Polyacrylamide (PAM) is a linear polymer

Polyacrylamide(PAM) is a linear polymer with the chemical formula (C3H5NO) n. At room temperature, it is a hard glassy solid, with products such as glue, latex, white powder particles, semi transparent beads, and thin films. Good thermal stability. It can dissolve in water in any proportion, and the aqueous solution is a uniform and transparent liquid. After long-term storage, the viscosity of the solution will decrease due to the slow degradation of the polymer, especially when the storage and transportation conditions are poor. Polyacrylamide, as a lubricant, suspension agent, clay stabilizer, oil displacement agent, loss control agent, and thickener, has been widely used in drilling, acidification, fracturing, water plugging, cementing, secondary oil recovery, and tertiary oil recovery. It is an extremely important oilfield chemical.

The viscosity of Polyacrylamide solution mainly reflects the internal frictional resistance between liquid molecules due to flow or relative motion. The internal friction resistance is related to factors such as the structure of the polymer, the properties of the solvent, the concentration of the solution, temperature, and pressure. The larger the value, the higher the viscosity of the solution.

1. The effect of temperature on the viscosity of Polyacrylamide

The viscosity of Polyacrylamide solution decreases with the increase of temperature, due to the entanglement of dispersed phase particles in the polymer solution to form a polymer network structure. The higher the temperature, the easier it is to break the network structure, resulting in a decrease in viscosity.

2. The effect of hydrolysis time on the viscosity of Polyacrylamide

The viscosity of Polyacrylamide solution changes with the prolongation of hydrolysis time, with shorter hydrolysis time and lower viscosity

3. The effect of mineralization on the viscosity of Polyacrylamide

As the mineral content increases, the formation of an ionization atmosphere reduces the polarity and viscosity of the polymer solution; At high concentrations, hydrogen bonding between ion groups competes with salt ion shielding, leading to changes in solubility and jointly affecting viscosity. At high salt concentrations, these effects maintain a lower viscosity of the polymer solution.

4. The effect of molecular weight on the viscosity of Polyacrylamide

The viscosity of Polyacrylamide solution increases with the increase of polymer molecular weight, as the viscosity of polymer solution is generated by the intermolecular interactions during molecular motion.

Fields of application：

Water treatment field：Water treatment includes raw water treatment, sewage treatment and industrial water treatment. It can be used in combination with activated carbon in raw water treatment for the cohesion and clarification of suspended particles in domestic water. Using the organic flocculant acrylamide instead of the inorganic flocculant can increase the water purification capacity by more than 20% even if the sedimentation tank is not modified. In sewage treatment, Polyacrylamide can increase the utilization rate of water reuse cycle, and can also be used as sludge dewatering. It is used as an important formulation agent in industrial water treatment. The largest application of Polyacrylamide in foreign countries is water treatment, and the application in this field is being promoted in China. The main role of Polyacrylamide in water treatment.

(1) Reduce the amount of flocculant. Under the premise of achieving the same water quality, Polyacrylamide can be used as a coagulant in combination with other flocculants, which can greatly reduce the amount of flocculant. (2) Improve water quality. In drinking water treatment and industrial wastewater treatment, Polyacrylamide can be used in combination with inorganic flocculants to significantly improve water quality. (3) Improve floc strength and sedimentation velocity. The floc formed by polyacrylamide has high strength and good sedimentation performance, which improves the solid-liquid separation speed and is conducive to sludge dewatering. (4) Anti-corrosion and anti-fouling of circulating cooling system. The use of Polyacrylamide can greatly reduce the amount of inorganic flocculant, so as to avoid the deposition of inorganic substances on the surface of the equipment, and slow down the corrosion and scaling of the equipment

Applications in oil recovery：Polyacrylamide is a multifunctional oilfield chemical treatment agent, which is widely used in drilling, cementing, completion, workover, fracturing, acidizing, water injection, water shut-off profile control, and tertiary oil recovery operations of oil exploitation, especially in the fields of drilling, water shut-off profile control and tertiary oil recovery. Polyacrylamide aqueous solution has high viscosity, good thickening, flocculation and rheological regulation, and is used as an oil displacement agent and drilling mud regulator in oil exploitation. In the middle and late stages of oil exploitation, in order to improve the oil recovery, polymer flooding and ternary composite flooding technology are mainly promoted in China. By injecting Polyacrylamide aqueous solution, the oil-water flow rate ratio was improved, and the crude oil content in the produced product was increased. The addition of Polyacrylamide to tertiary oil recovery can increase the displacement capacity, avoid the breakdown of the oil layer, and improve the recovery yield of the oil bed. China's petroleum industry is the largest user of Polyacrylamide, the scientific and technological progress of Polyacrylamide has promoted the development of China's petroleum industry, and the demand of the petroleum industry has accelerated the pace of scientific and technological innovation of polyacrylamide and the development of the industry.

Papermaking field：Polyacrylamide is widely used as a retention aid, filter aid, and leveling agent in the papermaking field to improve the quality of paper, pulp dehydration performance, retention rate of fine fibers and fillers, reduce raw material consumption and environmental pollution, and be used as a dispersant to improve the uniformity of paper. Polyacrylamide is mainly used in two aspects in the paper industry, one is to improve the retention rate of fillers, pigments, etc. to reduce the loss of raw materials and environmental pollution, and the other is to improve the strength of paper. The addition of Polyacrylamide to the paper stock can improve the retention rate of fine fibers and filler particles on the net, and accelerate the dehydration of the paper stock. The mechanism of action of polyacrylamide is that the particles in the slurry are electroneutralized or bridged, and the flocculation can be retained on the filter cloth. The formation of flocs can also make the water in the slurry easier to filter, reduce the loss of fibers in white water, reduce environmental pollution, and help improve the efficiency of filtration and sedimentation equipment.

Use features：

1. Flocculancy: PAM can make suspended substances play a flocculation role through electric neutralization and bridging adsorption.

2. Adhesion: It can play a role in adhesion through mechanical, physical and chemical actions.

3. Resistance reduction: PAM can effectively reduce the frictional resistance of the fluid, and adding a trace amount of PAM to the water can reduce the resistance by 50-80%.

4. Thickening: PAM has a thickening effect under neutral and acid conditions, and PAM is easy to hydrolyze when the pH value is above 10. The thickening will be more pronounced in a semi-reticular structure.

The use of Polyacrylamide should follow the following principles:

1. Granular Polyacrylamide flocculant cannot be directly added to sewage. It must be dissolved in water before use, and its aqueous solution must be used to treat sewage.

2. The water in which the granular polymer is dissolved should be clean (such as tap water), not sewage. Water at room temperature is sufficient, and generally does not need to be heated. The water dissolves slowly when the water temperature is below 5°C. The dissolution speed is accelerated when the water temperature increases, but the polymer degradation will be accelerated above 40 °C, which will affect the use effect. In general, tap water is suitable for the preparation of polymer solutions. Water with strong acid, alkali and high salt content is not suitable for preparation.

3. The selection of polymer solution concentration is recommended to be 0.1%-0.3%, that is, 1g-3g of polymer powder is added to 1 liter of water.