Abstract
The nematic-isotropic transition temperatures of MBBA(1) + 4-methoxybenzaldehyde(2) mixtures (where MBBA=N(4-methoxybenylidene)-4-n-butylaniline) for 0 x2 0.06 and additionally the transition enthalpy of pure MBBA were measured by a calorimetric method. Straight lines were found for the T1(x2) and Tn(x2) curves respectively where T1 and Tn are the upper and the lower limiting temperatures of the transition range for a given x2. The results are compared with literature data on similar systems and confirm the wellknown rule that the decrease of the nematic-isotropic transition temperature with increasing x2 depends more strongly on the size and the shape than on the polarity of component 2. From a plot of δT [tbnd] T1 - Tn against x2 the mole fraction of impurity in the original sample can be extrapolated.