Connecting Large Amplitude Oscillatory Shear Rheology to Steady Simple Shear Rheology and Application to Biomass Slurries

Abstract

Large amplitude oscillatory shear (LAOS) rheology is often performed in order to complement steady simple shear (SSS) rheology, i.e., probe rheological properties of materials that cannot be not observed with SSS alone. However, it is difficult to measure the SSS rheology of some problematic materials due to fracture and ejection, and LAOS may alleviate these issues, at least partially. Therefore, it is of interest to obtain SSS rheology information from LAOS measurements. We show that a constitutive modeling approach may be used to unify the analysis of LAOS data obtained from different viscometric geometries and modes of control and that the LAOS data may be used to predict SSS profiles. A model elastoviscoplastic material, a Carbopol solution, was used to validate the approach experimentally. LAOS rheometry of problematic biomass slurries was also performed, and the SSS profiles for the slurries were predicted with more confidence than could be obtained from SSS measurements directly.

Keywords

• laos
• elastoviscoplastic
• yield stress
• carbopol
• biomass slurry