Sedimentation potedtials under centrifugal force are studied on the dispersed systems which composed of titanium dioxide, alkyd resin and xylene. The relationship between the sedimentation potedtial Esed and the angular velocity to, cell length, the particle weight ∑4π/33ρn in the disperse systems are 3 discussed. It is found that the sedimentation potential at the initial time follows the following equation. (Esed) t, =0=k2·γ1+γ2/2ω2·3W/4πρ k2= (ρ-ρ0) D0τf/3Kη0 where a is the radius of the particle, ρ, ρo are densities of the particle and of the liquid respectively. r2, r1 are positions of electrodes from the revolution center. ω is the angular velocity, D0 is the dielectric constant of the liquid, τ is the zeta potential of the particle in the disperse system, f is the retardation factor, and K is the conductivity of the liquid. From the analysis of the sedimentation potential at the initial time of sediment, τ potential of the pigment in the disperse system is calculated. This value is almost coincident with the value from the electrophoretic method, which is reported by the author. As the sedimentation potential is proportional to the pigment weight in the cell, the particle size distribution of pigments can be calculated from the sedimentation potential-time curve. This particle size distribution is discussed in reference to the effect of the angular velocity and the pigment content in the disperse system. The mode diameters and the median diameters based on the particle weight are 0. 3-0. 4 μ and O. 4-0. 5μ respectively, over the range of experiments. In comparison of the particle size distribution obtained by this method with is compared with that obtained from the electromicroscopic, and the mode diameters were almost same values, for both methods. Using this particle size analysis, thep article size distribution is obtained in relatively short time (ca, 10-30 min) for even the small particles, which have below 1, μ diameter, and simultaneously ζ potential of the particle in the disperse system is calculated.
Mecharical properties and some other physical properties of the oxidative cured films from liquid 1, 2-polybutadiene (1. 2-PB) which prepared by anionic living polymerigation were studied. The effect of molecular weights, catalysts and baking temperatures are discussed. Furthermore performance of the films from the 1, 2-PB were compared with that of such similar resins as a commercial sodium catalyzed liquid polybutadiene, baking type acryl, and melamine alkyd. Results obtained are as follows : 1) As catalyst, Zn and PB gave the films of higher tensile strength, elongation and better hardness, bending resistance and impact resistance than that from Co and Mn. As to the viscoelastic properties, the Co catalyzed film give higher Tg (165°C) than that from Zn (Tg=75°C) 2) In accordance with the higher baking temperature, the tensile strength increases and elongation decreases. As molecular weight of 1, 2-PB increased, tensile of the films increased proportionally, but dependance to the baking temperature decreased. 3) The films from 1, 2-PB showed good phyoical properties as coating as well as melamine-alky baking aeryl, but the films form commercial sodium catalyzed liquid polybutadiene shoued inforion results. 4) Oxidative curing reaction of 1, 2-PB was followed with IR spectrum. From the change of unsaturation, hydroxyl and carbonyl contents, differences, in mechanism of the metals as catalyst were descussed.