SYNTHESIS OF LIGNIN EPOXY RESINS IN AQUEOUS SYSTEMS AND THEIR PROPERTIES/

A new resin system was developed only by mixing the alkaline solution of industrial kraft lignin with water-soluble epoxy compound, polyethy lene glycol diglycidyl ether (PEGDGE), and curing reagent. The viscoel astic properties of cured resin films were investigated. As the conten t of the kraft lignin in the resins increased, the absorption peak due to the glass transition for cured resins shifted to a higher temperat ure with spreading. It was found that the glass transition temperature of cured resins can be modified by changing kinds of PEGDGE and curin g reagents. Addition of the emulsion type of diglycidyl ether of bisph enol A (DGEBA) to the blendings also could make the glass transition t emperature of cured resins higher. Since only one broad dispersion pea k due to the glass transition could be observed, it was suggested that the cured resins had compatibility to form a kind of IPNs (Interpenet rating Polymer Networks).