A COMPARISON OF BINDING-ENERGY AND METASTABLE ZONE WIDTH FOR ADIPIC ACID WITH VARIOUS ADDITIVES

The binding energy of nine alkanoic acids to the major crystal faces o f adipic acid were calculated employing molecular modelling techniques . The results indicate that the alkanoic acids bind strongly to the su rface when compared to solvents and to adipic acid itself indicating t hat the alkanoic acids could be potential growth and nucleation inhibi tors. The binding energies were found to increase with increasing carb on number to C-14 to decrease from C-14 to C-16 and then to increase a gain. The effect of the alkanoic acids on the metastable zone width of adipic acid in ethanol solution were measured employing a differentia l scanning calorimeter. The results showed that each of the nine alkan oic acids increased the metastable zone width. The metastable zone wid ths were found to increase with increasing carbon number to C-14 to de crease from C-14 to C-16 and to then increase again thus correlating w ell with the results obtained from binding energies. These results ind icate that binding energy calculations appear to provide a valid metho d to screen impurities as potential nucleation inhibitors.