Polyacrylamide (PAM) is a linear polymer with the chemical formula (C3H5NO)n. It is a hard glassy solid at room temperature. The products include glue, latex and white powder, translucent beads and flakes. 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, 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 is used as a lubricant, suspending agent, clay stabilizer, oil-displacing agent, fluid loss agent and thickener, and has been used in drilling, acidification, fracturing, water plugging, cementing, secondary oil recovery, and tertiary oil recovery. Widely used, it is a very important oil field chemical.
Polyacrylamide (PAM) is a general term for acrylamide homopolymer or polymers obtained by copolymerization with other monomers. It is one of the most widely used varieties of water-soluble polymers. Because the polyacrylamide structural unit contains amide groups, it is easy to form hydrogen bonds, so that it has good water solubility and high chemical activity, and it is easy to obtain multiple modified products with branched or network structure through grafting or crosslinking. , Has a wide range of applications in petroleum exploration, water treatment, textile, papermaking, mineral processing, medicine, agriculture and other industries, and is known as "Auxiliary for All Industries". The main application areas abroad are water treatment, papermaking, mining, metallurgy, etc.; China currently uses the largest amount of oil in the field of oil production, and the fastest growing use is in the field of water treatment and papermaking.
Physical and chemical properties
Polyacrylamide is a water-soluble linear polymer polymerized by acrylamide (AM) monomer initiated by free radicals. It has good flocculation and can reduce the frictional resistance between liquids. It can be divided into ionic characteristics. There are four types of non-ionic, anionic, cationic and amphoteric type. Polyacrylamide (PAM) is insoluble in most organic solvents, such as methanol, ethanol, acetone, ether, aliphatic hydrocarbons and aromatic hydrocarbons, except for a few polar organic solvents, such as acetic acid, acrylic acid, chloroacetic acid, ethylene glycol, glycerin, Melt urea and formamide. However, these organic solvents have limited solubility and often require heating, otherwise they have little application value. It can be dissolved in water in any proportion, and the aqueous solution is a uniform and transparent liquid. The size of the molecular weight has little effect on the solubility, but when the solution concentration is higher than 10%, the high molecular weight polymer can exhibit a gel-like structure due to the bonding of hydrogen atoms between the molecules. High molecular weight solutions are pseudoplastic fluids.
At a suitable low concentration, the polyacrylamide solution can be regarded as a network structure, and the mechanical entanglement and hydrogen bonding between the chains form a network node; when the concentration is higher, the solution contains many chain-link contacts, which makes PAM The solution is gelatinous. PAM aqueous solution has good compatibility with many water-soluble organic substances, and has good compatibility with electrolytes, and it has good compatibility with ammonium chloride, calcium sulfate, copper sulfate, potassium hydroxide, sodium carbonate, sodium borate, and nitric acid. Sodium, sodium phosphate, sodium sulfate, zinc chloride, boric acid and phosphoric acid are not sensitive.
Polyacrylamide is a white powder or small granular substance, with a density of 1.302g/cm3 (23°C), a glass transition temperature of 153°C, and a softening temperature of 210°C. The general method of drying contains a small amount of water, and it will dry quickly. Absorb moisture from the environment, the homopolymer separated by freeze-drying method is a white soft amorphous solid, but when it is precipitated from the solution and dried, it becomes a glassy and partially transparent solid. The completely dried polyacrylamide PAM is brittle It is a white solid, commercial polyacrylamide is usually dried under moderate conditions, generally with a water content of 5% to 15%. The polymer film prepared by casting on a glass plate is a transparent, hard, and fragile solid.
Under anoxic conditions, heat to 210℃ and lose weight due to water loss; continue heating to 210~300℃, the amide group will decompose to form ammonia and water; when the temperature rises to 500℃, only 40% of the original weight will be formed black flakes .