Interfacial Dilational Properties of Two Different Structure Demulsifiers at Oil-Water Interfaces

The dilational properties of demulsifiers PE1 and PE2 at the decane-water interface were investigated. Meanwhile, the influence of demulsifiers on interfacial dilational modulus of 5% crude oil also was explored. The experimental results indicate that the diffusion process is still not the main factors to control the properties of interfacial film even at large concentration. The dilational modulus of demulsifier PE2 passes through a maximum with the increasing concentration, and that of demulsifier PE1 changes a little with the increasing concentration at the decane-water interface. The dilational moduli of crude oil inerfaces decrease with the addition of both demulsifiers. At low concentration, the effect on reducing the dilational modulus of crude oil is stronger for PE1, which maybe caused by its higher substitution ability. For PE2, the ability to decrease interfacial dilational modulus gets stronger with increasing bulk concentration, which might be explained by that the adsorption increases with increasing concentration. The results of relaxation experiments support those obtain by oscillating barriers method.