We describe an adaptation of the thin liquid film-pressure balance techniqu
e (TLF-PBT) for a systematic study of water/diluted-bitumen/water thin film
s. Recent research into the stability of water-in-oil emulsions, particular
ly those occurring in the oil industry, has not properly addressed the depe
ndence of the emulsion stability on the thin films that are formed between
approaching water droplets. The objective of this study is to obtain some i
nsight into the mechanisms that stabilize the emulsion with particular atte
ntion to the relative importance of the resin, asphaltene, and solids fract
ions of the bitumen. Measurements of film lifetime and equivalent thickness
indicated that the behavior of the film strongly depended on the type and
concentration of solvent used to dilute the bitumen. Toluene-diluted-bitume
n films drained continuously until a stable, uniform grey film was formed.
Heptane-diluted-bitumen films formed black films covered with a scatter of
small white dimples containing trapped liquid except at heptane:bitumen wei
ght ratios of 10:1-15:1, where a network of fine white spots of unknown ori
gin was formed. While the asphaltene and resin fractions alone provide a pa
rtially stable film, the combination of resin and asphaltene produced extre
mely stable films, a result that agrees well with emulsion studies by other
researchers. (C) 2000 Elsevier Science B.V. All rights reserved.