High molecular-weight-polyacrylamide

In addition, postreaction on high molecular weight polyacrylamides can be difficult because of the high viscosity of even fairly dilute aqueous polyacrylamide solutions. 

High molecular weight polyacrylamides are used as viscosity builders in freshwater muds (53) or as bentonite extenders. The ionic nature of the polyacrylamide may range from nonionic to anionic (30% hydrolyzed) depending on the situation. Molecular weights ranging from >3 x 10 are used for this purpose. Polymer concentrations of 0.7—2.8 kg/m (0.25—1.0 Ib/bbl) are used depending on the appHcation. 

A modified acrylamide polymer that is hydrophobically associating has remarkably improved the properties of salt resistance and temperature resistance, compared with high-molecular-weight polyacrylamide [1351]. 

Flow Properties. In water, high molecular weight polyacrylamide forms viscous homogeneous solutions. 

A feature of the neutron reflectivity study on polyDMDAAC and surfactant adsorption by Penfold et al. [74] was that the adsorbed layer of polyDMDAAC was remarkably robust and unaffected by the subsequent surfactant adsorption. This is not always the case, and Fielden et al. [76] reported a large increase in the thickness of the surface layer of AM-MAPTC on mica due to complex formation with SDS. Thickness increases with electrolyte and pH were reported for high molecular weight polyacrylamide adsorbed onto silica, measured by null ellip-sometry by Samoshina et al. [82] in the absence of surfactant. Complex formation at the interface, resulting in layer thickening, was also reported by Dedinaite et al. [83] for PCMA/SDS mixtures on mica from AFM measurements. 

Water (potable) High molecular weight polyacrylamides of low toxicity with usage of Must not exceed... 

Sewage sludge High molecular weight polyacrylamides 1-4 kg... 

Solid-grade, high molecular weight polyacrylamides can, reasonably easily, be made into solutions of up to about 1% by weight. Above this concentration, the solids become very difficult to dissolve. More normally the maximum strength of make-up is 0.5 to 0.7%. At these concentrations the solutions are extremely viscous, and they would then be further diluted before use, either in line on the way to the decanter or in a separate mixing tank. Two extreme examples of polymer viscosity are shown in Figure 5.2. These are not necessarily typical of the polymers specified, but just examples to show the viscosity extremes that could be encountered. 

Herr, J. W. and Routson, W. G. (1974) Polymer structure and its relationship to the dilute solution properties of high molecular weight polyacrylamide. SPE 5098. Proceedings of the SPE 49th Annual Fall Conference, Houston, TX, 6-9 October 1974. 

Polyacrylamides are produced commercially in an aqueous environment by free radical polymerization, which follows the classical vinyl polymerization model with initiation, propagation, and termination processes. In this model, the propagation/termination ratio kjk/ and chain transfer to monomer, polymer, initiator, and other small molecules impact the molecular weight of the formed polymer. High-molecular-weight polyacrylamides are possible because of the high ratio for acrylamide and the low chain-... 

The rate of polymer dissolution is an important property that impacts high-molecular-weight polyacrylamide availability and performance commercially. Polymer particle size distribution in dry powder polymers and the polymer solids content and level of activating surfactant in inverse emulsion polymers are factors that impact polymer dissolution. The rate of polymer dissolution is typically determined by following the rate at which the viscosity in a polymer solution builds during dissolution. 

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