Effects of Al(OH) ₃ nanoparticles and polymers on the rheology of fluorine-free foam under thermal action

Nanoparticles - and polymer-stabilized fluorine-free foams hold promise as the next generation of environmentally friendly firefighting foams. However, numerous aspects regarding the performance of aluminum hydroxide Nanoparticles - and guar gum -stabilized nonfluorinated foams have yet to be explored. In this study, a compound system was prepared using aluminum hydroxide nanoparticles, water-soluble polymer guar gum, a silicone surfactant (LS-408L), and a hydrocarbon surfactant (SM-2B-30). The surface tension, conductivity, foaming ability, and foam stability of the mixed dispersions were evaluated. Simultaneously, the flow behavior, viscoelasticity, and thixotropy of the mixed dispersions and foams under thermal influence were characterized. Results indicated that in the presence of Nanoparticles and/or guar gum, the foaming ability of the LS-408L/SM-2B-30 mixed dispersions diminished, while the foam stability improved. All the foams are non-Newtonian fluids exhibiting shear-thinning behavior. The presence of guar gum/Nanoparticles expanded the linear viscoelastic range of the foam, enhancing the viscoelastic range of the LS-408L/SM-2B-30 dispersions. Compared with guar gum, aluminum hydroxide Nanoparticles demonstrated a superior ability to enhance the viscoelasticity of the foam yet possessed a relatively poorer foam-stabilizing capacity. This experiment is the first to explore this specific combination in a fluorine-free environment, addressing an underexplored materials pairing problem. The rheological behavior (shear thinning, viscoelasticity, and thixotropy) under the influence of heat is fully characterized, filling the gap in the understanding of the effect of temperature on such systems. This study provides theoretical underpinnings for the industrial implementation of aluminum hydroxide Nanoparticles- and guar gum-stabilized fluorine-free foams.