The Influence of Aluminum Hydroxide Nanoparticles on the Rheological Properties of Fluorine‐Free Foams

ABSTRACT Fluorine‐free foams stabilized by nanoparticles have excellent fire‐extinguishing performance and are expected to become a substitute for traditional aqueous film forming foam (AFFF). However, there are still many problems in the performance of NP‐stabilized fluorine‐free foams that need to be studied. This investigation centers on the rheological behavior of fluoride‐free foams stabilized by nano‐hydroxide aluminum. Measurements of electrical conductivity, viscosity, and surface tension were conducted on the mixed dispersions, and the resulting data were used to evaluate the role of nanoparticles in modifying foam stability. Through model fitting, the rheological properties of the mixed dispersion and foam were studied in depth. It was observed that the viscosity and stability of the mixed dispersion were elevated in the presence of nanoparticles, with this promoting effect becoming more pronounced at higher nanoparticle loadings. The foams stabilized by nanoparticles have good resistance to external shear and thixotropic recovery ability, and the shear stress change of the foam is consistent with the Cross model. With the increasing nanoparticle concentration, the linear viscoelastic region (LVR) of the foam widens, the flow point is delayed, and the viscoelasticity increases. The creep deformation resistance of the foam also increases, and the stability of the internal structure is significantly improved. The findings of this work offer valuable guidance for formulating fluorine‐free firefighting foam agents.