Effects of surfactants/stabilizing agents on the microstructure and properties of porous geopolymers by direct foaming

Metakaolin-based porous geopolymers were synthesized by direct foaming using various surfactants/stabilizing agents with or without chemical pore-forming agent (hydrogen peroxide). The effects of surfactants/stabilizing agents and solid loading on their pore morphology, density, porosity, and some properties, such as thermal conductivity and compression strength, were investigated. Experimental data and different theoretical models were successfully applied to evaluate both compression strength (sigma) and effective thermal conductivity (lambda) as a function of porosity (epsilon). Porous geopolymers with higher epsilon presented both a lower value of mechanical strength and improved thermal conductivity performance. The variation of sigma with epsilon could be well described by the minimum solid area (MSA) model, and the variation of lambda with epsilon was found to be more accurately described using a universal model derived from the five basic models.

Automated summary

Metakaolin-based porous geopolymers were synthesized by direct foaming with various surfactants/stabilizing agents, and their pore structure, density, porosity, as well as properties like thermal conductivity and compression strength were studied. The relationship between compression strength and thermal conductivity with porosity was successfully evaluated using experimental data and theoretical models.