Two thermoplastic polyimides - one amorphous, the other crystallizable -- were subjected to isothermal stretching just above their glass transition temperatures. Room-temperature strengths in the stretch direction were greatly improved and, moduli increased up to 3.6-fold. Optimum stretching conditions were determined. Hinkley, Jeffrey A. and Klinedinst, D. and Feuz, L. Langley Research Center NASA/TM-2000-210094, NAS 1.15:210094, L-17953