Viscosity working point

LALS) in THF and the intrinsic viscosity of five of the samples was measured by the single point method. Combining the LALS data with the intrinsic viscosity work allows one to obtain the Mark-Houwink constants, and a, by plotting log[77] vs logMw. For PIPTBK, and a in THF at 25° were found to be 5xlO-3 ml/g and 0.75 respectively. 

The large variations in viscosity during reactive extrusion can lead to process instabilities as a result of competition between die effects and pressure build-up abilities of the screws. In general, two stable working points can be distinguished - one at low conversion with a short, fully filled length, and one at high conversion with a... 

The viscosities of some common liquids are given in Table 21.2 for comparison. Notice that at the working point... 

Fig. 18. Influence of salts on the relative viscosity of positive 0.42% ichthyocoli sols (37° C). a Part of the pH-viscosity curve at pH values lower than the I.E.P. (see Fig. 20 curve A), b, c d influence of salts in which a point is chosen respectively on the rising branch, at the maximum and on the falling branch of the curve in a as working point.

In continuous polymerizations, the main problem is the dynamic stability of the reactor. The stability problems have various different aspects the thermal stability as introduced above (see Section 11.2.4), the concentration stability, the particle number stability, and the viscosity stability. Even under isothermal conditions these problems may lead to multiplicity or oscillatory behavior. It is worth emphasizing the fact that stability and safety are in no case synonymous a reactor may be unsafe even if working at a stable working point, or conversely it may be run safely at an instable working point. But knowledge of stability limits of the reactor is essential for the design of a safe process. 

Working point is the temperature at which the viscosity is 10 poise. This is the viscosity at which a machine is able to work on glass without losing control. 

WorkingS olution Regeneration and Purification. Economic operation of an anthraquinone autoxidation process mandates fmgal use of the expensive anthraquinones. During each reduction and oxidation cycle some finite amount of anthraquinone and solvent is affected by the physical and chemical exposure. At some point, control of tetrahydroanthraquinones, tetrahydroanthraquinone epoxides, hydroxyanthrones, and acids is required to maintain the active anthraquinone concentration, catalytic activity, and favorable density and viscosity. This control can be by removal or regeneration. 

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