An electron diffraction analysis of banded structures in thermotropic polymers

Abstract

A detailed analysis of selected area electron diffraction patterns of a thermotropic liquid crystalline polymer exhibiting the banded structure, shows that the molecular trajectory is not sinusoidal in form, as was indicated by preliminary observations of the structure in the optical microscope. The use of electron microdiffraction techniques (for regions ∼150 nm in diameter) also supports the view that significantly more molecules are oriented parallel to the shear direction than predicted by a sinusoidal trajectory. Microdiffraction further shows that the “micro-orientation” of the molecules is significantly better than is apparent from X-ray or selected area electron diffraction patterns. The apparent contradiction with the optical microscopy measurements is discussed.