Rheology of the lecithin-water system in its lamellar phase

Though there exists already some knowledge about the rheological properties of the water-lecithin system in its lamellar phase we have resumed a more comprehensive study in this field. For this purpose, dispersions of hen-egg lecithin with a water content ranging from 5 to 42.5% were examined by means of a Weissenberg Rheogoniometer. Each sample was previously sheared at a low shear rate (0.229 s−1) to produce a steady state. The stresses arising from various mechanical deformations always applied according to the same protocol have been analysed. The deformations were induced by steady rates of shear or by a steady rate of shear partly modulated at various frequencies or by pure oscillatory rates of shear.