Performance of polyurethane and polyurethane nanocomposites modified by graphene, carbon nanotubes, and fumed silica in dry and wet environments

Polyurethane elastomers (PU) are used in various applications, such as wind turbine blades, to safeguard structural integrity, maintain shape, and enhance survivability under repeated impact loading from rain droplets and sand particles. This study investigates the impact of individual and combination of additive carbon nanotubes, graphene, and fumed nanosilica nanomaterials, totalling 0.3 wt% loading to PU, on water uptake capacity and any adverse effect on mechanical properties after exposure to saturation. Alongside the control pure PU, five types of PUs with varying additive nanomaterial types and contents are examined. Experimental measurements of the temperature-dependent moisture absorption, diffusion coefficients and permeabilities for the pure PU and its nanocomposites are conducted at 22°C, 32°C, and 45°C. In addition, uniaxial tensile tests were conducted on both dry and water-saturated coatings, and their mechanical properties were compared. Physicochemical characterisation of the coating materials is performed using the Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) techniques. Water contact angle (WCA) and surface free energy measured. Morphological features of fracture surfaces are studied by scanning electron microscopy (SEM) and optical microscopy.