Rheometry of Laponite/PEO suspensions

A full lest of rheometric investigation of Laponite/PEG suspension. Parts of the tasks have been submitted or published.

Observation during preshear

Comparison of different shear rates

Steady shear flow \eta vs \dot{\gamma}. Procedure: steady preshear at \dot{\gamma} = 200 s-1 for 200s, delay for 800s, steady state flow test.

Samples: L2S5, L2S5P35k0.1, 0.25, 0.63, 0.8, 1.0

Instrument: AR-G2

Comparison of different shear method: osc. vs cont.

Whether \gamma_0\omega=\dot{\gamma}, by checking the Cox-Merz rule

Sample: L2S5, L2S5P35k0.63

Instrument: AR-G2

Aging

Ageing under SAOS

Comparison of different preshear rates

Procedure: Steady preshear at \dot{\gamma} = 1, 2.5, 6.3, 16, 40, 63, 160, 200 s-1 for 200 s, oscillatory time sweep1.

Samples: L2S5, L2S5P35k0.1, 0.25, 0.63, 0.8, 1.0

Instrument: AR-G2

Comparison of different preshear method: osc. vs cont.

Procedure: preshear at \dot{\gamma} = 200 s-1 or γ = 200 %, ω = 10 rad/s, for 200 s, oscillatory frequency sweep.

Samples: L2S5, L2S5P35k0.63

Instrument: AR-G2

Effect of PEG concentration

Submitted.

Time-resolved viscoelastic property2

Procedure: steady preshear at \dot{\gamma} = 200 s-1 for 200 s, oscillatory time sweep at ω = 1, 1.6, 2.5, 4, 6.3, 10, 16, 25, 40, 63 rad/s for 400s.

Samples: L2S5P35k0.1, 0.25, 0.63, 0.8, 1.0

Instrument: AR-G2

Aging under LAOS

Procedure: steady preshear at \dot{\gamma} = 200 s-1 for 200 s, dynamic time sweep at ω = 6.283 rad/s and γ0 = 1 ~ 25 %, focusing on the yielding strain amplitude region.

Samples: L2S5P35k0.063, 0.1, 0.25, 0.4, 0.63, 1.0

Instrument: ARES

Aged gel

Steady LAOS

Published.

Yielding under LAOS

References: PRL 2011, 106, 248303. Soft Matter 2010, 6, 3482.
Procedure: steady preshear at \dot{\gamma} = 200 s-1 for 200s, delay 800s, arbitrary waveshape test at ω = 6.283 rad/s and γ0 = 10 ~ 100 % focusing on the yielding regime.

Samples: L2S5P35k0.1, 0.25, 0.4, 0.63, 0.8, 1.0

Instrument: ARES

Schedule