AbstractHeat treatment at temperatures of 224° to 310°C of hydrolytically degraded polyimide film has been shown to regenerate the ultimate tensile strength from 15.1 ksi to 24.3 ksi after 80 hr at 224°C and to 25.8 ksi after 2 hr at 310°C, whereas the elongation to failure is simultaneously increased from 6.3 to 38.3 at 224°C and to 50.7 at 310°C. Prior to degradation, the film had an ultimate tensile strength of 26.6 ksi and an elongation to failure of 62.0. The kinetics of this regeneration indicate that the reaction corresponds to the two‐step recombination of the hydrolytically attacked amide linkages that were initially present in the “as received” polyimide film. The regenerated polyimide exhibits a much improved hydrolytic stability over the untreated material and specimens heat treated directly without prior aqueous
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