The formation mechanism of a band texture of ethyl cellulose acetate (ECA) in dichloro-acetic acid (DCA) which exhibits a cholesteric mesophase has been investigated by using a parallel plates shearing apparatus. A critical shear rate of the band texture formation can be measured to be about 1.5 sec-1 for 30 wt% solution of ECA. The result obtained indicates that the band texture of ECA/DCA is not formed during shear

but it is formed during relaxation of shear orientation. The variation of the formed band texture was also studied during heat-ing

and found that the formedband texture will vanish at heating

but the macromolecular chain orientation persists in solution.If the temperature is lower the isotropic temperature of the solution the band texture will reappear during cooling.Finally

a model was suggested to describe the formation mechanism of band texture for liquid crystalline state of polymers by shear.