Exploratory Development of Addition Cured Polyimide Resins

摘要

Four diethynyl substituted polyimide prepolymers containing, as part of the anhydride moiety, the perfluoroisoproylidene group, were evaluated as reactive diluents for Thermid 600. The desired effects of utilization of these materials were: (1) lowering of cure and postcure temperatures, (2) increasing the liquid temperature range between melt and cure, (3) impart tack and drape qualities to glass and graphite prepregs. The diluents all had lower melting temperatures and cure temperatures than Thermid, and formed homogeneous melt phases with it. Mixtures having the composition of Thermid/diluent equal to 2:1 all had lower melting points than Thermid alone. Laminates were made, and tack and drape properties could be imparted to prepregs either by wetting with easily removable solvents, such as acetone, or by heating to melt the prepolymer. Mixtures of Thermid and diluent were used to prepare weldbond samples. Spotwelding was successful with aluminum filled mixtures of Thermid and diluent in the melt phase. S/N tests were run on spotwelded, adhesive bonded and weldbonded titanium specimens. The data base for HR602 bonded titanium specimens was expanded to include prepolymer prepared by the NMP solvent process. (Author)