Flocculation performance of three kinds of polyacrylamide (PAAm), linear-PAAm, Al(OH)(3)-PAAm hybrid, and star-PAAm, in kaolin suspensions have been investigated by Spectrophotometer. It was found that the flocculation performance of the polymer flocculant is enhanced at the beginning and then impaired with increasing parent solution concentration (C-p) and an optimal parent solution concentration (C-op) exists, which is directly proportional to both critical concentrations of C* and C-s of the polymer in the dilute aqueous solution, and can be roughly expressed by an empirical formula, C-op = 3.1 x 10(-3) + 643.1C(s). The findings suggests that flocculation performance of a given polymer is dependent on both of the interchain association and the chain contact of the polymer chains in the parent solution and in the kaolin suspension, respectively. (c) 2006 Wiley Periodicals, Inc.