Estimating the Enthalpy of Gasification of Acrylonitrile-Butadiene-Styrene Hybrid Rocket Fuels

摘要

This report investigates the pyrolysis properties of both extruded and additively manufactured acrylonitrile-acrylonitrile-styrene at material surface temperatures from 350 to 725℃. These temperatures approximate the range of surface temperatures reached during combustion when acrylonitrile-acrylonitrile-styrene is employed as a hybrid rocket propellant This temperature range is significantly higher than temperatures evaluated during previous acrylonitrile-acrylonitrile-styrene fire-safety combustion and pyrolysis studies. Linear regression rates of acrylonitrile-acrylonitrile-styrene fuel grain material specimens are measured during pyrolysis and used to derive estimates for both the molar and mass-based enthalpies of gasification. Molar values for enthalpy of gasification are estimated from the regression rate data using an Arrhenius-type process model. The mass-based enthalpy of ablation is calculated from the power duty cycle of the heating element used to produce the fuel pyrolysis. Test results compare favorably with the previously published enthalpies of gasification, obtained at significantly lower surface temperatures, for extruded acrylonitrile-acrylonitrile-styrene. The additively manufactured acrylonitrile-acrylonitrile-styrene specimens exhibit a minor, but statistically significant, lower enthalpy of vaporization when compared to the extruded specimens.