Isoextraction and solubility methods were employed to determine the dissociation constant or acidity constant of hardly soluble organic acids. The acidity constants thus obtained were in good agreement with the reported values determined by conventional methods. For dibasic acids, in particular, the successful method was introduced to determine the first dissociation constants where the solubility of undissociated acid was used as a parameter. Both are excellent method to examine the solution properties by taking advantage of constancy of chemical potentials of constituent chemical species of materials. Ionic surfactants also are hardly soluble materials in water at temperatures below the Krafft point. Steep increase in solubility above Krafft point was explained by micellar aggregation where the mass action model was used for micelle formation, and the Krafft point was examined by Gibbs' phase rule. Thenew term of “Micellar Temperature Range (MTR)” was introduced instead of Krafft point for elucidation of extraordinary solubility increase of ionic surfactants.
The mechanism of the yellowing of cellulose fibers caused by unsaturated fatty acids such as oleic and linoleic acids was studied by IR and UV spectroscopy, using thin film of cellophane as a model fiber. The following conclusions were made. (1) No chemical bonding occurs but a weak hydrogen-bond type interaction takes place between fatty acid and cellulose, and yellowing of cellophane itself is negligible. (2) Yellowing of fatty acid is enhanced by higher temperature and light, but not so by oxygen gas, in contrast to nitrogen gas. (3) No change in the absorbance of C-H band attached to double bond takes place following strong yellowing. (4) Yellowing is proportional to the increase in 204 and 210nm bands which can be assigned to double bonds formed by polymerization of oleic and linoleic acids. (5) Finally the main mechanism of yellowing reaction is not autoxidation but possibly kind of radical polymerization reaction of the double bonds of these fatty acids.
The effect of water hardness on the coagulation of iron (III) oxide particles and its deposition on nylon fabrics was studied in search of some substitutional builders for phosphates. The effect was examined as functions of water hardness (050ppm) at ionic strength 5×10-3, temperature 30°C and pH 11. The ζ-potentials of particles and a fabric, the distribution and mean diameter of coagulation particles in solution, and the amount of particle deposition on a fabric were measured. Particles were observed to be deposited on a fabric with a scanning electron microscope. The addition of a few ppm water hardness ions to a 0ppm solution markedly decreased the ζ-potential of particles and promoted their coagulation, and increased the deposition on the fabric. Above 5ppm water hardness, all these phenomena were approximately equilibrated. The ζ-potential of particles in the washing liquor may possibly be more important than that of fabric, since the coagulation of particles greatly influences the extent of their deposition on the fabric. Also coagulation of particles was found to correspond to the total interaction potential energy of homocoagulation between particles. These findings are in agreement with those of the previous paper on the effect of pH.
A comparison of the oxidation rates of randomized and non-randomized triglycerides (TG) of soybean oil was made by oxygen absorption techniques and peroxide value determinations. The randomized TG was found to undergo more rapid oxidation than the non-randomized TG. Molecular species of the randomized TG, therefore, were analyzed and compared with those of non-randomized TG, since the increase in oxidation rate may possibly be due to change in the molecular species of TG caused by randomizing. The results obtained indicated that, on randomizing, the content of molecular species such as LPL, LPLn, and LSL each having a saturated fatty acid linked at the 2-position of glycerol increased, while those such as OLL, OLO, and OLP having a linoleic acid linked at the 2-position decreased. These results suggest that TG having unsaturated fatty acids linked at 2-position, resulting in an increased oxidation rate of randomized TG.