Preparation and Characterization of Metallocene-catalyzed Isotactic Polypropylene and/or Syndiotactic Polypropylene Single Crystals; Preliminary Studies

Abstract

Single crystals of metallocene-catalyzed isotactic polypropylene (iPP) and/or syndiotactic PP (sPP) were prepared and preliminarily characterized. The crystallization was performed utilizing 0.1% by weight concentrations of each PP in ο-xylene in the range of temperature of 40∼90oC. Following the XRD patterns, samples were α-iPP and antichiral Cell Ⅲ of sPP. The XRD pattern of iPP shows three α-form peaks due to the (110), (040), (130) planes at 2θ = 14.2o, 17o, 18.8o, respectively. The XRD pattern of sPP is characterized by the presence of the (020) reflection at 16o. The melting point (123oC and 148oC, respectively) of the metallocene catalyzed iPP and sPP were generally lower than that of conventional PP (160∼170oC) due to the misinsertion of the monomer. When metallocene-catalyzed iPP samples were crystallized isothermally from solution grown at a lower temperature, lozenge shape single crystals were observed by transmission electron microscopy (TEM).