The phase behaviour of three binary mixtures of 4'-ethoxybenzylidene-4-n-butylaniline(EBBA)-p-azoxyanisole(PAA), C3-C4 which has substituted propyl-and butyl- in 4-(n-alkyl)-trans-(cyclohexane carboxylic acid)-4' -cyanophenol, respectively, and EBBA-C4 were investigated with DSC in determining the transion temperatures of mixtures and with Polarizing microscope by observing the textures of liquid crystalline phases.
The binary mixtures of EBBA-PAA showed the eutectic behaviour with wide nematic range near the eutectic point but concave nematic isotropic transition curve, indicating nonideal mixing behaviour by the difference of their terminal group polarity.
Although the phase behaviour of C4-C3 exhibited the same eutectic behaviour, the eutectic point appeared very close to 46 mole %, and the nematic isotropic transition curve was linear. The homologous series in differring with alkyl chain length only had simmilar molecular structures and maintained homogeneous mixed state.
On the other hand, the mixture of EBBA + C4 system with different linkage and end group exhibited mixed polymorphism, including smectic A and nematic at 25-43 mole%.
