For the first time, this study explores how the incorporation of ZnO nanowires (ZnO NW) in the interface affects moisture absorption and resultant mechanical properties of glass and carbon composites. ZnO NW were coated onto glass and carbon fabrics to modify the fiber/matrix interface in the composites. Moisture absorption, longitudinal tension, short beam shear, and mode‐I fracture tests were conducted. While the moisture absorption was found to decrease the interlaminar shear strength (ILSS) of glass composite, it was found to decrease the ILSS, tensile properties, and fracture toughness of carbon composites. The incorporation of ZnO NW was found to decrease the moisture absorption in both glass and carbon composites, increase the tensile modulus of dry and wet glass composites by ~17%, and prevent the delamination failure of wet carbon composites in tensile tests. Also, ZnO NW incorporation was found to increase the fracture toughness of all composites with a maximum of 141% improvement for dry carbon composite. Importantly, ZnO NW incorporation was believed to increase the stiffness and prevent bending failure of DCB arm in wet carbon composites. The uniqueness of this article includes demonstrating the benefits of ZnO NW to reduce the moisture absorption in composites and to reduce the extent of fiber/matrix interface degradation in wet carbon composites.

Moisture absorption in composites significantly influence the fiber/matrix interface regions and mechanical properties. Hence, it is very important to quantify the moisture storage in interfaces and correlate it to the mechanical behavior. The novelty of this article is that, for the first time, it explores the correlation of moisture absorption parameters with the mechanical behavior of composites. The paper studies four different types of moisture‐soaked composites—glass fiber/epoxy, carbon fiber/epoxy, ZnO nanowire incorporated glass fiber/epoxy, and ZnO nanowire incorporated carbon fiber/epoxy. One‐dimensional hindered diffusion model (1D HDM) was used for the extraction of moisture absorption parameters. The hindrance coefficient (ratio of bound to unbound moisture) of composites was found to increase proportionately with the increase in the volume of interfacial regions. Only in carbon fiber/epoxy composite, it did not increase proportionately due to the relatively larger degradation of interface. This was correlated well with mechanical test responses wherein carbon fiber/epoxy exhibited anomalous failure modes due to relatively larger degradation of interface. Numerical simulations were also carried out to describe the moisture absorption in composites. Numerical simulations of moisture absorption in composites using time‐varying boundary conditions matched very well with experimental as well as 1D HDM results.