A study of the lamellar thickness distribution in 1-butene, 4-methyl-1-pentene and 1-hexene LLDPE by small and wide angle X-ray scattering and transmission microscopy

Three samples were examined of commercial linear low-density polyethylene, containing different comonomers (I-butene, 4-methyl-1-pentene and l-hexene) and having comparable molecular weight and branching amount. An analysis was carried out by transmission electron microscopy and small- and wide-angle X-ray scattering. The thicknesses were determined of the polymer lamellae, as well as their distributions and the morphology of the crystalline phase. Moreover, small-angle X-ray scattering experimental spectra were analyzed by a fit with the profiles calculated from some theoretical distribution models of the lamellar thickness. The mathematical evaluation of small angle X-ray scattering patterns and the analysis by transmission electron microscopy have provided crystallinity values which were compared with those obtained by wide angle X-ray scattering in order to obtain information on the organization in lamellar stacks. The fitting method has also provided lamellar thickness values comparable to the transmission electron microscopy data. (C) 1998 Elsevier Science Ltd. All rights reserved.