Acetylene Additive Effects on Processing and Thermo‐Mechanical Properties of Analogous Phthalonitrile Resins

Thermosetting properties of two co‐resins, one terminated with acetylene and the other with phthalonitrile (PN), were analyzed. Both resins have an analogous backbone structure that includes an internal ether for improved processing and flexibility, as well as an internal imine initiator to allow self‐curing. A decrease in acetylene additive concentration was shown to lower resin melt viscosity as compared to the pure resins. Lower acetylene additive concentration was also shown to enable a lower onset of polymerization, creating resins with ~15% increased char yield as compared to the pure PN polymer while still maintaining similar stiffness, indicating high cross‐link density of the co‐cured thermosets. The co‐curing of these systems exhibits a 50%–60% lower exotherm than pure ODA‐Bz‐A. The controllable thermal cure of the co‐cured resin system significantly reduces processing hazards.