Epoxy-Amine Functionalization of PAN Fibers for Advanced Self-Healing Asphalt Composites: Mechanisms and Performance Enhancement

A critical challenge in self-healing asphalt is concurrently achieving repeatable healing and mechanical reinforcement. This study introduces epoxy-amine functionalized polyacrylonitrile (EA-PAN) fibers to address this gap, leveraging thermally activated chemistry at the fiber-asphalt interface. The fibers were synthesized and systematically characterized (SEM, AFM, FTIR, XPS), and their impact on asphalt composite performance was evaluated through rheological tests (DSR), damage-healing protocols, and nano-computed tomography (Nano-CT). Functionalization significantly enhanced interfacial compatibility. The surface roughness (Ra) of EA-PAN fibers increased to 272 nm, compared to 133 nm for unmodified PAN, and their formamide contact angle decreased to 36.14° from 67.57°. Consequently, the EA-PAN&SBS/MA composite exhibited superior high-temperature performance, with its dynamic shear modulus (G*) increasing by 112.5% at 82°C compared to the PAN&SBS/MA composite. Most notably, EA-PAN&SBS/MA achieved an excellent healing index of 85.11%, significantly surpassing the 61.54% of PAN&SBS/MA. Nano-CT analysis confirmed efficient microcrack repair in the EA-PAN&SBS/MA composite, with its interfacial void ratio decreasing from 83.67% to 11.33% post-healing. FTIR analysis revealed that healing is driven by new covalent bonds from residual epoxy and amine groups. This study validates that EA-PAN fibers provide an effective strategy for developing advanced asphalt composites that are both mechanically robust and highly self-healing.