# Micromechanism of the Dispersion Behavior of Polymer-Modified Rejuvenators in Aged Asphalt Material
## Materials and Methods
### Materials
#### 2.1.2 Rejuvenators  
Three different rejuvenators were used in this study, including one commercial rejuvenator (CR) and two polymer-modified rejuvenators (MR-1 and MR-2). The CR, produced by Dongying Mingde Petroleum Technology Co., Ltd. (Dongying, China), is a common rejuvenating agent used for pavement-recycling engineering in China. In this study, CR was used for comparison with the polymer-modified rejuvenators. The polymer-modified rejuvenators were prepared with second-line extract oil (Hengtai Shuangfeng Chemical Factory, Loudi, China), C9 aromatics petroleum resin (Puyang Hengfeng Petrochemical industry, Puyang, China), Linear-type SBS (YH-791, SINOPEC Baling Company, Yueyang, China), stabilizing agent (Dibutyl phthalate) and dispersing agent (Methacrylate quaternary copolymer). MR-2 was the main rejuvenator investigated in this study, while MR-1, which did not contain a dispersing agent, was investigated for comparison with MR-2 in dispersion analysis.  
The preparation process for polymer-modified rejuvenator is shown in Figure 2. Firstly, the extracted oil and petroleum resin are blended in a reactor at a temperature of 140 \({}^{\circ}\)C for 60 min (Figure 2a). Secondly, the SBS modifier and stabilizing agent are gradually added to a high-speed shearing machine at a temperature of 180 \({}^{\circ}\)C for 30 min (Figure 2b). Thirdly, the dispersing agent is added to the same shearing machine, at a lower shearing rate, at a temperature of 170 \({}^{\circ}\)C, for 5 min (Figure 2c). Finally, the mixture is kept at a temperature of 150 \({}^{\circ}\)C for 30 min (Figure 2d). MR-1 was prepared using steps (a), (b), and (d), as depicted in Figure 2, and MR-2 was prepared using steps (a), (b), (c), and (d).  
In the aforementioned process, the stabilizing agent was used to prevent the phase segregation of the SBS modifier, and the dispersing agent (in the case of MR-2), which contains carboxyl and amino groups, was used to help evenly disperse the oil, the modifier, and the other rejuvenator components  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Penetration (0.1 mm)** & **Softening Point (\({}^{\circ}\)C)** & **Ductility 25 \({}^{\circ}\)C (cm)** & **Viscosity 60 \({}^{\circ}\)C (Pa-s)** \\ \hline Virgin asphalt (AH-70) & 72.6 & 47.5 & 162 & 256 \\ Aged asphalt & 35.8 & 65.2 & 12.5 & 1285 \\ Modified asphalt binder (1-D) & 48.2 & 72.5 & 52.3 & 6370 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Basic properties of virgin, aged and modified asphalt binder.  
Figure 2: Preparation process of the polymer-modified rejuvenators: (**a**) blending the extracted oil and petroleum resin in reactor; (**b**) adding SBS modifier and stabilizing agent in high speed shearing machine; (**c**) adding dispersing agent in high speed shearing machine; (**d**) keeping the samples in oven.  
within the aged asphalt binder. The basic properties of the three rejuvenators are presented in Table 2, and the basic composition of the two rejuvenators prepared in the laboratory are presented in Table 3.