Gelation critical molar ratio

In the foregoing considerations, formation of elastically inactive cycles and their effect have not been considered. For epoxy networks, the formation of EIC was very low due to the stiffness of units and could not been detected experimentally the gel point conversion did not depend on dilution in the range 0-60% solvent therefore, the wastage of bonds in EIC was neglected. For polyurethanes, the extent of cyclization was determined from the dependence on dilution of the critical molar ratio [OH] /[NCO] necessary for gelation (25) and this value was used for the statistical calculation of the fraction of EIC and its effect on Ve as described in (16). The calculation has shown that the fraction of bonds wasted in EIC was 2-2.5% and 1.5-2% for network from LHT-240 and LG-56 triols, respectively. 

The critical excess for amino groups is more sensitive to the substitution effect within the amino group than the gel point conversion of a stoichiometric system and it is thus more suitable for characterization of q (Fig. 6). In this way, the value of q was found to be 0.33-0.40 for the aliphatic amino group and 0.18-0.24 for the aromatic group in DDM (Refs. 16 and 18 and impublished measurements). These values are close to these obtained in model reactions of compounds of low functionality. The determination of the critical molar ratio necessary for gelation i.e. the... 

Fig. 6. Theoretical dependence of the molar ratio necessary for gelation (critical excess of amine groups), (r lc, in dependence on kjAi = o...

Average dissociation energy of a single association Molar ratio of CTAB to the AAc units in the polymer CTAB/AAc molar ratio in the gelation solution Critical shear rate for shear thickening Relaxation rate of the fast mode Strain amplimde... 

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