How to distinguish the authenticity of polyacrylamide?

Polyacrylamide is a linear polymer with the chemical formula (C3H5NO) n. At room temperature, it is a hard glassy solid, and its products include glue, latex, white powder, semi transparent beads, and thin films. Good thermal stability. It can be dissolved in water in any proportion, and the aqueous solution is a uniform and transparent liquid. After long-term storage, due to slow polymer degradation, the viscosity of the solution will decrease, especially under poor storage and transportation conditions. So, how do we distinguish authenticity when purchasing polyacrylamide?

1. Premix: This is the method used by the manufacturer. For this adulteration method, it is difficult to distinguish specific indicators of polyacrylamide without detection, and it is also difficult to distinguish from traditional indicator detection. It requires rich experience and ordinary users cannot distinguish. The standard for detecting the molecular weight of polyacrylamide is the viscosity method, which means that by measuring the intrinsic viscosity and substituting it into the calculation formula, the average molecular weight of viscosity can be obtained. In fact, in the production process of polyacrylamide, there is almost no difference in tolerance for small sizes and production costs (unit weight of polymer products, without considering molecular weight and monomer consumption) regardless of molecular weight. In other words, regardless of molecular weight, the cost difference is very small, but the market is molecular based. Therefore, by adding a large amount of fillers, the original high molecular weight products can be sold as low molecular weight products. This greatly reduces costs and the actual weight of high molecular weight products is insufficient.

2. Post mixing method: It is a method adopted by many distributors, which involves mixing a large amount of inorganic salts (usually industrial salts) with purchased polyacrylamide products in a certain proportion (consistent with the principle of indicators), using different equipment (or manuals), with different quantities and product specifications, and preparing according to the corresponding proportion according to unused needs. This method is easy to identify and can be tested as follows.

Take a glass of water and sprinkle it evenly on the liquid surface. Due to differences in specific gravity and water absorption, the settling speed of salt is faster, while the relative wetting time of flocculants is longer.