Depolarized Light Intensity and Optical Microscopy of some Mesophase-forming Materials

Eight mesophase-forming compounds were studied by the technique of depolarized light analysis. The temperatures at which anisotropy changes occurred were compared with results from differential thermal analysis. Although anisotropy change and uptake of heat are usually synchronous, in some cases thermal uptake is almost complete prior to a significant change in the anisotropic behavior of the compound. The observations made explain many of the discrepancies between mesophase transition temperatures observed by differential thermal analysis and optical methods. Photomicrographs of the various mesophase types examined are presented.