Unambiguous polymorphic identification of the DSC peaks can be
achieved by using XRD. Fig. 2 shows the wide-angle X-ray diffraction
(WAXD) patte28 °C. The first peak appearing at 15 °C, at d=4.17 Å, is unequivocally
connected with an α polymorph. At the end of the isothermal period
(90 min), a diffraction pattern corresponding to a β′1 polymorph
could be observed (Braipson-Danthine & Gibon, 2007). A polymorphic
transition from α to β′1 had thus occurred. The same transition
could be observed at 18 and 20 °C (data not shown). The two melting
peaks observed in the DSC stop-and-return profiles thus corresponded
to the α and β′1 polymorph. On the other hand, at 28 °C, the first framesrns of palm oil isothermally crystallized at 15 and