The viscosity of polyacrylamide solution mainly reflects the internal friction resistance of liquid molecules due to the flow or relative motion.
The internal frictional resistance is related to the structure of the polymer, the properties of the solvent, the concentration of the solution and the temperature and pressure, and the larger the value, the greater the viscosity of the solution.
1. The effect of temperature on the viscosity of polyacrylamide: Temperature is a reflection of the intensity of the molecular irregular heat movement, the molecular movement must overcome the interaction between the molecules, and the interaction between the molecules, such as intermolecular hydrogen bonds, internal friction, diffusion, molecular chain orientation, entanglement, etc., directly affect the size of the viscosity, so the viscosity of the polymer solution will vary with temperature. The effect of temperature change on the viscosity of polymer solution is significant.
The viscosity of polyacrylamide solution decreases with the increase of temperature, the reason is that the dispersed phase particles of polymer solution are entangled with each other to form a net-structured polymer, the higher the temperature, the more easily the mesh structure is destroyed, so its viscosity decreases.
2. The effect of hydrolysis time on the viscosity of polyacrylamide: The viscosity of the polyacrylamide solution changes with the hydrolysis time, the hydrolysis time is short, the viscosity is small, this may be due to the high polymer is too late to form a network structure, hydrolysis time is too long, viscosity drop, this is the solution of polyacrylamide in the structure of the resulting pine.
Partially hydrolyzed polyacrylamide dissolved in water after dissolving into a negatively charged macromolecular, the intermolecular electrostatic repulsion and anion repulsion between different links in the same molecule cause the molecules to stretch in the solution and allow the molecules to cross each other, this is the reason that partially hydrolyzed polyacrylamide can make its solution viscosity increase significantly.
3, the effect of salinity on the viscosity of polyacrylamide: The cationic groups in the molecular chain of polyacrylamide are more than the number of anionic groups, the net charge is more, the polarity is larger, and the H20 is polar molecule, according to the principle of similar dissolution, the polymer has better water solubility and higher viscosity; with the increase of mineral content, positive electrostatic charge is surrounded by anions to form an ionic atmosphere. In combination with the surrounding positive electrostatic charge, the polymer solution polarity decreases, the viscosity decreases, the mineral concentration continues to increase, the positive and negative ion groups form molecules or intermolecular hydrogen bonds (resulting in the dissolution of the polymer in water), while adding salt ions by shielding positive, negative charge, splitting positive,
The interaction between anion and the formation of a salt bond has been destroyed (resulting in increased solubility of the polymer in water), which competes with each other so that the viscosity of the polymer solution at a higher salt concentration (>0.06 mol/l) remains small.
4. The influence of molecular weight on the viscosity of polyacrylamide: The viscosity of the polyacrylamide solution increases with the increase of the molecular weight of the polymer, because the viscosity of the polymer solution is produced by the interaction of molecules during molecular movement. When the molecular mass of the polymer is about 106, the polymer coils begin to penetrate each other, enough to influence the scattering of light. The mechanical tangle is sufficient to affect the viscosity when the content is slightly higher. When the content is quite low, the polymer solution can be regarded as a net structure, and the chain between the mechanical tangles and hydrogen bonds forms a joint of the network. When the content is high, the solution contains many chain-chain contact points, so that the polymer solution is gel-like.
Therefore, the larger the molecular weight of polymers, the more easily the formation of chain tangles, the greater the viscosity of the solution.