Hydrothermal Aging of Basalt Fiber‐Reinforced Epoxy Composites Modified With Star‐Like Polymer

ABSTRACT The hydrothermal aging of basalt fiber‐reinforced epoxy composites (BFRC), modified with star‐like n‐butyl methacrylate block glycidyl methacrylate polymer (SLP), was studied to assess their environmental stability. Before and after the hydrothermal aging, the interlaminar fracture toughness was evaluated by modified beam theory. 3D Fick's model was applied to evaluate sorption characteristics for the investigated materials. The obtained results revealed that the critical load and interlaminar fracture toughness of BFRC modified with SLP increased by 26% and 49%, respectively, compared to unmodified BFRC before the water absorption test. Nevertheless, due to enhanced water absorption, the critical load of the neat and star‐like polymer‐modified BFRC decreased by 14% and 33%, but the interlaminar fracture toughness decreased by 23% and 48%, respectively. The scanning electron microscopy revealed signs of degradation for both neat and star‐like polymer‐modified BFRC, with noticeable surface roughness, accumulation of debris between the fibers, and a possible fiber‐matrix interphase degradation, proving material degradation due to hydrothermal aging.