Properties and microstructures of epoxy resin/TiO2 and SiO2 hybrids

Epoxy resin/TiO2 and epoxy resin/SiO2 hybrids were prepared by different procedures, and their mechanical properties were correlated to their microstructures, as indicated by small-angle X-ray scattering (SAXS) measurements. Epoxy resin/TiO2 hybrids were prepared by mixing the epoxy resin (EP828) with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (S320) in acetone, and then titanium-n-butoxide (TnBU) was added. In addition, epoxy/SiO2 hybrids were prepared by mixing EP828 with a curing agent, a diamino heterocyclic compound (13002) in acetone, and an organo silica sol (silica nanoparticles dispersed in methylethylketone) was added. In the EP828/S320/TiO2 hybrid systems, the TiO2 component was attached to both of the chain ends of the epoxy matrix, hence leading to the formation of inorganic domains via the covalent bonds. SAXS profiles of these hybrids showed peaks at q = 2.3 nm(-1), caused by interference between the domains. The storage modulus increased with increasing TiO2 content above the T-g, owing to the strong interactions between TiO2 and the epoxy matrix. The tan delta peak position did not change, although the intensity decreased with increasing TiO2 content. The SAXS profiles of the EP828/B002/SiO2 hybrids were very different to those of the corresponding EP828/S320/TiO2 hybrids, and indicated that SiO2 particles with rough surfaces were randomly dispersed in the epoxy matrix. The storage moduli of the EP828/B002/SiO2 hybrid systems increased only slightly with SiO2 content, because of the weak interactions. These mechanical properties are well explained by the microstructures derived from the SAXS profiles. (C) 2004 Society of Chemical Industry.