DETERMINATION OF THE CHAIN ORIENTATION IN LIQUID-CRYSTALLINE POLYMERS BY MEANS OF MICROFOCUS X-RAY-SCATTERING MEASUREMENTS

A microfocus camera with a focus of 7 mu m fwhm and a flux of 10(11) photons/s at the ESRF in Grenoble was used to investigate the microstructure of liquid crystalline polymer samples of 4-oxybenzoate-co-6-oxy-2-naphthoate (73:27) (Vectra A950 from Hoechst-Celanese). These samples show isotropic scattering when examined by means of a conventional X-ray camera with a large focus (2 mm). In melt-pressed thin films, we observed local variations of the direction of molecular orientation, which is due to the presence of disclinations. Except at the center of the disclinations, the order parameter is nearly constant within the scanned area. In samples cut out of the center part of an injection-molded bar, we detected a four-point scattering pattern due to a zigzag chain conformation.