Strain sweep experiments

Figure 3-40 Illustration of Estimation of Critical Stress from a Stress Sweep at a Fixed Frequency Dynamic Rheological Experiment. Alternatively, as described in the text, one may conduct a strain sweep experiment.

An advanced rheometric expansion system (ARES) is used to determine Tg of samples. Strain sweep experiments from 0.01 to 1% strain are conducted to ensure that experiments are carried out in the linear viscoelastic region. All experiments are done at a frequency of IHz and a strain level of 0.05%, which is in the linear region. Temperature sweeps are conducted at a heating rate of 5°C/min over a temperature range which covers the glassy and rubbery regions of the soy flour samples at different water activities. The temperature at which the loss modulus (G") was at a maximum is used to estimate the T . 

Figure 14. The 8 cycle of strain sweep experiments at 140 °C and 1 Hz. (a) 30/70 DSF/SB composite (b) 20/80 DSF/SB composite (c) 30/70 SPI/SB composite (d) 20/80 SPI/SB composite. The samples were prepared by the casting method. Solid lines are the fit from the Kraus model. (Reproducedfrom reference 16.)...

Figure 1.10 A generalised plot of a strain sweep experiment where storage and loss moduli are plotted as a fimction of strain...

The filler-filler network can be reformed again after a certain time interval. Payne revealed that the value of E is largely recoverable upon return to smaller amplitudes in the linear regime. So, flexible mbber chains allow the filler particles to rearrange again to form a three-dimensional filler network in the rubber matrix [99]. In order to investigate the ability to recover the strain sweep experiments were also carried out in the reverse direction from higher to lower strain amplitudes for the samples with unmodified CNT dispersed by ethanoUc suspension. 

Fig. 27 (a) Effect of dynamic strain amplitude on storage modulus, (b) stress-strain behaviour of CR/EPDM blend in absence and in presence of nanoclay. For strain sweep experiment, tension mode was selected for the variation of the dynamic strain from 0.01 % to 40 % at 10 Hz frequency [106]... 

Fig. 6 Strain sweep experiments on carbon-black and silica filled SBR compounds with a closed-cavity torsional dynamic tester, drawn using data from Dick and Pawlowsky [20]...

We used the Batchelor theory in combination with the MM-Model to calculate the interfacial stress waves for a number of varying emulsion parameters and frequencies as a function of strain amplitude yo resembUng a strain sweep experiment. Initially monodisperse emulsions were considered, characterized by a single droplet radius R, the interfacial tension F and the viscosities of the eonstituents tjd and r]m. The two functions f and fz depend on the viscosity ratio A and the capillary number Ca (Eq. 11). The modelled stress oscillatory signals were Fourier transformed and the relative intensities of the third and fifth harmonic were extracted from the spectra to obtain their ratio, I5/3 = h/i/h/i as a function of strain amplitude yo. 

Strain sweep experiments on SSBR compounds with various levels of carbon black. 

Figure 6.10 shows typical dynamic properties of vulcanized PDMS-silica systems, as investigated through strain sweep experiments at constant frequency and temperature. As can be seen, dynamic strain softening is observed in a qualitatively similar manner to other filled polymers. It follows that models, which successfully fit conventional filled rubbers (e.g., carbon black filled compounds), are expected to well suit such data. This is indeed the case, as shown by the curves in Figure 6.10, drawn by fitting the Kraus-Ulmer equations, i.e.. 

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