Epoxy oligomers modified with epoxyphosphazenes

Phosphazene-containing epoxy oligomers are obtained through a one-stage method via the interaction of hexachlorocyclotriphosphazene with an excess of diphenylolpropane in the medium of epichlorohydrin in the presence of a solid alkali. With the use of 31 Р NMR and MALDI mass spectrometry, it is shown that the main components of the phosphazene fraction are penta- and tetra-aryloxysubstituted cyclotriphosphazene compounds with the corresponding numbers of epoxy groups. The maximum content of the phosphazene fraction in phosphazene-containing epoxy oligomers (~40 wt %) is attained at a hexachlorocyclotriphosphazene-to-diphenylolpropane molar ratio of 1: 8. Phosphazene-containing epoxy oligomers cured with isomethyltetrahydrophthalic anhydride have oxygen indexes of 26–28 and are self-extinguishing.