Effect of pH in aqueous (Hydroxy Propyl Methyl Cellulose) polymer solution

The ultrasonic velocity, density and viscosity have been measured for the aqueous solution of Hydroxy Propyl
Methyl Cellulose (HPMC) at different concentration and pH using ultrasonic interferometer at a frequency of 2
MHz and at a constant temperature of 303 K for the entire composition. The various physical parameters were
calculated from the measured values of ultrasonic velocity (U), density (ρ) and viscosity (η) using the standard
formula and the results are discussed in the light of molecular interaction present in the system. It is found that the
ultrasonic velocity values increases with increase in concentration due to the solute – solvent interaction through
hydrogen bonding. The increase in velocity near basic pH may be due to the fact that strong interaction between
the water-HPMC solutions.