Title: Lignin based adhesives for particleboard production
Abstract: The purpose of this study was to utilise lignin as a partial substitute for phenol in PF
resins. To achieve this, initially brown rot lignin was produced by a bioconversion
technique. During the course of the study, it became clear that the production of
brown rot lignin had a limited success.
Since brown rot lignin could not be obtained in sufficient quantity and purity by a
bioconversion method, other alternative lignin production methods, as well as
commercially available lignin, were chosen; namely production of lignin from black
liquor and Alcell® (organosolv) lignin. Before performing production of resin
formulations, the lignin sources were characterised in terms of reactivity and
physical properties of lignins. Both lignins had a similar reactivity, but organosolv
lignin was found to be more pure, with a low ash content. Since isolation of lignin
from black liquor in laboratory conditions is more complex and requires more time,
it was decided to use organosolv lignin for subsequent production of lignin-based
reSIns.
The lignin was introduced to the resin in two different ways. The first method was
the replacing of a certain percentage of phenol with lignin (as supplied) directly into
resins. In the second method, lignin was modified prior to resin manufacture by
phenolation. Different degrees of phenol substitution (from 5% to 60%) were tried
for the production of lignin-based resins.
Bond qualities of lignin-phenol-formaldehyde (LPF) , phenolated-ligninformaldehyde,
commercial phenol-formaldehyde (PF _com) and laboratory made
phenol-formaldehyde (PF _made) resins were assessed by using an Automatic
Bonding Evaluation System (ABES), prior to production of particleboards, in order
to eliminate some of the poor quality resins. The effect of press temperature and time
on bond strength appeared to be highly significant, as the lignin substitution levels
increased. Up to 30% phenol substitution was achieved without sacrificing bond
strength. The bond strength values of phenolated-lignin-formaldehyde resins were
similar to commercial phenol-formaldehyde and laboratory made phenolformaldehyde
resins, but better than the LPF resins. It was apparent that resins
containing a high level of lignin substitution gave the poorest bond strength values.
From these results, some of the resins were eliminated, prior to particleboard
production.
In order to evaluate the quality of lignin-based resins, particleboards were produced
and mechanical and physical tests performed. Effect of press platen temperature
(140°C, 160°C, 180°C) and press cycle time (5 min, 8 min, IS min) on the
mechanical properties of particleboard, produced by using lignin-based resins, were
investigated. It was found that particleboards bonded with up to 30% lignin content
resins gave similar mechanical and physical properties to commercial phenolformaldehyde
resin, as long as a sufficient heating regime and time were applied.
Publication Year: 2000
Publication Date: 2000-01-01
Language: en
Type: dissertation
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Cited By Count: 2
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