Analysis of complex viscosity and shear thinning behavior in poly (lactic acid)/poly (ethylene oxide)/carbon nanotubes biosensor based on Carreau–Yasuda model

Abstract

The complex viscosity of poly (lactic acid) (PLA)/poly (ethylene oxide) (PEO) blends and PLA/PEO/carbon nanotubes (CNT) biosensor as a function of frequency is measured and analyzed by Carreau–Yasuda model. This model correlates the complex viscosity to zero complex viscosity, relaxation time, power-law index as well as the shear stress and the width of the transition region between Newtonian and power-law behavior. The impacts of these parameters on the complex viscosity are justified to confirm the Carreau–Yasuda model. The calculations of Carreau–Yasuda model successfully agree with the experimental data at different frequency ranges. The prepared samples show different levels for parameters explaining the shear thinning behavior. A high zero complex viscosity, poor relaxation time, high power-law index, low frequency and a wide transition region between Newtonian and power-law behavior enhance the complex viscosity of samples. Among the studied parameters, the power-law index and the width of the transition region significantly change the complex viscosity. The prepared samples can develop the nano-bio-sensors for detection of various diseases such as cancer. Keywords: PLA/PEO blend, Carbon nanotubes, Biosensor, Complex viscosity, Carreau–Yasuda model