Effect of cellulosic fibers on foam dynamics

Aqueous foams consist of air bubbles stabilized in a fluid medium. Surface active agents adsorbed at the air/liquid interface may enhance foam stability by modifying the interfacial energy at the air/liquid interface. In addition, they affect the interfacial and bulk viscoelasticity as well as the capillary pressure across the plateau borders. The diffusion and adsorption kinetics of surface active agents in the foam and at interfaces impact the foamability to given extent. The foam dynamics (foamability, foam stability), in turn, is closely related to parameters that are used to define the physical chemistry of foams. We incorporated cellulosic fibers (wood fibers and cellulose nanofibrils) in surfactant-stabilized foams, producing bio-based systems that we expect to have a wide range of applications. The physical chemistry of the air/liquid interface in such foams was altered by the presence of various surfactant types (anionic, cationic and nonionic). The synergistic role of natural wood fibers and surfactants in foam generation and stabilization processes was evaluated as a function of surfactant concentration. Here we discuss the effect on foam dynamics of added wood fibers and cellulose nanofibrils, which were used as rheology modifier.