CROSS-LINKED LIGNIN-EPOXY RESINS .4.

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-formaldehyde, epoxy and polyurethane resins. This paper deals with the comparative properties of the binary blends (epoxy resins/lignin-epoxy resins) obtained in different reaction conditions and using various hardening agents. Crosslinked (cured) epoxy resins/lignin-epoxy resins with improved physical, mechanical and dielectric properties can be obtained only by modifying the hardening time, the fillers and the hardening agents. The advanced crosslinking reactions and the final tridimensional 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.