The disclosed compositions and methods for producing composite materials that are suitably adapted for use in elevated temperature environments generally include the use of oxyarylbisorthodinitrile matrix resins in conjunction with aromatic amines to produce an improved phthalonitrile-based composite. Various features and specifications may be controlled, adapted or otherwise optionally modified to improve the temperature-rated performance of the disclosed composite materials. Exemplary embodiments of the present invention generally provide composite materials that offer improved strength at temperatures in excess of 600° F.