Comparative study on the enhancement of the stability of siloxane-based Gemini/sodium alpha-alkenyl sulfonate mixed dispersions using xanthan gum, carboxymethyl cellulose, and gelatin.

Polymers are promising as stabilizers for developing eco-friendly foam extinguishing agents to solve the imminent pollution problem of fluorinated ones. Present work aims to elucidate the mechanisms by which polymers influence the performance of non-fluorinated foams. Specifically, it investigates the effects of three polymers-xanthan gum (XG), sodium carboxymethyl cellulose (CMCNa), and gelatin (GEL) on surface tension, conductivity, viscosity, foamability, foam stability, and rheology of the siloxane-based Gemini/sodium alpha-alkenyl sulfonate mixture. Further, drainage and liquid film experiments are conducted at various temperatures to assess drainage time and film lifetime. Results showed that the addition of three polymers increased viscosity and conductivity of the dispersions while inhibiting foamability, where GEL also enhanced the surface activity. The polymers delayed coarsening by forming the macromolecular gel network between bubbles, with the dimensionless bubble diameter growth exponent of about 1/2. Additionally, polymer-containing dispersions exhibited longer drainage times and film lifetimes at both room and elevated temperatures. Dispersions with XG and CMC-Na showed a viscoelastic solid rheological response at low oscillatory strains under room temperature, but lost elastic behavior at high temperatures. Conversely, dispersions with GEL maintained consistent rheological behavior across temperatures, displaying viscoelasticity at low strains and transitioning to flowing liquid state at higher strains.