Rheological equipment

This treatise wants to give a short but not necessarily complete overview of the standard rheological equipment of a modem laboratory in the food industry, starting off with purely empirical rheometers like the Ridgelimeter, the Pectinometer of Herbstreith Fox, and penetrometers, passing over to more sophisticated rheometers, capable to give fundamental data. 

Graves, G. and Fellin, E. "Automated Rheology Equipment Facilitates Acid Fracturing Fluid Characterization," Presented at the SPE Computer Technology Symposium, Texas Tech University, Lubbock, March 6, 1986. 

The rheological equipment requires certain capabilities in order to effectively measure composite adhesive resin systems. The transducer must have a dynamic range from 1 to 10 poise. This is a result of achieving a very low viscosity during an elevated temperature cure... 

Some of the typical apparatus used to measure the rheological behavior of fluids will be discussed in the following section. A detailed compilation of commercial rheological equipment is given in reference 12. 

The application of the theoretical treatment depends on the ability to measure the extrusion force and rate. Most commercial extruders do not allow for these types of measurement. Normal rheological equipment, such as cup-and-bob or cone-and-plate, do not have a suitable geometry or instrumentation to handle materials of the consistency normally used. A ram extruder is a suitable experimental design. 

Correct and imaginative use of suitable rheological equipment, such as the Monsanto Processability Tester, allows pertinent information to be obtained at lower cost than the classical trial-and-error approach. Furthermore, better cost efficiency can be achieved when interpreting capillary rheometer results in terms of processing and selecting the best operating conditions with respect to material flow properties. 

The method with the largest capacity is obviously the drop and bubble shape analysis, in the literature often named ADSA. This methodology does not provide data at extremely short adsorption times, however, it has quite a number of advantages. First of all it is applicable to hquid/gas and hquid/liquid interfaces, it requires very small amounts of samples, and it is easy to temperature control. Moreover, it gives access to surface rheology. Equipped with an additional... 

Obviously in each area, certain specific items of test equipment will be used, such as small extruders, paint rigs, Stevens texture testers and penetrometers, etc. However, here we are interested in those pieces of rheological equipment that we should also find. The following important features are generally measured in rheological studies for typical liquids listed above, with some specific examples ... 

Quality Control and Testing. Control of inks is done by examining their color strength, hue, tack, rheology, drying rate, stabiHty, and product resistance. Elaborate control equipment and laboratory testing procedures are employed to test the finished inks. Weather-Ometers,... 

Rheology. Both PB and PMP melts exhibit strong non-Newtonian behavior thek apparent melt viscosity decreases with an increase in shear stress (27,28). Melt viscosities of both resins depend on temperature (24,27). The activation energy for PB viscous flow is 46 kj /mol (11 kcal/mol) (39), and for PMP, 77 kJ/mol (18.4 kcal/mol) (28). Equipment used for PP processing is usually suitable for PB and PMP processing as well however, adjustments in the processing conditions must be made to account for the differences in melt temperatures and rheology. 

States or Australia. In some cases, pot stills, arranged in cascade, are still used. The more sophisticated plants employ one or more carbon steel or cast-iron vessels heated electrically and equipped with temperature controls for both the bulk Hquid and the vessel walls. Contact time is usually 6—10 h. However, modem pitches are vacuum-distilled, producing no secondary quinoline insolubles, to improve the rheological properties. 

The size of bottom hole equipment (liners, packers, etc.) reduces annular space and increases pressure losses. The fluid must maintain rheological properties which reduce pressure losses. 

Although the field of rheology is, in and of itself, fascinating, most people are interested in it chiefly because they are concerned about its implications. Specifically, we wish to know how a polymer will behave in a particular piece of processing equipment. These same considerations arise whenever we process polymers, so we will address them as we describe the individual polymer converting processes later in the book. 

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