The dispersion effect of different bitumen substrates on SBS may be due to their different oil content. According to the description in the reference information, the oil content of petroleum bitumen is relatively small, while the oil content of blended bitumen is more. The difference of oil content may lead to the different dispersion effect of SBS in different bitumen substrates.

The oil content of petroleum bitumen is relatively small, which may lead to uneven swelling and dispersion of SBS in the modification process. Because of the low oil content, the soft bitumenene in petroleum bitumen diffuses slowly into SBS, and more effective test conditions may be required to fully disperse SBS. The mixed bitumen has more oil content, which may make SBS disperse better and swell quickly, thus forming a better spatial network structure.

The soft bitumenene in the blended bitumen can diffuse to SBS more quickly, which is beneficial to the dispersion effect of SBS. In conclusion, the difference of oil content between petroleum bitumen and blended bitumen may lead to the different dispersion effect of SBS in different base bitumen. The oil content of petroleum bitumen is less, so more effective test conditions may be needed to fully disperse SBS. The mixed bitumen has more oil content, which is conducive to the dispersion effect of SBS.