Mass Transfer Characteristic Studies On Preparation Of Porous Polymers By Supercritical Fluids Induced Phase Inversion

Supercritical Fluids(SCF) induced phase inversion in producing porous polymers is a new technology put forward recent years. Studies on the mass transfer characteristic of this technology, analyse the mass transfer mechanism of ternary system'supercritical fluids-solvents-polymers',can define the the influence of the process conditions such as, pressure(P), temperature(T), intinal concentration of polymers(C) and operate time(t) on the mass transfer process and the structures of porous polymers obtained, formate the basic approach on forecast the porous structure by kinetics calculation. Besides, this study can optimize the technology and have significance on the industrical applications of it.This article took the mass transfer process in producing porous PCL and PLLA using this technology as subject investigated, established the kinetic model of this technology. Meanwhile, using the model established before simulated the mass transfer of this technology. The specific context for the study and the results are as follows:1.Established the corresponding kinetic model on mass transfer of supercritical Fluids induced phase inversion process, aim at different systems defined the resolution methods of model parameters. Using the kinetic model advanced simulated the differenet polymer systems. The validity of the model was validated by comparation between the experiments and simulations. The optimum process conditions of PCL and PLLA systems were confirmed by simulations and experiments.2. The mass transfer characteristic of SCF induced phase inversion in producing PCL porous structures was investigated. Besides, the influence of the process conditions such as, pressure, temperature, intinal concentration of polymers and operate time on the mass transfer process was also analysed. The simulation results indicated that:the liquid-liquid phase separation style existed in the process of PCL porous structures'formation. Pressure played minute role on the morphology of the pore size of the polymer while the increased temperature can enlarge the pore size obviously.3. The mass transfer characteristic of SCF induced phase inversion in producing PLLA porous structures was investigated. The simulation results indicated that:the pahse inversion style of PLLA system was also liquid-liquid, the increased pressure and temperature will enlarge the pore size of the polymer. The higher intinal concentration of polymer will obtain the polymers with smaller pore diameters.Through the establishing of the mass transfer model on ternary system'supercritical fluids-solvents-polymers', analysed the reasons for the difference between PCL and PLLA system on mass transfer, defined the design theory and method for the mass transfer process in SCF induced phase inversion technology. This article provides the scientific basis for the subsequent researches and scale-up of this technology.