We prepared a powder mixture composed of plate like particles (mica) and spherical particles (PMMA) by a conventional dry mixing and investigated to determine the effect of the particle size and the ratio of plate like particles to spherical particles on some dynamic behaviors of the powder bed. Interparticle friction of the powder bed consisted of a mixture of large size mica and small size (less than 1μm) PMMA decreased remarkably at small fraction of PMMA. From a SEM observation of the mixture, the microspherical PMMA was found to adhere uniformly on the mica surface. By the addition of PMMA, since the type of adhesion between mica particles changed from a “plane-parallel surfaces” to a “sphere and half-space”, the attractive force between the particles seemed to be decreased. Also the mixtures prevented card-pack coagulation of the mica particles. However, it was ascertained that the mixture was packed homogeneously in the compaction process because the dispersed mica behaves as primary particles.
An electropainting film is formed by the chemical reaction of dispersed particles with protons (or hydroxide ions) which are generated by water electrolysis. It is important to analyze a structure of dispersed particles in polymer resin solution, in order to understand the film formation. In the present paper, we have analyzed three suspension solutions from the material balance by using ultrafiltration (UF) technique. We found that pH of the suspension is determined by the molar concentration ratio of carboxyl groups oriented to water phase to 2-dimethylaminoethanol (DMAE) molecules. Actual neutralization degree for the dispersed particles (α0) could be easily estimated from pH of the suspension by using a pH curve of simple DMAE-MAA (methacrylic acid) solution. All the suspension systems resulted in α0>1. Consequently, the carboxyl groups oriented to water phase on the particle surface are ionized and dissociated completely, and hence the particles form ion pairs with conjugated acid of DMAE. In addition, because free DMAE molecules exist excessively in the vicinity of the dispersed particles, they govern conductivity and pH. Dissociation state of free DMAE molecules changes buffer capacity at an electrode interface. When α0 becomes greater value, buffer capacity increases. In this case, existence of free DMAE molecules affects deposited weight.
TiO2-photocatalyzed reaction (λ>280 nm) of azobenzenes in alcohols gave hydrazobenzenes, 1, 2, 4-triazolidines, and 2-phenylindazoles. The product distribution depended on the reaction conditions and the kinds of substrates. Those of unsubstituted, 4-methyl-, 4-fluoro-, and 4-chloroazobenzenes in methanol under an air atmosphere afforded both the hydrazobenzenes and 1, 2, 4-triazolidines. 4-Trifluoromethyl-and4- (acetoamido) azobenzenes provided the hydrazobenzenes. The TiO2-photocatalyzed reaction of 4-alkoxyazobenzenes in alcohols preferentially gave 5-alkoxy-2-phenylindazoles.