Investigation of the effects of gamma radiation on solid polybutadiene-based propellants for space applications

This study examines how curing chemistry and additives tailor the response of hydroxy-terminated polybutadiene (HTPB) and polybutadiene (PB) binder systems to gamma irradiation at 25, 45, and 130 kGy (in air, at room temperature). Three formulations were evaluated: conventionally cured HTPB (H), antioxidant-stabilized HTPB (Ha), and photocured PB. Raman, FTIR, EPR, colorimetry, and optical microscopy reveal distinct formulation-dependent behaviors. H undergoes minimal changes at low doses but significant oxidation at 130 kGy. Although Ha progressively browns with doses, the antioxidant effectively limits chemical and mechanical degradation. The PB highly reactive network produces early discoloration, oxidation, and persistent multi-species radical formation.