Manufacturing and thermal properties of Lignin-based resins

Lignin possesses reactive hydroxyl groups, thanks to which it shows the ability to condense with aldehydes among other compounds. In an alkaline medium the process of lignin polycondensation with glutaricdialdehyde runs in accordance with a mechanism consisting in electrophilic substitution in the ortho position in relation to the hydroxyl group. The aim of this research was to work out the method of manufacturing lignin-aldehyde resins, as well as to determine the possibilities and conditions for their cross-lingking. In order to carry out research, the lignin under brand name Curan (Lignotech, Sweden) as well as glutaricdialdehyde were used. The reaction was run over 0.5-4 hours in an alkaline medium at the boiling temperature of the reaction medium; then water educed during the above reaction was removed by vacuum distillation. After eduction of the reaction product its properties, specifically thermal, were determined.