A Miscibility study on pullulan/poly (Ethylene Glycol) blends

Miscibility of pullulan and poly(ethylene glycol) in aqueous solution has been determined by dilute solution viscometry. Blends of different compositions (100/0, 80/20, 50/50, 20/80, 0/100) with respect to pullulan/poly(ethylene glycol) have been prepared. Huggins plots of each homopolymer and polymer blend have been determined in aqueous solution at 25, 30 and 40 0C temperatures. From the data obtained from Huggins plots the miscibility parameters Δb, α, and μ have been calculated. The miscibility of polymers in a ternary system is measured by these parameters which are related to the slope of the Huggins’s plot and the intrinsic viscosities of the polymers and the polymer mixtures. In addition to solution viscosity measurements, blend films were prepared by the solvent casting method and were tested by SEM and DSC analysis methods for the investigation of blend miscibility in the solid state. Moreover the molecular interactions between pullulan and PEG were studied by FTIR spectroscopy. Favorable interactions via H-bonding have been confirmed. The results have shown that pul/PEG blend with a blend composition of (80/20) is miscible in solution with positive miscibility parameter values for Δb, α, and μ respectively. DSC and SEM results indicate miscibility in the solid state as well. Keywords: Viscosity, Miscibility, polymer blends, Pulluan, Poly(ethylene glycol).