Characterisation of metakaolin-based geopolymers as modified by organic phase

Geopolymers are potentially emerging class of new materials for building purposes due to their enhanced properties in comparison with Portland cement or other types of binders. Primary source for their production could be any natural alumosilicate material or the one coming from the industry in the form of waste. Production of geopolymers is considered as eco-friendly due to the low gas emission and potentially contributor to the lowering of the deposited industrial waste. The main problem in the geopolymer’s application rises along with potential brittleness caused by their porosity. The introduction of modifiers (inorganic and organic) could lead to the filling-the-pores process and consequently to the improvement of mechanical properties (compressive strength). Structure modification by organic phase leads to the production of so called “hybrids”. In this work, commercial epoxy resin and 3-(methoxyl) propyl methacrylate were used as organic modifiers. The purpose of this research was to make a comparison of the microstructural and mechanical properties between two different hybrids through the examination of relevant parameters such as the concentration of NaOH in the alkaline activator and the Si/Al mass ratio in the starting raw mixture. Hybrid geopolymer composities were characterised using XRD, DRIFT spectroscopy as well as SEM microscopy. © 2021, Scibulcom Ltd.. All rights reserved

Magnetic and power absorption measurements on iron oxide nanoparticles synthesized by thermal decomposition of Fe(acac)(3)

Iron oxide magnetic nanoparticles with diameters d, 7 nm LT = d LT = 12 nm, were synthesized by thermal decomposition of Fe(acac)(3). Different experimental conditions, keeping constant concetration of Fe ions in solvent, showed that the heating rates is the most important parameter determining the final particle size. Use of two different solvents, 1-eicosene and 1-octadecene, yielded similar nanoparticle sizes (7.1 nm LT = d LT = 7.5 nm), but different magnetic anisotropies. All samples were superparamagnetic at room temperature. Spin disordering was inferred in samples coated with trioctylphosphine oxide (TOPO) co-ligand in addition to oleic acid and oleyamine. The heating ability of similar to 12 nm-sized nanoparticles dispersed in hexane under alternating magnetic fields (3.98 kA/m LT = H-0 LT = 23.87 kA/m; 229.3 kHz LT = f LT = 828 kHz) has been studied, finding a nearly quadratic dependence upon H-0, as expected from the linear response theory. (C) 2017 Elsevier B.V. All rights reserved