Storage Stability of Bimodal Emulsions vs. Monomodal Emulsions

Abstract

Storage stability is a very important parameter that has to be considered in the formulation of asphalt emulsions. When monomodal emulsions are formulated, Stokes' law is fulfilled, therefore the higher the viscosity the less sedimentation, or the lower average droplet size the less sedimentation. But when bimodal emulsions are formulated, this rule does not apply. In this paper, two types of different emulsions are formulated: monomodal emulsions and bimodal emulsions. Bimodal emulsions are a combination of one large bitumen size and a small one. For this study, hard penetration bitumens were used, B35/50 and B15/25, because they are the most difficult bitumen to emulsify and, consequently, the worst sedimentation values are expected. Once the emulsions are manufactured, they are diluted to a bitumen rate concentration of 60% and 70%. Results show that bimodal emulsions, although having lower viscosity than their monomodal counterparts, have higher storage stability.

Characterization of Flaxseed Oil Bimodal Emulsions Prepared with Flaxseed Oil Cake Extract Applied as a Natural Emulsifying Agent

“…In this study, the bimodal character of emulsions is an effect of two different main components of FOCE (protein and polysaccharides fractions). According to Querol et al the bimodal emulsions have much higher stability than monomodal ones [ 25 ]. The authors suggested that an optimal formulation to obtain a stable emulsion should contain a first small-sized fraction of about 1 µm and the second fraction of about 5 µm with a proportion of 1:2, respectively.…”

“…Bimodal emulsions are unique systems that are non-common phenomenon, little known and poorly described in the literature. Whereas monomodal emulsions are characterized by one particle size distribution, bimodal emulsions are characterized by having two different and controlled droplet size and distributions [ 25 , 26 ]. The bimodal character of particle size distribution was described for animal protein (whey protein concentrate) with rapeseed oil [ 27 ].…”

Effect of slit dual-frequency ultrasonic emulsification technology on the stability of walnut emulsions

“…Due to the unstable mechanism of the emulsion system, the oil droplets and protein particles are regularly gathered or precipitated by the Law of Stokes [46] . UE emulsions with smaller oil droplets aggregated at a slower rate and were, therefore, more stable [47] , [48] . Oil droplets without sonication were close to each other, and there was a thin film with surface tension, which would promote the aggregation of droplets and poor stability.…”

Asphalt emulsion formulation: State of the art of formulation, properties and results of HIPR emulsions

“…The stability of the system will be preserved by a monolayer of surfactant adsorbed on the surface of the dispersed droplets in the emulsion, which is responsible for conferring an adequate magnitude to the disunion pressure. As mentioned above, in emulsions it is essential to control stability control [13] and the rheological properties during the formation process and later during storage and transport [3]. It is possible to control the properties of these systems through a careful control of the nature and magnitude of the interaction forces between drops.…”