Magnetic orientation of isotactic polypropylene

Magnetic orientation of a low molecular weight isotactic polypropylene (iPP) is reported. Unlike other crystalline polymers for which the magnetic orientation has already been reported by our group, iPP was less expected to undergo the magnetic orientation because its repeating unit does not contain aromatic rings which are the main source of the diamagnetic anisotropy. The magnetic orientation was observed for samples melted in a magnetic field (6 T) in the temperature range between 180 and 240 degrees C followed by cooling. This temperature range is well above the melting point (168 degrees C). The X-ray and crystallization kinetics measurements indicated that some ordered structure exists in this temperature range. The samples obtained by quenching exhibited the orientation of crystals with the b-axis aligned parallel to the magnetic field. (C) 1999 Elsevier Science Ltd. All rights reserved.