Processing of mica/epoxy nanocomposites by ultrasound mixing

Rubbery mica/epoxy nanocomposites are synthetized by in situ polymerization, and their morphology, mechanical, and viscoelastic properties were investigated by wide angle X-ray scattering (WAXS), transmission electron microscopy (TEM), tensile testing, and dynamic mechanical thermal analysis (DMTA). Ultrasonicator was used as a means of applying external shearing forces to disperse the silicate clay layers in the epoxy matrix. The first step of the nanocomposite preparation consisted of swelling the mica in a curing agent, i.e., aliphatic diamine based on polyoxypropylene backbone having a low viscosity for better diffusion into the intragalleries. Then, the epoxy prepolymer was added into the mixture. It was expected to have better dispersion and intercalation of the nanoclay in the matrix. The study showed that the organomodification of mica with octadecylammonium ions leads to an increase in the initial d-spacing ([d(001)] peak) from 12.3 to 28.1 angstrom, determined by WAXS, indicating the occurrence of an intercalation. The addition of 5 per hundred resin (phr) of MICAC18 into the epoxy matrix resulted in finer dispersion as evidenced by both the disappearance of the diffraction peak in the WAXS pattern and TEM images. The mechanical and viscoelastic properties were improved for both MICA and MICAC18 nanocomposites, however, more pronounced for the modified ones. (c) 2007 Wiley Periodicals, Inc.