MOLECULAR, THERMAL AND MORPHOLOGICAL CHARACTERIZATION OF NARROWLY BRANCHED FRACTIONS OF 1-OCTENE LLDPE .2. STUDY OF THE LAMELLAR MORPHOLOGY BY TRANSMISSION ELECTRON-MICROSCOPY

The lamellar morphology of a linear low density ethylene/1-octene copolymer (LLDPE A), and its fractions with short chain branching contents ranging between 3 and 28 branches per 1000 C atoms, has been investigated using transmission electron microscopy. The weight average molecular weight of the samples studied decreases from 2.7 x 10(5) at the lowest branching content down to 4.9 x 10(4) at the highest branching content. The branching content is the major factor determining the lamellar thickness, while the morphological structure of the lamellae depends both on the branching content and the molecular weight. In contrast to the unfractionated copolymer LLDPE A, lamellar stacks were observed in all fractions.