Viscosity alkali effects

The interaction between alkali and polymer, to be discussed in this section, includes alkaline effect on polymer viscosity, polymer effect on alkafine/oil IFT, and alkaline consumption in alkaline-polymer systems. 

Most of the current models of the mixed-alkali effect are based on the experimental observation of certain macroscopic properties, such as electrical conductivity, alkali ion diffusion and viscosity. However, the secret of the mixed-alkali effect must lie in the structure of the glass and in how the structure controls the mechanisms of alkali diffusion in the glass. 

PART II PARTIALLY HYDROLYZED POLYACRYLAMIDE, 622 Polymer Viscosity in Deionized Water, 623 Effect of Sodium Chloride on the Viscosity of HP AM, 624 Effect of Cation Type on Polymer Viscosity, 627 Effect of Alkali Type on Polymer Viscosity, 629 Effect of Surfactants on Polymer Viscosity, 634 Effect of Surfactants and Alkalis on Polymer Viscosity, 635... 

The viscosity calculated by the confined shear simulation is 1.11 Pa s at lOSO C. This agrees very well with the value measured previously for this composition within the (NNL). It also seems to have accounted for the mixed alkali effect, which could not be modeled using the simpler analytical methods. Comparisons at other temperatures and with other silicate, borosilicate, and aluminosilicate melts showed similar agreement. 

The viscosity and non-Newtonian flooding characteristics of the polymer solutions decrease significantly in the presence of inorganic salts, alkali silicates, and multivalent cations. The effect can be traced back to the repression of the dissociation of polyelectrolytes, to the formation of a badly dissociating polyelectrolyte metal complex, and to the separation of such a complex fi"om the polymer solution [1054]. 

The devitrification rate is extremely sensitive to both surface and bulk impurities, especially alkali. Increased alkali levels tend to increase the devitrification rate and lower the temperature at which the maximum rate occurs. For example, a bulk level of 0.32 wt % soda increases the maximum devitrification rate 20—30 times and lowers the temperature of maximum devitrification to approximately 1400°C (101). The impurity effect is present even at trace levels (<50 ppm) and can be enhanced with the addition of alumina. The devitrification rate varies inversely with the ratio of alumina-to-alkali metal oxide. The effect is a consequence of the fact that these impurities lower glass viscosity (102). 

The diffusion coefficient19 of sodium bromide is 0-86 at 10° for soln. of sodium bromide containing 2 9 mols. per litre and for iV-soln. of potassium bromide, 1 13 per sq. cm. per day. The capillary constant20 of fused sodium bromide is o2=4 08, and potassium bromide, a2=4 49 sq. mm. The surface tensions are respectively 49"0 and 484 dynes per cm. W. Herz and G. Anders 21 measured the viscosities of soln. of alkali bromides and F. Korber the effect of press, on the viscosities as indicated in Table XIX. 

As shown experimentally by Piest [75], cotton which was subjected to various operations, e.g. bleaching, treatment with alkalis or acids, strong heating prior to nitration furnishes nitrocellulose solutions of low viscosity. At the same time an increase in the solubility of the nitrocotton was also observed. This is evidence that the cellulose molecules are shortened and their content of terminal group is increased. A certain proportion of hydrocellulose and oxycellulose may result. The total effect is to bring about an increase in the reductive properties of the cellulose, i.e. an increase of the copper number. 

The effect of after treatment with alkalis on the viscosity... 

A much more extensive investigation of the effect of alkalies has been made in the case of polysaccharides, especially cellulose this is understandable in view of the industrial importance of mercerization, of the viscose process, and of cellulose ethers. Various complexes have been reported for cellulose and alkalies depending upon the nature of the alkali, upon its concentration, upon the washing treatment used, and upon the pretreatment of the cellulose. A discussion of this subject has been published by Nicoll and Conaway.84 There is general agreement on the formation of several compounds, which are susceptible to hydrolysis. The question as to whether these compounds are molecular complexes (XLVII), true alkoxides (XLVIII), or an equilibrium mixture of the two has not been answered. In recent studies Lauer65 has reached... 

The uncontrolled variation in the gypsum-hemihydrate or soluble anhydrite ratio (G-H or A) that occurs during production, storage and transportation of cement can cause compatibility problems with certain superplasticizers, particularly a reduction in workability. The extent of the reduction on workability properties is dependent on the G-H ratio (ranging from 80 20% to 20 80%), level of C A and alkalis present in the cement and the fineness of the cement. For the most reactive type of cement with a high content of both C A and alkalis, a reduced G-H or A ratio affects the yield stress, while piastre viscosity is not much affected. These effects are much less pronounced for a less reactive cement, but with the lowest G-H or A ratio, false set can occur [130-132], An increased fineness of cement increases the effect of the G-H or A ratio. The effect has been found to be most pronounced with melamine-based superplasticizers [130, 133],... 

---