Abstract
Using a light-beating technique for an appropriate scattering geometry, we have measured the bend orientational diffusivity (D
bend
) for an "hexa-n-alcanoyloxytruxene" (HATXC
12
H
25
) sample which exhibits a disk-like thermotropic nematic phase (N
D
) between 57°C and 84°C. From K
33
measurement by the Frederiks method, the bend viscosity (η
bend
) is deduced. It is about 100 times higher than those corresponding to rod-like thermotropic nematics. From previous measurements of D
splay
and D
twist
for HATXC
12
H
25
, we have deduced the elastic constants (K
11
K
22
) and the viscosities (η
splay
, η
twist
). It has been concluded that, although there is a difference between the two kinds of molecules (disk-like and rod-like), the backflow has the same effect as in rod-like nematic phase.