Study On Polyimide/Inorganic Nanocomposite Membrane Material

Polyimide acid(PAA) was prepared in this article through HQDPA and ODA in DMF solution, and the technics conditions of PAA and imidization were comprehensively studied in this paper, and the dynamics were studied primarily. On this condition, Polyimide/silica composite material films have been prepared by sol-gel approach; Then ethanol/water mixture were separated using PI film based on pervaporation.First the technics conditions of PAA using two-step method were discussed. In this method solution viscosity was used as measure to study the experiment conditions(solution content, molar ratio, reaction temperature and reaction time),the optimum conditions were determined with orthogonal test. Second the conditions of imidization were studied with its temperature and time, and the optimum conditions were selected. Basing on these conclusions, Polyimide/silica composite material films with different silica contents have been prepared by sol-gel approach, and the characters were tokened; Ethanol/water mixture were separated using PI film based on pervaporation, the changing relations of permeation flux, separation factor and concentration, temperature were studied. Finally the dynamics of PAA and imidization were discussed to open out their reaction mechanism.The result of the experiments showed that the optimum technics conditions of PAA were that the reaction temperature should be 10℃,the reaction time should be 6h,molar ratio of HQDPA:ODA should be 1.006:1; The optimum imidization condition was 80℃/h,150℃/h,240℃/h and 280℃/0.5h;IR spectra and element analysis showed that the films nearly finished a complete imidization, and the SEM showed that silicon dioxide particles dispersed in the PI matrix in a better way, coming into being organic/inorganic network structure through inorganic particles embedded into PI; TGA curves showed that the thermal stability was higher with thecontent of silicon dioxide was higher. Ethanol/water mixture experiments have been done by PI film, the experiment result showed that permeation flux and separation factor were better; The imidization reaction was a first-order reaction, the apparent activation energy and the coefficient were 184.6kJ?mor1 and 1.59xlO"27min"' separately.