EFFECT OF POLYMERIZATION METHOD ON STRUCTURE AND PROPERTIES OF A CATIONIC POLYACRYLAMIDE
聚合方法对一种正离子聚丙烯酰胺结构与性能的影响

A cationic polyacrylamide was synthesized by polymerization of acrylamide and 2-(methacryloyloxy)-ethyltrimethylammonium chloride (AM/MADQUAT)in solution or by inverse microemulsion polymerization using (NH_4)_2S_2O_8/NaHSO_3 as redox initiator.The sequence distribution and composition distribution were calculated from monomer reactivity ratios of different polymerization methods.The results show that charge distribution is more uniform for the copolymer prepared in inverse microemulsion,and copolymer composition distribution is close to unity and maintains approximately at feed ratio.Furthermore,influence of the structure of cationic polyacrylamides on kaolinite flocs size,reduction of zeta potential and flocs compressive yield stress has been investigated at pH 7.The results show that the kaolinite flocs size is strongly dependent upon copolymer microstructure; with greater flocs size being observed for copolymer prepared in inverse microemulsion than for that in solution.Copolymer microstructure has a marked effect on the zeta potential,whose decrease in magnitude was much greater in the presence of copolymer prepared in inverse microemulsion than that in solution.Greater compressive yield stress was achieved for the strong flocs produced by copolymer prepared in inverse microemulsion.The difference in flocs compressive yield stress may be attributed to the flocs structure.Therefore,in this paper,a strong correlation between the cationic polyacrylamide structure and flocculation property for kaolinite suspension was established.