CONTROL OF THE ANISOTROPIC MECHANICAL-PROPERTIES OF LIQUID-CRYSTAL POLYMER-FILMS BY VARIATIONS IN THEIR BANDED TEXTURE

Variations in the banded texture of sheared liquid crystal polymer films are shown to control the anisotropy of their mechanical properties. Films, prepared by shearing lyotropic liquid crystal polymer solutions of 2-hydroxypropyl cellulose, were submitted to elongation both along and normal to the shear direction. The films were found to be brittle along the shear direction and ductile in the transverse direction. Stretch along the shear direction does not significantly affect the molecular orientation for any of the films. However, in the transverse direction, profound molecular reorientation occurs on stretching the film, resulting in a fibrillar structure, except at very small band wavelengths. After the disappearance of the original bands due to the deformation in this transverse direction, new bands appear which are of a much smaller wavelength.