Investigating the Uni-HEUR thickener performance considering hydrophilic segment length

Hydrophobically modified ethoxylated urethane models were synthesized through hydrophobic modification of poly(ethylene glycol) (PEG) by octadecyl isocyanate. Their structure consisted of linear water-soluble PEG backbones of number average molecular weight 6000 and 10,000 which end capped by aliphatic C(18) chains attributed to octadecyl isocyanate. The behavior of thickener models was studied in both DDI (double distilled water) and a water-based resin of vinyl acrylic copolymer emulsion. The steady and oscillatory shear viscosity of both aqueous and resin systems containing the thickener models were determined. The result for constant hydrophobic length (C(18)) showed that the associative thickener with higher molecular weight of PEG or longer hydrophilic length presents superior theological properties. The concentration of thickeners can influence the phase behavior of the systems in such a way that for smaller length of the thickener the interconnection among micelles and the emulsion particles exist at equilibrium (concentrations of 2-3 wt%). However, for the higher-length associative polymer, it disappears upon a concentration rise to 4 wt%. (C) 2010 Elsevier B.V. All rights reserved.