C. Jolivetdalmazzone et al., SOLID-PHASE NUCLEATION OF BULK AND DISPERSED 3-METHOXY-4-HYDROXYBENZALDEHYDE, Industrial & engineering chemistry research, 36(3), 1997, pp. 874-880
Studies of the solid-phase nucleation of molten 3-methoxy-4-hydroxyben
zaldehyde (vanillin) were performed either on bulk (a few cubic millim
eters) or on emulsified (cubic microns) samples. The results obtained
from macroscopic observations and differential scanning calorimetry ha
ve pointed out undercooling phenomena characterized by roughly the sam
e order of undercooling degrees Delta T = T-m - T-s (T-m, melting temp
erature; T-s, the most probable solidification temperature) for steady
cooled (-3 degrees C/min) bulk and emulsified samples, namely, Delta
T approximate to 43 degrees C. At a fixed temperature, the solidificat
ion of the dispersed droplets can be described by an S-shaped curve th
at has been interpreted in terms of a polynuclear mechanism. Finally,
the decrease of the undercooling degree exhibited after a solidificati
on-melting process has been explained by the formation of nucleating s
ites at the liquid-emulsifying medium interface.