Two-stage cure polyimide oligomers using citraconic anhydride

摘要

Disclosed is a method for using citraconic anhydride as an addition cure end cap in reactions for forming polyamic acid oligomers and polyimide oligomers, wherein the formed oligomers are used to make high temperature, low void volume, fiber-reinforced composites from prepregs using a two-stage cure schedule; wherein: in a first stage, a prepreg, which comprises a solution of the formed oligomers in a fibrous reinforcing material, is cured to remove volatiles, the viscosity of the oligomers during the first stage being less than or equal to 2500 poise; and in a second stage, full cure is effected by crosslinking via a nonvolatile-producing reaction.