(747d) Understanding Effect of Viscometric Measurements and Thermodynamic Interactions on Blend Polymer Membranes

The suitability of a solvent for a particular polymer or polymer blend can be determined from its thermodynamic properties. In this paper the authors have tried to understand those thermodynamic properties and their manifestation in Polymer-blend/solvent/non-solvent quaternary system. Cellulose Acetate(CA)/Polysulfone(PSF) (18:2 and 2:18 weight ratio) blend was prepared in three different solvents viz., N-Methyl 2-Pyrrolidone (NMP), Dimethyl Formamide (DMF), and Dimethyl Sulfoxide (DMSO).The molecular interactions were studied by molecular dynamics using blend module available in material studio software package version (7.0). The dilute solution viscometry (0.2-1wt%) method was used to determine intrinsic viscosity, interaction parameter (B) which signified the interactions between CA-PSF were attractive in nature when dissolved in DMSO followed by DMF and repulsive in nature when dissolved in NMP solvent respectively. similarly, Huggins coefficient (K) also signified that CA-PSF blend is more miscible in DMSO followed by DMF and less miscible in NMP solvent respectively. The cloud point analysis has been carried out at relatively higher concentration (1-10wt %) where CA-PSF-NMP solution was found thermodynamically more stable than CA-PSF-DMF followed by CA-PSF-DMSO. At very higher concentration (20wt %) hollow fiber membranes were extruded and the cross section of each membrane was observed under scanning electron microscope and the results were found more in favor with cloud point analysis than viscometry. The membrane characteristics such as permeability, porosity, and mechanical strength of all extruded membranes were also determined and hence, the multiscale analysis has been done to explain the thermodynamic behavior of quaternary system and to bridge the gap between molecular level to the bulk level properties.