Reduced viscosity over time

Figure 4. Reduced viscosity over time. Material stored at room temperature(-), and at 5°C (----).

During secondary liquefaction at 95 C or 90 C, a r id reduction in viscosity was observed. At 90 C, the viscosity reduction was monitored over time with a Nametre viscometer. The results demonstrated there was a r id reduction in viscosity to 400 centipoise x gm/cm by 7 minutes into secondary liquefaction (Figure 6). The action patterns of the liquefied starches following secondary liquefaction demonstrated the characteristic cyclodextrin action pattern at both temperatures. DE values were < 1.0 indicating the absence of reducing end-groups consistent with the mechanism of a CGTase. 

In addition to temperature, the viscosity of these mixtures can change dramatically over time, or even with applied shear. Liquids or solutions whose viscosity changes with time or shear rate are said to be non-Newtonian, that is, viscosity can no longer be considered a proportionality constant between the shear stress and the shear rate. In solutions containing large molecules and suspensions contain nonattracting aniso-metric particles, flow can orient the molecules or particles. This orientation reduces the resistance to shear, and the stress required to increase the shear rate diminishes with increasing shear rate. This behavior is often described by an empirical power law equation that is simply a variation of Eq. (4.3), and the fluid is said to be a power law fluid ... 

To a 250 ml flask equipped with a stirrer, a thermometer, a water condenser and Dean-Stark trap was added 11.42 g of 4.4 -isopropylidenediphenol (0.05 moles), 13.1 g of a 42.8% potassium hydroxide solution (0.1 mole KOH), 50 ml of dimethyl sulfoxide and 6 ml of benzene. The reaction mixture was kept under an atmosphere of nitrogen and the water was azeotroped oft over a 3 to 4 hours period (130—135° C). At the end of this time the reaction mixture consisted of the potassium salt of the biphenol and was essentially anhydrous. After cooling the mixture there was added 14.35 g (0.05 moles) of 4.4 -dichlorodiphenyl sulfone and 40 ml of anhydrous dimethylsulfoxide. The reaction mixture was maintained, under a nitrogen atmosphere, between 130 and 140° C with stirring for 4 to 5 hours. The viscous orange solution was then poured into 300 ml of water in a Waring Blendor and the polymer separated by filtration and dried at 110° for 16 hours. A yield of 22.2 g (100%) of polymer with a reduced viscosity in chloroform (0.2 g per 100 ml at 25°) of 0.59 was obtained. 

Sollinger and Voges8 at Akzo Nobel (Obemburg, Germany) used off-line transmission NIR to monitor the key quality parameters in cellulose fiber (viscose) spinning solutions over time. The business value lay both in reducing the time and cost of analysis by consolidating four or... 

First, volatiles exert an important control on the physical properties of the mantle. For example, the presence of water reduces the strength of olivine aggregates and seriously alters the viscosity of the mantle. Experimental studies show that at 300 MPa, in the presence of water, the viscosity of olivine aggregates deformed in the dislocation creep regime is reduced by up to a factor of 140. Thus a wet mantle is a low viscosity mantle. Conversely a mantle that is dried out by partial melting will be stiffer and more refractory, as is the case for the lithospheric "lid" to modern oceanic mantle. Thus, if it is possible to estimate the volatile content of the mantle both now and in the Archaean, it will be possible to set some physical constraints on models of mantle evolution over time. 

Lubricating oils for precision instruments and large clocks must have excellent oxidation stability, good anti-wear and anti-corrosion properties and retain their viscosity over a long period of time. Sometimes small amounts of gel-forming soaps, e.g. an aluminium soap, are added in order to reduce the creeping effect. 

The cause was found to be microbiological contamination in the starch tank. Whenever a fresh batch of starch was pumped over, the tank viscosity and FPR rose. Over time, the biological activity in the starch tank reduced the viscosity of the starch and the FPR fell. The cycle was repeated when the next batch of starch was pumped over. 

The speed and resolving power are important in any chromatographic process. The driving force in TLC is capillary action through the fine matrix of the solvent mixture chosen to be best for the separation. If we can reduce the viscosity of the mobile phase, it would improve flow rate. Likewise, if we develop the plate to shorter distances then the development time will be much less. Realizing these factors from chromatographic theory, various particle size ranges shown in Table 1 were developed over time. 

Leakage flow varies with the flight clearance. It is also enhanced by low-viscosity melts and high head pressures. With new screws and barrels, leakage flow is minor and has no apparent effect on extruder output. As the flight clearance increases, leakage flow rises, thereby reducing output. Consequently, the decrease in extruder output over time is used to monitor screw and barrel wear. 

The analytical requirement given to us by our customer is to determine the presence of VX at concentrations below 20 ppb. We have solved this problem using HPLC with Atmospheric Pressure Ionization MS/MS and developed it into a technique that can be applied to large numbers of samples. A chromatogram and a scan of parent and daughter ions for VX is shown in Figures 3 and 4. The technique of HPLC-API/MS/MS has been used by this laboratory for over 2 years for determination of VX in aqueous environmental samples. In that application, the technique has sub-PPM sensitivi. In this application, the reaction mixture must be diluted in a buffer solution to reduce viscosity and adjust pH prior to injection on the HPLC system or the retention times will not be reproducible. This reduces the sensitivity of the method for this application to 5 PPB. 

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