Enhancing Functional Properties of different Materials through Geopolymerization: Improved Flame-Retardancy and Pollutant Absorption

Geopolymers, recognized for their three-dimensional networks of silicon (Si), aluminum (Al), and oxygen (O) bonds, have gained significant attraction due to their superior mechanical properties and potential to mitigate the environmental impact of Portland concrete production, which is responsible for 5-7% of global CO2 emissions[1]. Beyond construction applications, geopolymers can enhance the properties of composite materials[2], such as increasing flame-retardancy in flammable polymers like cellulose and improving pollutant absorption due to their enhanced porosity. This study presents the development and comparative analysis of two nanocomposite systems designed for advanced functional properties: flame-retardant hydroxypropyl cellulose/halloysite nanotubes (HPC/HNTs) composites and pollutant-absorbing geopolymerized gel beads, alongside a pure inorganic clay-based film geopolymerized to obtain different characteristics. The XRD, TGA, and SEM analyses confirmed successful geopolymerization across all samples. Thermal analyses were conducted through thermogravimetric measurements to evaluate the CO2 adsorption capacity of the samples, and DMA measurements were performed to assess their mechanical properties. Geopolymerized gel beads and inorganic films demonstrated significantly higher CO2 adsorption capacity than their non-geopolymerized counterparts, attributed to increased porosity observed in SEM images. Dodecane adsorption tests supported these findings, with geopolymerized samples showing enhanced hydrocarbon absorption. The flame-retardant properties of geopolymerized HPC/HNTs composites were particularly notable, extinguishing flames within 0.5 seconds post-ignition source removal, outperforming both pure HPC films and non-geopolymerized composites. This study underscores the potential of geopolymers to improve the functional properties of composite materials significantly. The enhanced CO2 and hydrocarbon adsorption capacities and superior flame-retardancy position these materials as promising candidates for applications demanding high performance and environmental sustainability. Future research could further optimize these properties and explore additional applications in various industrial domains.