Nano-attapulgite Functionalization by Silane Modification for Preparation of Covalently-integrated Epoxy/TMPTMA Nanocomposites

Nano-attapulgite (nano-AT) particles organically-modified with the silanecontaining epoxide groups were incorporated into a mixture of trimethylol-1,1,1-propane trimethacrylate, a tri-functional acrylate (TMPTMA) and methyl-hexahydrophthalic anhydride (MeHHPA)-cured CER was prepared for nanocomposites. The surface modification with silane of nano-AT was characterized by means of Fourier transform infrared spectroscopy (FTIR), and the results showed that the characteristic peaks of silane, such as 2966, 2886, 1010, 804 and 750 cm-1 were observed in the FTIR spectra of nano-AT modified by silane, which indicated that silane coupling agent had already been grafted successfully on the surface of AT nanoparticles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the microscopic structures of nanocomposites. The microscopy results displayed that a uniform dispersion of organically-modified nano-AT by silane in thepolymeric matrix was obtained, which led to the improvement of the macroscopic properties of nanocomposites. The macroscopic properties of nanocomposites, such as impact strength, storage modulus, tan δ, thermal stability and the dielectric properties were measured. It is found that within the range of 10 to 20 pbw the higher the nano-AT modified by silane concentrations the greater is impact strength of nanocomposites where at 30 pbw it reaches 11.2 kJ/m2 in contrast with 5.9 kJ/m2 ofthe CER/TMPTMA system. Dynamic mechanical analysis (DMA) results showd that a glass transition temperature (Tg) found in nanocomposites was assigned to the epoxy phase modified by TMPTMA. With increase in nano-AT modified by silane concentration there were gradual higher values in both Tg and the storage modulus of nanocomposites. Additionally, the results of thermogravimetric analysis (TGA) revealed that thermal stability of nanocomposites was apparently improved in comparison with the CER/TMPTMA system. Dielectric measurements showed that the resulting nanocomposites also displayed quite different dielectric behaviours compared with the CER/TMPTMA system.