Styrene-butadiene-styrene (SBS)-modified bitumen shows good cracking resistance at low temperatures.With the knowledge of the microstructure of SBS-modified bitumen being incomplete, the reasons for thelow-temperature performance remain partly unclear. In this work, modulated differential scanning calorimetry(MDSC) was used to study the ordering of crystallizable alkanes and that of alkyl aromatics in SBS-modifiedbitumen. These compounds are responsible, respectively, for the cold-crystallization (CC) and the sterichardening (SH) visible on the nonreversing heat-flow (NRHF) curves obtained from MDSC. In blends of bitumen with 3, 6, and 10 wt % SBS, CC and SH enthalpies were measured. SBS was found to reduce boththe CC and the SH in bitumen, the reduction being disproportionately higher than expected on the basis ofpolymer concentration. The loss of CC and SH enthalpies demonstrate the reduced capacity of alkanes andalkyl aromatics to order in the presence of SBS.
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