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Polyacrylamide is a polymer with the formula (-CH2CHCONH2-).
Polyacrylamide has a linear-chain structure.
Polyacrylamide is highly water-absorbent, forming a soft gel when hydrated.
CAS: 9003-05-8
MF: (C3H5NO)x
MW: 71.08
EINECS: 231-545-4
Synonyms acrylamide,polymers;acrylamidehomopolymer;americancyanamidkpam;americancyanamidp-250;aminogenpa;ap273;CPAM;pam1800
In 2008, an estimated 750,000,000 kg were produced, mainly for water treatment and the paper and mineral industries.
Polyacrylamide, also briefly referred as PAM, is commonly a polymer with acrylamide monomers bonded connected by end to end configuration; it is a hard glassy solid at room temperature.
Because of the difference in production methods, the products can be white powder, translucent beads and flaky like.
Polyacrylamide's density is 1.302 g/cm3 (23 °C) with glass transition temperature being 153 °C and softening temperature being 210 °C.
Polyacrylamide has good thermal stability and is soluble in water; its aqueous solution is clear and transparent with its viscosity increasing with increased molecular weight of the polymer, and also having a logarithmic relationship with the change in concentration of the polymer.
Except for a few solvent such as acetic acid, acrylic acid, ethylene glycol, glycerol and formamide, Polyacrylamide is generally insoluble in organic solvents.
Polyacrylamide is formed by the polymerization of free acrylamide monomer radical.
Polyacrylamide can be produced by several methods such as solution polymerization, inverse emulsion polymerization, suspension polymerization and solid state polymerization.
Demanded product should have controllable molecular weight, good water solubility and with little residual monomers.
Polyacrylamide is one of the most widely used water-soluble polymer species with a large number of pendant amide groups presenting on its molecular backbone.
Amide group has a high chemical activity which can forms a series of derivatives with many kinds of compounds.
Polyacrylamide has effects of flocculation, thickening, drag reduction, adhesive, colloidal stabilizing, filming and preventing scale.
Polyacrylamide is widely used in papermaking, mining, coal washing, metallurgy, oil exploitation and other industrial sectors and is also a important chemical for water treatment.
Polyacrylamide is non-toxic and with a high molecular weight and is highly water soluble, and can introduce a variety of ionic groups for adjusting the molecular weight to obtain specific performance; Polyacrylamide has good adhesion to many solid surface and dissolved substances, and can adhere or bridge the suspended particles dispersed in the solution for flocculation of them which is easy for filtration and separation.
Anionic polyacrylamide can be used as a cytoplasm additive in the paper industry with better retention and drainage effect.
Polyacrylamide has a particularly dispersing effect for long-fiber pulp when its molecular weight is greater than 3.5 million.
In addition, Polyacrylamide can also be used as a water treatment agent.
In petroleum industry, it can be used as oilfield mud additives, thickeners, and settling agents.
In coal industry, Polyacrylamide is used as coal-washing additive.
Anionic polyacrylamide has generally two ways of preparation, one is copolymerization, which was prepared by the copolymerization of acrylamide and acrylic acid or sodium acrylate aqueous solution; the other is the chemical conversion method, that is, from partial alkaline hydrolysis of polypropylene amide, or prepared by alkaline hydrolysis of poly-acrylonitrile.
Here is copolymerization method whose procedure is simple and easy to control.
The specific method is by mixing the 20% acrylamide and sodium acrylate aqueous solution in certain ratio.
200 parts of this mixed monomer were added about 1 part of 1% EDTA solution, and then add Polyacrylamide into 460 parts of deionized water; then add 2-3 parts of both 5% ammonium persulfate and sodium hydrogen sulfite solution under continuous flow of nitrogen, stir for 3-4 hours at 40~50 °C.
Polyacrylamide is a polymer that is used in many industrial and research applications. Polyacrylamide can be used to separate biomolecules, such as proteins, based on their size.
Polyacrylamide also has been shown to have a high chemical stability and is used in clinical pathology for the detection of basic proteins.
Polyacrylamide has also been shown to be efficient in wastewater treatment and biological studies.
Polyacrylamide can be used to bind with basic proteins, which are important for sample preparation.
The polyacrylamide gel electrophoresis technique is also commonly used for the separation of DNA molecules.
Polyacrylamide has been shown to be effective against solid tumours in rats and liver microsomes from rat livers.
Polyacrylamides are usually immobilized on surfaces or membranes by covalent bonding or adsorption, depending on the application.
Polyacrylamide Chemical Properties
Melting point: >300 °C
Density: 1.189 g/mL at 25 °C
Tg: 165°C
Refractive index: n20/D 1.452
Fp: >230 °F
Storage temp.: 2-8°C
Solubility: Water
Form: Granules
Color: White to faintly yellow
Odor: odorless
Water Solubility: SOLUBLE
Stability: Stable. Incompatible with strong oxidizing agents, aluminium, copper, iron, iron salts
EPA Substance Registry System: Polyacrylamide (9003-05-8)
Polyacrylamide is a polyolefin.
Polyacrylamide can be viewed as polyethylene with amide substituents on alternating carbons.
Unlike various nylons, polyacrylamide is not a polyamide because the amide groups are not in the polymer backbone.
Owing to the presence of the amide (CONH2) groups, alternating carbon atoms in the backbone are stereogenic (colloquially: chiral).
For this reason, polyacrylamide exists in atactic, syndiotactic, and isotactic forms, although this aspect is rarely discussed.
The polymerization is initiated with radicals and is assumed to be stereorandom.
Polyacrylamide is relatively stable to heat with its solid only being softened at 220~230 °C and its solution subjecting to significant degradation only at above 110 °C.
Polyacrylamide is insoluble in benzene, toluene, xylene, gasoline, kerosene, diesel fuel, but soluble in water.
Polyacrylamide can react with alkaline with partial hydrolysis of polyacrylamide.
Polyacrylamide will have imidization reaction in strongly acidic (pH≤2.5) which will reduce its solubility in water.
Polyacrylamide can be cross-linked by the poly-nuclear olation complex ion formed between aldehyde (such as formaldehyde) and high metal (such as aluminum, chromium, zirconium, etc.) and is easy to be degraded by the action of the mechanical and (or) oxygen.
In oil exploitation, Polyacrylamide is mainly used as oil displacement agent, water blocking agent, profile control agent, thickener, drag-reducing agent, water treatment agent.
Physical properties
Solubility in water: upon rapid mechanical stirring, polyacrylamide is easily soluble in cold water form a transparent adhesive solution.
Increasing the temperature does not affect its solubility and only affects its dissolution when the concentration is increased to a high viscosity.
Solubility in Other Solvents: polyacrylamide has a over 1% solubility in solvents such as glycerol, ethylene glycol, formaldehyde, acetic acid and lactic acid (these materials may be used as the plasticizer for laminating polyacrylamide).
However, Polyacrylamide can only be swelled without being dissolved in solvents such as propionic acid, propylene glycol; Polyacrylamide is also not soluble in solvent such as acetone and hexane.
Stability: polyacrylamide has a moderate hygroscopic property, if not exposed to position of high temperatures, the powdered polyacrylamide can subject to long-term storage.
For liquid polyacrylamide, when its concentration is greater than 17%, Polyacrylamide can be stored for more than one year with no significant change in the solution viscosity.
In the pH range of 3 to 9, it can maintain a good degree of stability; at high pH, the viscosity will be increased gradually.
Miscibility: in generally used concentration, polyacrylamide has miscibility with most water-soluble natural or synthetic resins, latex systems, and most of the salts. Polyacrylamide can also quickly miscible with non-ionic, cationic and anionic surfactants, though with certain surfactants affecting the viscosity.
Viscosity: The viscosity of polyacrylamide solution has a linear correlation with its molecular weight; in addition, the higher the temperature, the lower the viscosity.
Intrinsic viscosity: the increase of the molecular weight of polyacrylamide will cause increased intrinsic viscosity.
Ion property: the carboxyl group in long-chain yields anionic polyacrylamide; the amino group yields cationic version.
Because of the existence of amino group or carboxyl group in the long-chain of polyacrylamide, it is easy for flocculation when encountering aluminum ions.
Retention property: The retention trend of polyacrylamide is similar with that of rosin soap with the former one having a high retention rate.
Toxicity: Polyacrylamide itself is non-toxic, but if it contains polymerized monomers (a double bond), it would be toxic to humans.
For this reason, upon the completion of its preparation, a certain amount of sodium bicarbonate should be added to remove residual monomers.
Copolymers and modified polymers
Linear polyacrylamide is a water-soluble polymer.
Other polar solvents include DMSO and various alcohols.
Cross-linking can be introduced using N,N-methylenebisacrylamide.
Some crosslinked materials are swellable but not soluble, i.e., they are hydrogels.
Partial hydrolysis occurs at elevated temperatures in aqueous media, converting some amide substituents to carboxylates.
This hydrolysis thus makes the polymer particularly hydrophilic.
The polymer produced from N,N-dimethylacrylamide resists hydrolysis.
Copolymers of acrylamide include those derived from acrylic acid.
Uses
1. Polyacrylamide is used as a flocculant in water treatment industry.
Also used in petroleum geology drilling configuration for removing non-dispersing low solid phase mud.
2. Polyacrylamide can be used as setting agent in sugar industry settling agent (sugar co-agent); film formers.
3. Polyacrylamide can be used as a soil conditioner, flocculants, and can be used in textile and paper sizing reinforcement.
4. Polyacrylamide can be used at coal field, oil field and flocculant agents.
5. Polyacrylamide can be used as efficient flocculants for neutral and alkaline medium, and can be used as drilling mud additives.
6. Polyacrylamide can also be used as oilfield mud additives, sewage treatment agent, and for textile sizing, paper reinforcement.
7. Polyacrylamide is an important water-soluble polymer, and also has various values effects such as flocculation, thickening, cleavage resistant, reducing resistance, and dispersing properties.
These properties are biased according to the difference of the derivative ions.
Therefore, Polyacrylamide has wide application in various fields such as oil exploration, mineral processing, coal washing, metallurgy, chemicals, paper, textile, sugar, medicine, environmental protection, building materials, and agricultural production.
8. Polyacrylamide can be used as the flocculant for water-based drilling fluid which can improve the rheological properties of the drilling fluid, reducing friction.
9. Polyacrylamide is widely used in petrochemical, metallurgy, coal, mineral processing and textile and other industrial sectors, and is also used as precipitation flocculant, oil field water thickeners, drilling mud treatment agent, textile pulp, paper reinforcing agent, fiber modifier, soil conditioners soil stabilizing agent, fiber paste, resin finishing agents, synthetic resin coatings, adhesives, and dispersing agents.
Binding agent, dispersing aid, lubricant, drag reduction and crystal formation control.
polyacrylamide is a binder, film former, and fixative with greater use in hair and nail than in skin care preparations.
Polyacrylamide is used in some hand and body lotions and cleansing creams.
Polyacrylamide is a polymer formed from acrylamide subunits.
Polyacrylamide has been extensively used in applications such as polyacrylamide gel electrophoresis.
In the 1970s and 1980s, the proportionately largest use of these polymers was in water treatment.
The next major application by weight is additives for pulp processing and papermaking. About 30% of polyacrylamide is used in the oil and mineral industries.
Flocculation
One of the largest uses for polyacrylamide is to flocculate solids in a liquid.
This process applies to water treatment, and processes like paper making and screen printing.
Polyacrylamide can be supplied in a powder or liquid form, with the liquid form being subcategorized as solution and emulsion polymer.
Even though these products are often called 'polyacrylamide', many are actually copolymers of acrylamide and one or more other species, such as an acrylic acid or a salt thereof.
These copolymers have modified wetting and swellability.
The ionic forms of polyacrylamide has found an important role in the potable water treatment industry.
Trivalent metal salts, like ferric chloride and aluminum chloride, are bridged by the long polymer chains of polyacrylamide.
This results in significant enhancement of the flocculation rate.
This allows water treatment plants to greatly improve the removal of total organic content (TOC) from raw water.
Production methods
1. Acrylonitrile is hydrated to obtain acrylamide with copper as the catalyst, and further polymerized into polyacrylamide in the action of K2S2O8.
Copper-aluminum alloy is converted into catalyst by alkali washing and pour into the hydration reactor.
The raw material of acrylonitrile is pumped to storage tanks and then into the measuring tank, pour the water subjecting to post-ion exchange process into the measuring tank and then pump raw materials through the pre-heater continuously into the hydration reactor in proportion; control at 85-125 °C for hydration reaction to obtain aqueous solution of acrylamide with the remaining acrylonitrile recovered through flash column and condenser and further flowed back into the water metering tank for recycling usage and the acrylamide solution flowing from flash tank into the tank; Pump it into high slot to the resin exchange column to become 7-8% monomer after entering into tank, send it to the polymerization reactor to produce gel-like polyacrylamide gel package which is the final product.
2. Colloidal polyacrylamide: add 1 200 kg of deionized water into the hydrolysis reactor, add under stirring of acrylonitrile, 0.3 kg of aluminum hydroxide, cupric hydroxide for complex catalysis, and have hydrolysis reaction at 85~125 °C.
After completion of the reaction, distill off the unreacted monomer acrylonitrile.
Prepare a 7% to 8% acryloyl aqueous solution, add polymerization vessel and have polymerization reaction upon the triggering of ammonium persulfate.
High molecular weight-polyacrylamide; hydrolyze acrylonitrile at 110~140 °C, 0.3 MPa into acrylamide.
Add PAGE into the polymerization vessel containing deionized water, and have reaction for 8 to 24 h in the triggering of 50 mg/kg of ammonium persulfate.
Then, it is hydrolyzed into the final product under alkaline conditions and at 70~80 °C.
3. Acrylonitrile is first catalyzed into acrylamide, and then further polymerized into polyacrylamide in the presence of K2S2O8.
4. Add measured acrylonitrile into the reaction vessel; further add a catalytic amount of copper-based catalyst.
Stir and warm up to 85~120 °C.
The reaction pressure was controlled at 0.29~0.39 MPa.
In continuous operation, the feed content was controlled at 6.5% with empty velocity of about 5h-1.
The obtained acrylamide was then transferred polymerization vessel; add a certain amount of deionized water.
Have the polymerization reaction in the triggering of potassium persulfate; add an appropriate amount of sodium bisulfite at 10 mins after the start of the reaction.
Gradually heat to 64 °C, cool the reaction mixture, and have reaction at about 55 °C for 6h.
Remove the unreacted monomer at vacuum (80 °C) under reduced pressure to obtain the finished product.
