Characterization of polyethylenes by x-ray diffraction and 13C-NMR: Temperature studies and the nature of the amorphous halo

X‐ray diffraction patterns of linear and branched polyethylenes typically show two sharp reflections and an amorphous halo. The position of the halo depends on branch content and temperature. A single curve describes the position of the halo maximum (2θhalo) for a range of liquid hydrocarbons and polyethylenes in the 20–140°C range. At temperatures well below their melting point, branched polymers give 2θhalo values which differ significantly from those observed for the liquid Linear polymers show a greater divergence, indicating that some of the material giving rise to the halo is much better packed than in the liquid.Parallel 13 C NMR spin‐lattice relaxation studies suggest that this relatively ordered material has a trans conformation but a low average T1c value. © 1993 John Wiley & Sons, Inc.