Progress in Polymer Science 36 (2011) 1697–1753 Contents lists available at ScienceDirect Progress in Polymer Science journal homepage: www.elsevier.com/locate/ppolysci A review of nonlinear oscillatory shear tests: Analysis and application of large amplitude oscillatory shear (LAOS) Kyu Hyun a,∗ , Manfred Wilhelm b , Christopher O. Klein b , Kwang Soo Cho c , Jung Gun Nam d , Kyung Hyun Ahn d , Seung Jong Lee d , Randy H. Ewoldt e , Gareth H. McKinley f a School of Chemical and Biomolecular Engineering, Pusan National University, Jangjeon-Dong 30, Busan 609-735, Republic of Korea b Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 18, 76128 Karlsruhe, Germany c Department of Polymer Science and Engineering, Kyungpook National University, Sangyeok-Dong 1370, Daegu 702-701, Republic of Korea d School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Republic of Korea e Institute for Mathematics and its Applications & Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA f Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA article info Article history: Received 10 May 2010 Received in revised form 11 February 2011 Accepted 16 February 2011 Available online 11 March 2011 Keywords: LAOS (Large amplitude oscillatory shear) Nonlinear response FT-Rheology Stress decomposition (SD) abstract Dynamic oscillatory shear tests are common in rheology and have been used to investigate a wide range of soft matter and complex fluids including polymer melts and solutions, block copolymers, biological macromolecules, polyelectrolytes, surfactants, suspensions, emul- sions and beyond. More specifically, small amplitude oscillatory shear (SAOS) tests have become the canonical method for probing the linear viscoelastic properties of these com- plex fluids because of the firm theoretical background [1–4] and the ease of implementing suitable test protocols. However, in most processing operations the deformations can be large and rapid: it is therefore the nonlinear material properties that control the system response. A full sample characterization thus requires well-defined nonlinear test proto- cols. Consequently there has been a recent renewal of interest in exploiting large amplitude oscillatory shear (LAOS) tests to investigate and quantify the nonlinear viscoelastic behavior of complex fluids. In terms of the experimental input, both LAOS and SAOS require the user to select appropriate ranges of strain amplitude ( 0 ) and frequency (ω). However, there is a distinct difference in the analysis of experimental output, i.e. the material response. At sufficiently large strain amplitude, the material response will become nonlinear in LAOS tests and the familiar material functions used to quantify the linear behavior in SAOS tests are no longer sufficient. For example, the definitions of the linear viscoelastic moduli G (ω) and G (ω) are based inherently on the assumption that the stress response is purely sinu- soidal (linear). However, a nonlinear stress response is not a perfect sinusoid and therefore the viscoelastic moduli are not uniquely defined; other methods are needed for quantifying the nonlinear material response under LAOS deformation. In the present review article, we first summarize the typical nonlinear responses observed with complex fluids under LAOS deformations. We then introduce and critically compare several methods that quantify the nonlinear oscillatory stress response. We illustrate the utility and sensitivity of these proto- cols by investigating the nonlinear response of various complex fluids over a wide range of frequency and amplitude of deformation, and show that LAOS characterization is a rigorous test for rheological models and advanced quality control. © 2011 Elsevier Ltd. All rights reserved. ∗ Corresponding author. E-mail address: [email protected] (K. Hyun). 0079-6700/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.progpolymsci.2011.02.002
A review of nonlinear oscillatory shear tests: Analysis and application of large amplitude oscillatory shear (LAOS)
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