# Bitumen and Bitumen Modification: A Review on Latest Advances
## 3 Bitumen Chemical Modifiers
### Nanocomposite Modifiers
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Formulation** & \multicolumn{3}{c}{**S (\({}^{\circ}\)C)**} \\ \hline SEBS \%(w/w) & SEBS/KC (w/w) & Top (S\({}_{\text{t}}\)) & Bottom (S\({}_{\text{b}}\)) & \(\Delta\)S \\ \hline
3 & 100/0 & 53.0 & 50.0 & 3.0 \\
3 & 100/50 & 52.5 & 52.8 & \(-\)0.3 \\
4 & 100/0 & 57.0 & 53.8 & 3.2 \\
4 & 100/10 & 56.5 & 50.8 & 5.7 \\
4 & 100/30 & 55.0 & 52.0 & 3.0 \\
4 & 100/50 & 55.5 & 55.8 & \(-\)0.3 \\
4 & 100/50 \({}^{\text{a}}\) & 59.0 & 52.0 & 7.0 \\
4 & 100/70 & 52 & 52.5 & \(-\)0.5 \\
5 & 100/0 & 70.5 & 58.0 & 12.5 \\
5 & 100/50 & 57.0 & 58.0 & \(-\)1.0 \\
6 & 100/0 & 85.0 & 67.5 & 17.5 \\
6 & 100/50 & 59 & 60.5 & \(-\)0.5 \\ \hline \hline \end{tabular} \({}^{\text{a}}\) Mix prepared using PM. \(\Delta\)S = S\({}_{\text{t}}-S_{\text{b}}\).  
\end{table} 
Table 3: SEBS/KC-modified bitumen storage stabilities at high-temperature (from Table 4 of [133] with the permission of Elsevier). polymer molecules to intercalate the clay stacks is strongly influenced by the mixing sequence. Finally, once the clay-polymer interactions are established, bitumen molecules are not necessarily expected to substitute the polymer chains in clay interlayers. For these reasons the similarity in the XRD spectra does not necessarily mean a similarity in the internal structure of PM and MB mixes. From a morphological point of view, Figure 13 shows three different systems: (a) the binary NB/SBS blend, (b) NB/SBS/clay PM blend, and (c) NB/SBS/clay MB blend. As can be seen NB/SBS blend is characterized by a biphasic morphology, which results in high-temperature storage instability. The NB/SBS/clay PM blend still shows a biphasic pattern, but the smaller microdomains indicate an improved compatibility and stability of the system. A further improvement of the morphology is observed for the NB/SBS/clay MB blend, which has the canonical aspect of a perfectly compatible PmB pattern. In addition, Figure 13a,b show the important role of clay, which favors the contact between the polymer chains and those bitumen molecules that would otherwise be confined in the ARP. Clays acts as the substrate where polymer and asphaltene molecules come into contact, reducing the differences in composition between the PRP and ARP phases. Later, [PERSON] et al. (2017, 2018) prepared different PmBs using EVA as a polymer and studied the effect of two different organoclays: 20A and another OMMT known as Dellite 43B (namely referred to as 43B). Figure 14 shows the fluorescence microscopy images of the blends studied. Figure 12: XRD pattern of neat bitumen, Closite 20A, SBS/20A, B/20A, B/SBS/20A (PM) and B/SBS/ 20A (MB) (reprinted from ([PERSON] et al., 2019) with the permission of Elsevier). Figure 14: Fluorescence images of (**a**) BA/EVA, (**b**) BA/EVA/20A PM, (**c**) BA/EVA/20A MB, (**d**) BA/EVA/43B (PM), and (**e**) BA/EVA/43B (MB) (reprinted from Figure 1 of [217] with the permission of Elsevier). Figure 13: Fluorescence Images of (**a**) BA/SBS, (**b**) BA/SBS/20A PM, and (**c**) BA/SBS/20A MB (reprinted from [46] reprinted with the permission of Elsevier). The pictures show results similar to those described for SBS. However, clay 43B has a compatibilizing effect less pronounced than 20A. The differences observed among the blends prepared using PM or MB are reflected in the macroscopic behavior. Rheological tests have shown an improvement in thermo-mechanical properties of the ternary blend prepared using MB. Therefore, the MB procedure is preferable to the PM since it guarantees better homogeneity, stability, and mixture performance. However, the PM has the advantage of being simpler from a practical point of view because it involves a single step using classic paving equipment.