Concentration of elastically active network chains and cyclisation in networks obtained by alternating stepwise polyaddition

The crosslinking statistics for the post-gel stage of a stepwise alternating polyaddition of a bi- and tri-functional component has been developed. The treatment includes formation of elastically inactive cycles and their activation resulting in formation of elastically active network chains (EANCs). Model calculations have shown that in networks formed from telechelic polymers the fraction of bonds wasted in elastically inactive cycles amounts only to several percent, but their effect on lowering the concentration of EANCs is rather important. The effect of cyclisation on the concentration of EANCs can be strongly reduced if the concentration of EANCs is compared at the same relative conversion with respect to that at the gel point or at the same gel fraction. The concentration is rather sensitive to incompleteness of the reaction or to deviations from the stoichiometrically equivalent ratio of the functional groups.