Morphology and Molecular Motion of Polyethylene Reactor Powders pp. 45-67
Authors: (Hiroki Uehara, Takeshi Yamanobe)
Abstract: For semi-crystalline polymers, it is widely accepted that several phases, including crystalline and amorphous phases, coexist within a sample. Reactor powder morphology forms during polymerization with non-equilibrium state, thus it inevitably contains the intermediate phase, which connects between crystalline and amorphous phases. One of the major differences among these phases lies in their molecular dynamics. Several methods, such as thermal analysis and X-ray measurement, can quantitatively characterize these different phases; however, their analytical results are usually limited to information concerning the crystalline phase. In contrast, 1H-NMR relaxation analysis enables separate evaluation of crystalline and amorphous molecular dynamics without the requirement of scaling factors. Rather, such individual scaling factors, including relaxation time scale, component percentage and decay functions, can be compared among the phases contained in the sample, based on the 1H-NMR technique.