Synthesis and characterization of isocyanic bonding agents by the reaction of TDI and 5,5‐dimethylhydantoin for use in composite propellants

This paper aims to present the study of obtaining a potential isocyanic bonding agent. The process is based on introducing free isocyanate groups into hydantoin ring. In addition to acting as bonding agents, they can act as curing agents, promoting the formation of cross‐links with the binder so that the propellant cures. The synthesis process consisted of the reaction between toluene diisocyanate (TDI) and 5,5‐dimethylhydantoin (DMH) under different parameters (time, temperature, reaction atmosphere, solvent, and product purification). The reactions were monitored by Fourier transform infrared spectroscopy in the mid‐infrared region (FT‐IR). Furthermore, the product obtained was characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), elemental analysis (CHN), and volumetric chemistry (determination of the isocyanate‐NCO index). Changes in physical characteristics and the results of the determination of index NCO, FT‐IR, TGA, DSC, and CHN analysis indicate that the proposed reactions occurred. It is concluded that, among the parameters studied, those most suitable for the reaction system between isocyanic reagents TDI and DMH are a temperature of 90 °C, coupling of a nitrogen cylinder, and use of toluene solvent in the reaction system.