Journal of the Japan Society of Colour Material

The rates of sedimentation and sedimentation volumes of bare and iron hydrosol modified-nylon 12 powders in water and various organic liquids were measured at definite intervals.
From the experiments, the following results were concluded.
Both nylon powders were well dispersed in organic liquids having observed about 11 of solubility parameters value.
Slightly better dispersibility was observed for modified-nylon powder.
The above facts were confirmed from the data of sedimentation volume and also the contact angles for water (θ_bare=117°, θ_modified=102°).

View full abstract

Show abstractHide abstract

The preparation of the spherical silica particles had been examined for sodium silicate solutionammonium salt solution system by interfacial reaction method, in which the silica had been formed by the reaction of aqueous sodium silicate solution emulsified in benzene with aqueous ammonium salt solution. The factors examined were kinds and concentrations of ammonium salts, concentrations of emulsifiers (nonionic surfactants), and W/O ratio in the emulsion. The concentration of sodium silicate solution was constant, 4 mol/l. For the purpose of surface-treatment, the organic compounds (monomer), benzal acetone and phthalic acid diallyl ester, were adsorbed on the surface of the silica particles.
The properties of powder were determined by the scanning electron microscopic photograph, the particle-size distribution, the specific surface area, the differential thermal analysis, the infrared spectrum and the heat of immersion.
The best condition for the preparation of the spherical silica particles was as follows :
(1) Ammonium sulfate was better than ammonium chloride,
(2) The concentration of the ammonium sulfate was 1. 5 mol/l,
(3) The W/O ratio in the emulsion was 1/3,
(4) The concentration of the nonionic surfactants was from 18 g/l to 21g/l
The particle diameter is in the range of 1-10μ, and the specific surface area obtained by N₂adsorption was 100-500 m²/g, the value of which is excessively larger than the value calculated from the particle size. The result suggests that the particle has porous surface.
The heats of immersion of the silica into water suggested that the hydrophobicity of the surface of the spherical silica particles proceeded with the treatment with benzal acetone and phtoalic acid diallye ester.

View full abstract

Download PDF (1145K)

Register with J-STAGE for free!