The dominant parameters for stereocomplexation have been
reported to be the mixing ratio and the molecular weights of PLLA
and PDLA [20,21]. Equimolar mixing has been found to be favored
for stereocomplexation, and with a deviation of weight ratio from
50:50, the ratio of stereocomplex crystallites to homocrystallites
decreases [22]. Fig. 3 shows WAXD profiles and DSC melting curves
of non-equimolar PLLA/PDLA blends prepared by the low temper-
ature approach (at processing temperature of 160 C), and the
WAXD and DSC data are shown in Table 2. It should be noted that
the WAXD profile of PLLA60/PDLA40 blend in Fig. 3(a) only shows
the characteristic peaks of stereocomplex crystallites, and the DSC
melting curve in Fig. 3(b) also shows a single peak at 229.1 C,
indicating that stereocomplex crystallites is the exclusive crystal-
line species in such a non-equimolar high-molecular-weight
PLLA60/PDLA40 blend and no homocrystallites is formed. The Xc(sc)
of PLLA60/PDLA40 blend is 49.5%, in marked contrast with the
results of PLLA50/PDLA50 prepared by conventional melt blending
and solution casting methods, where Xc(sc) are 20.1% and 24.9%
respectively (See Fig. 2 and Table 1).