Enhanced ethanol retention and thermal stability in calcium chloride-stabilized ethyl cellulose gel fuels
Abstract
The design of thermally stable, thixotropic gel systems with tunable mechanical properties is essential for advanced functional materials. In this study, ethanol-based ethyl cellulose (EC) gels were fabricated via incorporation of calcium chloride (CaCl2), and their microstructural, rheological, and thermal behaviours were systematically investigated. Ethanol–EC solutions form viscous liquids; however, CaCl2 induces gelation through a synergistic mechanism of ionic coordination with ethanol and cellulose chains, promoting a robust polymer network. At an optimal EC:CaCl2 ratio of 2:1 (sample EC100s50), oscillatory rheology confirmed a true gel state (G’ > G" in the linear viscoelastic region, yield stress ≈ 115 Pa), accompanied by shear-thinning behaviour. Phase-contrast microscopy revealed a homogeneous, interconnected network, while thermogravimetric analysis indicated enhanced ethanol retention, with delayed evaporation up to 165 °C and single-step EC decomposition occurring at 312 °C. The activation energy for EC decomposition in the optimized sample (EC90s45) reached 185 ± 15 kJ mol−1, exceeding that of pure EC, yet ethanol was still released for ignition, with an activation energy of 45 ± 4 kJ mol−1 and a total combustion energy density of 29.3 kJ g−1. These results demonstrate that CaCl2-assisted ionic coordination is an effective strategy for engineering soft-solid ethanol–EC gels with tuneable viscoelasticity and thermal resistance, offering potential for applications in energy materials and propulsion-related functional composites.
Alessia De Cataldo
PhD Student (Dec'23-May'24)
My research interests include synthesis, micro and bulk rheology of fuel gels used for aersopace propulsion.
Roberto Cerbino
Professor of Experimental Soft Matter Physics
My research interests include Soft matter physics, living matter, cell biophysics and quantitative microscopy.