Selected X-ray diffraction and differential scanning calorimetry measurements on nonaqueous liquid crystals and gel phases in the K-myristinate/glycerol binary system

Samples from the three selected concentrations x(KC14) = 0.25, 0.37, and 0. 50 of the K-myristinate/glycerol (KC14/Gl) binary system have been investig ated by means of small- and wide-angle X-ray diffraction measurements as we ll as differential scanning calorimetry (DSC) measurements as a function of temperature. The results are - The G(l) gel phase: contained in the preliminary phase diagram according to Dorfler and Senst [(1993) Colloid Polym Sci 271: 173], is nonexistent. - The same applies of the isotropic phase in the preliminary phase diagram according to Dorfler and Senst. Initially an isotropic of a cubic phase was assumed based on polarized microscopy texture observations. X-ray diffract ion and DSC measurements provided no indication for their existence. - Due to the nonexistence of the G(l) and isotropic phases the preliminary phase diagram of the KC14/Gl binary system had to be corrected. The region of the lamellar phase extends over a wider region. - X-ray diffraction and DSC measurements provided concordant results, which were further confirmed by electron microscopic investigation. Differences in phase-transition points from DSC data obtained for rising and falling te mperatures have been observed. - The crystalline-to-gel phase transition correlates with a sharp shift in the d value of the first small-angle reflex. - The gel phase is accompanied by a distinct splitting of the first small-a ngle reflexes. The wide-angle reflexes show rearrangement and reduced inten sity. - Similar to the crystalline-to-gel phase transition, the gel-to-lamellar p hase transition is accompanied by a sharp change in the d values.