Shear-induced smectic ordering in the melt of isotactic polypropylene.
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.
Li
Liangbin
L
FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
de Jeu
Wim H
WH
D040761:Biomimetic Materials / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D008968:Molecular Conformation; D011126:Polypropylenes / Q000737:chemistry*; D033081:Shear Strength
D011126:Polypropylenes