Non-Gaussian behavior of crystalline and amorphous phases of polyethylene

We report on measurements of the incoherent elastic neutron-scattering inte nsity I-el(Q) of polyethylenes with degrees of crystallinity 0.46 and 0.96 in a wide Q (length of scattering vector) range from 0.4 to 6.2 Angstrom(-1 ) to observe the deviation from the Gaussian behavior. The non-Gaussian beh avior was observed in both the amorphous and the crystalline phases. The no n-Gaussian behavior in the theoretically well-known crystalline phase can b e understood more or less quantitatively;in terms of the anisotropy of the mean-square displacement. The result implies that at least a part of the no n-Gaussian behavior of the amorphous phase is due to the same source, while another part may be due to the dynamical heterogeneity inherent to the amo rphous phase.