Other Saturated Fatty Acids and Related Substances

3 Other Saturated Fatty Acids and Related Substances 

There has inevitably been a great deal of industrial interest in examining the effect of fatty acids other than stearic acid. However little of this work has been published. Pure fatty acids are all considerably more expensive than the blends generally described as stearic acid and dramatic effects would be needed to make their use worthwhile. This probably explains why there are very few commercial examples of other acids being used. Iso-stearic acid is sometimes used, probably because it is a liquid and easier to use in dry coating processes. The branched structure may also improve the dispersion effects obtainable, but would be expected to reduce the mono-layer amount and prevent a tightly 

The study of the adsorption of stearic acid onto calcium carbonate from alcohol solution by Ivanishchenko and Gladkikh [6] has already been mentioned. They also determined adsorption isotherms and the variation of ohmic resistance and water adsorption with coating level for shorter chain acids. Acids with ten and twelve carbon atoms appeared to form mono-layers on chalk with 1.5 x 10 moles g of filler while longer chain acids only required 0.9 x 10 moles g (unfortunately the surface area of the filler was not specified). With the shortest chain acid (Cjo), about three molecular layers were required to maximise hydrophobicity, but when more than 14 carbon atoms were present then only one mono-layer was needed. Their results also indicated that, for the shorter acids at least, the first molecular layer was packed differently from subsequent layers. 

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