Stabilization discrepancies of kaolin foams under different surfactant systems and their effects on the preparation of porous materials

Porous materials have received extensive attention in the fields of industrial thermal insulation and green environmental protection due to their high porosity. The foam slurry stability is a key factor in the preparation of porous materials. Herein, a comparison of interfacial behavior and rheology of hexadecyl trimethyl ammonium bromide (SR), dodecyl sodium sulfonate (SDS), and synthetic vegetable protein foaming agent (WHZ) in gel systems reveals the effect of the kaolin foam stability on the pore formation. At 6 mg/mL agent concentration, the hydrophobicity degree of the kaolin surface was SR (80.12°) > WHZ (48.89°) > SDS (41.33°). In the kaolin foam slurry system, the capillary pressure generated by SR and WHZ can reach up to 5000 Pa and 2000 Pa. It effectively reduces the extrusion of the thin liquid film layer, and foam stabilization is still achieved during 3 h of static storage. Similar to SR, WHZ enables kaolin foam slurries to have a high storage modulus (100 Pa) at a particle loading of 50 wt%. This foam solid-state behavior and the stabilization enabled the preparation of a clay porous green body with pore sizes less than 100 μm and compressive strengths greater than 100 kPa.