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- What are the main factors affecting the viscosity of polyacrylamide?
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Factors influence the viscosity of polyacrylamide
Anionic polyacrylamide solution viscosity reflects mainly due to internal friction between molecules of the liquid flow generated by the movement or relative. Friction within the structure of the polymer, the nature of the solvent, solution concentration and temperature and pressure and other factors, the greater its value, indicating that the greater the viscosity of the solution.
1, the effect of temperature on the viscosity of anionic polyacrylamide
Temperature is random thermal motion of molecules are reflected intensity, molecular movement must overcome the intermolecular interaction, and the interaction between molecules, such as intermolecular hydrogen bonding, friction, diffusion, molecular chain orientation, entanglement, etc., a direct impact on the size of the viscosity, it is the viscosity of the polymer solution will vary with temperature. Effect of temperature changes on the polymer solution viscosity is significant. Anionic polyacrylamide solution viscosity with increasing temperature decreases, the reason is dispersed particle entangled polymer solution with each other to form a network structure of the polymer, when the higher the temperature, the more easy to destroy the network structure, so the viscosity decline.
2. Effect of Hydrolysis on anionic polyacrylamide viscosity
Anionic polyacrylamide solution viscosity over prolonged hydrolysis time is changed, the hydrolysis time is short, a small viscosity, which may be due to polymer had a chance to form a network structure due; hydrolysis time is too long, the viscosity decreased, which is an anionic polymer release induced by acrylamide structure in solution. Partially hydrolyzed anionic polyacrylamide dissolved in water dissociate into negatively charged macromolecules, anionic repulsion electrostatic repulsion between molecules and the different link on the same molecule extending between lead molecules in solution and make mutually between molecules winding, which is partially hydrolyzed anionic polyacrylamide solution viscosity can make significant reason for the increase.
3, the impact of salinity on the viscosity of anionic polyacrylamide
Anionic polyacrylamide molecular chain cationic group with respect to the larger number of anionic groups, more net charge, polarity, and H20 is a polar molecule, according to the similarity dissolves, the polymer is preferably a water-soluble, characteristic high viscosity; mineral content increases, the electrostatic charge being formed portion is surrounded by anionic ion atmosphere, so that in combination with the surrounding positive electrostatic charge, the polarity of the polymer solution decreases, the viscosity decreases; mineral concentrations continued to increase , the positive and negative ions groups form intramolecular or intermolecular association of hydrogen bonds (resulting in decreased solubility of the polymer in water), while adding salt ions by masking the positive and negative charge, break up positive association between negative and key is the salt formed is destroyed (leading to an increase in solubility of the polymer in water), these two competing effects, such that the polymer solution at a high concentration (> 0.06 mol / L) is kept small viscosity .
4. Effect of molecular weight anionic polyacrylamide viscosity
Anionic polyacrylamide solution viscosity with increasing molecular weight of the polymer increases, which is due to the viscosity of the polymer solution when the interaction between molecules by molecular motion. When the polymer molecular weight of about 106, polymer coils begin to penetrate each other enough to affect light scattering. When the content is slightly higher mechanical entanglement enough to affect viscosity. When the content is relatively low, the polymer solution can be regarded as a network structure, mechanical entanglement and hydrogen bonding between chains together form a network node. When higher levels, a solution containing many chain - link contacts to make the polymer solution was gelled. Thus, the greater the relative molecular mass of the polymer, the more easy to form intermolecular chain entanglement, the greater the viscosity of the solution.