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.