Revealing compatibility mechanism of nanosilica in asphalt through molecular dynamics simulation

The compatibility between asphalt and nanosilica (nano-SiO₂) is critical to determine the performance of nano-SiO₂-modified asphalt. However, a comprehensive understanding of the compatibility behavior and mechanism of asphalt components and nano-SiO₂ in the modified asphalt is still limited. In this study, the compatibility was revealed through molecular dynamics (MD) simulation. Virgin asphalt, nano-SiO₂-modified asphalt, and oxidation aged asphalt models produced with the COMPASS force field; meanwhile, the proposed models were validated by comparisons with reference data. The compatibility of asphalt and nano-SiO₂ was analyzed by solubility and the Flory-Huggins parameters and interaction energy. Results show that the solubility parameters decreased with the increase of system temperature while increased with the asphalt's oxidation level increase. Meanwhile, the compatibility of the asphaltene, resin, and aromatic components in asphalt is better than the compatibility with saturates, which may be due to saturates being volatile; however, the compatibility of the nano-SiO₂ and saturates is much better than those with asphaltene, resin, and aromatic components. The incorporation of nano-SiO₂ alleviates the volatilization of saturates. The present results provide insights into the understanding of the compatibility behavior and mechanism of nano-SiO₂ and asphalt components.

Toughening Anhydride-Cured Epoxy Resins Using Fatty Alkyl-Anhydride-Grafted Epoxidized Soybean Oil

The aim of this work is to develop a series of advanced biobased tougheners for thermosetting epoxy resins suitable for high-performance applications. These bio-rubber (BR) tougheners were prepared via a one-step chemical modification of epoxidized soybean oil using biobased hexanoic anhydride. To investigate their toughening performance, these BR tougheners were blended with diglycidyl ether of bisphenol A epoxy monomers at various weight fractions and cured with anhydride hardeners. Significant improvements in fracture toughness properties, as well as minimal reductions in glass transition temperature (T_g), were observed. When 20 wt % of a BR toughener was utilized, the critical stress intensity factor and critical strain energy release rate of a thermosetting matrix were enhanced by >200 and >500%, respectively, whereas the T_g was reduced by only 20 °C. The phase-separated domains were evenly dispersed across the fracture surfaces as observed through scanning electron microscopy and atomic force microscopy. Moreover, domain sizes were demonstrated to be tunable within the micrometer range by altering the toughener molecular structure and weight fractions. These BR tougheners demonstrate the possibility of achieving toughness while having the thermal properties of standard bisphenol epoxy thermosetting resins.

Study on the synthesis of bio-based epoxy curing agent derived from myrcene and castor oil and the properties of the cured products

Two biobased curing agents derived from castor oil and myrcene were prepared and were used to cure epoxy E-51.

Rubber-like Quasi-thermosetting Polyetheramine-cured Epoxy Asphalt Composites Capable of Being Opened to Traffic Immediately

This paper reports the facile preparation, mechanical performance and linear viscoelasticity of polyetheramine-cured rubber-like epoxy asphalt composites (EACs) with different asphalt contents. Compared with previous EACs prepared via complex chemical reactions and time-consuming high-temperature curing, the EACs reported here were obtained by using a compatible, bi-functional polyetheramine and a simple physical co-blend process, which make the EACs feasibly scalable for production at a lower cost. The EACs were cured for 1 h at 160 °C and 3 d at 60 °C; therefore, these composites can be opened to traffic immediately. The EACs have a much greater temperature stability than common thermoplastic polymer-modified asphalt composites from -30 °C to 120 °C, but their complex shear moduli at higher temperatures slightly decrease instead of remaining constant when temperatures are greater than 80 °C, especially for the higher asphalt content composites; that is, these composites are quasi-thermosetting. Wicket plots illustrate that the EACs reported here are thermorheological simple materials, and the master curves are constructed and well-fitted by generalized logistic sigmoidal model functions. This research provides a facile, low-cost method for the preparation of polyetheramine-cured EACs that can be opened to traffic immediately, and the concept of quasi-thermosetting may facilitate the development of cheaper EACs for advanced applications.