Preparation And Characterization Of PVA/PDADMAC Anion Exchange Membrane

PVA is one of the most popular materials that widly used around the world recently. Owing to its good film forming, hydrophilicity, processability, biocompatibility and anti-pollution it has great potential to be an ion exchange membrane as a polymer matrix.In this thesis, Poly (vinyl alcohol) (PVA) and Poly (diallydimethylammoniumchloride) (PDADMAC) was chosen as the polymer matrix and as the cationic polyelectrolyte to provide active gourp, inspectively. Glutaraldehyde (GA) was chosen as cross-linking agent. The self-stand anion exchange membrane was prepared by using evaporating method. Also the nylon-enhanced composite anion exchange membrane was prepared by using casting method. Both anion exchange membrane, in which there are semi-interpenetrating (SIPN) structure, can be applied for electrodialysis process. Also it is dicussed that the effect of PDADMAC content, Cpc , annealing temperature and GA concentration on the properties of the membrane, such as water content, charge density, membrane resistance, dynamic transport number and mechanical performance in this thesis.The experiment results showed that water content of the self-stand and the composite membrane is proportional to PDADMAC content, Cpc. The water content of self-stand membrane decreased with an increase in annealing temperature and the water content of composite membrane decreased with an increase in GA concentration. The self-stand and the composite membrane both equally attained their maxium charge density when Cpc was 20wt%. The membrane charge density of self-stand membrane is proportional to annealing temperature. And the membrane charge density of the composite membrane is proportional to the GA concentration. The membrane resistance of both self-stand and composite membrane decreases with an increase in Cpc value. It is valid that the increase of annealing temperature will decrease the membrane resistance of self-stand membrane. It was found that the membrane resisitance of the composite membrane increases with an increase in the GA concentration. The membrane dynamic transport number of the self-stand and the composite membranes increases with an increase in Cpc value. For the self-stand membrane, its dynamic transport number could be rised by means of increasing the annealing temperature. For the composite membrane an increase in the GA concentration could raise the dynamic transport number. The ion exchange capacity (IEC) is proportional to the Cpc value.In addition compared with basic and mechanical properties between the self-stand and the composite membrane under the same treatment condition, which the annealing temperature was 160oC, GA concentration was 0.05vol%, PDADMAC content was 10wt%, 15wt%, 20wt%, 30wt%, respectively. It was found that the water content and the dynamic transport of the self-stand membrane is slightly higher and the membrane resisitance is lower than the composite membrane. The tensile stenth and Young's modulea of the composite membrane were twice as much as the self-stand membrane, between 20MPa and 40MPa, 400MPa and 700MPa respectively. When the composite membrane was treated by a high GA concentration solution, the composite membrane sample has the similar chemical properties as the best self-stand membrane sample PC-14 and has much better mechanical performance than the self-stand membrane.