INTERPRETATION OF DOUBLE-PEAK ENDOTHERM ON DSC HEATING CURVES OF BITUMEN

Since the late 1960s, differential scanning calorimetry (DSC) has been used to characterize petroleum bitumen, in particular, for the determination of the crystallized fraction (CF) content. This procedure is based on the construction of a baseline after identifying the CF dissolution endotherm on the heating curve. However, many bitumens commonly exhibit double-peak endotherms during a DSC heating scan. In this case, the task of constructing the corresponding baseline does not have a unique solution because the interpretation of the heat flow profile is ambiguous. Several interpretations have been proposed earlier to explain the origins of the double-peak endotherm. However, the double-peak endotherm is currently still not fully understood, and a comprehensive consensus has not been achieved. If the determination of the baseline location is incorrect, the CF content can be over- or underestimated by 20-30%. In the current work, double-peak endotherm behavior was investigated by temperature modulation DSC...