User:Andrew Sun/Notebook/LAOS study on physical gelation/2009/05/14

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LAOS Experiment of PAAc/Fe(III) Gels

Fig. 1
Fig. 2
Fig. 3
Fig. 4

Objectives

Find the critical gel point

Samples

Gels from 5 wt% PAAc solution (Mv=51100): f=1.15e-3, 1.44e-3 (f=[Fe(III)]/[COOH])

Instruments

ARES Rheometer

Results

Frequency Sweep

Fig. 1 shows that the f=1.44e-3 sample underwent significant dissociation after LAOS, while Fig. 2 shows that the f-1.15e-3 sample has been less dissociated. Fig. 3 shows the frequency sweep of four samples: f=1.15e-3, 1.30e-3, 1.44e-3 and 1.73e-3.

FT-Rheology

Fig. 4 shows that sample f=1.30e-3 has the highest nonlinearity. Samples f=1.44e-3 and 1.15e-3 have comparable nonlinearity. Sample f=1.73e-3 is hardly nonlinear in the range of strain amplitude studied.