In this work optically transparent nanocomposites were prepared and characterized. An organically modified boehmite was added at different concentrations in a conventional diglycidyl ether of bisphenol A (DGEBA) epoxy matrix. Subsequent curing of the polymer matrix was performed using a polyether diamine. Nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), light transmittance, dynamical mechanical analysis (DMA), flexural, impact and hardness tests. The visible spectrum of nanocomposites and SEM images indicates that the boehmite particles have been homogeneously dispersed in the polymer matrix at least at the lower concentration. The effect of the nanofiller concentration on the nanocomposites physical-mechanical properties was also studied. A significant increase of glass transition temperature, Shore D hardness, toughness, flexural strength modulus were observed. Mechanical and thermal properties increase with nanofiller content, up to 10% by weight of nanofiller, indicating a decreased efficiency of the bohemite particles at higher concentrations. The improved mechanical properties of nanocomposites were interpreted by the micromechanic approach of Halpin-Tsai, leading to the determination of the average aspect ratio of the nanofiller.

Keywords: epoxy, boehmite, nanocomposites, optical properties