Swelling of Nitrile Vulcanizates by Polar and Non-Polar Liquids-Part 1

Two sets of numbers can be used to describe the polarity of a liq uid. One set, which includes the Hildebrand solubility parameter and dielec tric constant, is based solely on the properties of the liquid itself. The other set depends on the interaction of the liquid with one or more reference materials. This group includes aniline point, miscibility number, molar transition energy, and polarity index. Since the aniline point is mainly concerned with paraffin hydrocarbons, no attempt was made to relate it to the other parameters. How ever, it was found that a parabolic rather than a straight line relationship ex ists between the logarithm of the volume change of the NBR vulcanizate and the aniline point of the oils. There is no correlation between the solubility pa rameter and either dielectric constant or the members of the other group. While the molar transition energy increases with increasing polarity index, there is a large amount of scatter. There is better correlation between polarity index and the miscibility number, particularly if the values for alcohols are ignored.