Effect of hydroxypropyl methylcellulose and ferric chloride on hypergolic ignition of solidified ethanol fuels

• Hypergolic ignition of reaction-driven solidified fuels with varying concentrations of hydroxylpropyl methylcellulose and ferric chloride has been investigated for the first time. • FTIR and TGA techniques has been used to study molecular interactions between hydroxylpropyl methylcellulose and ferric chloride. • Hypergolic ignition delay tests with 90 % H 2 O 2 reduced ignition delay with increase in the concentration of gellant and dopant. • Higher fuel temperature improved spreading and wetting behavior of H 2 O 2 droplets. • Solidification of ethanol using HPMC with FeCl 3 eliminates the need for a separate catalyst. This study investigates the hypergolic ignition of reaction-driven solidified ethanol (RDSE) fuels, focusing on the effects of varying concentrations of hydroxypropyl methylcellulose (HPMC) gellant and ferric chloride (FeCl 3 ) dopant. Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA) are employed to examine molecular interactions and thermal properties. FTIR results indicate that no new covalent bonds are formed upon adding FeCl 3 , whereas interactions primarily governed by weak hydrogen and ionic bonds. The apparent activation energy ( E a ) has been determined for the fuel samples using iso-conversional model-free kinetics approach and found that E a decreased with HPMC and FeCl 3 concentrations. Hypergolic ignition delay tests were attempted with the droplet study rocket grade hydrogen peroxide (90 % RGHP; H 2 O 2 ) as an oxidizer, demonstrated that increasing HPMC concentration by 3 wt.% reduced ignition delay by ∼20 %, while a 5 wt.% increase in FeCl 3 concentration led to a ∼25 % reduction. Higher fuel temperatures enhanced the wetting and spreading behavior of H 2 O 2 droplets, improving oxidizer-fuel interaction and reducing ignition delay. Overall, solidification of ethanol using HPMC with FeCl 3 eliminates the catalyst as FeCl 3 acts as both catalyst and binding agent.