Synthesis of copolymer of acrylamide with sodium vinylsulfonate and its thermal stability in solution

The copolymer of acrylamide and sodium vinylsulfonate (PAMSVS) was synthesized by inverse emulsion polymerization and its thermal stability in aqueous and saline solution was investigated. Four samples with different monomer ratio were prepared and the thermal degradation of these samples in aqueous solutions was carried out at 90 °C, 120 °C and 150 °C, respectively. The variation of apparent viscosity during the degradation was investigated. The results indicate that all three PAMSVS samples have better performance of heat endurance than polyacrylamide. Moreover, the sample, which contains 3.4% (molar ratio) sulfonic groups, has the most excellent property of heat endurance. The salt tolerance test of these samples was carried out at 57 °C in 5 mmol/L CaCl₂, 5 mmol/L MgCl₂ and mineralized water, respectively. The results show that all three PAMSVS samples exhibit better property of Ca²⁺ ion tolerance than PAM and the best one is the sample, which contains 6.5% (molar ratio) sulfonic groups.