High-temperature sedimentation characteristics

High-temperature sedimentation characteristics. Slurry settling rates at temperatures in excess of 100 C have been obtained in quartz tube 8 mm in diameter [54]. These data, obtained with a slurry of thorium oxide prepared by a 650°C calcination of thorium formate [55], indicated that the slurry was already in the compaction zone of settling above 500 g Th/kg H2O at 200 to 300°C. At a concentration of 1000 g Th/kg H2O, no settling occurred at temperatures above 100°C. The small diameter of the tube probably affected the concentration at which the slurry went into compaction. 

The importance of water soluble polymers such as the polyacrylamides is well established but only now are fundamental data on these systems beginning to accumulate. The unperturbed dimensions of these polymers tend to depend on the lateral substituent, and specific interactions are thought to produce large chain expansions with a corresponding low chain flexibility. In some cases the specific interactions can lead to a system exhibiting a pseudo-lower critical-solution temperature. The characteristic parameter C for polyacrylamide in water has also been reassessed in the belirf that the published value is too high. The excluded volume parameter and unperturbed dimensions have also been measured for poly ( -1,1-dimethyl-3-oxobutylacrylamide) in MEK. Many of the papers mentioned in Table 1 contain additional data on the sedimentation behaviour and thermodynamic parameters. 

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