Kj. Kim et Sk. Ryu, NUCLEATION OF THIOUREA ADDUCT CRYSTALS WITH CYCLOHEXANE-METHYLCYCLOPENTANE SYSTEM, Chemical engineering communications, 159, 1997, pp. 51-66
To study the homogeneous nucleation of thiourea adducts, the metastabl
e zone widths for the thiourea adducts formed with guests of cyclohexa
ne, methylcyclopentane (MCP) and their mixtures were determined. The i
nfluence of moderate agitation rate and saturation temperature on the
maximum allowable undercooling (i.e., metastable zone width) was studi
ed. The metastable zone width is markedly affected by the cooling rate
and the agitation rate. MCP in guests roles to retard the nucleation
rate of cyclohexane-MCP-thiourea adducts by causing k(2) to decrease.
The order of the nucleation in the nucleation process of thiourea addu
cts is in the range between 3 and 6, and appears to be dependent on th
e saturation temperature and the guest concentration. The nucleation r
ate constant (i.e., frequency factor (k(2)/N-obs)) has shown to exclus
ively depend on the concentration of guest and the temperature. The re
tarding effect of MCP in the thiourea adduction was found to be caused
by, not only the increase of surface energy, but the decrease of k(2)
/N-obs.