Solution Casting Blending: An Effective Way for Tailoring Gas Transport and Mechanical Properties of Poly(vinyl butyral) and Pebax®2533

Polymer blending is a suitable approach for tailoring the gas-separation properties of polymeric membranes. Films based on poly(vinyl butyral)/poly(ether-block-amide) (PVB/Pebax) blends were prepared by the solution casting and solvent evaporation technique. The films were characterized for miscibility, mechanical and spectral properties by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing and Fourier transform infrared (FT-IR) spectroscopy. The permeation of permanent gases was measured at a feed pressure of 1 bar. The data were interpreted with theoretical macroscopic models. Miscible blends were obtained, as shown by thermal and mechanical testing, while specific molecular interactions between the two polymers were revealed by FTIR analysis. DMA and DSC results indicated that the two components were miscible, while the permeation tests provided data consistent with a homogeneous blend system due to the interfacial interaction between the phases. The developed PVB/Pebax blend membranes provided an optimized performance with a good combination of permeability, selectivity, thermal and mechanical stability.