Miscibility studies of hydroxy propyl methyl cellulose and poly(ethylene oxide) by viscometry, ultrasonic, and refractometric methods

Interactions between polymer molecules in dilute solution changes the effective dynamic volume of the molecules, which influences the viscosity. In a plot of reduced viscosity against concentration, the slope of the curve may decrease or increase according to the miscibility of the polymers. This change of slope in a ternary system can be used as a criterion to determine the compatibility of a polymer–polymer blend in dilute solution. In the present study the compatibility of PEO and HPMC was investigated in water by the viscosity technique; the blend was found to be semicompatible in nature. The semicompatible nature of the blend was confirmed by ultrasonic, refractive index, and density measurements