Pyrolysis of Acrylonitrile-Butadiene-Styrene (ABS) Under High Heat Flux Conditions

Abstract

Acrylonitrile-butadiene-styrene (ABS) is a common industrial plastic that is widely used for structural and piping applications. Because ABS possesses a variety of advantageous material properties, within the past three years ABS plastic blends have been investigated as a potential fuel for hybrid-and solid-propelled rocket systems. Promising results have been achieved. Because ABS as a rocket propellant is a very recent development, a database describing the pyrolysis properties of ABS at the temperatures and heating rates experienced by rocket systems does not exist. Especially important is the current lack of established values for the specific enthalpy of gasification (latent heat of vaporization) for various ABS material formulations. All existing ABS pyrolysis data were collected during fire prevention studies, and were performed at heating rates nearly an order of magnitude lower than those experienced during rocket combustion. This report investigates the pyrolysis properties of ABS at high flux levels and material temperatures from 350 to 700 C. Linear regression rates are measured and used to derive estimates for the specific enthalpy of gasification based on the power duty cycle of the heating element used to produce the fuel pyrolysis. Results for both extruded and additively manufactured ABS are compared. Nomenclature A= Arrhenius pre-exponential scale factor, mm/s ABS = acrylonitrile-butadiene-styrene (acronym) A burn = fuel grain surface burn area, cm 2 A c = fuel chamber cross sectional area , cm 2 A ox = effective total oxidizer injector area, cm 2 A * = nozzle throat area, sonic choke area, cm 2 B = free energy of formation curve fit slope parameter CEA = chemical equilibrium with applications (acronym) c fx = local skin friction coefficient c p = specific heat of solid propellant fuel grain, J/kg-K D final = test specimen final diameter, mm