Polyacrylamide production

Polyacrylamide and a number of its co-polymers have been used in many parts of the oil industry in addition to polymer flooding processes, e.g. as scale inhibitors and in drilling fluids. However, the technical specifications of these products are rather different from those of improved oil recovery 

There are three main chemical approaches which may, in theory, be used to synthesise HPAMs. Firstly, there is the direct free-radical polymerisation to produce polyacrylamide (PAM)  

A second approach is to co-polymerise chosen proportions of acrylamide and acrylic acid directly  

The third chemical route to HPAM would be to polymerise acrylic acid to give polyacrylic acid (PAA)  

In addition to the chemical procedure used to produce HPAMs, there are different possible media or phases in which the polymerisation process can be carried out. All of the above three chemical reactions can be carried out as  

---

The powder form of resin is considerably easier to handle, when compared to the more commonly known polyacrylamide products used for retention or effluent treatment. The much lower molecular weights of these materials allow dissolution to be made at much higher active solid levels, including over 10% active. Both manual and automatic make-down systems are available to achieve a homogeneous solution of the resin. The important point is to ensure that each powder particle is fully wetted out, and can dissolve in the bulk of the water. A collection of particles, which together are wetted around the outside, will take much longer to dissolve, and can result in gels. The presence of these on a paper machine may lead to breaks or spots in the paper. 

The yields of this reaction are typically 40—80%. C-nmr studies (41) indicate that the reaction is a second-order process between polyacrylamide and dim ethyl am in om eth an ol, which is one of the equiUbrium products formed in the reaction between formaldehyde and dimethylamine [124-40-3] C2H2N. The Mannich reaction is reversible. Extensive dialysis of Mannich polyacrylamides removes all of the dimethyl aminomethyl substituents (42). 

Solution Polymerization. Plant scale polymerizations ia water are conducted either adiabaticaHy or isotherm ally. Molecular weight control, exotherm control, and reduction of residual monomer are factors which limit the types of initiators employed. Commercially available high molecular weight solution polyacrylamides are usually manufactured and sold at about 5% soHds so that the viscosities permit the final product to be pumped easily. 

Before polyacrylamides are sold, the amount of residual acrylamide is determined. In one method, the monomer is extracted from the polymer and the acrylamide content is determined by hplc (153). A second method is based on analysis by cationic exchange chromatography (154). For dry products the particle si2e distribution can be quickly determined by use of a shaker and a series of test sieves. Batches with small particles can present a dust ha2ard. The percentage of insoluble material is determined in both dry and emulsion products. 

Polyacrylamide powders are typically shipped in moisture-resistant bags or fiber packs. Emulsion and solution polymers are sold in dmms, tote bins, tank tmcks, and tank cars. The transportation of dry and solution products is not regulated in the United States by the Department of Transportation, but emulsions require a DOT NA 1693 label. 

Acidic suspensions such as those produced by acid leaching often respond to natural products such as guar as well as nonionic polyacrylamides and anionic polyacrylamides containing sulfonic acid groups. 

Both in situ cross-linking of partially hydroly2ed polyacrylamides (69) and injection of quaternary ammonium salt polymers having long hydrophilic side chains (70) have been used to reduce the permeabiUty of water-producing 2ones adjacent to production wells. This permeabiUty reduction decreases the produced water oil ratio as does injection of polyacrylamide in high hardness brine to reduce permeabiUty (71). 

Alcosorb 400 Water-Retaining Polymer," undated product Hterature, AHied CoUoids describes agricultural uses of cross-linked polyacrylamide gels. 

S. N. Floerger, "Polymer Soil Conditioners," undated product Hterature, Saint Etienne, Erance describes functions and uses of cross-linked anionic polyacrylamides in agriculture. 

The enzyme can be immobilized on the electrode by several techniques (53). The simplest method, first used in 1962, is to trap an enzyme solution between the electrode surface and a semipermeable membrane. Another technique is to immobilize the enzyme in a polymer gel such as polyacrylamide which is coated on the electrode surface. Very thin-membrane films can be obtained by electropolymerization techniques (49,54,55) using polypyrrole, polyindole, or polyphenylenediamine films, among others. These thin films (qv) offer the advantage of improved diffusion of substrate and product that... 

Postpolymerization Reactions. Copolymers can also be formed by postpolymetization reactions on polymers. A well-known example is the partial hydrolysis of polyacrjiamide (PAM) to hydrolyzed polyacrylamide (HPAM). The product becomes a random copolymer of acrylamide and acryUc acid (44) (see Acrylamide polya rs). 

Additions of new flocculants after conventional thickening produce further dewatering of mineral slimes. A clay flocculated with polyacrylamides and rotated in a dmm can produce a growth of compact kaolin pellets (84), which can easily be wet-screened and dewatered. A device called a Dehydmm, which flocculates and pelletizes thickened sludges into round, 3-mm pellets, was developed for this purpose. Several units reported in commercial operation in Japan thicken fine refuse from coal-preparation plants. The product contains 50% moisture, compared with 3% soflds fed into the Dehydmm from the thickener underflow (85). In Poland, commercial use of the process to treat coal fines has been reported (86), and is said to compare favorably both economically and technically to thickening and vacuum filtration. 

Synthetic organic polymers, which are used as polymeric supports for chromatography, as catalysts, as solid-phase supports for peptide and oligonucleotide synthesis, and for diagnosis, are based mainly on polystyrene, polystyrene-divinylbenzene, polyacrylamide, polymethacrylates, and polyvinyl alcohols. A conventional suspension of polymerization is usually used to produce these organic polymeric supports, especially in large-scale industrial production. 

The Mannich reaction of polyacrylamide with formaldehyde and an amine may be used for the obtaining product that contains N-methylol groups (or ethers or ethers thereoO-... 

Polyacrylamide (pAM) and copolymers of acrylamide are used on a large scale in waste water treatment and other industrial applications. All of these reasons show that the production and use of polyacrylamide (pAM) and copolymers of acrylamide are a material objective. 

---