Development of highly oriented polymer crystals from row assemblies

The development of organized structures from sheared isotactic polypropylene melts with different amounts of dibenzylidene sorbitol (DBS) as a nucleating agent has been followed in real time using small angle X-ray scattering in conjunction with synchrotron radiation. The results show that, above a certain DBS concentration threshold, the lamellar crystals are highly oriented perpendicular to the direction of the prior applied shear field. The role of the directing agent in nucleating the crystallization and templating the crystal anisotropy is discussed.