Mechanical Properties of the Epoxy Resin Composites Modified by Nanofiller under Different Aging Conditions

The effects of aging conditions on the mechanical properties of epoxy resin (EP) with halloysite nanotube (HNT) were studied. The aging conditions include soaking in water at various temperatures, soaking in acid solution, soaking in alkali solution, thermal shock cycling (TSC), and soaking coupled with subsequent thermal shock cycling (i.e., composite aging conditions). Under aging conditions, the EP is degraded, plasticized, and swelled, resulting in different degrees of cracks and pores in EP. The tensile and bending properties of EP and HNT/EP nanocomposites decreased after aging, indicating that the durability of the EP decreased under aging conditions. The addition of HNT could improve the immersion aging resistance and delay the immersion aging behavior of EP. Under TSC conditions, the reduction in mechanical properties of HNT/EP nanocomposites with HNT is slightly more than that of the neat EP due to different thermal expansion coefficients between HNT and EP. The fracture morphology and chemical change were studied to reveal the aging degradation mechanisms in the presence of HNT addition.