VISCOSITIES OF SOME LONG-CHAIN FATTY-ACIDS AND THEIR RELATIONSHIP WITH CHAINLENGTH

The densities and viscosities of octanoic, decanoic, dodecanoic and tetradecanoic acids were determined at temperatures ranging from 20 to 80-degrees-C. When the fluidities were plotted against the molal volumes of the acids, curves were obtained. The intrinsic volumes were determined by extrapolation to zero fluidity and compared with previously reported values. Based upon Hildebrand's equation for non-associated liquids, semiempirical equations relating the fluidity with the carbon number were obtained. The equations predict the fluidities of fatty acids with carbon number ranging from 4 to 18 at 4 temperatures from 20-degrees-C to 75-degrees-C with reasonable agreement with the experimental values.