Morphology and micromechanical behavior of blends of ethene/1-hexene copolymers

Using (Me5Cp)(2)ZrCl2 and Et(Ind)(2)ZrCl2 activated by methylaluminoxane (MAO), ethene/1-hexene copolymers of markedly different densities were produced under the same conditions. Binary blends were produced by melt blending of a high-density ethene/1-hexene copolymer with an elastomeric ethene/1-hexene copolymer. Transmission electron microscope (TEM) investigations of ultrathin sections of samples stained with ruthenium tetroxide revealed the morphology of the different blends. Depending on the blend composition, the degrees of segregation differed. An analysis of the TEM micrographs shows that increasing the segregation of the elastomeric blend component seems to be accompanied by an increase of the mean thickness of the crystalline lamellae of the matrix. Corresponding to the TEM results, typical morphological structures were also revealed by scanning force microscope (SFM) investigations using the tapping mode and a force modulation mode. Furthermore, these SFM techniques were applied to study in situ local deformations and changes in the morphological structures in a certain specimen position while the external stress was successively increased. Results of these experiments, as well as those from additional TEM in situ tensile tests of thin sections, show that the deformation that appears homogeneously down to the micron range is strongly inhomogeneous in the submicron range.