Epoxide networks fraction

In this contribution, we report equilibrium modulus and sol fraction measurements on diepoxidet-monoepoxide-diamine networks and polyoxypropylene triol-diisocyanate networks and a comparison with calculated values. A practically zero (epoxides) or low (polyurethanes) Mooney-Rivlin constant C and a low and accounted for wastage of bonds in elastically inactive cycles are the advantages of the systems. Plots of reduced modulus against the gel fraction have been used, because they have been found to minimize the effect of EIC, incompleteness of the reaction, or possible errors in analytical characteristics (16-20). A full account of the work on epoxy and polyurethane networks including the statistical derivation of various structural parameters will be published separately elsewhere. 

An agreement with experimental results was obtained by taking into account the increased effective fraction of the filler, Veff, due to the glassy interphase of the bound epoxide layer and assuming a co-continuous morphology of the epoxy-silica hybrid network. Mechanical properties in dependence on the phase continuity are treated by parallel and series models for bicontinuous morphology and discontinuous phases, respectively. The equivalent box model (EBM) developed by Takayanagi (13) (eqs 2-5) and Davies model (14) (eq. 6) were used to compare the experimental data with the theory (9). 

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