Adhesive and composite properties of cured imide oligomers containing pendent and terminal phenylethynyl groups

As part of a program to develop high performance/high temperature structural resins for aeronautical applications, imide oligomers with calculated number average molecular weights of similar to 5000 g/mole containing pendent and terminal phenylethynyl groups were prepared, characterized, thermally cured and the cured resins evaluated as adhesives and composite matrix resins. The chemical structure of the oligomer backbone was altered to obtain a resin with an attractive combination of properties including processablity using conventional equipment, high mechanical properties and microcrack resistance. The imide oligomers containing phenylethynyl groups were fabricated into adhesive specimens using titanium adherends and composite specimens using IM-7 fiber. The laminates were fabricated in a vacuum press under 1.4 MPa for 1 hr at 350-371 degrees C. The mechanical properties measured at room and elevated temperature varied depending on the chemical structure of the oligomer backbone. Microcrack resistance was dependent upon the oligomer chemical structure. The neat resin and composite properties of these oligomers and their cured polymers will be presented.