Stability and rheological properties of firefighting foams with sodium carboxymethyl cellulose and hydrocarbon/silicone surfactants

Firefighting foam stability is a critical aspect in determining fire extinguishing efficiency. The stability and rheological properties of environmental firefighting foams are investigated in this work. The results show that increasing NaCMC polymer concentration decreases the equilibrium surface tension of CTAB/501W surfactants, while enhancing the viscosity and conductivity. And the yield strain and yield stress of the foam improve. However, when the NaCMC concentration is enhanced to 0.8 wt.%, the NaCMC concentration has less effect on the change in rheological characteristics. Slight NaCMC concentration addition enhances the foaming ability of CTAB/501W surfactant solutions, but further addition of NaCMC concentration decreases its foaming ability. Increasing NaCMC cocentration reduces the height decay of the foam produced by CTAB/501W surfactant solutions, retarding the bubble coarsening and liquid drainage process, and leading to foam stability enahncement, where the stability turning point occurs when NaCMC concentration is 0.5 wt.%. This is mainly attributed to the interaction between NaCMC polymer and CTAB molecule, and the increased viscosity.