Mechanical testing of an advanced polyimide resin (LaRC(tm)-SI) with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. Elastic and inelastic properties were characterized as a function of molecular weight and test temperature. It was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature. The combined analysis of calculated yield stress and notched tensile strength indicated that low molecular weight materials tended to fail in a brittle manner, whereas high molecular weight materials exhibited ductile failure. The microphotographs of the failure surfaces also supported these findings.Whitley, Karen S. and Gates, Thomas S. and Hinkley, Jeffrey A. and Nicholson, Lee M.Langley Research CenterELASTIC PROPERTIES; POLYIMIDE RESINS; MOLECULAR WEIGHT; TEMPERATURE; TENSILE STRENGTH; STIFFNESS; MICROPHOTOGRAPHS; BRITTLENESS; DUCTILITY; MODELS...