99664 ⎘
Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups - ; Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule; Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors Polyisoimides