The addition of poly (styrene sulfonate) (PSS) to flocculated sodium dodecyl sulfate (SDS) adsorbed alumina enabled the alumina to redisperse due to the adsorption of PSS on the alumina, where the replacement of SDS by PSS occurred to some extent. The dispersion behavior of such a system was well correlated with the change of zeta potential of alumina. The fluorescence spectra of pyrene and pyrene-3-carboxaldehyde indicated that the micropolarity at inner region in the SDS-PSS adsorbed layer was lower than that in the PSS-adsorbed layer, while that at the external region for both the layers it was almost the same. The ESR spectra of 2, 2, 6, 6-tetramethylpiperidinyl-1-oxy suggested that the microviscosity in the SDS-PSS-adsorbed layer was greater than that in the PSS-adsorbed layer.
The aim of this study was to synthesize fine nickel particles by reducing a copper complex in an organic solvent. The materials used were : bis (acetylacetonato) copper (II) as a copper complex ; tetrahydrofuran, anisole and diphenyl ether as solvents ; sodium borohydride, lithium hydride and hydrazine as reducing agents. Fine copper particles could be produced when the copper complex dissolved in diphenyl ether was refluxed in N2 atmosphere for one hour with sodium borohydride, of which amount was 7. 5 times greater than the complex in molar ratio. The purity of the product was about 93%, and the particle size was 10 to 20 nm.
Copper-phthalocyanine (CP) pigment surface was modified by its derivatives containing acid or base functional groups. The surface-modified CP pigments were characterized with three viewpoints : (1) ζ-potential in aqueous system, (2) acid and base amounts in methyl isobutyl ketone and (3) heat of adsorption of acid and base. The relationship between these characteristics and dispersion stability of the pigments in acrylic paints was also investigated. The dispersion stability was determined by TI value (ratio of viscosity at 6 rpm/ at 60 rpm). Isoelectric point (IEP) in ζ-potential, acid and base amounts, and heat of adsorption of the surface-modified CP pigments changed as it had been predicted from the structure of functional group of CP pigment derivatives used for the modification. When pigments were classified with their IEP value, the dispersion stability of acidic pigments was good in basic polymer, and vice versa, following Sörensen's acid-base concept. Heat of adsorption of acetic acid and triethyamline was correlated with the dispersion stability in acidic polymer and in basic polymer, respectively. Base amounts of pigments also effected dispersion stability in acidic polymer
Dispersion of TiO2 particles in methylcyclohexane was investigated through adsorption of polymers with various functional groups. The amount of adsorbed polymer was dependent on the kind of functional groups : The large amounts of adsorbed polymer perfectly covered the polar particle surfaces to form a thick adsorbed layer. The dispersions which had large amounts of adsorbed polymer were found to be more stable from the measurements of the rheological properties, the gloss, and the sedimentation rate. It was confirmed that the adsorbed polymer layer played an important role to enhance dispersion stability and the polymer functional groups provided a significant effect.
1,3,5,7-Tetramethylcyclotetrasiloxane (H4) was deposited on magnetite at 80°C by utilizing a chemical vapor deposition method. As a result of the deposition, the magnetite was covered with a 1.4 nm thickness of poly (methyl siloxane) (PMS) and became hydrophobic. Magnetite treated with H4 (PMS-magnetite) was calcinated at below 1000°C and its color was measured. Although magnetite turned brown at about 200°C and to red-brown at about 500°C, the color changes of PMS-magnetite occurred at higher temperatures. The reason for the color change was investigated by TG-DTA and X-ray diffraction. In the color change at about 200°C, an exothermic weight increase was observed, which suggests the change of magnetite to maghemite. On the other hand, the color change at about 500°C is attributable to. crystal dislocation from maghemite to hematite. Thus, the oxidation of magnetite and the crystal dislocation of maghemite were depressed by the coating of the PMS film. These results show that the surface definitely played an important role even in crystal dislocation which is regarded as the transformation of the entire crystal itself.
Total reflection X-ray fluorescence spectrometry (TXRF) was applied to elemental analysis of toners and of a copied letter. Four different elements, Fe, Cu, Cr and Ti, were detected as main elements in four different toners, and each one of these toners could be discriminated easily from the others. Also, each one of six toners which contained Fe as a main element could be differentiated from the others by the comparison of elemental ratios of trace elements in toners. Moreover, elements composing a toner could be detected in a single copied letter and a trace amount of the toner was found to attach to a paper surface, which looked white in appearance, after a copy process. Se, detected in a recovered toner from a copy machine which had been used for a long time, was concluded to be derived from the photosensitive drum material of the copy machine.
The film formation of polymer particles was applied as a new thermal-recording method. The polymer parricles had a double-layered and core/shell-type structure. The inner layer (core) was cross-linked polystyrene, and the outer layer (shell) was acryl-styrene copolymer. When the thermal-recording layer of the polymer particles was formed on a colored layer, the particles remained spherical, at which surface the light was scattered and reflected, leaving the layer white. Therefore, the colored layer was hidden by this white thermal-recording layer. When the thermoenergy was added to the white thermal-recording layer, the polymer particles fused and became transparent, which enabled the colored layer to be seen. It was investigated that the relationship between the properties of the polymer particles, such as the mass, the glass transition temperature, and the molecular weight of the shell polymer, and the reflection densities of the white and transparent layers.