Determination of Primary Nucleation Kinetics of Acetylsalicylic Acid in Ethanol

The metastable zone width (MSZW) for the acetylsalicylic acid‐ethanol system was determined by the polythermal method. Nucleation parameters were calculated applying the self‐consistent Nyvlt‐like approach and the classical three‐dimensional theory approach. The results showed the usual increments in MSZW with increases in the cooling rate, mixed effects when raising the agitation rates, and an unusual behavior that reduced MSZW when the saturation temperature decreased. The apparent nucleation order proved to be independent of all three analyzed variables. The interfacial energy increased with higher saturation temperature and activation energies incremented when agitation rates raised. In general, the two approaches explained closely the experimental results.