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Routine measurements of viscosity is important in many industrial processes such as mixing and pumping, spraying and coating, extrusion, material consumption and leveling. Rotational Rheometer usually employed many non-Newtonian flow characteristics of the measuring system, but which may be difficult and quite expensive to buy and maintain. They may require a minimum level of operator.

Lower-cost, simple operation, rotation of the viscometer can provide a similar profile of the flow curve of non-Newtonian materials, provided they are designed and manufactured for a particular application, with built-in temperature control system, and associated with user-friendly, but powerful Windows software package. This article describes the Merlin built-in rotation viscometer (Reologica measures, Bordentown, NJ) (Fig. 1), which is capable of performing routine rheological tests completed in the short, single-point viscosity checks flow profiles and yield determinations without complicated test setup method, laboratories, for example, compressed air and the external fluid circulation and / or temperature control dial.

Merlin viscometer is well suited to study mixing, stirring, pumping and treatment coatings, emulsions and dispersions, as well as a normal flow rate and viscosity profile experiments. The innovative design incorporates Peltier temperature control system, which allows the isothermal step, and / or temperature ramp profiles. DIN standard sample measurement systems, cone and plate, parallel plate, bob and cup (Fig. 2), together with a wide shear rate and torque range (Table 1) measured the viscosity range from 1 to 1E08 CP. This is achieved by using the DIN measurement system within the specified torque and / or the angular velocity varies Merlin viscometer and then merge the results.

Viscometer in a better quality specifications of the various materials, including paints, coatings, inks, surface, polymer solutions, food, pharmaceutical, cosmetics, biochemicals, asphalt, molten polymers, adhesives, sealants, and petrochemical testing.

Viscometer operating

To prove that the measure results with all three of measurement 1) 30 mm diam parallel plates, 2) 30 mm / 5 ° cone and plate, and 3) 25 mm diam and a cup of Bob's nominal 1000-CP silicone oil was estimated at 25 ° C. Parallel plate experiment was performed with 0.5 mm gap, and the 5 ° cone and plate was 0.150 mm truncation. Steady shear experiments were performed using the Windows ™ MICRA user interface software (Microsoft, Redmond, WA) (Fig. 3). From high to low shear rate.

For a constant viscosity (Pa s) is plotted relative to the torque (ACT), Figure 4 (torque is plotted on the abscissa, rather than the shear rate [s-1] to normalize the data for three experiments). As expected, all three measurement systems show similar data. The ability to use different sample geometry allows the user to extend the capabilities of various devices and / or to accommodate a wider range of materials and sample size / amount. Bob and cup system is well suited for low viscosity materials and / or low shear rate measurements, because it provides more contact surface area of ??the sample and therefore more torque signal. Three repeat is shown in Figure 5, the viscosity (Pa s) is plotted as a bob and cup system is a function of torque (ACT), which shows Merlin viscometer work during the working torque range of measures.

Bob and cup geometry was used to test several different viscosity standards, covering from 10 to 10.000 cP at 25 ° C. All data are acceptable ranges of viscosity, as shown in Figure 6. Again, the data is compared with the torque is plotted normalized abscissa.

Set the nominal temperature of 1000 cP oil viscosity (Pa s) shear rate (S-1) function is shown in Figure 7. Ability to monitor and / or systematic change of the sample temperature is extremely vibrant rheology and viscosity measurements. Viscometer built in Peltier temperature control system supports all measurement systems, including cone and plate, parallel plate and cup and BOB. Measure temperature using the BCS and the cup measurement system accuracy are summarized in Table 2. Clearly, the temperature was well calibrated across the range studied. Heat shield can increase performance at high temperatures.

Another advantage compared to other commercial viscometer viscometers Merlin's ability to perform user-defined, controlled temperature ramp. It is vitally important for temperature sensitive materials. The activation energy Ea can be estimated from the experiment. Figure 8 shows the temperature profiles for heating and cooling experiments between 10 and 80 ° C and a rate of ° C / min .. Bob and cup geometry was used for this test is 1000 cP oil at a constant shear rate 10 s-1. It is clear that the temperature can be well controlled Peltier temperature control system. Figure 9 as 1 / T function of the heating experiment, which may be appropriate Arrhenius model, ? = language / T, which is associated with the activation energy is constant, k EA, R-Boltzmann constant viscosity. In this experiment, the activation energy obtained from the heating run was 16.9 kJ / mol. Other controlled temperature ramp from 0.1 to more than 2 ° C / min.

Merlin viscometer can also measure the dynamic yield strength or yield point of the sample and MICR software supports this method of experimental investigation. Using a 25 mm BCS and cup, ketchup commercial sample was evaluated. Figure 10 shows the results of the selection of the shear stress (Pa) versus time (s). Yield experiment was performed using 0.1 s-1 shear rate measurement of stress responses. Maximum stress of the yield stress value measured in the sample, approximately 14.7 Pa the ketchup. The yield stress measurement capability is much higher than other available viscometers, the viscosity is only one speed. MICRA software also allows the user to define the shear rate sweeps, shear rate of increase / decrease gradually, allowing the full flow curve profile will be established. Figure 11 shows the shear rate compared with the commercial ketchup sample the shear rate range 1-1000 s-1 viscosity. The data show that the sample is shear thinning (pseudoplastic), and clearly can not be one of the viscosity values ??obtained from other commercial viscometers.

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