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 electron microscopy

Three samples were examined of commercial linear low-density polyethylene, containing different comonomers (1-butene, 4-methyl-1-pentene and 1-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.