SYNTHESIS AND CHARACTERIZATION OF SOME IRON-LIGNOSULFONATE-BASED LIGNIN-EPOXY RESINS

Coupling reactions with micro-(phenol, beta-napthol, bisphenol) and ma cromolecular (novalak) phenols of the iron-lignosulfonate, followed by reactions with epichlorohydrine in strong alkaline medium, led to the obtaining of new lignin-epoxy resins. The physico-chemical properties of the brown liquid fractions (molecular weight 18,000-35,000; conten t of epoxy groups 0.06-0.178 %; dynamic viscosity 10,000-80,000 cP) pe rmit their utilization in binary mixtures containing epoxy resins, fur ther used for the obtaining of new composite materials. Physico-chemic al characterization by IR and expecially Mossbauer spectroscopy of all solid fractions (both the coupling products between the iron-lignosul fonate and phenols and those obtained after epoxidation) showed import ant modifications of the complex compound iron-lignosulfonate, referri ng both to the metal-ligand bonds and to the change of valency of the coordinated iron. The catalyst role played by iron ions during these r eactions should be mentioned.