Effect of gum arabic on the surface tension and surface dilational rheology of trisiloxane surfactant

The surface tension and surface dilational properties of trisiloxane surfactant silwet408, gum arabic, and their mixed solutions are reported. The dilational rheological properties are measured by means of oscillating drop method. The influences of dilational frequency, bulk concentration and aging time on dilational rheology properties have been investigated. The adsorption films of silwet408 behave elastic in nature at low bulk concentration. With increasing concentration, the dilational modulus becomes more frequency dependent and reaches a maximum value. The addition of 1 wt% gum arabic has no remarkable influence on the silwet408 films since the adsorption ability of silwet408 is much better than that of gum arabic. However, the maximum of dilational modulus and dilational elasticity are shifted toward a higher concentration, which has been correlated with the decreased molecular exchange in the presence of 1 wt% gum arabic. (C) 2012 Elsevier Ltd. All rights reserved.