Polyacrylamide (PAM) needs to be dissolved in water in a certain proportion when used, so the shelf life of polyacrylamide (PAM) aqueous solution is much lower than that of polyacrylamide (PAM). Shelf life of solids. If not used in time, the viscosity will decrease when used again. There are many customers who have failed to degrade due to improper use and excessive use of aqueous solutions. So what is the reason for the decrease in viscosity of polyacrylamide (PAM), and does the decrease in viscosity affect the use effect? The following Henan Laixing Water Purification will answer this question in detail.
1. Storage time
The longer the storage time of polyacrylamide (PAM) solution, the faster the degradation rate, the lower the viscosity, and the worse the flocculation effect. Generally speaking, anionic polyacrylamide (HPAM) solutions can be stored for about 5-7 days, and cationic polyacrylamide (CPAM) solutions can be stored for about 24 hours. If the temperature is too high or too low, the storage time will be shortened. The longer the storage time, the more severe the degradation of the polyacrylamide (PAM) solution and the lower the viscosity. The degradation of cationic polyacrylamide (CPAM) is more significant than that of anionic polyacrylamide (HPAM) due to the increase in the stiffness of the molecular chain and the elimination of the amide group to form an imide group due to the elimination of NH3 by the amide group.
2. Ambient temperature
Polyacrylamide (PAM) solutions are also affected by temperature, which is especially noticeable in summer. When the ambient temperature is higher than 25°C, the molecular weight of the prepared polyacrylamide (PAM) solution at a concentration of 1/1000 will degrade rapidly with the prolongation of preparation time, especially cationic polyacrylamide (CPAM). The higher the temperature, the faster the degradation rate, the lower the viscosity, and the final loss of the use effect.
3. Mixing speed
Stirring is required to prepare polyacrylamide (PAM) solution, and the stirring speed should be strictly controlled at about 60 revolutions per minute. The stirring speed is too slow, which is easy to cause polyacrylamide (PAM) to form a lump; If the stirring speed is too fast, it is easy to break the molecular chain of polyacrylamide (PAM) and affect the flocculation effect.
4. Water quality impact
When dissolving polyacrylamide (PAM), the water should be clean tap water. If treated circulating water or water containing impurities is used, it will have a negative impact on the viscosity of the polyacrylamide (PAM) solution, reducing the use effect to a certain extent and increasing the cost.
The viscosity of polyacrylamide (PAM) solution mainly reflects the internal frictional resistance between liquid molecules caused by flow or relative motion. Internal friction resistance, polymer structure, solvent properties, and solution concentration are related to temperature and pressure. The higher the value, the higher the viscosity of the solution. On the one hand, the viscosity of polyacrylamide (PAM) can be representative of its application effect. The higher the molecular weight, the greater the viscosity and vice versa.