Preparation of double-layer film modified polyacrylonitrile fiber modifier for designing and performance evaluation of PAN/SBS composite asphalt.

[Display omitted] • Innovative application of APTES, co-deposition of PEI and PDA in the modification of polyacrylonitrile fibers. • Double-layer membrane structure modified polyacrylonitrile fibers. • P-P/A-P/PAN and A-P/PAN with higher surface free energy, roughness and adhesion. • P-P/A-P/PAN/SBS@MA and A-P/PAN/SBS@MA had better viscoelastic properties. • P-P/A-P/PAN/SBS@MA and A-P/PAN/SBS@MA had better low temperature crack resistance and high temperature adhesion properties. To further enhance the properties of polyacrylonitrile (PAN) fiber incorporated modified asphalt, a new method of PAN fiber modification with a double membrane was developed. The influence of interface characteristics of modified fiber on the properties of fiber-reinforced asphalt was revealed from the free energy of the fiber surface and the adhesion between the modified fiber and matrix asphalt. Two types of PAN modified fibers with single-layer membrane structure (A-P/PAN) and double-layer membrane structure (P-P/A-P/PAN) were prepared, which were applied to synthesize three types of modified asphalts (Mas), i.e., PAN/SBS@MA, A-P/PAN/SBS@MA, and P-P/A-P/PAN/SBS@MA. Dynamic shear rheometer (DSR) experiment showed that at 46℃, the G*, G', and G' of P-P/A-P/PAN/SBS@MA were 24%, 19%, and 37% higher than those of PAN/SBS@MA. Similarly, at 175 ℃, the maximum yield strength of P-P/A-P/PAN/SBS@MA was 16.38% and 32.7% higher than those of A-P/PAN/SBS@MA and PAN/SBS@MA, respectively, which was attributed to the better surface free energy and adhesion work of the modified fibers. The surface contact angle test results showed that free energy of the surface and adhesion work of P-P/A-P/PAN fibers are 62% and 26.5% higher than those of PAN fibers, respectively. Scanning electron microscopy, atomic force microscopy, and UV-Vis tests indicated that the fiber's surface has successfully constructed a double-layer membrane structure. The fluorescent microscopy and cryo-SEM tests of the modified asphalt further confirmed that the modified PAN fiber had better interfacial interaction with the base asphalt. This study shows that the double-layer film modified PAN fiber composite SBS asphalt has good viscoelastic properties, high temperature adhesion, and low temperature fracture resistance, and hence carries critical practical engineering applications for highways, low temperature area pavements, airport pavements, and construction pavement. [ABSTRACT FROM AUTHOR]