抄録
A differential scanning calorimeter equipped with a shearing system was developed to reveal thermodynamic
properties of fluid materials under shear flow. Using the developed calorimeter, liquid crystalline material 4′-n-octyl-4-cyano-biphenyl (8CB) and rod-like micellar system of cationic surfactant cetyltrimethylammonium bromide (CTAB) aqueous solution were investigated. The heat flow caused by the shearing was evaluated from the shear stress data, and successfully subtracted from the measured DSC curve. The shear-rate dependences of the transition peaks were investigated for both systems. For 8CB, onset temperature of the smectic-A to nematic transition was found to be lowered by the shearing, whereas no considerable change was found for the nematic to isotropic liquid transition. For CTAB/water system, the transition from CTAB crystal coexisting with its aqueous solution to the rod-like micellar state was found to shift to lower temperature with increasing shear rate at 0 < 𝛾 < 1 s-1, whereas it shifted to higher temperature at 30 < 𝛾 < 100 s-1. The former change was attributed to the decrease in the grain size of the crystallites, whereas the latter one was ascribed to the orientational ordering of the rod-like micelles due to the shearing.
