Abstract
The surface of γ-hematite treated with alcoxysilanes was investigated by means of the microanalysis, surface area, number of surface group, magnetic properties, pyrolysis and extrusion test of their blend with paraffine. The followings were clarified: (1) Since the number of surface group was estimated to be 3×1014 CM-2 from carbon content and surface area, and this value nearly agreed with the number of surface hydroxide of γ-hematite, γ-hematite was ascertained to be effectively treated with alcoxysilanes according to the following reaction, =Fe(OH)+RSi(OR')3→=FeOSi(OR)2R+R'OH; R', CH3 or C2H5 (2) Since the magnetic saturation, residual magnetization and coercive force of the surface treated γ-Fe2O3 agreed with those of the original one, the surface-treatment showed to be unaffected on the properties of the substrate (3) Since the CO or CH2=CH2 was not observed in the pyrolysos products of the surface-treated γ-hematite, the surface group was recognized not to include the alcoxy group and the unreacted alcoxy groups were displaced by hydroxyl groups through hydrolysis (4) The pyrolysis products were observed to be composed of water and hydrocarbon of the organic functional group in the surface group evolved at 200°C and CO2 generated remarkably at 350°C. The evolution of hydrocarbon was noticed to result from the following reaction, =FeOSi(OH)2R→=FeOH+RH+SiO2 and the vigorous generation of CO2 was recognized to be due to the reduction of =FeOH by RH thus generated (5) The extrusion test of the blend of surface-treated γ-hematite with paraffine showed the better flow property than that of original γ-hematite.
