Abstract
Alloying of polybenzoxazine with polyimide was examined. Polymer alloy films were prepared by blending benzoxazine monomer with poly (amide acid), a precursor of polyimide, followed by film casting and the thermal treatment for ring-opening polymerization of benzoxazine and imidization. The resulting alloy films were made up of a semi-interpenetrating polymer network consisting of linear polyimide and crosslinked polybenzoxazine. AB-type co-crosslinked polymer alloy films were also obtained by the copolymerization of benzoxazine with polyimide containing phenolic hydroxyl as an activated aromatic group. Both types of polymer alloys were effective to improve the brittleness of polybenzoxazine and to increase its Tg and thermal degradation temperature. The semi-IPN formation was especially effective for toughening the polymers, while the AB-type crosslinked polymer network did for increasing Tg values.
