G-values for scission and crosslinking on gamma-radiolysis of Ultem at 303 K

Sheila Devasahayam, David J. T. Hill, Andrew K. Whittaker

Research output: Contribution to journalArticle


The radiation chemical yields G(S) and G(X) for H-linking and Y-linking models for Ultem have been calculated from molecular weight analysis by gel permeation chromatography. These G-values have been compared with the G-values obtained from analysis of soluble fractions above the gel dose, Which have been reported in previous works. An analysis of the molecular weight data in terms of H-linking and Y-linking mechanisms yielded values of G(S-H) = 1.0 x 10(-3) and G(H) = 6.0 x 10(-3) and G(S-Y) = 1.3 x 10(-2) and G(Y) = 1.8 x 10(-2). The corresponding values obtained from the solubility data were G(SH) = 0.53 x 10(-2), G(H) = 1.39 x 10(-2), G(S-Y) = 4.2 x 10(-2) and G(Y) - 4.6 x 10(-2). The origin of the disagreement between the molecular weight and solubility values is not clear, but it could arise as a result of observed microgel formation below the reported gel dose of 0.13 MGy. Whether the crosslink mechanism proceeds by an H-linking or Y-linking process is also unclear and will require direct observation of the crosslinking structures.

Original languageEnglish
Pages (from-to)259-267
Number of pages9
JournalHigh Performance Polymers
Issue number3
Publication statusPublished - Sep 2003
Externally publishedYes


  • G(S)
  • G(X)
  • radiolysis
  • molecular weight
  • sol/gel

Cite this