Formation process of end-linked networks by gel permeation chromatography

Abstract

The size growth of clusters and the broadening of the size distribution during the formation process of end-linked network have been measured by gel permeation chromatography (GPC). The chromatograms obtained have been compared to the theoretical ones calculated on the basis of the Flory and Stockmayer model and Gaussian statistics. The experimental chromatograms at high degree of conversion (p) show a long tail in the low elution volume region which is not expected by the theory, while the experimental results at low p agree well with the theoretical prediction. Comparison of experimental chromatograms with theoretical ones suggests that the reactivity of functional sites in the cross-linker is not independent of p, and that the reaction to connect the branched clusters linearly occurs at high p prior to reaction for higher degrees of branching. The p-dependent reactivity is estimated to be due to the steric hindrance around functional groups in the cross-linker.