Metallocenic Copolymers of Isotactic Propylene and 1‐Octadecene: Crystalline Structure and Mechanical Behavior

Abstract

Abstract Summary: A set of copolymers of isotactic propylene and 1‐octadecene (CiPOD) and the corresponding isotactic poly(propylene) homopolymer (iPP) have been synthesized using a metallocene catalyst. The influence of the incorporation of this long chain comonomer on the structure and final properties exhibited by iPP has been examined. Wide‐angle X ray diffraction and optical microscopy have been used to analyze the effect of introducing 1‐octadecene comonomer within the iPP backbone. The initial monoclinic crystal lattice with a well‐developed lamellar morphology is transformed into a mesomorphic modification showing very small entities. All these structural changes significantly influence the mechanical behavior of these copolymers. Thus, stiffness and microhardness are diminished and the brittle‐ductile transition can be observed by simply varying composition when deformation takes place at room temperature. On the other hand, the intensity of the process associated with cooperative movements within the amorphous phase ( β relaxation) significantly goes up with the incorporation of 1‐octadecene and its location is shifted to lower temperature because of the decrease in the crystallinity content. X‐ray diffraction patterns at room temperature, with increasing comonomer content. magnified image X‐ray diffraction patterns at room temperature, with increasing comonomer content.