| Surface rheology, using oscillating pendant drop technique, has been used to probe qualitatively and quantitatively the mechanical strength of interfacial films formed when a droplet of model oil (de-asphalted bitumen also known as DAB, asphaltene, and bitumen all diluted with toluene) is in the vicinity of pre-contacted water.;There is no detectable phase shift between sinusoidal area input and interfacial tension (IFT) response for de-asphalted bitumen. There is, however, obvious phase shift between sinusoidal area input and interfacial tension (IFT) response for asphaltenes and diluted bitumen within the linear viscoelastic regime.;For three concentrations and four frequencies of the sinusoidal excitations on the interfacial area studied for each sample, it is concluded that: the complex dilatational modulus increases with ageing of interfacial film but decreases with increasing bulk concentration. |
