Rheology and colloidal structure of silver nanoparticles dispersed in diethylene glycol

Rheological behavior of agglomerated silver nanoparticles (similar to 40 nm) Suspended in diethylene glycol over a wide range of volumetric solids concentrations (phi = 0.11 -4.38%) was studied The nanoparticle suspensions generally exhibited a yield pseudoplastic behavior Bingham plastic, Herschel-Bulkley and Casson models were used to evaluate the shear stress-shear rate dependency Analyzing the effect of silver concentrations oil the yield stress and viscosity of the suspensions followed an exponential form, revealing an increase in the degree of interparticle interactions with increasing solid concentrations. Fractal dimension (D(f)) was estimated from the suspension yield stress and phi dependence. and was determined as D(f) = 1.51-1.62 for the flocculated nanoparticle suspensions This suggested that the suspension structure was probably dominated by the diffusion-limited cluster-cluster aggregation (DLCA) due mostly to the strong attractions involved in the nterparticle potentials. Maximum solids concentration of the suspensions was determined to be phi(m) = 11%. (C) 2009 Elsevier B V All rights reserved