Curing of binary mixtures of polyimides

Apparently homogeneous mixtures of PMDA-ODA and BTDA-ODA/MPDA polyamic acid lead upon curing to compatible systems. These are either compatible blends or more or less blocky copolyimides formed through anhydride and amine intermediaries during the imidization reaction. The latter becomes possible due to catalysis of the imidization process by the higly acidic PMDA based polyamic acid. In any case the obtained mixtures exhibit usually only one sharp glass transition at temperatures intermediate to the ones of the starting materials.