| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥3,100,000 (Direct Cost: ¥3,100,000)
|
|---|
| Research Abstract |
The suspension polymerization has been done normally by dispersing monomer in the water with stirrer in a tank polymerization reactor, whereas the polymer particles obtained have rather broad size distribution and the classification of polymer particles is necessary. Therefore, it is usually requested to save energy and material in the polymerization process. We have studied experimentally and theoretically the behavior of bubble formation at a single nozzle submerged in liquid. This research was extended to the two-phase bubble formation, that is, the vapor bubble formation with phase change at the single nozzle submerged in continuous liquid whose temperature is lower than the boiling point of dispersed liquid. In this research, the volume and shape of two-phase bubble were simulated by the theoretical model based on our non-spherical bubble formation model under the constant flow condition. In this model, the experimental data such as a length of bubble neck as a condition of bubble
… More
detachment does not need and the bubble naturally detaches if the neck of the bubble closed. The calculated results elucidate relatively well the experimental ones. The parameters which affect two-phase bubble formation process are temperature difference between vapor phase inside the two-phase bubble and continuous liquid phase, vapor flow rate through the nozzle and nozzle inner diameter. This two-phase bubble formation model predicts well the droplet size at complete condensation from two-phase bubble.
Based on this fundamental understanding of two-phase bubble formation, we tried to produce the uniform-sized polymer particles by the circulating bubble column type polymerization reactor made of pyrex glass. This reactor is constructed from the downcomer part composed of the still part, the formation part of monomer vapor bubble and the polymerization part of monomer, and the riser part where the temperature of the circulating continuous phase is controlled. In the still part, the monomer liquid was heated and vaporized so that the monomer vapor bubbles were formed at the constant flow nozzle in the formation part. The tapered pipe was used for the polymerization part. To keep the monomer droplet in this polymerization part, the superficial velocity of the circulating continuous phase was controlled by the circulation pump. To produce vinyl acetate polymer particles by this reactor, the order of feed materials addition was investigated and the appropriate order was selected. The size and size distribution of the polymer particles obtained were measured with digital microscope. The sharp size distribution of vinyl acetate polymer particle was obtained by this reactor was compared with that by the conventional stirred tank polymerization reactor. Less
|
