Reduced viscosity acrylamide copolymers

Figure 7. Effect of copolymer concentration on the reduced viscosity of copolymers of acrylamide with 0.50 mol % decylacrylamide of varying molecular weights in 0.342 M NaCl at 25 °C and a shear rate of 1.28 s. ...

Flynn and Goodwin prepared copolymers of acrylamide and dodecyl methacrylate using micellar copolymerization [96]. The hydrophobe content was varied from zero (polyacrylamide) to 0.7 mol%. Polymer solutions contained O.IM NaCl, and sodium azide was added as a biocide. Figure 38 depicts the variation of the reduced viscosity with polymer concentration at various hydrophobe contents. At 0 mol% hydrophobe, the reduced viscosity increased linearly with polymer concentration indicating no hydrophobic association. At 0.2 mol% hydrophobe, the reduced viscosity increased linearly with polymer concentration, but at a polymer concentration of 600 ppm there was an upward variation in the reduced viscosity. Similar results were obtained at hydrophobe contents of 0.4 and 0.7 mol%. However, the polymer concentration at which the upward variation occurred decreased with increasing hydrophobe content. 

Figure 38. Reduced viscosity by capillary viscometer, acrylamide/dodecyl methacrylate copolymers. Hydrophobe (mole%) 0.67 (A), 0.36 (O), 0.22 ( ), and 0.0 (A) [96].

Fig. 4,2, Reduced viscosity q ed a function of the concentration c for different molar masses of the polycation poly(acrylamide-co-(A/,A/,A/-trimethyl-A/-[2-methacryloethyl]-ammoniumchloride) (PTMAC) in 0.1 mol/l NaN03 solution. Data from [87]. All data points are measured at concentrations below the critical concentration c [ j.The copolymer consists of 8 mol%TMAC and 92 mol% AAm...

Aqueous Solution Properties. Acrylamide copolymers containing even small quantities of surfomer units (i.e. < 0.5 mol %) also exhibit interesting solution properties. For example, below C the surfomer copolymers show lower intrinsic viscosities rj and elevated Huggins constants, (Table 3.1). As with the RAM polymers, below C the chains interact intramolecularly to collapse the coil, lowering [rj ] and raising the slope of the reduced viscosity concentration plot, i.e. /ch [1 ] ... 

One major disadvantage of HPAM is its high sensitivity to salts [41]. This is not so for hydrophobically associating polyacrylamide. Figure 45 shows the effect of salts on the apparent viscosity at 1.3 s for HPAM and hydrolyzed copolymer of N-octylacrylamide/acrylamide. All polymers have the same degree of hydrolysis at 18%. The two associating polymers contained hydrophobe contents of 1 and 1.25 mol%. The addition of hydrophobe reduced the sensitivity to salts, especially at the higher hydrophobe content examined. 

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