Effect of Graphene Oxide-Modified CaAl-Layered Double Hydroxides on the Carbon Dioxide Permeation Properties of Fluoroelastomers.

This work aimed to investigate the CO gas barrier and mechanical properties of fluorine rubber nanocomposites filled with Ca/Al layered hydroxide (graphene oxide [GO]/LDH-CaAl) modified by GO. GO/LDH-CaAl nanocomposite fillers were prepared by depositing Ca/Al layered hydroxide (LDH-CaAl) into the surface of alkalized GO (Al-GO). The prepared GO/LDH-CaAl nanocomposite fillers and complexes were characterized by Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) for structural and micromorphological characterization. The results showed that GO/LDH-CaAl was successfully prepared with strong interactions between Al-GO and LDH, and the compatibility of GO/LDH-CaAl nanocomposite fillers with the polymer was significantly improved compared with that of LDH-CaAl. Consequently, both the fracture strength () and strain () of GO/LDH-CaAl nanocomplexes remarkably increased, and they exhibited excellent mechanical properties. Differential scanning calorimetry and thermogravimetric analysis were used to characterize the thermal stability of GO/LDH-CaAl nanocomposite fillers, and GO/LDH-CaAl nanocomposite fillers have better thermal stability than LDH-CaAl. The reaction products (S-LDH-CaAl and S-GO-CaAl) of LDH-CaAl and GO/LDH-CaAl with CO were characterized using XRD and TGA, respectively, and the results show that LDH-CaAl reacts readily and chemically with CO, resulting in a lower diffusion coefficient of CO in the LDH-CaAl nanocomplexes than that of the GO/LDH-CaAl nanocomplexes and leading to the destruction of the laminar structure of LDH-CaAl, while GO/LDH-CaAl has better CO resistance stability. GO/LDH-CaAl nanocomplexes exhibited a reduced content of hydroxyl groups with pro-CO nature exposed on the surface of LDH-CaAl, improving the interfacial interaction between the nanofillers and the rubber matrix and enhancing the dispersion of GO/LDH-CaAl in the polymers. Moreover, CO in the soluble GO/LDH-CaAl nanocomposites was significantly reduced, while the diffusion properties demonstrated weak temperature dependence on solubility. The mechanism of the CO gas barrier of polymers filled with GO/LDH-CaAl was proposed on the basis of the Arrhenius equation.