The usual Morse functions are determined from the energy of dissociation, the equilibrium separation of the nuclei, and the fundamental vibration frequency. Two additional spectroscopic constants, ωexe and αe, are available for most of the common diatomic molecules and permit us to add a two-parameter correction term to the Morse curve. Both the potential V/D=(1−e−x)2+cx3(1+bx)e−2x and the extended Morse curve of the Coolidge, James and Vernon type, V/D=C2(1−e−x)2+C3(1−e−x)3+C4(1−e−x)4 agree with accurate potentials in those cases where they are known. Here x = 2β(r—re)/re. The constants for the first of these potentials are easy to evaluate and are given for 25 common diatomic molecules. With only a few exceptions, the improved potentials lie above the Morse curves and the corrections for moderately large internuclear separations may amount to ten percent of the energy of dissociation. Our treatment is based on the work of Dunham and the analysis of Coolidge, James and Vernon.
temperature and the water layer separated. The resin layer was not dried but was condensed with rosin as outlined above, after determining solids at 110°C. to estimate the resin content. The percentages shown on the curves are in mole per cent of trireactive phenol.It will be readily seen that a wide variety of highly viscous resins can be prepared. If bisphenol or m-cresol is substituted for phenol, the resulting products have approximately the same viscosity, as is the case when p-cresol or amylphenol is substituted for butylphenoi. The cloud point is lower when larger side groups are present.
UTILIZATION OF CONDENSATESThe condensates in Figure 8 cannot be esterified with glycerol. Attempts to form the glyceride led to insoluble gels before the acidity was greatly reduced. Here again is an indication of combination of the phenolic resin and the rosin. If the rosin acted only as a solvent, there is no reason to expect gel formation if it is converted to an ester. However, if the rosin acids are combined with the phenolic resin to form dibasic acids, gelation on esterification with glycerol would be expected.The resins can be dispersed in linseed or soybean oil ( 6) without too great difficulty, but because of their high viscosity they do not dissolve quickly. After heating for some time at 250°C. or higher with the oil, it is possible to add glycerol and neutralize the resin acidity. Acid interchange has occurred with the oil, and gelation is prevented by the presence of the fatty acids in the ester structure. The viscosity of the resulting varnish is high, as might be expected from the highly viscous resin that is dispersed in it.These highly viscous resins cannot therefore be utilized as the usual modified phenolic resins, but when processed in the manner outlined above hold promise of becoming useful varnish resins.
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