Shear-induced smectic ordering in the melt of isotactic polypropylene

Phys Rev Lett. 2004 Feb 20;92(7):075506. doi: 10.1103/PhysRevLett.92.075506. Epub 2004 Feb 20.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomimetic Materials / chemistry
  • Chemical Phenomena
  • Chemistry, Physical
  • Molecular Conformation
  • Polypropylenes / chemistry*
  • Shear Strength

Substances

  • Polypropylenes