Influence of boehmite nanoparticles on moisture absorption and temperature effects in GFRP used for wind turbine blades

Kurzfassung

While boehmite nanoparticle integration enhances GFRP mechanical performance under standard conditions, their behavior under environmental stressors is less understood. This study investigates the effect of moisture absorption and temperature on nanoparticle-reinforced GFRP. A wind power-proven epoxy resin was modified with 5 and 10 wt% taurine-modified boehmite nanoparticles using a three-roll mill. Appropriate processing parameters are identified using viscosity and DSC measurements. Nanomodified GFRP composites are prepared via Vacuum Assisted Resin Infusion (VARI). Furthermore, the influence of moisture and temperature on GFRP properties, considering particle content and layer thickness, was investigated. Therefore, samples are stored under hot-wet conditions (50 ◦C; 70 % RH) until water saturation. Tensile properties of saturated and dry samples are then evaluated at test temperatures between − 20 ◦C and + 60 ◦C. Rheological tests have shown that the viscosity increases more quickly with rising temperature and increasing particle content. At the same time, the initial viscosity drops and the pot life extends by increasing the temperature, particularly for the particlereinforced resins. DSC measurements confirm that the investigated particle modification only has a small impact on the epoxy system’s cross-linking, while the addition of water leads to reduced cross-linking. Furthermore, the storage of GFRP samples under hot-wet conditions showed that particle modification leads to reduced moisture absorption, which, however, increases again with increasing particle content. Different mechanisms, particularly based on polarity and tortuosity effects, are discussed. The tensile tests reveal that storage under hot-wet conditions results in a decrease in secant modulus (up to 58 %), ultimate tensile strength (up to 53 %) and strain to failure (up to 62 %). This effect is more pronounced in materials with particle modification