this case C and E. Between these pointsG^00 <0 and, as illustrated for
composition D, any demixing, however small, will lead to a decrease inG.
Phase separation will thus occur spontaneously; it is called spinodal
decomposition. C and E correspond to the points on the spinodal curve at
T¼T 1. Between A and C and between E and F,G^00 >0 and, as shown for
composition B, demixing initially leads to an increase inG. Hencenucleation
is needed to initiate phase separation in the composition range between the
binodal and the spinodal.
FIGURE14.8 Liquid–liquid phase separation. Hypothetical example of (a) the
effect of temperatureTon the binodal and the spinodal and (b) the mixing free
energyGat temperatureT 1 , of a binary liquid system as a function of the mole
fractionmof one of the components.