To explore the interactions and mechanisms of Thermoplastic polyurethane (TPU)-modified asphalt with different kinds of mineral fillers, a micro-mechanical model for TPU-modified asphalt mastic was established, which considered the interaction between asphalt and mineral powder to effectively analyze the internal mechanisms affecting the rheological properties of TPU-modified asphalt mastic. In this study, according to the micro-mechanics of composites’ principles, the dynamic shear modulus (|G^*|) of asphalt mastic with different mass ratios of filler/asphalt (F/A) was calculated by the homogenize morphologically representative pattern (H-MRP) model. The key ratio of F/A, which is close to the test result, can be determined, and a four-phase H-MRP model of the TPU modified asphalt mastic was established after considering the structure of asphalt layer thickness. The results were interpreted based on the known reactions of TPU with asphalt model compounds. The |G^*| of TPU-modified asphalt mastic was predicted by using this model. Furthermore, the effects of the complex shear modulus, Poisson’s ratio of TPU-modified asphalt, Poisson’s ratio, particle size of mineral powder, and thickness of the structural asphalt layer in the |G^*| of TPU-modified asphalt mastic were analyzed in the whole-model construction, as well as the internal mechanism of the |G^*| of TPU modified asphalt mastic. In addition, can also be found the predicted value of |G^*| calculated by the four-phase H-MRP model is close to the experimental value after choosing a structural asphalt layer of appropriate thickness.

In recent years, eucommia ulmoides gum (EUG), also known as gutta-percha, has been extensively researched. Molecular dynamic simulations and experiments were used together to look at how well gutta-percha and asphalt work together and how gutta-percha-modified asphalt works. To investigate the gutta-percha and asphalt blending systems, the molecular models of asphalt and various dosages of gutta-percha-modified asphalt were set up using Materials Studio (MS), and the solubility parameters, intermolecular interaction energy, diffusion coefficient, and mechanical properties (including elastic modulus, bulk modulus, and shear modulus) of each system were calculated using molecular dynamic simulations at various temperatures. The findings indicate that EUG and asphalt are compatible, and sulfurized eucommia ulmoides gum (SEUG) and asphalt are more compatible than EUG. However, SEUG-modified asphalt has better mechanical properties than EUG, and the best preparation conditions are 10 wt% doping and 1 h of 180 °C shearing. Primarily, physical modifications are required for gutta-percha-modified asphalt.

Presently, there is a significant focus on the investigation and advancement of polymer-modified asphalt that is both high-performing and environmentally sustainable. This study thoroughly examined the performance and modification mechanism of gutta-percha (GP) as a novel asphalt modifier. The investigation was conducted using a combination of macro- and microscopic testing, as well as molecular dynamics simulations. This work primarily examined the compatibility of GP with asphalt molecular modeling. This paper used molecular dynamics to identify the most suitable mixing temperature. Next, the gray correlation theory was used to discuss the most effective method for preparing gutta-percha-modified asphalt (GPMA). The macro-rheological tests and microscopic performance analysis provided a full understanding of the impact of GP on asphalt properties and the process of alteration. The findings indicate that eucommia ulmoides gum (EUG) exhibits good compatibility with asphalt, while sulfur-vulcanized eucommia ulmoides gum (SEUG) does not demonstrate compatibility with asphalt. Both EUG and SEUG enhance the thermal stability and resistance to deformation of asphalt at high temperatures, with SEUG having a particularly notable effect. However, both additives do not improve the resistance of asphalt to cracking at low temperatures. The manufacturing method for EUG-modified asphalt (EUGMA) involves physical mixing, whereas sulfur-vulcanized eucommia ulmoides gum-modified asphalt (SEUGMA) involves physical mixing together with certain chemical processes. This research establishes a theoretical foundation for the advancement of GP as a novel environmentally friendly and highly effective asphalt modification.

In recent years, sulfurized eucommia ulmoides gum (SEUG) has been used and developed in many fields due to its good properties. The cross-linking degree is crucial to the performance of SEUG. In order to explore the effect of the cross-linking degree on SEUG in depth, this paper combines macroscopic and microscopic techniques, and molecular discrete system models of EUG and SEUG with different cross-linking degrees are calculated by molecular dynamics simulation, and the density and solubility parameters of EUG, glass transition temperature, radial distribution function and mechanical property parameters of SEUG are derived. The results show that (1) the suitable minimum degree of polymerization of EUG is N = 30; (2) the degree of cross-linking has a significant effect on the intramolecular radial distribution of SEUG, but it has a small effect on the intermolecular radial distribution of SEUG; (3) the degree of cross-linking of SEUG should be controlled to be between 40% and 80% because the mechanical properties of SEUG, namely the bulk modulus, shear modulus, elastic modulus, Poisson’s ratio, Corsi pressure, are the best ones. Therefore, the conclusions of this study provide a theoretical basis for engineering practices.