Viscometric and Rheological Behaviour of Chitosan-Hydrophilic Polymer Blends

R. K. Wanchoo, A. Thakur and Sweta

Abstract
Blends of chitosan with hydrophilic polymers were investigated for miscibility. Chitosan/poly (vinyl alcohol) (CS/PVA), chitosan/poly vinylpyrollidone (CS/PVP) and chitosan/poly (ethylene oxide) (CS/PEO) blends were prepared in dilute aqueous acetic acid (φ = 1 %) and found to be miscible over the entire composition range by dilute solution viscosity and rheological measurements. The miscibility of blends by viscosity measurements at 25 ∓ 0.1 °C was estimated on the basis of experimental and ideal values of miscibility parameters Δbm, Δ[η]m and μ. The rheological studies were performed on blends of mass fraction w = 2 % in dilute aqueous acetic acid (φ = 1 %) at 25 ∓ 0.1 °C in controlled rate mode. The flow curves of blends and viscosities were found to lie between those of principal components of the blend over the entire compositional range. The flow behaviour index of blends was determined by the Power law model, indicating pseudoplastic behaviour with pseudoplasticity increasing with CS mass concentration. The rheological data of blends was best described by the Cross model. Results from Fourier transform infrared spectroscopy also indicate the blends to be miscible.

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Keywords
chitosan, poly (vinyl alcohol), poly vinylpyrollidone, poly (ethylene oxide), blends, miscibility, rheology, dilute solution viscosity