Fig. 1. PVC suspension (60%) in Dinch.

(A to D) Portions of the time traces of the macroscopic shear rate under constant shear stress. See section S1 for the signals over 1800 s. The applied shear stress in the peak hold stress experiments are: 270 Pa (A, black), 200 Pa (B, red), 133 Pa (C, cyan), and 50 Pa (D, green). In a Couette cell, the measured average shear rate and the period T_rot of the motor are linked by $\frac{1}{T_{\text{rot}}}=\frac{R_{\mathrm{o}}^2-R_{\mathrm{i}}^2}{R_{\mathrm{o}}^2+R_{\mathrm{i}}^2}\frac{\dot{\mathrm{\gamma }}}{2\mathrm{\pi }}$, where R_o is the stator radius and R_i is the rotor radius (R_o = R_i − e). In our case, this leads to T_rot = 8.8 s for a macroscopic shear rate of 17 s⁻¹ and to T_rot = 11 s for a macroscopic shear rate of 13.5 s⁻¹. Above the shear thickening transition, large oscillations are observed with a period roughly equal to 18 s for (A) to (C), i.e., two times that of the rotor period rotation (T_rot= 8.8 s). Below the shear-thickening transition, the oscillation has a much smaller amplitude and their period is equal to the rotor period rotation, i.e., 11 s. (E) Variation of the apparent viscosity as function of the shear rate recorded in a Couette geometry by ramping up the imposed stress with 60 s per point (small empty black circles) and through subsequent constant stress experiments of at least 3600 s (filled colored circles; shear rate is averaged over the last 2500 s of each step). (F) Same as (E), viscosity as a function of the shear stress. (G) Effect of the eccentricity (indicated above the curve, in μm; steps of 150 s) of the Couette cell on the dynamics. The applied shear stress is 200 Pa.