Investigating Miscibility of Polymers and Its Impact on the Morphology, Thermal, and Mechanical Properties of Polymer Blends

The miscibility of polystyrene (PS)/poly(styrene-co-acrylonitrile) (PSAN) blend films, prepared by the solution casting technique using tetrahydrofuran as a common solvent, was characterized by scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetry, Fourier transform infrared (FTIR) spectroscopy, and tensile testing. Morphological observations revealed partial miscibility of the blend. FTIR measurements also ascertained partial miscibility of the blend as slight variations in the spectra for various blend compositions were observed. DSC studies also confirmed the semicompatible nature of the examined blend by displaying a single for the composition, 25/75, and two 's for compositions, 50/50 and 75/25. The enhancement in thermal stability and mechanical properties which were quite pronounced for the composition, 25/75, also favored partial miscibility of the blend. The partial miscibility of the PS/PSAN blend may be attributed to the intramolecular repulsive effect, characteristic of a homopolymer/copolymer blend system, and the Pi-Pi stacking of phenyl rings of the blend components due to some structural similarities.