EFFECT OF CHEMICAL MODIFICATION OF LIGNIN ON THE GLUEBOND PERFORMANCEOF LIGNIN-PHENOLIC RESINS

Lignin obtained from eucalyptus wood by acetic acid pulping was methyl olated or phenolated and used to prepare lignin-phenol-formaldehyde re sins. The amount of formaldehyde consumed in the methylolation reactio n, and supporting comparison of pre- and post-methylolation H-1 and C- 13 NMR spectra, showed the reactivity of the crude acetosolv lignin wi th formaldehyde to be relatively high. Pine and eucalyptus plywood boa rds manufactured using the resins prepared with the modified lignins c omplied with European Standard EN 314-1:1993 for WBP qualify boards an d gave knife test results similar to those of boards manufactured with a commercial phenol-formaldehyde resin. (C) 1997 Elsevier Science Ltd .