A flexible inflator for an inflation assembly and related gas generating propellant compositions are provided. The flexible inflator includes at least one elongated strand of a propellant co-extruded with a moisture barrier. The propellant compositions are adapted for co-extrusion with a plastic sheath which forms the moisture barrier surrounding the propellant and include a binder fuel component effective to render the composition flexible and to impart sufficient adhesive properties such that the propellant composition and the plastic sheath adhere together, and an oxidizer.