Research On Polymeric Miro-Particles Formation By Precipitation With Compressed-Carbon Dioxide Antisolent

The study on the micro-particle has already become a hot field in current new and high technology. Supercritical Fluids (SCF) crystallization technique has some great advantages that some traditional ones do not have. The technique is a new prospective micro-particles manufacturing technique with little environmental pollution. Many scholars have carried on a number of experiments to study it. But some experimental phenomena are still too difficult to explain. The relationship between particle size, morphology and operating conditions has not been exactly correlated yet. Models are correlative rather than predictive. The inherent relationship among unit dimension, construction of equipment, process parameters, particle size and morphology has not been established because the dominant controlling factors are not thoroughly understood.The object of this paper was to find out the effect of process parameters on polymeric micro-particles produced by Supercritical Antisolvent Solution (SAS) techniques. In the experiments, the system of polymer-toluene-carbon dioxide was chosen.In the first chapter of this paper, the technique of micro-particles formation by Supercritical Fluids (SCF) was introduced. And then, the paper reviewed the methods of producing compound particle techniques by SCF. The methods included Rapid Expansion of Supercritical Solution, Supercritical Anti-solvent (SAS), Immersion, Chemical Reaction, Gas Saturated Solutions.In the second chapter, a computer program was designed, which was used to regress binary acting parameters and calculate phase equilibrium property. The calculating results were precise in comparison with the experimental values of the references. The paper also built a model to simulate the SAS process. The model can well describe the effects of density of carbon dioxide, diameters of jets, and solubility of solvent in anti-solvent on droplet dispersion time.The third chapter introduced experimental process, materials and SAS experimental apparatus which was designed and made by ourselves.At the final part of the paper, the experimental results were listed and effects of process parameters on these results were discussed. The experiments found flow rate had an important influence on particle formation. In a long-time and continuous process, the content of toluene in the high pressure vessel should be smaller or a little bigger than the solubility of toluene in supercritical carbon dioxide. Finally, the paper suggested how to choose proper time of washing and analysed the effect of flow rate, washing time, density of carbon dioxide, temperature, solute concentration, et al on the experimental results.