropylene at temperatures well above its melting point. The necessary stiffness in the polymer chain is provided by shear-induced coil-helix transitions. Coupling between the conformational ordering and the density generates the smectic layering. The periodicity of about 4 nm is built up from a rigid helical sequence of at least 11 monomers and a random-coil part of about 1.4 nm. These results also provide new clues to the question of preordering before polymer crystallization.

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Persistent URL dx.doi.org/10.1103/physrevlett.92.075506
Journal Phys. Rev. Lett.
Li, L, & de Jeu, W. H. (2004). Shear-induced smectic ordering in the melt of isotactic polypropylene. Phys.Rev.Lett., 92(Article number: 75506), 1–3. doi:10.1103/physrevlett.92.075506