Thickening of butyl acrylate/styrene/2-hydroxyethyl methacrylate/acrylic acid lattices with dispersion of crosslinked ethyl acrylate/methacrylic acidcopolymer

Thickening of lattices of styrene-acrylic copolymers containing a small amo unt of acrylic acid and various amounts of 2-hydroxyethyl methacrylate (HEM A) with alkali-swellable dispersion of crosslinked ethyl acrylate/methacryl ic acid copolymer has been studied using capillary viscometry and dynamic a nd steady shear measurements. The higher the amount of HEMA incorporated in to the latex copolymers, the stronger the thickening effect is. A compariso n of flow behavior of thickened systems with those of neat lattices confirm ed a significant influence of the effective volume fraction of alkalinized swollen latex particles on the thickening process. Under these conditions, to obtain the same rheological properties, the necessary amount of thickene r was lower for the latex copolymers with higher amounts of HEMA because a part of the thickener volume fraction was replaced by an increased volume f raction of swollen latex particles. These findings indicate weakly interact ing dispersion systems without strong compression of particle domains. (C) 2001 Elsevier Science B.V. All rights reserved.