# Phase Separation Study on the Storage of Technically Specification Natural Rubber Modified Bitumen
## 3 Results and Discussion
### Storage Stability of TSNR-Modified Asphalt
Effects of Sulfur Addition and Decreased Storage Temperature on Storage Stability of TSNR-Modified Asphal  
The 8-12% TSNR-modified asphalt evaluation revealed that it performed best at 10% TSNR. As a result, further testing was performed on the asphalt's storage stability for up to 72 h. The addition of sulfur to the modified asphalt mixture was further investigated. The purpose of adding sulfur in TSNR-modified asphalt is to improve the compatibility of the mix of asphalt and TSNR components [54; 55; 56]. The results of the storage stability test at 160 \({}^{\circ}\)C with a shelf life of up to 72 h for samples without and with sulfur addition can be seen in Figure 8 and Table 2.  
Figure 8: (**A**) Storage stability test of 10% TSNR-modified bitumen without sulfur and (**B**) with sulfur addition at 160 \({}^{\circ}\)C for 72 h.  
Figure 8 and Table 2 show that the phase separation is still ongoing for 72 h, characterized by a greater difference in the softening point between the top and bottom. This indicates that a large amount of TSNR phase with a smaller size and lower molecular weight has less mobility and, thus, requires more time to accumulate at the top [6, 53, 57]. Figure 8 and Table 2 demonstrate that adding 1 phr sulfur has no effect on the compatibility of asphalt and TSNR components. Other studies have suggested that adding sulfur to polymer-modified asphalt is a stabilizing agent [55]. However, the exact mechanism of improving storage stability through sulfur addition, as well as its relationship to vulcanization reactions, remains to be fully understood. However, in general, sulfur addition to modified asphalt is thought to improve storage stability [55, 56]. of the mixture to inhibit the rate of phase separation [17; 55; 60]. In this study, the addition of sulfur only increased the density of the TSNR phase to a higher level. However, the mixture's viscosity decreased due to the nonoptimal sulfide or polysulfide bonding of polymer molecules to asphalt, and ultimately, the compatibility of asphalt and TSNR could not be achieved. The homogeneity of the reaction is very important to reduce the occurrence of local coagulants formed from sulfide or polysulfide bonds in the rubber asphalt matrix. Although phase stability of the modified asphalt was not achieved, the addition of sulfur increased the TSNR-modified asphalt's softening point. Figure 8 shows a comparison of modified asphalt without and with sulfur. The graph shows that the asphalt with sulfur addition has a higher softening point in each section than the modified asphalt without sulfur. Adding sulfur to the modified asphalt raises the combined transition temperature even higher than TSNR alone. Furthermore, the formation of agglomerated TSNR phases can absorb more maltene fraction and increase the asphaltene fraction to a significantly higher degree [21; 40]. In this study, the addition of sulfur increased the density of the TSNR phase. However, the mixture's viscosity decreased as a result of nonoptimal sulfide or polysulfide bonding of polymer molecules to asphalt, and, thus, asphalt and TSNR compatibility was not achieved. The reaction's homogeneity is critical for reducing the formation of local coagulants in the rubber asphalt matrix caused by sulfide or polysulfide bonds. One approach to reducing phase separation in TSNR-based modified asphalt is to lower the storage temperature and maintain continuous homogenization. Temperature influences the rate of mobility and diffusivity in the TSNR phase. Higher temperatures accelerate the diffusion of asphalt components into the TSNR phase. This, in turn, determines an increase in the speed with which the TSNR phase swells, as well as coalescence and flocculation phenomena [44].