Résumé
The direct incorporation of low viscosity vegetable oil (OL) such as sunflower oil into fresh geopolymers (GP) is easier than for mineral oil. This corresponds to a suitable dispersion of the oil in the form of fine micrometric droplets. 1H NMR studies have shown that during the formulation time at liquid state, no surfactant is formed (by hydrolysis due to the basic nature of the solution) and the easy incorporation of the vegetable oil into the fresh geopolymer is due to the property of the oil (viscosity, polarity, surface tension, etc.) rather than the surfactant action of saponification products. The kinetic monitoring of the chemical evolution of sunflower oil in contact with the activating solution was carried out by 1H NMR spectroscopy at room temperature. The NMR study confirmed that the percentage of disappearance of triglycerides was correlated with the percentage of production of fatty acids, and that the saponification reaction was complete in 4 days. The evolution of the sunflower oil trapped in the geopolymer was carried out by grinding and extraction operations in petroleum ether and in water. 1H NMR has shown using both triglyceride disappearance or glycerol production that saponification reaction occurs (45 % hydrolysis in 7 days), even if oil is trapped into solid geopolymer.