The literature research deals with extractants of bark.
The rise in costs of fossil and non-renewable raw
materials used by the chemical industry has prompted an
increase in the research concerning the pure chemicals
and aliquot raw materials which can be derived from bark.
This interest has been directed, in particular, to
phenolic compounds which may be derived from bark.
Initially, these compounds were tried experimentally as
raw material for adhesives used in the plywood and
particle board industry.
Tannins or the phenolic components of bark are obtained
by extraction from wood bark. The quality of both the
yields and the derivatives varies according to the
solvent used and the conditions of extraction. Tannins
are aliquots of polymeric polyphenols which also include
small amounts of monomeric polyphenols and carbohydrates.
Tannins are used in glues as the phenols which they
contain react with formaldehyde in the same way as most
phenols, thought at a faster rate. A condensation product
from the reaction hardens when heated in a manner typical
of phenol resins.
Owing, however, to the volume of polymeric polyphenols,
the tanninformaldebyde resins have a significantly higher
viscosity than their synthetic counterparts in the same
concentrate. Additionally, the adhesive bond is weaker
than that of the synthetic phenol resins. The utilisation
potential of tannins has captured the attention of
scientists around the world for two reasons in
particular. Firstly, they are found in renewable natural
resources, and secondly, they have less harmful effect on
the environment than the products found in oil-based raw
|Place of Publication||Espoo|
|Publisher||VTT Technical Research Centre of Finland|
|Number of pages||69|
|Publication status||Published - 1983|
|MoE publication type||D4 Published development or research report or study|
|Series||Valtion teknillinen tutkimuskeskus. Tutkimuksia - Research Reports|
- spruce wood
- pine wood