THE PHYSICAL PROPERTIES OF LYSOLECITHIN AND ITS SOLS: Part II. Refractive Indices and Densities of Sols. Micelle Formation

Abstract

The refractive index difference (nsol- nwater) and density difference (ρsol - ρwater) of lysolecithin sols indicate a change in the properties of the sols in the region of 0̇02 per cent w/v, above this concentration the refractive index difference:concentration relation and the density difference:concentration relation are linear. Values for the partial specific volumes of lysolecithin in water, calculated from density measurements, are given. Surface tension:concentration measurements at four different temperatures indicate that the critical micelle concentration increases with an increase in temperature. Values for the change in heat content in the molecular aggregation process, calculated from the temperature coefficient of the critical micelle concentration are small and negative, increasing numerically from 3432 calories at 20° to 6100 calories at 40°. The associated entropy changes in this process are small and show a slight increase negatively with an increase in temperature.