Einfluß des Wassers und der thermischen Vorgeschichte auf das Phasenverhalten homologer Kephalin/Wasser-Systeme

1. By means of differential scanning calorimetry the phase behaviour of the following cephaline/water systems was studied: 1,2-dilauroyl-cephaline/water; 1,2-dimyristoyl-cephaline/water; 1,2-dipalmitoyl-cephaline/water; 1,2-distearoyl-cephaline/water; 1,2-diarachinoyl-cephaline/water. The phase transition temperatures (T _u ), enthalpies (ΔH _u ) and specific heat capacities (c _sp ) were determined and compared as a function of the water content and the alkyl chain length of the cephalines.
2. TheΔH _u andT _u values of the monohydrates depend systematically on the chain length. Differences occurred for the first and the second heating run.
3. With increasing water content theT _u values decrease while theΔH _u values become larger if one system cephaline/water is considered.
4. In the heterogeneous two phase region the increase of the chain, length of the homologous cephalines leads to a systematical increase of theΔH _u as well as theT _u values.
5. Below the annealing temperature dehydration and recrystallization occur. The kinetics of the phase transitionL _α →C was studied in the heterogeneous two phase region.