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P. Król

The kinetic models of progressive polyaddition and their experimental verification by the GPC method

Polimery 1997, No 7-8, 458


DOI: dx.doi.org/10.14314/polimery.1997.458


Summary

This work continues earlier studies [8] on the kinetic modeling of progressive polyaddition in volving diisocyanates and diols. A scheme, and a kinetic model derived fromit, are presented for the synthesis of linear polyurethane(s) from 2,4-TDI and1,4-butanediol. The model allows for the various reactivities of the two isocyanate groups and — by Flory's postulate — changing reactivities of the functional groups consequent upon the kinetic effect of substitution in the urethane oligomers. The model is represented by a finite system of tendifferential equations [eqns.(8)—(17)]; their initial conditions refer to the stoichiometric polyaddition [eqn. (18)]. The rate constants for major reactions, used in the model, were expressed by two quantities related to the reaction of 2,4-TDI's 4-NCO with 1,4-butanediol's –OH group (kED) and by a constant representing the substitution effect in aromatic isocyanateurethanes (kj). GPC studies on the progress of the polymerization reaction allowed to verify the model experimentally and to determine the kinetic parameters. The usefulness of GPC for following progressive diisocyanate—diol polyadditions and the applicability of the present and the quasi-optimum [8] models to numerical simulations of polyaddition are discussed.


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