Polymers acrylamide

In diis article the term acrylamide polymer refers to all polymers which contain aciylamide as a major constituent. Consequently, aciylamide polymers include functionalized polymers prepared from polyacrylamide by postreaction and copolymers prepared by polymerizing aciylamide (2-propenamide, C3H5NO) witii one or more comonomers. 

Manufacturing processes have been improved by use of on-line computer control and statistical process control leading to more uniform final products. Production methods now include inverse (water-in-oil) suspension polymerization, inverse emulsion polymerization, and continuous aqueous solution polymerization on moving belts. Conventional azo, peroxy, redox, and gamma-ray initiators are used in batch and continuous processes. Recent patents describe processes for preparing transparent and stable microlatexes by inverse microemulsion polymerization. New methods have also been described for reducing residual aciylamide monomer in finished products. 

Solid Polymer. Completely dry polyacrylamide is a brittle white solid. Commercially available dry polyacrylamide powders are typically dried under mild conditions and usually contain 5 —15% water. The powders are hygroscopic, and generally become increasingly hygroscopic as the ionic character of the polymer increases. Cationic polymers are particularly hygroscopic. 

Polymers in Solution. Polyacrylamide is soluble in water at all concentrations, temperatures, and pH values. An extrapolated dieta temperature in water is approximately —40°C (17). Insoluble gel fractions are sometimes obtained owing to cross-link formation between chains or to die formation of imide groups along die polymer chains (18). In very dilute solution, polyacrylamide exists as unassociated coils which can have an ellipsoidal or beanlike structure (19). Large aggregates of polymer chains have been observed in hydrolyzed polyacrylamides (20) and in copolymers containing a small amount of hydrophobic groups (21). 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

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POWDERS,HANDLING - DISPERSION OF POWDERS IN LIQUIDS] (Vol 19) -polyacrylamides in [ACRYLAMIDE POLYMERS] (Voll)... 

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