Viscosity of gels

These parameters have significant effect on the final viscosity of gel in the fracture. Correlations to estimate friction pressures in field size tubulars have been developed from laboratory test data. In conjunction with field calibrations, these correlations can aid in accurate prediction of friction pressure of borate-crosslinked fluids. 

Starch can readily be modified by concurrent heat, application of moisture, and pressure. Such modifications may be conducted in extruders. Low moisture content favors formation of water-soluble starch with increased water-binding capacity, 65a 65e The solubility, water binding-capacity, and viscosity of gels prepared from extruded starch do not show linear relationships against either the moisture content in starch or the extrusion temperature.65c-65f Such extruder variables as the type of screw (either single or twin), pattern of the barrel and die heating, screw velocity, and geometry of the screw thread are also essential factors.65 ... 

Fig. 13 a, b Changes of the viscosities of Gel-20K-60 as a function of agitation time at a shear rate of 120s-1 a, and restoration of the viscosities of the gel after 20min agitation at a shear rate of 120s-1 b [67]... 

In another study, carboxymethyl xanthan was converted into Ca-carboxymethyl xanthan matrix by using CaCl solution and the swelling, erosion and drug release behavior of the matrix was investigated. The amotmt of Ca + ion was found to alter the viscosity of gel layer formed arotmd the matrices and affect the swelling and erosion of the matrix, resulting in different drug release profiles. The release data conformed to the Korsmeyer-Peppas model [87]. 

In the next chapter, we examine the phenomenology of drying and show that the theory presented here is in qualitative accord with observations. Quantitative tests of the model are not possible, because of lack of data for properties such as the permeability and viscosity of gels. 

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