Membranas poliméricas obtidas a partir de nanocompósitos de PA 6.6/argila montmorilonítica pela técnica de inversão de fases.

Abstract

Microporous membranes were obtained from nanocomposites of polyamide 6.6 with 1 and 3% of national bentonite clay, by phase inversion process. It was used two kinds of precipitation bath: with distilled water and a of formic acid. The nanocomposites were obtained from the intercalation by melting technique and presented exfoliated and / or partially exfoliated structure as shown by XRD. By differential scanning calorimetry (DSC), it was observed that the presence of the clay did not significantly alter the melting temperature of the nanocomposites when compared with the pure polyamide. The membranes were characterized by SEM, XRD, measurements of flow and water vapor permeation. In general, asymmetric membranes showed a morphology detected by SEM: A selective layer and a porous layer with variations in its microstructure. The precipitation bath with acid solution led to a decrease in the thickness of the selective layer of the membranes compared to membranes obtained in a precipitation bath of water. In general, the membranes with 1% clay and water bath precipitation showed relatively good permeate flux for all used pressures (1, 2 and 3 bar). For membranes obtained from a precipitation bath in a acid solution gave a gradual increase in water vapor permeation, as it increased the clay content. For membranes obtained from a precipitation bath with water, there was a significant reduction in the permeability in relation to the pure PA 6.6, in the range of 66 to 48% for membranes with 1% and 3% of clay, respectively. Therefore, microporous membranes obtained from nanocomposites were obtained, and the precipitation bath type and the amount of clay influenced on the morphology and permeability of the membranes.