Recent studies have demonstrated that spent sulfite liquors with a low
content of ammonium, sodium or calcium lignosulfonate can be use das
reagents in different macromolecular syntheses, as modified phenol-for
maldehyde, epoxy and polyurethane resins. This paper deals with the co
mparative properties of the binary blends (epoxy resins/lignin-epoxy r
esins) obtained in different reaction conditions and using various har
dening agents. Crosslinked (cured) epoxy resins/lignin-epoxy resins wi
th improved physical, mechanical and dielectric properties can be obta
ined only by modifying the hardening time, the fillers and the hardeni
ng agents. The advanced crosslinking reactions and the final tridimens
ional structure of the binary blends (epoxy resins/lignin-epoxy resins
) have been demonstrated by the decrease in the content of free polar
groups total insolubility in common solvents, improved mechanical and
dielectric properties and electron microscopy images.