Durability study of vinylester/silicate nanocomposites for civil engineering applications

The durability of fiber-reinforced polymer (FRP) composite materials in humid and harsh environments is an important consideration for acceptance of these materials in civil engineering applications. Reducing the moisture ingress may improve the durability of FRPs. The addition of modified inorganic powder, such as silicate nanoparticles, may improve several important properties of polymers, such as barrier properties, fire retardancy, dimensional stability and mechanical strength. The present work aims to evaluate the effect(s) of the addition of silicate nanoparticles on the durability-related properties of vinylester polymer used as matrix for FRPs in civil engineering applications. To conduct this preliminary study, nanocomposites containing 5% organo-modified or untreated silicate were characterized by using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The diffusivity of moisture was measured by immersing samples in a 50 °C water bath. Barrier properties were determined by measuring the maximum water uptake, water absorption rate and coefficient of diffusion. Aging was performed by complete immersion of nanocomposites samples in a NaOH solution at 50 °C. Scanning Electron Microscopy (SEM), tensile tests and Fourier Transform Infrared spectroscopy (FTIR) analyses were performed before and after conditioning to evaluate the matrix degradation. Experimental results show that the use of organo-silicate leads to an improvement of barrier properties characterized by a decrease of the coefficient of diffusion. It also increases mechanical properties and leads to a significant decrease of chemical degradation.