Shear-thickening properties of waxy maize starch dispersions

The influences of starch concentration and test conditions on the shear-thickening behavior of waxy maize starch (WMS) dispersions were investigated. During steady shear tests, both the concentration of WMS and test temperature influenced the shear thickening behavior of the WMS dispersions significantly. The critical shear rate for shear thickening was increased with the increasing of temperature and the decreasing of WMS concentration. No effect of gap size on the shear thickening of the WMS dispersions was observed when a parallel plate geometry was used for the rheological measurements. The dynamic strain thickening property of the samples was also studied through dynamic shear tests. In dynamic frequency sweeps, the critical frequency for strain thickening decreased with the increasing of the strain amplitude (γo). In dynamic strain tests, the critical strain of the WMS dispersions was an inverse function of the WMS concentration when the WMS concentration was beyond 4.0 wt.%.

► Waxy maize starch (WMS) dispersions displayed thickening in both steady and dynamic shear.
► Effects of WMS concentration and temperature on shear-thickening were evaluated.
► Effects of frequency and WMS concentration on dynamic strain-thickening were studied.
► Mechanisms for shear-thickening were provided and compared.