Influence of Silane-Modified Graphene Oxide or Zirconia-Doped Multiwalled Carbon Nanotubes on the Degradation of Epoxy Resin in Concrete Environments

This study investigated the reinforcing effects of nanoparticles on epoxy resin and examined the aging behavior of the resin before and after modification. Two nanofillers, i.e., silane-modified graphene oxide (MGO) and zirconia-doped multiwalled carbon nanotubes (Zr-MWCNTs), were comparatively evaluated. The mechanical, thermal, and hydrophobic properties of the modified resins were systematically characterized through tensile tests, contact-angle measurements, and thermogravimetric analysis. The results showed that a nanoparticle loading of 0.5 wt % yielded an optimal performance. At this concentration, MGO-modified composites exhibited an increase of 44.5% in tensile strength and a rise of 47.9% in contact angle, while Zr-MWCNT composites achieved gains of 30.96% in tensile strength and 35.6% in contact angle. After aging, the optimized composites maintained superior property retention, with only a 20.84% loss in tensile strength (vs 27.93% for the control), 83.5% retention of flexural strength (12.7% higher than the control), and a 26.0% rise in glass transition temperature ( T g ). Microstructural analysis revealed synergistic mechanisms: MGO improved interfacial bonding via chemical cross-linking, whereas Zr-MWCNTs constructed a three-dimensional network that physically hinders moisture ingress. Together, these barrier and chemical effects effectively suppressed the diffusion of corrosive species, highlighting the potential of nanoparticle-enhanced epoxies for durable fiber-reinforced polymer applications in aggressive environments.