Preparation Of Gel Membranes And Research On Gas Permeability And Permselectivity

With the development of the society constantly, more and more high requirement of quality of life, especially air quality to human, and green living environment is becoming be favorred. In the face of the greenhouse effect on the worsening of the global problems, CO₂ separation and removal are particularly important. At present, it is urgent to develop efficient CO₂ separation technology to reduce carbon dioxide pollution of the environment. Especially in today’s society, the outstanding separation technology is membrane technology. Gas separation membrane technology achieved industrialization was around 1970, with advances in technology, membrane technology continues to develop, a large number of new membrane continued emission, so that people see to the prosperity of membrane science. In recent years, because of its advantages of gel membrane in gas permeation separation neighborhood, it has gradually become a unique research focus, such as its solid- liquid network structure, greatly increasing the flux of gas. Solid skeleton supporting to provide some mechanical support for gel film, liquid medium is dispersed in a solid network, providing the priority channel for gas permeation separation. For the preparation of the gel film, the select of liquid substance and the polymeric substrate are critical.My present research was elastomeric polymer--polyether block amide（PEBA1657） and cellulose diacetate（CA） for the base of gel film. The choice of ethylene glycol phenyl ether acetate（EPA） and ethylene glycol phenyl ether（EPH） as a gel medium by thermally induced phase separation（TIPS） and solvent evaporation（SE） to prepare for gel film. Research contents and results are as follows:（1） Thermally induced phase separation and solvent evaporation prepared for gel film of PEBA1657 / EPA, and studied the influence of the physical and chemical performance of both preparation and different content of functional carrier-- EPA in gel film. Experimental results indicated that the gel film prepared by two methods have advantages and disadvantages in performance. With the increase of the content of EPA, the permeate flux increased of gel film. in the method of solvent evaporation, when the amount of EPA is increased to 60wt%, CO₂ permeability coefficient of the film to 881.0Barrer, and EPA content is 40wt%, CO₂ / N2 selectivity coefficient was 165, exceeding the upper limit of Robeson, but its stability of the film compared to the film prepared by thermally induced phase separation was weaker, and higher volatilization amount of EPA.（2） Via thermally induced phase separation method at different cooling temperatures, PEBA1657/EPA、PEBA1657 / EPH gel films were prepared. According to the experimental results that enhancing the cooling temperature can prompte the increases of permeability coefficient. The mechanical propertie and stability of the gel film PEBA1657 / EPA-60 were greater than PEBA1657 / EPH-60 film. DSC and polarizing microscopy analysis showed that the less of degree of crystallinity was conducive to gas permeation through, EPA molecules showed the advantages as gel media.（3） Utilizing intermolecular hydrogen bonding to support gel system. the low-crystalline cellulose diacetate as a gelling substrate to prepare for gel film, EPH as a function of the carrier. When the mass fraction of EPH from 0wt% to 40wt%, the relative degree of crystallinity gel film was significantly reduced and the amorphous regions was increased, CO₂ permeability coefficient was from 13.62 barrer to 178.66 barrer, the selective of CO₂ / N2 increase from 22.7 to 90.92.（4） In order to improve the mechanical properties and the content of EPH in the gel film, modifing CA / EPH film for crosslinked interface composite film, modified results showed that the content of theirs and the mechanical properties can be improved, but drastically its gas permeability coefficient reduced, which indicates the next experimental research direction of the subject.