Stress Enhancement in the Delayed Yielding of Colloidal Gels

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Introduction

Networks of aggregated colloidal particles are solidlike and can sustain an applied shear stress while exhibiting little or no creep; however, ultimately they will catastrophically fail. We show that the time delay for this yielding decreases in two distinct exponential regimes with applied stress. This behavior is universal and found for a variety of colloidal gel systems. We present a bond-rupture model that quantitatively describes this behavior and highlights the role of mesoscopic structures. Our result gives new insight into the nature of yielding in these soft solid materials.

File:/Users/Bryan/Desktop/Harvard/AP 255 Condensed Soft Matter/Wiki Papers/Images/Fig1 Stress Enhancement.jpg
Fig. 1. Experimental and theoretical plots for R/R_o - L/L_o relation: (left)for Cu/Kapton film (right)for Cu/Cr/Kaption film