SHEAR-INDUCED TEXTURES OF THERMOTROPIC ACETOXYPROPYLCELLULOSE

Acetoxypropylcellulose is a thermotropic cellulose derivative which is cholesteric from below room temperature up to 170 degrees C. Its text ures during and after shear flow were studied by optical microscopy an d small-angle light scattering (SALS) light scattering. The main featu res are similar to those occurring in hydroxypropylcellulose solutions , i.e., a polydomain texture evolving into a striated texture, as seen by optical microscopy. Elliptical or else four lobes with a streak ar e seen in the SALS patterns. Defects appearing as short dark lines not aligned with the flow direction are shown to be responsible for the e xistence of the four lobes of the SALS patterns. In addition these def ects seem to be located where the band texture develops during relaxat ion. (C) 1997 The Society of Rheology.