Title: Dynamic localization and shear-induced hopping of particles: A way to understand the rheology of dense colloidal dispersions

Abstract

For decades, attempts have been made to understand the formation of colloidal glasses and gels by linking suspension mechanics to particle properties where details of size, shape, and spatial dependencies of pair potentials present a bewildering array of variables that can be manipulated to achieve observed properties. Despite the range of variables that control suspension properties, one consistent observation is the remarkably similarity of flow properties observed as particle properties are varied. Understanding the underlying origins of the commonality in those behaviors (e.g., shear-thinning with increasing stress, diverging zero shear rate viscosity with increasing volume fraction, development of a dynamic yield stress plateau with increases in volume faction or strength of attraction, development of two characteristic relaxation times probed in linear viscoelasticity, the creation of a rubbery plateau modulus at high strain frequencies, and shear-thickening) remains a challenge. Recently, naïve mode coupling and dynamic localization theories have been developed to capture collective behavior giving rise to formation of colloidal glasses and gels. This approach characterizes suspension mechanics of strongly interacting particles in terms of sluggish long-range particle diffusion modulated by varying particle interactions and volume fraction. These theories capture the scaling of the modulus with the volume fraction and strengthmore » of interparticle attraction, the frequency dependence of the moduli at the onset of the gel/glass transition, together with the divergence of the zero shear rate viscosity and cessation of diffusivity for hard sphere systems as close packing is approached. In this study, we explore the generality of the predictions of dynamic localization theory for systems of particles composed of bimodal particle size distributions experiencing weak interactions. Here, we find that the mechanical properties of these suspensions are well captured within the framework of dynamic localization theory and that suspension mechanics can be understood in terms of a dynamical potential barrier, the magnitude of which governs the zero shear rate viscosity, and onset of a dynamic yield stress plateau as volume fraction or strength of interaction is raised.« less

Authors:

Jiang, Tianying ^[1]; Zukoski, Charles F. ^[2]

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+ Show Author Affiliations

1. Univ. of Illinois at Urbana-Champaign, IL (United States); 3M Corporate R&D, Maplewood, MN (United States)
2. Univ. of Illinois at Urbana-Champaign, IL (United States); Univ. of Buffalo, NY (United States)

Publication Date:

Tue Aug 26 00:00:00 EDT 2014

Research Org.:

Univ. of Illinois at Urbana-Champaign, IL (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1875139

Grant/Contract Number:  

FG02-07ER46471; FG02-07ER46453

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Rheology

Additional Journal Information:

Journal Volume: 58; Journal Issue: 5; Journal ID: ISSN 0148-6055

Publisher:

Society of Rheology

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Rheological properties; Shear thickening; Shear thinning; Particle size analysis; Glass transitions; Mechanical stress; Interatomic potentials; Colloids; Rheology and fluid dynamics; Potential energy barrier