Small-angle X-ray scattering from high-density polyethylene: lamellar thickness distributions

Small-angle X-ray diffraction patterns were recorded for a number of high-density polyethylene samples and were successively analysed by a fit with the calculated patterns corresponding to certain theoretical models. The parameters determined by the above fits were as follows: long-period, crystallinity, mean dimensions of the crystalline lamellae, amorphous thickness, crystallinity and lamellar dimension distributions. Regarding the latter, two mathematical functions were used for the fits, i.e. a symmetrical and an asymmetrical type, and for all of the samples examined the function was determined which gives the best results. Finally, a correlation is suggested between the polymer molecular weight and lamellar dimension distributions

Small- and wide-angle X-ray scattering characterization of 1-hexene linear low-density polyethylene

Four ethylene-1-hexene copolymer samples were studied by small-angle X-ray scattering in order to investigate the correlation between the crystalline lamellar thickness and the comonomer content. The lamellar thickness was determined from the identity period of the one-dimensional scattering function and from the analysis of the one-dimensional correlation function. The crystallinity and the volume of the crystalline unit cell were determined by wide-angle X-ray scattering. Some considerations are reported on the effect of the side chains during the crystallization and on the polydispersity of the lamellar thickness