Abstract

Differential Scanning Calorimetry is used to study the curing reaction of phenol formaldehyde and metilolated-Kraft-lignin-phenol-formaldehyde adhesive sistems synthesized at Laboratory scale. The phenol formaldehyde adhesives shown exothermic peaks at 144 degrees C and 150 degrees C. This is due to the condensation reaction of the hydroxymethyl groups present in the phenolic ring. The use of lignin,as a replacement of phenol,in this adhesive modify the thermal behavior of the sistem lowering the exothermic peak of the polimerization reaction to 110 degrees C. The decrease of the crosslink density of the polymer network formed account for this result. A 40% lignin replacement showed to affect significantly the adhesive properties.