A simple method to analyze materials under quasilinear large amplitude oscillatory shear flow (QL-LAOS)

Abstract

A new method to analyze materials exploring the quasilinear oscillatory regime has been described. One of its advantages is a significant reduction of the number of rheological tests needed, as compared to the originally proposed quasilinear large-amplitude oscillatory shear flow method. Furthermore, the authors improved the data analysis to a great extent, rendering it quite straightforward and physically sound. To validate the new method, we used two materials of qualitatively different rheological behavior, namely, a commercial hair gel and a solution of polyacrylamide in water/glycerol. The data obtained are presented in two distinct forms. The first one uses either the traditional Kelvin–Voigt analysis—which yields as material functions the storage and loss moduli G ′ and G ″, respectively—or the traditional Maxwell analysis, which yields as material functions the storage and loss compliances J ′ and J ″, respectively. The second form originates from a Jeffreys analysis, which gives as output two material functions, namely, the relaxation time θ 1 and the retardation time θ 2. The results of the different analyses are compared and discussed.A new method to analyze materials exploring the quasilinear oscillatory regime has been described. One of its advantages is a significant reduction of the number of rheological tests needed, as compared to the originally proposed quasilinear large-amplitude oscillatory shear flow method. Furthermore, the authors improved the data analysis to a great extent, rendering it quite straightforward and physically sound. To validate the new method, we used two materials of qualitatively different rheological behavior, namely, a commercial hair gel and a solution of polyacrylamide in water/glycerol. The data obtained are presented in two distinct forms. The first one uses either the traditional Kelvin–Voigt analysis—which yields as material functions the storage and loss moduli G ′ and G ″, respectively—or the traditional Maxwell analysis, which yields as material functions the storage and loss compliances J ′ and J ″, respectively. The second form originates from a Jeffreys analysis, which gives as ou...