Shear-induced memory effects in boehmite gels

Colloidal gels are formed by the aggregation of Brownian particles into clusters that are, in turn, part a space-spanning percolated network. In practice, microstructure colloidal gels, which dictates their mechanical properties, strongly depends on particle concentration and nature interactions. Yet another critical control parameter is shear history experienced sample, controls size density cluster population, via aggregation, breakup, restructuring. Here, we investigate impact acid-induced boehmite, an aluminum oxide. We show following primary gelation, these display dual response depending rate ??p used to rejuvenate microstructure. identify ??c, above boehmite gel-like viscoelastic spectrum upon flow cessation, similar obtained gelation. However, cessation after rejuvenation below glassylike together with enhanced elastic properties. Moreover, nonlinear rheological properties also differ both sides ??c: weak at ??p>??c yield strain constant, independent ??p, whereas strong ??p<??c significantly increases ??p. Our results can be interpreted light literature shear-induced anisotropy, accounts for reinforced ??p<??c, while rationalize ??c terms dimensionless quantity, Mason number, comparing ratio strength interparticle bond force.