Optimization of interleaved structures with amorphous halloysite nanotubes for superior performance of CFRP pipes in various environmental conditions

•A-HNTs incorporated composite significantly reduced the moisture absorption rate.•Before moisture absorption, composite with A-HNTs exhibited higher flexural properties.•After moisture absorption composite with A-HNTs showed better retention than without A-HNTs.•Pipes with A-HNTs had higher stiffness before and after moisture absorption and after drying.•The A3 and E2A1 structures identifies as the most advantageous for industrial applications. The carbon fiber-reinforced polymer (CFRP) pipes are extensively used in various industrial sectors and are routinely exposed to diverse environmental conditions, making it imperative to enhance their performance and durability. To address this need, our study investigates the effects of incorporating amorphous halloysite nanotubes (A-HNTs) in different layers of five distinct layer arrangements on the bending and pipe stiffness properties of interleaved CFRP flat (F) and cylindrical (C) structures under various environmental conditions. Notably, the maximum moisture absorption rate of carbon/epoxy composites (A3), encompassing all layers of epoxy modified with A-HNTs, was 190 % lower than that of carbon/epoxy (E3) composites containing unmodified epoxy resin in all layers. Furthermore, F(A3) exhibited the highest flexural strength at 3141 MPa among all composites tested. A-HNTs significantly improved pipe stiffness, with C(A3) exhibiting remarkable stiffness enhancements of 314 % after moisture absorption and 268 % after drying compared to C(E3). The composite C(E2A1), which included a bottom layer of epoxy modified with A-HNTs, also demonstrated significant stiffness enhancements of 308 % after moisture exposure and 290 % after drying, compared to C(E3). Consequently, we recommend the use of A3 and E2A1 composites for industrial applications.