Rheology Room temperature

Pons et al. have studied the effects of temperature, volume fraction, oil-to-surfactant ratio and salt concentration of the aqueous phase of w/o HIPEs on a number of rheological properties. The yield stress [10] was found to increase with increasing NaCl concentration, at room temperature. This was attributed to an increase in rigidity of films between adjacent droplets. For salt-free emulsions, the yield stress increases with increasing temperature, due to the increase in interfacial tension. However, for emulsions containing salt, the yield stress more or less reaches a plateau at higher temperatures, after addition of only 1.5% NaCl. 

Three factors support the contention that the rheological properties -n and t may not be correct (a) no temperature dependency measurements are available and the room-temperature data cannot possibly apply rigorously (b) with the more dilute suspensions, Bonilla et al. (B6) encountered serious settling problems in the Mac Michael viscometer used to measure these properties (c) for all suspensions the reported values of r are surprisingly low. 

Milk fat and butter can be tailored to have desired properties and functionalities. Treatments are often aimed at improving cold spreadability without compromising room temperature stability. To modify the texture and rheological properties of butter, composition and processing conditions can be manipulated... 

Disulfide bonds between proteins have an energy of 49 kcal/mole and are not broken at room temperature except as the result of a chemical reaction. The effects of oxidizing agents on the rheological properties of dough... 

Shown in Figure 10 are the rheological properties of the prepreg and the neat matrix resin after aging for 21 and 60 days at room temperature. The viscosity determinations, run at 1.5 Hz, were made using a process cycle typical of a production shop. 

Rheological Experiments. Melt viscosity and low-strain oscillatory experiments were performed on a Rheometrics RDS-7700 dynamic spectrometer equipped with a 0.2-2.0-g-cm torque transducer. The samples were mounted on 25-mm-diameter parallel-plate fixtures with a gap of 0.5 mm. Prior to each scan, samples were heated to 50 °C and then cooled slowly to room temperature. Steady-shear... 

Rheological Behavior. Figure 4 shows the room-temperature steady-shear viscosity as a function of shear rate for PDM-PMAS polymers and their precursors. Polymers with Ciq, C12, and C14 side chains exhibit Newtonian behavior over the range of shear rates monitored. 

Figure 11.15 (a) Recoverable strain yr versus time for a 52.8% liquid-crystalline hydroxypropy-Icellulose solution in water at room temperature, 22°C. The curves from left to right were obtained by imposing stresses of 50, 125, 250, 500, 1000, and 2000 dyn/cm before recovery. These imposed shear stresses correspond to various values of the prior shear rate yq. (b) The same plotted against yot all curves fall within the indicated region between the curves for 50 and 2000 dyn/cm. (From Larson and Mead 1989, with permission from the-Joumal of Rheology.)... 

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