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Factors affecting the viscosity of polyacrylamide

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The viscosity of polyacrylamide solution mainly reflects the internal frictional resistance between liquid molecules due to flow or relative movement. The internal friction resistance is related to the structure of the polymer, the nature of the solvent, the concentration of the solution, temperature and pressure and other factors. The polyacrylamide manufacturer tells you that the larger the value, the greater the viscosity of the solution.

1. The influence of temperature on the viscosity of polyacrylamide

Temperature is the reflection of the intensity of the irregular thermal motion of molecules. The motion of molecules overcomes the interaction force between molecules, and the interaction between molecules, such as intermolecular hydrogen bonding, internal friction, diffusion, molecular chain orientation, entanglement, etc., directly Affect the size of the viscosity, so the viscosity of the polymer solution will change with temperature. The effect of temperature change on the viscosity of the polymer solution is significant. The viscosity of the polyacrylamide solution decreases with the increase of temperature. The reason is that the dispersed phase particles of the polymer solution are entangled with each other to form a polymer with a network structure. The higher the temperature, the easier the network structure is broken, so its viscosity decreases. .

2. The influence of hydrolysis time on the viscosity of polyacrylamide

The viscosity of the polyacrylamide solution changes with the extension of the hydrolysis time. The hydrolysis time is short and the viscosity is small. This may be due to the fact that the polymer has not had time to form a network structure; the hydrolysis time is too long and the viscosity decreases. This is polyacrylamide. The structure is loosened in the solution. Partially hydrolyzed polyacrylamide dissociates into negatively charged macromolecules after being dissolved in water. The electrostatic repulsion between molecules and the anionic repulsive force between different chains on the same molecule cause the molecules to stretch in the solution and make the molecules entangle with each other. This is the reason why partially hydrolyzed polyacrylamide can significantly increase the viscosity of its solution.

3. The influence of salinity on the viscosity of polyacrylamide

The number of cationic groups in the polyacrylamide molecular chain is larger than that of anionic groups, the net charge is higher, and the sex is greater. H20 is a sex molecule. According to the principle of similar compatibility, the polymer has better water solubility and higher intrinsic viscosity. ; With the increase of mineral content, the positive electrostatic charge part is surrounded by anions to form an ionic atmosphere, thereby combining with the surrounding positive electrostatic charge, the polymer solution property decreases, and the viscosity decreases; the mineral concentration continues to increase, positive and negative ions The group forms the association of intramolecular or intermolecular hydrogen bonds (resulting in the decrease of the solubility of the polymer in water), and the added salt ions can shield the positive and negative charges and break up the association between the positive and negative ions to make the formed The salt bond is destroyed (resulting in the solubility of the polymer in water), and these two effects compete with each other, so that the viscosity of the polymer solution remains small at a higher salt concentration (>0.06 mol/L).

4. The influence of molecular weight on the viscosity of polyacrylamide

The viscosity of the polyacrylamide solution varies with the molecular weight of the polymer. This is because the viscosity of the polymer solution is generated by the interaction between the molecules when the molecules move. When the relative molecular weight of the polymer is about 106, the polymer coils begin to penetrate each other, which is enough to affect the scattering of light. When the content is higher, mechanical entanglement is enough to affect the viscosity. When the content is relatively low, the polymer solution can be regarded as a network structure, and the mechanical entanglement and hydrogen bonds between the chains together form the nodes of the network. At higher levels, the solution contains many chain-link contacts, making the polymer solution gel-like. Therefore, the higher the relative molecular mass of the polymer, the easier it is to form chain entanglements between the molecules and the greater the viscosity of the solution.


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