Surface modification of carbonyl iron powders with silicone polymers in supercritical fluid to get higher dispersibility and higher thermal stability

The surface of carbonyl iron powder (CIP) was modified in supercritical fluid with silicone polymers containing reactive Si-OCH3 groups. Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermo gravimetric analysis were adopted to characterize CIP. The dispersibility of CIP in epoxy resin matrix was evaluated by castor oil absorption factor, dynamic viscosity, Mooney viscosity, and scanning electric micrograph. The electromagnetic reflectivity of the CIP-filled epoxy resin coatings was also checked. It was confirmed that comparing with those treated at atmosphere, the supercritical treated CIP presented higher surface carbon content, higher dispersibility, higher thermal stability, and its original crystalline structure did not change greatly. Even though it experienced a high temperature and a high pressure (250 degrees C, 7.8 Mpa) during supercritical treatment, it was not oxidized, and its electromagnetic reflectivity did not decrease. Copyright (C) 2016 John Wiley & Sons, Ltd.