FORMATION PROCESS OF END-LINKED NETWORKS BY GEL-PERMEATION CHROMATOGRAPHY

The size growth of clusters and the broadening of the size distributio n during the formation process of end-linked network have been measure d by gel permeation chromatography (GPC). The chromatograms obtained h ave been compared to the theoretical ones calculated on the basis of t he Flory and Stockmayer model and Gaussian statistics. The experimenta l chromatograms at high degree of conversion (p) show a long tail in t he low elution volume region which is not expected by the theory, whil e the experimental results at low p agree well with the theoretical pr ediction. Comparison of experimental chromatograms with theoretical on es suggests that the reactivity of functional sites in the cross-linke r is not independent of p, and that the reaction to connect the branch ed clusters linearly occurs at high p prior to reaction for higher deg rees of branching. The p-dependent reactivity is estimated to be due t o the steric hindrance around functional groups in the cross-linker.