THE CROSS-LINKING MECHANISM IN GAMMA-IRRADIATION OF POLYARYLSULFONE -EVIDENCE FOR Y-LINKS

Measurements of molecular weights, soluble fractions and examination o f NMR spectra of bisphenol-A polysulfone, after gamma irradiation in v acuum at 150 degrees C were used to elucidate the mechanism of crossli nking. Excellent agreement was obtained between G(S) and G(X) determin ed from measurements above and below the gel dose when a Y-linking mec hanism was assumed, whereas poor agreement was obtained when an H-link mechanism was assumed, which is the mechanism normally believed to be responsible for crosslinking. New resonances were observed in the C-1 3 NMX spectra of the irradiated polymer which were consistent with the formation of Y-links involving phenylene units in the backbone chain. (C) 1998 John Wiley & Sons, Ltd.