Linear rheology of nanoparticle-enhanced viscoelastic surfactants

Nanoparticles have been mixed with viscoelastic surfactants to improve the thermal sensitivity and elastic features of the original surfactant solution. The resulting mixtures have demonstrated improvements on rheology and thermal stability. However, very little attempt has been made to implement novel models that can accurately predict their rheological behavior in the linear regime. In this study, we present the capability of the Continuous Maxwell Model on representing the Maxwellian rheological behavior of nanoparticle-enhanced viscoelastic surfactant solutions at high frequencies and various temperatures. This capability is demonstrated by using rheological data from five different solutions: one data set generated in this work, and four from the literature. We, for the first time, provide evidence for the frequency-dependence of the relaxation time for these mixtures. We also found that for the prepared solution (Aromox APA-TW surfactant and aluminum oxide nanoparticle mixture) the Al2O3 nanoparticles increased the viscosity but only slightly affected the viscoelastic properties of the solution. A plausible hypothesis for the nanoparticle-micelle interactions that explains the results is proposed. (C) 2019 Elsevier B.V. All rights reserved.