Crystallization kinetics study on tilted ordering in N-(p-n-alkyoxybenzylidene)-p-n-alkylanilines (nO.m compounds) by thermal and electrical techniques. Part I

Abstract

Abstract A systematic kinetic study of crystallization among two smectogens of higher homologues of the benzylidene aniline nO.m series viz. 15O.12 and 15O.16 has been carried out by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and dielectric studies. The crystallization kinetics was studied by two techniques viz. the traditional thermal analysis (DSC) and dielectric technique viz. capacitance and dielectric loss variation with temperature. The DSC thermograms were run from crystallization temperature to the isotropic melt for different time intervals. The liquid crystalline behaviour together with the rate of crystallization of smectic ordering in newly synthesized nO.m compounds were discussed in relation to the kinetophase (which occurs prior to the crystallization). The molecular mechanism and dimensionality in the crystal growth were computed from the Avrami equation. The characteristic crystallization time (t*) at each crystallization temperature was deduced from the individual plots of log t and ΔH. Further, it was observed that the data obtained from DSC, POM and dielectric studies were in good agreement with one another.