Octasilsesquioxane reinforced DGEBA and TGDDM epoxy nanocomposites: Characterization of Thermal, Dielectric and Morphological properties

The octa-functionalized polyhedral oligomeric silsesquioxane (POSS) containing nanocomposites of epoxy resin are prepared via in situ co-polymerization of epoxy resins with 4,4’-diaminodiphenylsulfone (DDS) in the presence of octaaminophenyl silsesquioxane (OAPS). Two of the most common, technologically relevant epoxy resins, diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM) are studied and the organic-inorganic hybrid nanocomposites containing up to 20 wt% of OAPS are obtained. The curing reaction involving epoxy, DDS and OAPS is investigated using Fourier transform infrared (FT-IR) spectroscopy. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) show that the glass transition temperature (Tg) of the POSS containing nanocomposites are higher than the corresponding neat epoxy systems at lower concentrations of POSS (≤ 3 wt%). For the POSS-epoxy nanocomposites, the storage moduli of the rubbery plateau are higher than that of the neat epoxy when the resins contain less than 20 wt% POSS, indicating the nanoreinforcement effect of POSS cages. Thermogravimetric analysis (TGA) indicates that the POSS containing epoxy nanocomposites display high ceramic yields, suggesting the flame retardant behaviour of the materials is improved. The increasing concentration of OAPS into epoxy-amine networks exhibit a decreasing